Data sets by Time Period (Long-Term or Short-Term)

With the exception of the LFDP Census data (#119), which is collected every five years and the CTE Plot Treatment, collected only after trimming events (#165), we update in this website and in the LTER Network Depository, PASTA, all of our non-spatial and non-meteorological ongoing data sets EVERY 2 Years. Met data from El Verde Field Station are updated each month or after data has gone through our quality control processes (not after a month).

The total number of LUQ's token data sets is: 151 (Added to 1 that has been deprecated and 2 non-LTER hosted data set for a total of 154)
The last Record Number Used for a Data Set is 195
The total number of Long-Term LTER data sets is 69 (Ongoing: 33, Completed: 36)
The total number of Short-Term LTER data sets is 83 (Completed: 83) Note: Long-Term data sets are defined as Duration of more than 5 years

Total of your current selection is: 83

Notes: Highlight both options to obtain a complete list of both Long and Short Term Data Sets
Duration (Period of Time): Short-Term
Numeric Data Set ID Title (Data Set Identifier) Abstract Owner/Creator Duration (Period of Time) Status Date Range
1 Anole ground level transects (Bisley and El Verde)

Transects are surveyed through the upper and lower cut plots at Bisley to determine the distribution and minimum abundance of anoles within and adjacent to the plots. Surveys began prior to cutting will continue seasonally (wet and dry) to document changes as the plots regenerate. One set of two transects has been established near the walkway towers in the 9 ha grid at El Verde. Each transect is 90 m long (wet 1989 and dry 1990) and 120 m long thereafter. Two transects, each 120 m long are established near the tower at Bisley. Survey methods and data recorded are the same for all transects, except that distance along the transect is recorded for cut plot transects only.

Douglas Reagan Short-Term Completed 1989 to 1992
2 Anole treefall gap transects (Bisley and El Verde-H10 Gaps)

Transects were established through large recent treefall gaps to determine the relative abundance of different anole species at different distances from the center of the gap.

Douglas Reagan Short-Term Completed 1989
4 Anole Vertical Transects (tower data)

Transects are conducted to note the vertical distribution and relative abundance of anole species. Data permit the calculation of average sighting distance for each species which is used in the final calculation of abundance.

Douglas Reagan Short-Term Completed 1989 to 1992
5 Anole Mark and Resight Study The population distribution research area of the LEF LTER is designed to gather information on the distribution and abundance of key plant and animal species within the forest under different disturbance regimes. Multiple mark and resight studies were conducted to determine the population density of Anolis stratulus at one undisturbed forest site and one site in a partially regenerated treefall gap. Tower surveys were conducted in order to access individuals in the forest canopy. Douglas Reagan Short-Term Completed 1989 to 1992
6 Anole Grid Study Transects 60 m long are conducted at alternate points in the 9 ha grid at El Verde. Transects 80 m long are conducted at alternate points at the Bisley Grid in watersheds #1 and #2. Data are used to support the GIS database. Douglas Reagan Short-Term Completed 1989 to 1990
7 Soil sample from landslide ES1 (Espiritu Santo El Verde), ES2, and RB2 (Rio Blanco)

Analysis of soil nutrients in top 9 cm of soil in Landslide Revegetation Plots.

Lawrence R. Walker Short-Term Completed 1988 to 1989
8 Canopy gap survey at El Verde The survey of gaps at El Verde covers about 35 ha, including the 9 ha grid. We defined a treefall gap at El Verde as a hole in the forest canopy extending down to an average height of about 3 m or less above ground. The edge of a gap was delineated by the vertical projection of the edge of the canopy foliage. We measured the dimensions ofs present in the 35-ha study site in August 1989, one month before Hurricane Hugo. For each gap we measured L, the longest axis of the gap (distance between edges), and W, the longest axis perpendicular to L, and then approximated gap area as that of an ellipse: Area = p LW/4 (Runkle 1992). Only openings ³ 20 m2; were counted as gaps. Nickolas Brokaw Short-Term Completed 1988
22 Cecropia growth at El Verde gaps

While doing the survey of gaps at El Verde the number and height of Cecropia saplings found in gaps where recorded. Since this species is mostly restricted to gaps, an estimate of the total population of Cecropia in the regeneration size classes in the forest can be obtained. (There are others along the edges of the Sonadora and Prieta.) The abundance, dispersion, and size class distribution of the Cecropia population is an index of disturbance in tabonuco forest and make an interesting study in its own right.

Nickolas Brokaw Short-Term Completed 1989
24 Anoline Lizard Food Habits The stomach contents of 10 adult individuals of each of three anole species (Anolis gundlachi, A. evermanni, and A. stratulus) were collected to determine the number, type, and volume of prey consumed following Hurricane Hugo. Gut contents were identified to the lowest taxon possible and were measured. Douglas Reagan Short-Term Completed 1989 to 1991
25 Frog transect data

Relative abundance of all size classes of Eleutherodactylus coqui was measured along control and experimental transects in a variety of disturbance regimes.

Lawrence L. Woolbright Short-Term Completed 1989
30 Frog grid data (Bisley)

Population estimates from 1987 to 1995 are reported for the terrestrial anuran, Eleutherodactylus coqui, from four long-term study plots in the Luquillo Experimental Forest of northeastern Puerto Rico. The major factor influencing population size during this time was Hurricane Hugo, which deposited much of the canopy onto the forest floor in 1989. Population densities since Hurricane Hugo have been influenced by succession, with continued high densities associated with thickets of Cecropia and Heliconia. Trefalls, which are similar to hurricanes on a local scale, also were shown to influence population sizes. Years with prolonged dry periods reduced numbers of juvenile frogs, but rainfall patterns alone did not explain most population variation. Population levels of invertebrate predators were related to variation in frog numbers.

Lawrence L. Woolbright Short-Term Completed 1989
37 Regeneration after Hurricane Hugo, woody species > 10 cm tall (9Ha grid, El Verde) (9Ha Plots Small Data Set)

The purpose of this data set is to document vegetation damage and recovery following Hurricane Hugo, a borderline category 3-4 hurricane with winds from 130 to 160mph (110kts) and a pressure of 945 to 946.1 mb, which hit Puerto Rico in September 18th, 1989

Nickolas Brokaw Short-Term Completed 1990 to 1994
38 Regeneration after Hurricane Hugo woody species more than 1m tall (9ha grid, El Verde) (Large 9Ha Grid)

The purpose of this data set is to document vegetation damage and recovery following Hurricane Hugo, a borderline category 3-4 hurricane with winds from 130 to 160mph (110kts) and a pressure of 945 to 946.1 mb, which hit Puerto Rico in September 18th, 1989.

Lawrence R. Walker Short-Term Completed 1990 to 1994
39 Regeneration after Hurricane Hugo woody species greater than 1cm tall (9ha grid, El Verde)(Wood fall from Hurricane Hugo 9Ha Grid)

The purpose of this data set is to document vegetation damage and recovery following Hurricane Hugo, a borderline category 3-4 hurricane with winds from 130 to 160mph (110kts) and a pressure of 945 to 946.1 mb, which hit Puerto Rico in September 18th, 1989.

Lawrence R. Walker Short-Term Completed 1990 to 1992
40 Regeneration after Hurricane Hugo woody species > 1m tall and below 3m: percent cover (9 ha grid, El Verde)

Purpose was to document vegetation damage and recovery following Hurricane Hugo.

Lawrence R. Walker Short-Term Completed 1990 to 1993
46 Elevation at grid points on the Luquillo Forest Dynamics Plot (LFDP)

This file contains data that describe the physical and environmental attributes of the LFDP. The attributes include elevation, topography type, and percentage slope. All data are given for the 20 m by 20 m quadrat scale. Information on soils are taken form an interpolation of the soil map produced by the Natural Resources Conservation Service, US Department of Agriculture (Soil Survey 1995). Other information from the elevation of each of the corner posts defining the quadrats. The National Science Foundation requires that data from projects it funds are posted on the web two years after any data set has been organized and "cleaned". The data from each census of the LFDP will be updated at intervals as each survey of the LFDP shows errors in the previous data collection. After posting on the web, researchers who are not part of the project are then welcome to use the data. Given the enormous amount of time, effort and resources required to manage the LFDP, obtain these data, and ensure data accuracy, LFDP Principal Investigators request that researchers intending to use this data comply with the requests below. Through complying with these requests we can ensure that the data are interpreted correctly, analyses are not repeated unnecessarily, beneficial collaboration between users is promoted and the Principle Investigators investment in this project is protected. Submit to the LFDP PIs a short (1 page) description of how you intend to use the data; · Invite LFDP PIs to be co-authors on any publication that uses the data in a substantial way (some PIs may decline and other LFDP scientists may need to be included); If the LFDP PIs are not co-authors, send the PIs a draft of any paper using LFDP data, so that the PIs may comment upon it; In the methods section of any publication using LFDP data, describe that data as coming from the "Luquillo Forest Dynamics Plot, part of the Luquillo Experimental Forest Long-Term Ecological Research Program"; Acknowledge in any publication using LFDP data the "The Luquillo Experimental Forest Long-Term Ecological Research Program, supported by the U.S. National Science Foundation, the University of Puerto Rico, and the International Institute of Tropical Forestry"; · Supply the LFDP PIs with 10 reprints of any publication using LFDP data. · Accept that the LFDP PIs can not guarantee that the LFDP data you intend to use, has not already been submitted for publication or published.

Jess Zimmerman Short-Term Completed 1990 to 1992
47 Physical environment of the Luquillo Forest Dynamics Plot (LFDP), Puerto Rico

This file contains data that describe the physical and environmental attributes of the LFDP. The attributes include elevation, topography type, and percentage slope. All data are given for the 20 m by 20 m quadrat scale. Information on soils are taken form an interpolation of the soil map produced by the Natural Resources Conservation Service, US Department of Agriculture (Soil Survey 1995). Other information from the elevation of each of the corner posts defining the quadrats.The National Science Foundation requires that data from projects it funds are posted on the web two years after any data set has been organized and “cleaned”. The data from each census of the LFDP will be updated at intervals as each survey of the LFDP shows errors in the previous data collection. After posting on the web, researchers who are not part of the project are then welcome to use the data. Given the enormous amount of time, effort and resources required to manage the LFDP, obtain these data, and ensure data accuracy, LFDP Principal Investigators request that researchers intending to use this data comply with the requests below. Through complying with these requests we can ensure that the data are interpreted correctly, analyses are not repeated unnecessarily, beneficial collaboration between users is promoted and the Principle Investigators investment in this project is protected.

Jess Zimmerman Short-Term Completed 1990 to 1991
51 MRCE/LTER Soil and Microbial Biomass Nitrogen

The data reported here are only for tabonuco forest at El Verde. Following plot setup and one year of pre-treatment measurements, Hurricane Hugo struck before the first planned fertilization. Because a year and a half of annual above ground litter inputs of phosphorus were dropped onto the forest floor in the form of leaf litter, we added a debris removal treatment to the original two, fertilized & control.

These data were used to determine the pools of readily available nitrogen in soil solution in debris removal and fertilizer treatments applied to tabonuco forest at El Verde immediately after Hurricane Hugo struck in September 1989. The treatments (complete removal of litter and woody debris, total fertilization, and control). Both ammonium and nitrate were low in the May 1990 samples. All samples had more KCl extractable ammonium in September, but negligible nitrate. Increases in ammonium were greatest in the fertilized and debris removal plots as compared to the control treatment. These results were positively correlated with litterfall production and canopy closure, with faster rates of recovery in the fertilized and debris removal treatments as compared to the control. Soil extractable (readily available) N was negatively correlated with microbial N in the samples collected one year after Hurricane Hugo, indicating microbial immobilization of N. Century modeling results were consistent with our observations and indicated that woody debris increased the input of low-nutrient substrate to the soil thereby stimulating microbial uptake/immobilization. Thus the soil microbes in the control plots outcompeted the trees for limiting N, thereby slowing their recovery.

D. Jean Lodge Short-Term Completed 1990
52 Above ground biomass in the Espiritu Santo landslide nearby the El Verde Field Station (ES-1)

To establish the dry mass of several species that grow on landslides. To make regressions of biomass against height and basal diameter. This way one can estimate biomass on permanent plots where one cannot harvest the plants.

Lawrence R. Walker Short-Term Completed 1990
55 Spatial and temporal differences in shrimp numbers (1 year, 20 pools)

We added woody debris to stream pools in three streams in an experiment designed to increase cover for freshwater shrimp. We trapped four species of freshwater shrimp during 4 months following wood additions. Stream pool morphology was estimated using maximum depth, surface area, and volume.

Mark Pyron Short-Term Completed 1995
57 Tree damage by Hurricane Hugo on the Luquillo Forest Dynamics Plot (LFDP), Puerto Rico

Hurricane Hugo struck the Caribbean national forest in September 1989. Files LFDP_HURRDAM.TXT and LFDP_HURRDAMa.TXT contain data on the damage to trees caused by the hurricane collected by Mr. R. DeLeon between August 1990 and September 1991. Mr. DeLeon walked throughout the plot to find stems >= 10 cm diameter that had apparently been damaged or killed by the hurricane in an effort to collect information before the damaged stems rotted. The information on these stems was later combined with the results of the first census to reconstruct the forest, as it would have appeared, at the time of Hurricane Hugo. This file contains the hurricane damage data collected for stems damaged by Hurricane Hugo combined with data for the stems recorded subsequently in the first complete LFDP census starting in 1990. Some stems that were measured in Census 1 survey 2 and survey 3 or Census 2 that were believed to have been missed in Census 1 survey 1, are also included (see census history above) and are assumed to have been undamaged by Hurricane Hugo. The structure of the data files is the same for both files LFDP_HURRDAM.TXT and LFDP_HURRDAMa.TXT but the diameter of the trees in LFDP_HURRDAMa.TXT have been calculated by extrapolating diameters backwards from subsequent measurements to the time of the Census 1 survey 1. Diameters in file LFDP_HURRDAMa.TXT can not be used for growth measurements. For our publications we treat files LFDP_HURRDAM.TXT and LFDP_HURRDAMa.TXT as one data set. The National Science Foundation requires that data from projects it funds are posted on the web two years after any data set has been organized and "cleaned". The data from each census of the LFDP will be updated at intervals as each survey of the LFDP shows errors in the previous data collection. After posting on the web, researchers who are not part of the project are then welcome to use the data. Given the enormous amount of time, effort and resources required to manage the LFDP, obtain these data, and ensure data accuracy, LFDP Principal Investigators request that researchers intending to use this data comply with the requests below. Through complying with these requests we can ensure that the data are interpreted correctly, analyses are not repeated unnecessarily, beneficial collaboration between users is promoted and the Principle Investigators investment in this project is protected. Submit to the LFDP PIs a short (1 page) description of how you intend to use the data; · Invite LFDP PIs to be co-authors on any publication that uses the data in a substantial way (some PIs may decline and other LFDP scientists may need to be included); If the LFDP PIs are not co-authors, send the PIs a draft of any paper using LFDP data, so that the PIs may comment upon it; In the methods section of any publication using LFDP data, describe that data as coming from the "Luquillo Forest Dynamics Plot, part of the Luquillo Experimental Forest Long-Term Ecological Research Program"; Acknowledge in any publication using LFDP data the "The Luquillo Experimental Forest Long-Term Ecological Research Program, supported by the U.S. National Science Foundation, the University of Puerto Rico, and the International Institute of Tropical Forestry"; · Supply the LFDP PIs with 10 reprints of any publication using LFDP data. · Accept that the LFDP PIs can not guarantee that the LFDP data you intend to use, has not already been submitted for publication or published.

Jess Zimmerman Short-Term Completed 1990 to 1993
60 Tree Map for Census at the Luquillo Forest Dynamics Plot (LFDP), Puerto Rico

This data set shows the Tag number, Quadrat location, Species code, diameter and XY coordinates of stems >=10 cm D130 present at the time of Hurricane Hugo and in the first census. The data set is composed of two files both with the same file structure. In LFDP_C1treemap.txt the diameters (Fdiam) are as recorded in the field data. In LFDP_C1TREEMAPa.txt the stem diameters (Fdiam) were calculated to allocate "missed" stems (stems >=10 cm D130) that were found in survey 2, 3 or Census 2 to Census 1 survey 1. We calculated the diameter the stem would have had, if it had been recorded at the same time the quadrat it was located in was assessed, in the appropriate survey for that stem size.

To extrapolate the stem size back in time, we used the actual growth rate of that individual stem if more than one measurement was available. If only one diameter measurement was available we used the median growth rate for that species in the appropriate size class stems >=10, <30 cm D130). In our publications we will combine data sets LFDP_C1treemap.txt and LFDP_C1TREEMAPa.txt to make Census 1 and to reconstruct the forest for stems >= 10 cm D130 at the time of Hurricane Hugo. We have divided the data into two separate files to ensure that when stem diameters are compared to future censuses the diameter data in LFDP_C1TREEMAPa.txt are not used to calculate growth rates. The last corrections to the Census 1 data were made in May 2001. The National Science Foundation requires that data from projects it funds are posted on the web two years after any data set has been organized and "cleaned". The data from each census of the LFDP will be updated at intervals as each survey of the LFDP shows errors in the previous data collection. After posting on the web, researchers who are not part of the project are then welcome to use the data. Given the enormous amount of time, effort and resources required to manage the LFDP, obtain these data, and ensure data accuracy, LFDP Principal Investigators request that researchers intending to use this data comply with the requests below. Through complying with these requests we can ensure that the data are interpreted correctly, analyses are not repeated unnecessarily, beneficial collaboration between users is promoted and the Principle Investigators investment in this project is protected. Submit to the LFDP PIs a short (1 page) description of how you intend to use the data; · Invite LFDP PIs to be co-authors on any publication that uses the data in a substantial way (some PIs may decline and other LFDP scientists may need to be included); If the LFDP PIs are not co-authors, send the PIs a draft of any paper using LFDP data, so that the PIs may comment upon it; In the methods section of any publication using LFDP data, describe that data as coming from the "Luquillo Forest Dynamics Plot, part of the Luquillo Experimental Forest Long-Term Ecological Research Program"; Acknowledge in any publication using LFDP data the "The Luquillo Experimental Forest Long-Term Ecological Research Program, supported by the U.S. National Science Foundation, the University of Puerto Rico, and the International Institute of Tropical Forestry"; · Supply the LFDP PIs with 10 reprints of any publication using LFDP data. · Accept that the LFDP PIs can not guarantee that the LFDP data you intend to use, has not already been submitted for publication or published.

Jess Zimmerman Short-Term Completed 1990 to 1993
76 Frog abundance in fertilization plots

Population estimates and body sizes of E. coqui were collected on fertilization, litter removal, and control plots.

Lawrence L. Woolbright Short-Term Completed 1993
87 Germination in three R/FR light environments (El Verde)

Experiments were conducted in the Tabonuco forest at Luquillo Experimental Forest to determine the germination success of a number of species in different light environments. Species tested included: Byrsonima spicata, Calophyllum brasiliense, Carapa sp., Choven venosa, Guarea guidonia, Manilkara bidentata, Ochroma pyramidale and an unidentified species known locally as Jobo. Seeds were collected as they fell and placed on moist towling in horticulture trays at four sites. Seeds were kept moist and germination was recorded daily for 81 days and three times weekly for an additional 75 days. Light environments included a site exposed to full sun (FS) and sites with 55%, 75% and 80% cover. Instantaneous light measurements were made with a Licor 1800 spectroradiometer to determine the Red (660 nm) to Far-red (730 nm) ratio (R/FR) (Lee, 1987). Analysis of light data indicated that the four sites chosen provided three significantly different R/FR ratio environments, and that germination of some species was affected by the light environment (Smith, H. & Whitelam, G.C. 1990). Three species failed to germinate in any of the four light environments.

Table 1. Red/Far-red ratio & Percent Germination of five species in four sites.

site 
%cover
R/FR Calophyllum Manilkara Ochroma Carapa Jobo
1 55
0.53 21% 46%
10%
40%
3%
2 80 0.20
16%
48% 14%
16%
8%
3 FS 1.2
4%
16%
12%
0
0
4 75 0.20
3%
32%
16%
16%
3%

Jude Jardine Short-Term Completed 1995
89 Long-term Intersite Decomposition Experiment (LIDET)

LIDET is the LTER Longterm Intersite Decomposition Experiment Team. It is a leaf, wood, and root decomposition study carried out at 28 LTER and other sites including LUQ. The duration of the study is designed to be approximately 10 yrs at temperate zone sites and approximately 3 yrs at tropical zone sites because of higher decomposition rates there. The same decomposing materials, litter bags, and study design are used at all sites to facilitate intersite comparisons. Not all species were used at all sites. Six leaf litter species were used extensively at all sites that cover a range of leaf quality to permit a comparison of effects of litter quality and climate on decomposition. The others were present in the study as "wild cards", with at least one species contributed by each site. Three species of roots, and one species of wood were used.

D. Jean Lodge Short-Term Completed 1990 to 1993
91 Earthworms in tropical tree plantations and secondary forests

We compared patterns of earthworm abundance and species composition in tree plantations and secondary forests of Puerto Rico. Tree plantations included pine (Pinus caribaea Morelet) and mahogany (Swietenia macrophylla King) established in the 1930s, 1960s, and 1970s; secondary forests were naturally regenerated in areas adjacent to these plantations. We found that (1) earthworm density and fresh weight in the secondary forests were twice those in either of the tree plantations, and did not differ between the plantations, and (2) the exotic earthworm species, Pontoscolex corethrurus M ller, dominated both plantations and the secondary forests, but native earthworm species, Pontoscolex spiralis Borges & Moreno, Estherella montana Gates, and E. gatesi Borges & Moreno, occurred only in the secondary forests. Our results suggest that naturally-regenerated secondary forests are preferable to pine and mahogany plantations for maintaining a high level of earthworm density, fresh weight, and native species.

Xiaoming Zou Short-Term Completed 1994
92 Earthworms in abandoned tropical pastures

Plant community succession alters the quantity and chemistry of organic inputs to soils. These differences in organic input may trigger changes in soil fertility and faunal activity. We examined earthworm density and community structure along a successional sequence of plant communities in abandoned tropical pastures in Puerto Rico. The chronological sequence of these plant communities were pasture, grass-vine-fern, shrub-small tree, and forest. Earthworm density was the highest in pasture (831 worms/m2 in top 0.25 m soil), decreased as secondary succession proceeded, and reached the lowest (32 worms/m2) in the forest. Whereas only soil feeding Pontoscolex corethrurus was present in the pasture and grass-vine-fern communities, both soil and litter feeding worm species were found in the shrub-small tree and forest communities. Ground litter biomass had a negative correlation with earthworm density. Soil water content differed slightly among the successional communities, but were unlikely to play an important role in triggering differences in worm density among these abandoned lands. Soil pH values did not differed along the successional changes. These results suggest that decrease in earthworm density and increase in worm community diversity during secondary succession may result from changes in the quantity and chemistry of organic inputs, rather than in soil properties. We conclude that successional development from grass-dominated pastures to woody species-dominated forests reduces earthworm density and diversifies worm community structure in humid tropical soils.

Xiaoming Zou Short-Term Completed 1993
93 Litter decomposition of the tabonuco forest before hurricane Hugo

We examined forest structure, tree species composition, litterfall rate, and leaf litter decomposition in a mid-successional forest (MSF) and an adjacent mature tabonuco forest (MTF) in the Luquillo Experimental Forest of Puerto Rico. Whereas the MTF site received limited human disturbance, the MSF site had been cleared for timber production by the beginning of this century and was abandoned after hurricanes struck the Luquillo Mountains in the 1920s and 1930s. We found that the MSF was dominated by successional tree species 50 yrs after secondary succession, and did not differ in tree basal area and litterfall rate from the MTF. Leaf decomposition rate in the MSF was higher than in the MTF, but this difference was small. Our results show that deforestation has long-term (>50 years) influence on tree species composition and that leaf decomposition processes in secondary forest is relatively faster than recovery of tree species composition.

Xiaoming Zou Short-Term Completed 1980 to 1981
94 Litterfall of the tabonuco forest before Hurricane Hugo

We examined forest structure, tree species composition, litterfall rate, and leaf litter decomposition in a mid-successional forest (MSF) and an adjacent mature tabonuco forest (MTF) in the Luquillo Experimental Forest of Puerto Rico. Whereas the MTF site received limited human disturbance, the MSF site had been cleared for timber production by the beginning of this century and was abandoned after hurricanes struck the Luquillo Mountains in the 1920s and 1930s. We found that the MSF was dominated by successional tree species 50 yrs after secondary succession, and did not differ in tree basal area and litterfall rate from the MTF. Leaf decomposition rate in the MSF was higher than in the MTF, but this difference was small. Our results show that deforestation has long-term (>50 years) influence on tree species composition and that leaf decomposition processes in secondary forest is relatively faster than recovery of tree species composition.

Xiaoming Zou Short-Term Completed 1980 to 1981
95 Litterfall along topographic gradients at lower Bisley

Litterfall (fine and coarse) due to Hurricane Hugo and subsequent fine annual litterfall inputs (1, 2 and 5 yr after Hugo) were determined for two sites (El Verde and Bisley) in the Luquillo Experimental Forest in Puerto Rico. Litter transfers into streams, riparian and upslope areas were determined within each catchment. The recovery rate of aboveground fine litterfall (leaf, fine wood <1 cm diameter, and other miscellaneous inputs) to predisturbance levels were determined 1, 2, and 5 yr after Hurricane Hugo. The amount of total litter transfers and their individual components into the riparian and upslope areas due to Hurricane Hugo varied significantly by catchments within the Luquillo Experimental Forest. At El Verde, 26-39%, 31- 35%, 14-35% and 7-12% of the total litter transfers were contributed by leaf litter, fine wood, coarse wood and fine roots, respectively. At Bisley, 28-31%, 26-29%, 33-35% and 8-10% of the litter transfers were contributed by the same categories. Differential decay rates contributed to the relative importance of fine and coarse litter inputs. The recovery of fine aboveground litterfall to pre-hurricane levels after 5 yr varied by topographic location (streams had the slowest recovery, upslope areas the highest) and catchment (El Verde: 55-77%; Bisley: 39-82% of pre-hurricane values).

Alan Covich Short-Term Completed 1989 to 1992
98 Soil organic matter dynamics in the tabonuco forest, a plantation and a secondary forest in Guzman

In this project we try to find out the relationship between the primary production and the soil organic carbon fractions.

Xiaoming Zou Short-Term Completed 1996 to 1997
99 Herbivory of eight common species at El Verde from 1994 to 1996

In seasonal and aseasonal tropical forests, leaf production is often highly synchronous, concentrating herbivore resources in only a few months. As a result levels of herbivory on young leaves can vary throughout the year. To determine the importance of food availability on herbivory, leaf phenology and leaf damage were studied in an aseasonal forest, Luquillo Experimental Forest (LEF) in Puerto Rico. Leaf production was associated with an increase in light availability but leaf damage was relatively constant throughout the year. Leaf phenology and leaf damage was compared between LEF and a seasonal forest, Barro Colorado Island (BCI) Panamá. In BCI leaf production was associated with increases in water availability and leaf damage was significantly higher on leaves produced after the peak in leaf production. Leaf damage was significantly lower in LEF in comparison with BCI. Differences in the trophic structure between the two forests may explain the differences in levels of leaf damage. The density of frogs and lizards in LEF was approximately an order of magnitude greater than in BCI and these predators may limit the populations of herbivores and reduce leaf damage levels.

Maria del Pilar Angulo Short-Term Completed 1994 to 1996
100 El Verde Coffee Plantation permanent plot vegetation sampling

Permanent plot data is expected to show (1) rapid increases in percent cover and tree stem density, and (2) rapid turnover from early to late successional plant species. Plant-plant competition indices should show quick increases in intensity with exotics as top competitors which may lead to exclusion of some trees common after landslide and pasture disturbance. Spatial patterns of invading trees should include edge effects due to dispersal limitation with clumping of bird-dispersed species before the first five years. Because of increased nitrogen levels due to plantings of Inga Sp. with coffee, trees should grow, as measured by biomass (productivity), height and basal diameter increases, significantly faster compared to landslide.

Randall W. Myster Short-Term Completed 1998 to 1999
102 Leaf miners (Acrocercops species) larvae performance on young leaves of Manilkara bidentata

Manilkara bidentata is attacked by a specialist leaf miner(Acrocercops sp.(microlepidoptera:gracillariidae).  More than one larvae can be found per mine within a leaf. The purposes of this study is to determine the effect of group feeding for this species since larval density within a leaf vary from 1-14 larvae per mine (Angulo-Sandoval personal observation). This variation allows to determine the effect of larval density on the amount of leaf damage, larval survivorship and larval growth. Leaves with mines varied in area from 10 to 224 cm2 (mean = 85.7 cm2) and the number of larvae per leaf ranged from 1 to 14 (mean = 5.7 larvae/mine). There was no relation between the size of the leaf and the number of larvae found within the leaf.

There was a relationship between the number of larvae in a blotch mine and amount of damaged tissue. Herbivory increases from approximately 10% for one larva per leaf to 50% in leaves with eight larvae. In leaves with more than eight larvae, herbivory decreased . There was an effect of initial larval density on percent larval survivorship.Survivorship was high (70%) in leaves with one to three larvae. In intermediate density (4-8 larvae per mine) 50% of larvae survived and in high densities (9 - 14 larvae per mine), only 22% survived. Even though there was a decrease in larvae number in high densities, the final number of larvae remained higher, compared with low or intermediate densities. A linear relationship was found between number of larvae present in the leaf and the time it took the larvae to complete their larval stage. Larvae in high density (> 9 larvae per mine) tended to develop faster (3-8 days) than larvae in low densities (5 - 10 days). Larval size upon emergence ranged from 8 to 12 mm (mean= 9.27) but there was no effect of larval density on the final larval size. The total number of surviving larvae varied according to the initial larval number and was highest in mines with eight individuals of which on average 4.7 survived. The number of surviving larvae was less than three for all other clutch sizes. Even though eight larvae appears to be the optimum clutch size, most females produced smaller clutches (4- 6 larvae per leaf).All larvae that emerged built a cocoon and 90% emerged as butterflies.

Maria del Pilar Angulo Short-Term Completed 1995 to 1996
103 Effect of plant density and light availability on leaf damage in Manilkara bidentata

Variation in herbivory is often associated with plant density and light environment. To determine the effect of these variables on herbivory we studied leaf production and herbivory on saplings, juveniles and adults of Manilkara bidentata (Sapotaceae) in the Luquillo Experimental Forest (LEF), Puerto Rico. The major herbivore of M. bidentata is microlepidoptera leaf miner (Acrocercopssp.; Gracillariidae). To determine the effect of plant density on herbivory, 24 - 20 x 20 m plots were established and the density of saplings, juveniles and adults were determined. Leaf production, herbivory and growth were measured on all saplings in the plots. In addition, plant density was determined in 8-20 x 20 m plots surrounding the 24 focal plots. The effect of light environment was determined by comparing leaf phenology, leaf quality and herbivory in the vertical and horizontal profile. Sapling density in 60 x 60 m plots was associated with increased levels of herbivory. In the vertical profile, leaf production was continuous in the canopy and synchronous for juveniles and saplings and herbivory increased from the canopy (1.3%) towards the understory (35.6%). In the horizontal profile leaf production was related with the light environmen. Saplings in low light environment produced leaves in June, while plants in gaps had a broader peak of leaf production. Differences in leaf phenology did not result in differences in herbivory possibly because there was high variation in herbivory among leaves. Although many saplings lost more than 80% of new leaf area, there was no detectable effect on plant growth.

Maria del Pilar Angulo Short-Term Completed 1995 to 1996
104 Experimentally manipulated biota over a 30-40d period in two streams with distinctly different macrobiotic assemblages

Here we test the hypothesis that differences in macrobiotic assemblages can lead to differences in the quantity and quality of organic matter in benthic depositional environments among streams in montane Puerto Rico. We experimentally manipulated biota over a 30-40d period in two streams with distinctly different macrobiotic assemblages: one characterized by high densities of omnivorous shrimps (Decapoda: Atyidae and Xiphocarididae) and no predaceous fishes. To incorporate the natural hydrologic regime and to avoid confounding artifacts associated with cage enclosure/exclosure (e.g., high sedimentation), we used electricity as a mechanism for experimental exclusion, in situ. In each stream, shrimps and/or fishes were excluded from specific areas of rock substrata in four pools using electric "fences" attached to solar-powered fence chargers. In the stream lacking predaceous fishes (Sonadora), the unelectrified control treatment was almost exclusively dominated by high densities of omnivorous shrimps that constantly ingested fine particulate material from rock surfaces. Consequently, the control had significantly lower levels of inorganic sediments, organic material, carbon and nitrogen than the exclusion treatment, as well as less variability in these parameters. Tenfold more organic material (as ash-free dry mass, AFDM) and fivefold more nitrogen accrued in shrimp exclosures (10.6 g AFDM/m2, 0.2 g N/m2) than in controls (1.1 g AFDM/m2, 0.04 g N/m2). By reducing th quantity of fine particulate organic material and associated nitrogen in benthic environments, omnivorous shrimps potentially affect the the supply of this important resource to other trophic levels. The small amount of fine particulate organic matter (FPOM) that remained in control treatments (composed of sparse algal cells0 was of higher quality than that in shrimp exclosures. This is evidenced by the significantly lower carbon-to-nitrogen (C/N) ratio (an indicator of food quality, with relatively low C/N indicating higher food quality) in the control relative to the shrimp exclosure treatment. In contrast, the stream with predaceous fishes (Bisley) was characterized by very low numbers of shrimps, and macrobiota had no significant effect on benthic sediments, organic matter, C, N, and C/N. All parameters were highly variable through time, with levels and ranges in variability similar to the shrimp exclusion treatment in the Sonadora. Our experimental results are consistent with findings of an independent survey of six streams in four different drainages. Four streams that had an abundance of omnivorous shrimps but lacked predaceous fishes, had extremely low levels of fine benthic organic and inorganic material. In contrast, two streams that had low densities of shrimps and contained predaceous fishes had significantly higher levels. Results show a strong linkage between species and ecosystem characteristics: interstream differences in the quantity and quality of fine benthic organic matter resources were determined by the nature of the macrobiotic assemblage. Furthermore, patterns in the distribution of shrimp assemblages reflected landscape patterns in the benthic depositional environment among streams.

Catherine Pringle Short-Term Completed 1994
105 Enclosure/exclosure experiments in a montane Puerto Rican stream examining direct and indirect effects of two dominant taxa of atyid (Atyidae) shrimp, Atya lanipes Holthius and Xiphocaris elongata Guerin-Meneville (Shrimp/ Algae/ Oecologia (1993))

Freshwater shrimp dominate the faunal biomass of many tropical headwater streams: however, their role in community organization is unclear. Enclosure/exclosure experiments in a montane Puerto Rican stream examined direct and indirect effects of two dominant taxa of atyid (Atyidae) shrimp, Atya lanipes Holthius and Xiphocaris elongata Guerin-Meneville. Both shrimp taxa caused significant reductions in sediment cover on rock substrata, reducing sedimentation and enhancing algal biovolume on clay tiles in cages. When tiles incubated in shrimp exclosures for 2 wks were placed outside of cages, atyid shrimp removed 100% of sediment cover within a 30 min. observation period. Atyid shrimp appear to play an important role in stream recovery after high discharge events in rapidly removing sediments and detritus deposited on benthic substrata in pools. We evaluated the mechanism by which A. lanipes influences algae and benthic insects by comparing patterns of algal biomass, taxonomic composition and shrimp-presence treatments both with and without manual sediment removal. The shrimp exclusion treatment without manual sediment removal had significantly lower algal biomass and greater sedimentation than all other treatments. The treatment in which shrimp were excluded but sediment was manually removed, however, accrued almost the same algal biovolume as the shrimp enclosure treatment, supporting the hypothesis that sediment removal enhances the biovolume of understory algal taxa. Algal community composition was similar between stream bottom bedrock exposed to natural densities of shrimp and all experimental treatments for both Atya and Xiphocaris: a diatom community strongly dominated (78-95%) by the adnate taxon, Achnanthes lanceolata Breb ex. Kutz. Atyid shrimp are important in determining the distribution and abundance of benthic insects through both direct and indirect effects. Sessile, retreat-building chironomid larvae (Chironomidae: Diptera) are negatively affected by both A. lanipes and X.elongata, through direct removal by foraging activities and/or indirectly through depression of sediment resources available to larvae for the construction of retreats. In contrast, the mobile grazer, Cleodes maculipes (Baetidae: Ephemeroptera) was not adversely affected and atyid shrimp have the potential to exert positive indirect effects on this taxon by facilitating its exploitation of algal resources and/or through enhancement of understory algal food resources through sediment removal.

Catherine Pringle Short-Term Completed 1990
106 Effects of biotic (shrimp) and abiotic (discharge) factors on the depositional environment quantified in a montane stream in Puerto Rico. (Shrimp/Algae/Can J. Fish Aquat. Sci. (1994))

Effects of biotic (shrimp) and abiotic (discharge) factors on the depositional environment were quantified in a montane stream in Puerto Rico. Electricity was used experimentally to exclude large (approximately >1cm in length) biota without artificially increasing sedimentation as in cage enclosure/exclosure experiments in stream systems. Shrimp (>1cm in length) were excluded from substrata by semicircular fence hooked up to battery-powered fence chargers which emitted continuous pulses of electricity. Unelectrified control substrata had natural high densities of atyid shrimp. Significantly greater masses of total sediment, fine and large organic particles, and algal biovolume occurred in shrimp exclusion treatments relative to controls. Shrimp exclusion treatments experienced slow and steady accumulation of sediments under base flow conditions and a large stepwise increase in sediment following a storm. No measurable sediment accrued in the presence of natural densities of shrimp under base flow conditions. Shrimp rapidly removed sediments that accrued during the storm (440-620 g*m2 dry mass-1), decreasing sediment mass in control treatments to near prestorm levels (5-13 g*m2 dry mass-1) within 30 h. Atyid shrimp can significantly affect the accumulation of organic and inorganic materials on rock substrata in stream pools between high-discharge events.

Catherine Pringle Short-Term Completed 1992 to 1994
108 Patterns in soil chemical and physical properties of the Bisley Watersheds 1 and 2 (Big Dig 1988, Big Dig 1990)

(1) Soil chemical (carbon, nutrients, aluminum, exchangeable acidity, and pH) and physical (bulk density) properties were measured systematically every 40 m on two 12 ha watersheds in Puerto Rico before and after Hurricane Hugo. Exchangeable cation concentrations were measured using different soil extracting procedures (fresh soil and air-dried and ground soil) to establish a range of nutrient availability in the soil, and to determine the relationship between different, but commonly used laboratory protocols. (2) Soils extracted using fresh soils generally yielded significantly lower exchangeable Ca , Mg, and K concentrations than soils which were dried and ground prior to extraction. Soil nutrients generally decreased with depth in the soil. (3) Several soil properties varied predictably across the landscape and could be viewed in the context of a simple catena model. In the surface soils, exchangeable base cation concentrations and pH decreased along a gradient from ridge tops to riparian valleys, while soil organic matter, exchangeable Fe and acidity increased along this gradient. On the ridges, N,P, and K were positively correlated with soil organic matter; on slopes, N and P were positively correlated with organic matter, and Ca, Kg, and pH were negatively correlated with exchangeable Fe. (4) Soil nutrient availability in the upper catena appears to be primarily controlled by biotic processes, particularly the accumulation of organic matter. Periodic flooding and impeded drainage in the lower catena resulted in a more heterogeneous environment. Drying and grinding the soil prior to extraction had a greater impact on exchangeable cations from the upper catena than in the valley positions, probably due to greater soil organic matter content. See Silver, W.L., F.N. Scatena, A.H. Johnson, T.G. Siccama, and M.J. Sanchez. 1994. Nutrient availability in a montane wet tropical forest in Puerto Rico: spatial patterns and methodological considerations. Plant and Soil 164:129-145.

Whendee Silver Short-Term Completed 1988 to 1990
109 Rio Icacos hyporheic and riparian chemistry

Hydrologic and chemical characteristics were determined for both riparian and hyporheic subsurface flow along a 100-m reach of a sandy-bottom tributary of the Rio Icacos in the Luquillo Experimental Forest, Puerto Rico. Hydrologic data (vertical hydraulic gradient and hydraulic conductivity of streambed sediments) and the topographic and morphological features of the watershed indicated diffuse inputs of groundwater from the near-stream riparian zone along this site. Cumulative groundwater discharge, determined by tracer dilution techniques, was ~1.5 L/s or 10% of the total stream discharge. Spatial heterogeneity in hydrologic and chemical properties of riparian and hyporheic sediments was large. Hydraulic conductivity explained much of the variation in NH4-N and dissolved organic carbon (DOC) concentrations, with highest concentrations in sites having low conductivity. A mass-balance approach was used to examine the influence of the near-stream zone on nutrient transport and retention. Outwelling riparian groundwater had the potential to increase stream N concentrations by up to 84% and DOC concentrations by up to 38% along our 100-m reach. Because stream concentrations were constant downstream despite this input, we conclude that significant N and C retention or loss were occurring in the near-stream zone. Lotic ecosystems and their associated riparian groundwater can have a quantitatively significant impact on the nutrient budgets of tropical headwater catchments.

William H. McDowell Short-Term Completed 2003 to 2007
110 Spatial Variation of Soil Carbon, Nitrogen and Phosphorus in the Luquillo Experimental Forest (LEF) (LEF_SOIL_CNP)

Hongqing Wang, a Ph.D graduate student of SUNY-ESF, with the help of many others, took soil samples in 119 locations over the entire Luquillo Experimental Forest (LEF) during the summer of 1998 and 1999. Soil organic carbon, total nitrogen and acid-extractable phosphorus were measured in the laboratory of SUNY-ESF; soil moisture and bulk density were measured at the laboratory of the El Verde Station of UPR. The geodetic coordinates (Lat., Lon.) and elevation of each sampling location were determined using a Global Positioning System (GPS Pathfinder Basic Receivers, Trimble Navigation Ltd.) in the field. Meanwhile, slope angle, aspect and topographic features (Ridge, slope I (<35 deg.), slope II (>=35 deg.), valleys) were also measured and observed in the field.

Charles A.S. Hall Short-Term Completed 1998
112 Landslide Removal Experiment vegetation cover and pole touches

The purpose of this data set is to document recovery of vegetation in removal plots in landslides in the Luquillo Experimental Forest (LEF.)

Lawrence R. Walker Short-Term Completed 1997 to 2000
113 Seedling and sapling dynamics of treefall pits and undisturbed florest floor in El Verde, Puerto Rico

Seedling and sapling dynamics in a Puerto Rican rain forest were compared between forest understory and soil pits created by the uprooting of 27 trees during Hurricane Hugo. No difference in N and P levels were found in pit or forest soils under two trees with N-fixing symbionts (Inga laurina and Ormosia krugii) compared to soils under a tree species without N-fixing symbionts (Casearia arborea), but other soil variables ( Al, Fe, K) did vary by tree species.

Lawrence R. Walker Short-Term Completed 1991 to 1992
114 Rio Mameyes diatoms in the Rio Mameyes from 1998 to 2001

Survey expeditions of the diatoms of Puerto Rico and other Caribbean islands were conducted briefly in the late 1800's and early 1900's,. However, until now no intensive study of changes in freshwater diatom community over time has been undertaken. In conjunction with other measures of quality of water in the Rio Mameyes, i.e. pH, conductivity, temperature, nutrients, periphytic diatoms have been collected monthly for two years in an effort to detect the effects of disturbances such as hurricanes and human demands on a river ecosystem.

Brynne Bryan Short-Term Completed 1998
115 Short-term disappearance of foliar litter of three tree species native to rain forest of Puerto Rico

Litter disappearance was examined before (1989) and after (1990) Hurricane Hugo in the Luquillo Experimental Forest, Puerto Rico using mesh litterbags containing abscised Cyrilla racemiflora or Dacryodes excelsa leaves or fresh Prestoea montana leaves. Biomass and nitrogen dynamics were compared among: i) species; ii) mid- and high-elevation forest types; iii) riparian and upland sites; and iv) among pre- and post-hurricane disturbed environments. Biomass disappearance was compared using multiple regression and negative exponential models in which the slopes were estimates of the decomposition rates subsequent to apparent leaching losses and the y-intercepts were indices of initial mass losses (leaching). C. racemiflora leaves with low nitrogen (0.39 %) and high lignin (22.1 %) content decayed at a low rate and immobilized available nitrogen. D. excelsa leaves had moderate nitrogen (0.67 %) and lignin (16.6 %) content, decayed at moderate rates, and maintained the initial nitrogen mass. P. montana foliage had high nitrogen (1.76 %) and moderate lignin (16.7 %) content and rapidly lost both mass and nitrogen. There were not significant differences in litter disappearance and nitrogen dynamics among forest types and slope positions. Initial mass loss of C. racemiflora leaves was lower in 1990 but the subsequent decomposition rate did not change. Initial mass losses and the overall decomposition rates were lower in 1990 than in 1989 for D. excelsa. D. excelsa and C. racemiflora litter immobilized nitrogen in 1990 but released 10-15% of their initial N in 1989, whereas P. montana released nitrogen in both years (25-40 %). Observed differences in litter disappearance rates between years may have been due to differences in the timing of precipitation. Foliar litter inputs during post-hurricane recovery of vegetation in Puerto Rico may serve to immobilize and conserve site nitrogen.

William H. McDowell Short-Term Completed 1989 to 1990
116 Bromeliad chemistry at different elevations in the LEF

Mean concentrations of various nutrients in dried bromeliad leaf and in the coarse, medium and fine portions of debris retained by the bromeliad rosette.

Barbara A. Richardson Short-Term Completed 1996
118 Species names and codes of the Luquillo Forest Dynamics Plot (LFDP), Puerto Rico

File LFDP_spp contains the current species list with family for the Luquillo Forest Dynamics plot and the codes for these species found in LFDP1 and LFDD1a As new species are encountered or renamed and species renamed then this list will be updated Species identifications are assisted by reference to Liogier (1985, 1988, 1994, 1995, 1997), Little and Wadsworth (1964) Little, et al (1974), Little and Woodbury (1976).The National Science Foundation requires that data from projects it funds are posted on the web two years after any data set has been organized and “cleaned” The data from each census of the LFDP will be updated at intervals as each survey of the LFDP shows errors in the previous data collection After posting on the web, researchers who are not part of the project are then welcome to use the data Given the enormous amount of time, effort and resources required to manage the LFDP, obtain these data, and ensure data accuracy, LFDP Principal Investigators request that researchers intending to use this data comply with the requests below Through complying with these requests we can ensure that the data are interpreted correctly, analyses are not repeated unnecessarily, beneficial collaboration between users is promoted and the Principle Investigators investment in this project is protected   Please comply with the following requests:

  • Submit to the LFDP PIs a short (1 page) description of how you intend to use the data;Invite LFDP PIs to be co-authors on any publication that uses the data in a substantial way (some PIs may decline and other LFDP scientists may need to be included);
  • If the LFDP PIs are not co-authors, send the PIs a draft of any paper using LFDP data, so that the PIs may comment upon it;
  • In the methods section of any publication using LFDP data, describe that data as coming from the “Luquillo Forest Dynamics Plot, part of the Luquillo Experimental Forest Long-Term Ecological Research Program”;
  • Acknowledge in any publication using LFDP data the “The Luquillo Experimental Forest Long-Term Ecological Research Program, supported by the U.S National Science Foundation, the University of Puerto Rico, and the International Institute of Tropical Forestry”;
  • Supply the LFDP PIs with 10 reprints of any publication using LFDP data.
  • Accept that the LFDP PIs can not guarantee that the LFDP data you intend to use, has not already been submitted for publication or published.
Jess Zimmerman Short-Term Completed 1990 to 1992
120 Shrimp populations variability in numbers and sizes in response to disturbance and seasons on 20 pools along the reach of Quebrada Prieta, Luquillo Experimental Forest

Shrimp populations were monitored at approximately 3 week intervals to determine the variability in numbers and sizes of each species in response to disturbance and seasons.

Karen M. Buzby Short-Term Completed 1990
121 Fern distribution in El Verde MRCE plots

A fern survey was done of the plots established by under MRCE funding to assess controls on primary productivity along an elevational gradient. The control plots (CP), fertilized plots (FP) and plots where only leaf litter (ll) was removed at El Verde were survey and all ferns present in the plots listed, mapped and measured in Fall of 1995, several years after the initial fertilization and leaf litter treatment had been applied. The objective was to determine the extent to which the fern flora had been affected by the treatments.

Leslie Finical Short-Term Completed 1995
122 Experimental Understory Food Web data in the El Verde area of the Luquillo Experimental Forest

These data include date, treatment, block number, number of coquies, number of anoles, number of insects collected on two sticky traps, number of insects counted on 4 Piper glabrescens and 4 Manilkara bidentata seedlings, percent herbivory on the aforementioned plants and number of spiders. All these measurements were taken within exclosures for closed controls, anole exclusions, coqui exclusions and total exclusions. Open controls were sampled from an area of similar dimension not enclosed in an exclosure.

Paul Klawinski Short-Term Completed 1999 to 2000
123 Long-Term Elevation Plots (LTEP) (Altitudinal transects vegetation data along three rivers in the Luquillo Experimental Forest)

The composition of plant communities changes with elevation in the Luquillo Experimental Forest (LEF). The goal of this project is to document the patterns of these changes, and in particular, to determine whether the distributions of individual species are independent of one another, or whether they are related, in either a congruent or a hierarchical manner. Thirty-two permanent vegetation plots, each 50m by 20m are being established in the LEF, with 5 plots along the Icacos river, 11 along the Mamayes river and 16 along the Sonadora stream. The plots were established at every 100m in elevation, starting at 200m above sea level. All woody, free-standing stems greater than 1cm dbh were marked, identified and mapped into 5x5 subquadrats. We anticipated that gradient analysis will show whether the distributions of species are coincident or independent, enabling us to evaluate whether separate, genuine plant communities exist in the LEF. Because the plots are permanent, we also expected that they allow us to better evaluate how different vegetation types, at different elevations, respond to large scale disturbances, especially hurricanes.

Jess Zimmerman Short-Term Completed 2001 to 2002
124 Factors influencing decomposition of leaves for five plant species at El Verde

We evaluated the influences of leaf quality, climate and microsite on the decomposition of leaves of five tropical tree species. Single-species litterbags were used to determine weight loss during the first three months of decomposition in the Luquillo Experimental Forest, Puerto Rico. Significant differences were found in decomposition rates among leaf species (Inga fagifolia < I. vera < Manilkara bidentata < C-roton poecilanthus << Sapium laurocerasus), but only S. laurocerasus differed significantly from the other species. Lignin had a suggestive negative correlation with leaf decomposition while carbon content and the lignin:N ratio were significantly correlated with mass loss. Content of N, P, Ca, and polyphenol were not significantly correlated with mass loss, but several of the litter quality variables were correlated with each other. Leaf species decomposed faster under canopies of their source trees than in a common plot where the source species were absent. Decomposition in two species in the Euphorbiaceae, S. laurocerasus and C. poecilanthus, was significantly affected by microsite. Leaching losses during the first three weeks were greater under source trees than in the common plot, and may have been associated with differences in canopy structure and throughfall. Differences in detrital communities, however, could have contributed to the differences in decomposition between microsites. Leaves of all species decomposed significantly faster in the wet than in the dry period (P = 0.001) despite little climatic variation in this subtropical wet forest type. This suggests that decomposition of tropical leaf litter might be sensitive to microclimatic changes on the forest floor resulting from either global climate change, or from natural or anthropogenic disturbances that open the canopy.

Mirna Santana Short-Term Completed 2000
125 Interactions between plants and fungi and their roles in decay rates and CO2 release in five tropical leaf species

A microcosm experiment was used to test for the effects of interactions between particular plant and fungal decomposer species on rates of leaf decomposition. Each microcosm contained one species of leaf that was sterilized with gamma irradiation and then inoculated with a single fungus. Five plant species and ten fungal species (two dominants from each of the litter types) were used in all possible combinations. Plant species were selected for pair-wise comparisons based on phylogenetic relationships and litter quality characteristics. Decomposition was measured by both mass loss and CO2 release. Differences in weight loss and CO2 evolution were highly significant for plants, fungal species, and their interactions. Mass loss was positively correlated with CO2 evolution. Contrary to our hypotheses, however, microfungal dominants did not decompose their source leaves faster than microfungal dominants from other leaf species, nor were responses to other types of specificity detected. Matching of fungi to leaf substrates by their source, by phylogenetic relationships, or by chemical, physical and structural characteristics was not associated with consistent increases in decomposition. Although previously documented differences in microfungal species composition and dominance among decomposing leaves of different trees were confirmed in this study, such differences apparently do not directly affect the rates of ecosystem processes. The presence in a few of the microcosms of a generalist basidiomycete that had ligninolytic enzymes, Melanotus eccentricus, significantly accelerated the rate of decomposition. Non-specific basidiomycetes may therefore have a stronger effect on early stages of leaf litter decomposition than host-selective microfungi.

Mirna Santana Short-Term Completed 2000
128 Coarse Woody Debris in Bisley Experimental Forest and the Rio Icacos Basin

Organic matter pools appear to differ in composition between Bisley and Icacos. On average (n=30), 79% of Bisley organic matter was composed of coarse woody debris. Of the remaining 21% organic matter pool, approximately 2% was from leaves, 9% was from fruit, 9% was from miscellaneous matter, and 1% was from wood matter with diameters < 2.5 cm. In comparison, 57% (n=30) of Icacos organic matter was composed of coarse woody debris. Of the remaining 43% organic matter pool, approximately 0% was from fruit, 16% was from leaves, 10% was from miscellaneous matter, and 18% was from wood matter with diameters < 2.5 cm. The data suggest a less recalcitrant organic matter pool in the Icacos environment and higher rates of turnover than in the Bisley environment. It was also apparent that woody matter (< 2.5 cm diameter) deposition was a significant source of OM inputs in the Icacos plots.

William H. McDowell Short-Term Completed 2001 to 2002
130 Heliconia invertebrate counts

Identification and number of invertebrates recovered from each Heliconia inflorescence sampled.

Barbara A. Richardson Short-Term Completed 1996 to 1998
132 Heliconia fluid and organic matter analyses

Mineral concentrations of Heliconia bract fluid and organic matter accumulated in the bracts. Data collected during a study of the invertebrates in Heliconia bract fluid.

Barbara A. Richardson Short-Term Completed 1998
133 Heliconia collection data

Mineral concentrations of Heliconia bract fluid and organic matter accumulated in the bracts. Data collected during a study of the invertebrates in Heliconia bract fluid.

Barbara A. Richardson Short-Term Completed 1996 to 1998
135 Recovery of a tropical stream after a harvest-related chlorine poisoning event

1. Harvest-related poisoning events are common in tropical streams, yet research on stream recovery has largely been limited to temperate streams and generally does not include any measures of ecosystem function, such as leaf breakdown. 2. We assessed recovery of a second-order, high-gradient stream draining the Luquillo Experimental Forest, Puerto Rico, three months after a chlorine-bleach poisoning event. The illegal poisoning of freshwater shrimps for harvest caused massive mortality of shrimps and dramatic changes in those ecosystem properties influenced by shrimps. We determined recovery potential using an established recovery index and assessed actual recovery by examining whether the poisoned reach returned to conditions resembling an undisturbed upstream reference reach.3. Recovery potential was excellent (score=729 out of a possible 729) and can be attributed to nearby sources of organisms for colonization, the mobility of dominant organisms, unimpaired habitat, rapid flushing and processing of chlorine, and location within a national forest.4. Actual recovery was substantial. Comparison of the reference reach with the formerly poisoned reach indicated: (1) complete recovery of xiphocaridid and palaemonid shrimp population abundances, shrimp size distributions, leaf breakdown rates, and abundances of oligochaetes and mayflies on leaves, and (2) only small differences in atyid shrimp abundance and community and ecosystem properties influenced by atyid shrimps (standing stocks of epilithic fine inorganic and organic matter, chlorophyll a, and abundances of chironomids and copepods on leaves). 5. There was no detectable pattern between any measured variables and distance downstream from the poisoning. However, shrimp size-distributions indicated that the observed recovery may represent a source-sink dynamic, in which the poisoned reach acts as a sink which depletes adult shrimp populations from surrounding undisturbed habitats. Thus, the rapid recovery observed in this study is consistent with results from other field studies of pulse chlorine disturbances, harvest-related fish poisonings, and recovery of freshwater biotic interactions, but it is unlikely to be sustainable if multiple poisonings deplete adult populations to the extent that juvenile recruitment does not offset adult shrimp mortality.

Catherine Pringle Short-Term Completed 1999
137 Litter invertebrate communities at different elevations in the LEF

Identification and number of invertebrates recovered from each litter sample.

Barbara A. Richardson Short-Term Completed 1999 to 2001
139 Indirect upstream effects of dams: consequences of migratory consumer extirpation in Puerto Rico Large dams degrade the integrity of a wide variety of ecosystems, yet direct downstream effects of dams have received the most attention from ecosystem managers and researchers. We investigated indirect upstream effects of dams resulting from decimation of migratory freshwater shrimp and fish populations in Puerto Rico, USA, in both high- and low-gradient streams. In high-gradient streams above large dams, native shrimps and fishes were extremely rare, whereas similar sites without large dams had high abundances of native consumers. Losses of native fauna above dams dramatically altered their basal food resources and assemblages of invertebrate competitors and prey. Compared to pools in high-gradient streams with no large dams, pool epilithon above dams had 9 times more algal biomass, 20 times more fine benthic organic matter (FBOM), 65 times more fine benthic inorganic matter (FBIM), 28 times more carbon (C), 19 times more nitrogen (N), and 4 times more non-decapod invertebrate biomass. High-gradient riffles upstream from large dams had 5 times more FBIM than did undammed riffles but showed no difference in algal abundance, FBOM, or non-decapod invertebrate biomass. For epilithon of low-gradient streams, differences in basal resources between pools above large dams vs. without large dams were considerably smaller in magnitude than those observed for pools in high-gradient sites. These results match previous stream experiments in which the strength of native shrimp and fish effects increased with stream gradient. Our results demonstrate that dams can indirectly affect upstream free-flowing reaches by eliminating strong top-down effects of consumers. Migratory omnivorous shrimps and fishes occur throughout the tropics, and the consequences of their declines upstream from many tropical dams are likely to be similar to those in Puerto Rico. Thus, ecological effects of migratory fauna loss upstream from dams encompass a wider variety of species interactions and biomes than the bottom-up effects (i.e., elimination of salmonid nutrient subsidies) recognized for northern temperate systems. Effie A. Greathouse Short-Term Completed 2008
140 Neritina snails upstream migrations at the intersection of Rio Mameyes with road PR Route 3 (bridge 1771)

This data set includes N. virginea densities and sizes from two channels in lower Rio Mameyes under PR Route 3 bridge during the upstream migration season Aug-Dec 2000. Microhabitat use (near-bed water velocities and depth) within both channels is also included. Massive migrations in long trails occurring on the sloped concrete embankment of the main channel were also documented during 99 weeks. Individual size from migratory aggregations was measured during selected dates.

Juan Felipe Blanco Short-Term Completed 2000 to 2002
141 Neritina snails hierarchical distribution

This data set includes N. virginea densities and sizes relative to streambed substrate type, water depth, and habitat type in a low land reach in Río Mameyes near PR Route 3 bridge, and presence and inland extent of distribution of in 32 coastal rivers around the island. Hydrologic and water chemistry variables are reported as predictors of snail distribution at regional and stream-network scales.

Juan Felipe Blanco Short-Term Completed 2000 to 2003
142 Does the River Continuum Concept apply on a tropical island? Longitudinal variation in a Puerto Rican stream

We examined whether a tropical stream in Puerto Rico matched predictions of the River Continuum Concept (RCC) for macroinvertebrate functional feeding groups (FFGs). Sampling sites for macroinvertebrates, basal resources, and fishes ranged from headwaters to within 2.5 km of the fourth-order estuary. In a comparison to a model temperate system where RCC predictions generally held, we used catchment area as a measure of stream size in order to examine truncated RCC predictions (i.e., cut off to correspond to the largest stream size sampled in Puerto Rico). Despite dominance of generalist freshwater shrimps, which use more than one feeding mode, RCC predictions held for scrapers, shredders, and predators. Collector-filterers showed a trend opposite that predicted by the RCC, but patterns in basal resources suggest that this is consistent with the central RCC theme: longitudinal distributions of FFGs follow longitudinal patterns in basal resources. Alternatively, the filterer pattern may be explained by fish predation affecting distributions of filter-feeding shrimp. Our results indicate that the RCC generally applies to running waters on tropical islands. However, additional theoretical and field studies across a broad array of stream types should examine whether the RCC needs to be refined to reflect the potential influence of top-down trophic controls on FFG distributions.

Effie A. Greathouse Short-Term Completed 2001
145 Canopy Trimming Experiment (CTE) Litter decomposition and Connectivity basket data

This experiment was designed to decouple the effects of canopy opening from those of increased detrital inputs on rates of detrital processing and resultant community and ecosystem processes. In a study initiated after massive inputs of organic matter from Hurricane Georges in 1998, the forest floor returned to prehurricane values very quickly, within 2-10 months (Ostertag et al. 2003). However, it was unclear to what extent this homeostasis was caused by increased rates of decomposition. Furthermore, if accelerated decomposition was implicated in rapid recovery, the relative contributions of environmental and resource changes wrought by canopy opening versus green leaf deposition on the forest floor were unclear because these factors are confounded in hurricane damage. A full factorial design was therefore used to tease apart the separate and combined effects of simulated storm damage on rates of mass loss in pre-weighed senesced and green litter cohorts inserted into litter decomposition baskets following application of canopy trimming and debris deposition treatments. Natural litter cohorts (i.e., organic forest floor material and subsequent natural litterfall separated into 3-month cohorts) were also weighed when replicate baskets were harvested at approximately 3-month intervals. In addition to obtaining mass and percent moisture of litter cohorts, the extent of fungal connections between litter cohorts was quantified. Fungal connections between partly decomposed and fresh leaf litter have been shown to be important in importation of phosphorus (the most limiting major nutrient in decomposition of tabonuco forest litter) into the freshly fallen leaves in order to rapidly build fungal biomass and associated acceleration of decomposition (Lodge 1993, 1996). The thickest of these fungal colonization & translocation organs (rhizomorphs, cords and hyphal strands) are primarily basidiomycete fungi, which have an almost unique capacity to cause white-rot by breaking down lignin in low-quality litter. A few white-rot basidiomycetes produce finer connections comprised of diffuse wefts of hyphae (e.g., Marasmius leoninus and related species), but the majority may represent ascomycetes and water molds that lack enzyme systems for breaking down lignin. White-rot basidiomycetes were shown in separate experiments to accelerate rates of decomposition of tabonuco leaves (Dacryodes excelsa) by 15% to 20% (Santana et al. 2005; Lodge et al. 2008), so any changes in fungal connectivity by basidiomycete fungi in response to the treatments should be related to nutrient exchanges between litter cohorts and changes in rates of mass loss.

Litterbaskets are used to study decomposition and nutrient cycling questions, and are often a better for understanding interactions between different litter cohorts than are leaf decomposition bags. We know from previous work here and elsewhere that: 1) basidiomycete fungi rapidly colonize freshly fallen litter (within the first 3 weeks of litterfall) from partly decomposed litter on the forest floor using rhizomorphs and cords (Lodge & Asbury 1988); 2) these fungal root-like structures transport nutrients from the old food base in order to build their biomass in the freshly fallen leaves, and are capable of tripling the phosphorus content in a senesced tabonuco leaf as indicated using radioactive phosphorus tracer in microcosm experiments (Lodge 1993; 1996); and 3) basidiomycete colonization accelerates leaf decomposition in the LEF (Lodge et al. 2008). Fungal translocation of nutrients is probably responsible for the increase in total CONTENT of N and P in leaf litter above 100% in El Verde (as in Zou et al.) and elsewhere in the tropics within 3-6 weeks of leaf fall (see Lodge 1993). In contrast, temperate forest floor litter is not usually colonized by basidiomycete fungi from the forest floor until 9-15 months after litterfall. Translocation of phosphorus into tropical litter with low phosphorus concentrations likely contributes to accelerated rates of leaf decomposition associated with basidiomycete colonization in tabonuco forest (Lodge et al. 2008), but the enzymatic capacity of basidiomycete to degrade lignin is a contributing factor (Santana et al. 2005).

Previous research in temperate forests shows a positive effect of increased litter depth on colonization by basidiomycete fungi. Unpublished data of Lodge & Asbury showed that drying of the litter layer reduced or eliminated basdiomycete colonization, while Lodge & Cantrell (1995) showed disappearance of some basidiomycete colonies in canopy gaps on ridges at El Verde after hurricane Hugo, or replacement of drought-sensitive strong nutrient translocators (i.e., Collybia johnstonii) with more drought tolerant species that translocated less P32. There were no previous data on effects of litter depth on basidiomycete fungi from tropical forests. We knew from studies after Hurricane Georges that 1. forest floor mass in secondary forest returned to pre-hurricane levels in about a year (Ostertag, Silver & Scatena?), but we did not know whether this was due to accelerated decomposition or reduced litter inputs after the storm. Thus, it was not really clear what mechanisms were involved in control of forest floor decomposition following hurricane disturbance.

This litterbasket decomposition experiment was designed to mimic as closely as possible post-hurricane conditions in order to follow mass loss and nutrient content of specific litter cohorts. To this end, a layer of SURFACE AIR-DRIED tabonuco leaves was placed between two screens on top of the existing forest floor layer in the litterbaskets (on the ground). In debris-addition plots, green leaves of Dacryodes, Manilkara and Sloanea IN HURRICANE AMOUNTS (as determined in Lodge et al. 1991) were added on top of the senesced litter layer screen after the canopy manipulations were completed in the CTE plots. Additional cohorts of litterfall were demarcated using screens added to remaining baskets when these were harvested ca. quarterly.

So far, we know that 1) canopy opening inhibited fungal connectivity between litter cohorts (mostly basidiomycete fungi, but the highest counts may be from diffuse hyphal connections by ascomycetes and water molds); 2) addition of green litter buffered the layers below from drying, mostly compensating for the effects of canopy opening; 3) fungal connectivity to the weighed layer of senesced tabonuco leaves was positively and significantly correlated with rates of leaf decomposition; 4) litter decomposition rates were higher than in dried leaf litter in a litterbag experiment in the CTE (González et al, unpublished), as in previous unpublished comparisons of dried versus undried litter; 5) but despite this, forest floor mass had not returned to pre-hurricane levels 1.5 years after CTE initiation. The data of Cantrell and Ortíz (lterdb165) on microbial composition in the litter cohorts from these baskets used methods that cannot distinguish basidiomycetes from other fungi. The results, however, suggest that colonization by basidiomycetes colonize accelerates the rate of early leaf decomposition and changes the trajectory of community succession. Nutrient analyses to determine if increases followed by decreases in inorganic nutrient pools, especially phosphorus, are associated with changes in patterns of fungal connectivity between the litter cohorts, and whether cohorts with low connectivity at the beginning have net losses rather than net gains in N & P stores.

D. Jean Lodge Short-Term Completed 2005 to 2007
149 Effects of a tropical stream poisoning: do they reflect effects of small-scale experiments?

Small-scale experiments in tropical streams have suggested that freshwater shrimps play a critical role in determining the quality and quantity of benthic organic matter and overall nutrient dynamics. We quantified the effects of a whole-reach shrimp poisoning event in the Sonadora, a second-order stream draining the Luquillo Experimental Forest in northeastern Puerto Rico. The illegal poisoning (for shrimp harvest) caused massive mortality of shrimps and aquatic insects. Atyid and xiphocaridid shrimp abundances in pools of the poisoned reach were reduced by ~95%, relative to abundances in an upstream reference reach. A survey of poisoned vs. reference pools, combined with a manipulative experiment (in which atyid and xiphocaridid shrimps were added to 3 poisoned pools), showed that reduced shrimp abundances due to the poisoning had strong impacts on benthic resources. The benthos of poisoned pools, where shrimp abundances were reduced, had 4 times more chlorophyll a, 6 times more algal biovolume, 4 times more fine particulate organic matter, 14 times more fine particulate inorganic matter, 5 times more carbon, and 4 times more nitrogen than did the benthos of pools in the reference reach. These increases in benthic resources were consistent with increases in algae, organic/inorganic matter, and nutrients in previous small-scale shrimp exclusion experiments conducted in the study river and tributaries. Effects of shrimp poisoning on the benthos varied by habitat, with riffles showing fewer significant differences than did pools. Compared to reference riffles, poisoned riffles had higher standing stocks of fine particulate inorganic matter, nitrogen, and biovolume of filamentous algae, and lower epilithic C:N ratios. Overall, previous small-scale exclusion experiments were highly predictive of the direction of effects due to large-scale shrimp removal by poisoning. Our study provides a tropical data set to add to the short list of stream studies that examine the predictive power of small-scale experiments for larger scales.

Catherine Pringle Short-Term Completed 1999
151 Neritina snails responses to channel realignment

This data set includes N. virginea densities and sizes relative to streambed substrate type, water depth, and near-bed water velocity in three sites in a low land segment in Río Mameyes near PR Route 3 bridge: 1) 50 m upstream from bridge, 2) immediately downstream from bridge, and 3) 200 m downstream from bridge (upper Westin Riomar Golfcourse). In addition, above variables are reported for pools and riffles located at PRASA Intake (Río Mameyes) and at La Curvita (Río Espíritu Santo).

Juan Felipe Blanco Short-Term Completed 2000 to 2003
154 Soil factors predict initial plant colonization on Puerto Rican landslides

Tropical storms are the principal cause of landslides in montane rainforests, such as the Luquillo Experimental Forest (LEF) of Puerto Rico . A storm in 2003 caused 30 new landslides in the LEF that we used to examine prior hypotheses that slope stability and organically enriched soils are prerequisites for plant colonization. We measured slope stability and litterfall in 1 m2 plots 8-13 months following landslide formation. At 13 months we also measured microtopography, soil characteristics (organic matter, particle size, total nitrogen, and water holding capacity), elevation, distance to forest edge, and canopy cover, as well as plant aboveground biomass, plant cover, and root biomass.

Aaron Shiels Short-Term Completed 2003 to 2006
157 Canopy Trimming Experiment (CTE) litterbag invertebrate counts and weights data

Identification, number and dry weight of invertebrates recovered from each litterbag.

Barbara A. Richardson Short-Term Completed 2005 to 2007
160 Canopy Trimming Experiment (CTE) Microbial EL-FAME Data

The canopy trimming experiment at El Verde simulates some aspects (canopy openness and biomass redistribution) of hurricane disturbances. Soil samples and leaf litter were gathered from three replicate blocks, each with four treatment plots in Tabonuco Forest at in El Verde. Treatments (canopy trimming and debris addition) were applied in a 2 x 2 factorial design. Samples were obtained both before and after the canopy were trimmed and debris was applied in the appropriate treatments. Samples were collected every four months before and after treatments were applied. Molecular approaches such as EL-FAME are useful indicators of microbial community shifts in response to environmental change. In this experiment we analyzed microbial community composition and abundance in soil and leaf litter samples as reflected by EL-FAME profiles. All soil samples were cleaned by removing rocks and roots, and leaf litter samples were ground.

Fatty acid nomenclature: Fatty acids are named according to the conversion X:YωZ, where X represents the number of carbon atoms in the chain, followed by Y after the colon which represents the degree of the unsaturation. The symbol ω and Z represent the number of double bonds nearest to the carboxyl end. The prefixes a, i, cy and d refer to anteiso, iso, cyclopropyl branching and dicarboxylic fatty acid respectively; br indicates that the type of branching is unknown, while a number followed by Me indicates position of methyl group. Prefixes a and b indicate that the OH groups of an OH fatty acid are located at positions 2 and 3 respectively. Numbers preceded by w indicate the position of OH groups from the aliphatic end of the fatty acids (Kaur et al 2005).

Community analysis based on fatty acids: Fatty acid biomarkers could represent a group of particular microorganisms present in soil and leaf litter. Fatty acids used in literature as biomarkers are: Branched chain fatty acids (br 17:0, br 18:0, i17:0, a17:0, i16:0, i16:1, 10Me16:0, 10Me17:0), iso and anteiso isomers of 15:0 for gram positive bacteria; Cyclopropane fatty acids (cy17:0, cy19:0, 16:1w9, 16:1w7c, 16:1w5, 18:1w7,19:1) for gram-negative bacteria; 18:2w6 for fungi; 10Me16:0, 10Me17 : 0 and 10Me18 : 0 for Actinomycetes; cy17:0 and 10Me16:0 for Sulphate reducing bacteria; 16:1w8, 18:1w8 for Methanogens (Modified from Zelles, 1999; Kaur et al 2005).

Sharon Cantrell Short-Term Completed 2002 to 2006
161 Bromeliad invertebrates at different elevations in Dominica

Collection details of bromeliads collected for invertebrate community and diversity analysis from 3 localities in Dominica. Dates, location, plant size, amounts, pH and temp. of contained water, weights of debris retained by the bromeliads, and counts of organisms, identified to species or morphospecies, collected from each plant.

Barbara A. Richardson Short-Term Completed 2002
166 Chemistry of soil solution collected from zero tension lysimeters in the Canopy Trimming Experiment (CTE) plots

Soil solution chemistry: Soil solution was collected monthly from zero tension lysimeters installed in the CTE plots. Sampling began prior to cutting the canopy and continue to the present.

William H. McDowell Short-Term Completed 2003 to 2007
167 Urban-Rural Temperature Data-relation between land-cover and the Urban Heat Island in San Juan, Puerto Rico

Our objective in this study is to quantify the UHI created by the San Juan Metropolitan Area over space and time using temperature data collected by mobile and fixed-station measurements. We used the fixed-station measurements to examine the relation between average temperature at a given location and the density of vegetation located upwind. We then regressed temperatures against regional land-cover to predict future temperature with projected land-cover change. Our data show the existence of a nocturnal UHI, with average nighttime urban-rural temperature differences (ΔTU-R) of up to 3.02°C.

Each of the stations listed in this excel file were used to calculate the urban heat island created by the San Juan Metropolitan Area.

Charles A.S. Hall Short-Term Completed 2006
168 2004 Estuarine Fish Sampling - Managing freshwater inflow to estuaries in northeast Puerto Rico

Chapter 1 (fish community data): Historical data are often one of the only resources for documenting and assessing causes of environmental change, particularly in developing regions where funding for ecological studies is limited. In this study, previously unpublished data from a 1977 year-long study of the fish community of the Espiritu Santo estuary are presented. This dataset is among the oldest and most extensive surveys of a Caribbean island estuarine fish community. A comparison of these historical data with data collected in June and July 2004 using identical sampling methods allowed description of potential long-term changes in the fish community, identification of vulnerable species, and assessment of potential drivers of change. Results strongly suggest a decline in species richness and abundance in the Espiritu Santo estuarine fish community, with greater declines in freshwater-tolerant than marine or euryhaline species. Declines in freshwater inflow to the estuary, due to large-scale upstream water abstractions for municipal use, have increased since the initial 1977 survey. This is the first study to examine long-term change in the fish community of a tropical island estuary. Additional research and conservation efforts are needed to understand mechanisms of change and to protect Caribbean island estuarine fish communities.

Chapter 2 (isotope and gut content data): The contribution of riverine-derived organisms and organic matter to four fishes along the salinity gradient in two Puerto Rican estuaries, the Espiritu Santo and Mameyes, was examined via stable isotope and gut content analyses. Stable isotope analyses indicated that riverine organic matter potentially contributed as much as 69% of the diet of one (caitipa mojarra, Diapterus rhombeus) of four fishes sampled. In contrast, riverine organic matter was of little direct importance to the three other fishes, tarpon snook (Centropomus pectinatus), ground croaker (Bairdiella ronchus), and white mullet (Mugil curema) contributing less than a third of their assimilated material even in the estuaries’ upper reaches. Gut content analysis of estuarine fishes demonstrated that several species of pelagic or omnivorous fish consume riverine-derived organisms, specifically juvenile migratory freshwater shrimps, during their residence in the estuary. Freshwater shrimps were frequently encountered (in 37 and 39% of guts examined) and composed an average of 18 and 22% of gut content material of omnivorous fishes sampled in the Espiritu Santo and Mameyes estuaries, respectively. To our knowledge, this is the first study to examine the contribution of riverine subsidies to a Caribbean island estuary. Given increasing demand for water resources on tropical islands and the importance of diadromy in these systems, there is a need for additional research on this topic to better inform water management decisions.

Katherine Smith Short-Term Completed 2004
170 Phrynus habitat selection

This data set comprises a single data file, which contains data on the abundance and distribution of the whipspider Phrynus longipes on the Luquillo Forest Dynamics Plot in July 2001.

Christopher P. Bloch Short-Term Completed 2011
171 Terrestrial gastropods abundance data along an elevational gradient within the Sonadora River watershed

The data set includes 3 files that contain abundance data for terrestrial gastropods along an elevational gradient within the Sonadora River watershed. Two files (1 and 2) contain data from the same transect but differ in the year during which they were collected (2007 and 2008). The third file (3) contains data from a separate elevational transect (sites were located at the same elevation as in files 1 and 2) in palm dominated forest within the same watershed that was collected during the same time period in 2008 as data from file 2. Note: Plots at 250 m of elevation were not sampled in 2008 on either transect and a plot at elevation 750 m in the palm transect was never sampled.

Michael R. Willig Short-Term Completed 2007 to 2008
176 Lotic Intersite Nitrogen eXperiment I (LINX1): Stream nitrogen (N) dynamics in streams on the eastern side of Puerto Rico

This study was part of the Lotic Intersite Nitrogen eXperiment (LINX); a series of identical 15NH4 tracer additions to streams throughout North America. 15NH4Cl was added at tracer levels to a Puerto Rican stream for 42 days. Samples were collected from selected food web and dissolved nitrogen compartments throughout the addition and for several weeks afterwards to determine the uptake, retention and transformation pathways of nitrogen in the stream.

William H. McDowell Short-Term Completed 1998
177 Lotic Intersite Nitrogen eXperiment II (LINX2): Stream nitrogen (N) dynamics in streams on the eastern side of Puerto Rico

Stream nitrogen (N) dynamics were studied in streams on the eastern side of Puerto Rico. Rates of nitrate uptake and denitrification were measured in nine tropical low-order streams with contrasting land use as part of the Lotic Intersite Nitrogen eXperiment II (LINX II) in Puerto Rico using short term (24-hour) additions of K15NO3 and NaBr. Background nitrate concentrations ranged from 105 to 997 µg N L-1 and stream nitrate uptake lengths were long, varying from 315 to 8480 m (median of 1200 m). Other indices of nitrate uptake (Vf,, cm s-1 and U, g N m-2 s-1) were low in comparison to other regions and were related to chemical, biological, and physical parameters. Denitrification rates were highly variable (0 to 133 g N m-2 min-1; median = 15), were dominated by the end product N2 (rather than N2O), and were best predicted by whole-stream respiration rates and stream NO3 concentration. Denitrification accounted for 1 to 97% of nitrate uptake with 5 of 9 streams having 35% or more of nitrate uptake via denitrification, showing that denitrification is a substantial sink for nitrate in tropical streams. Whole-stream nitrate uptake and denitrification in our study streams closely followed 1st order uptake kinetics, indicating that NO3 uptake is limited by delivery of substrate (NO3) to the organisms involved in uptake or denitrification.

William H. McDowell Short-Term Completed 2004 to 2006
179 Elevation Gradient (EG) Soil Microbial diversity FAME and TRFLP data

Soil fungal communities respond to multiple abiotic and biotic factors that change along elevation gradients. The limited information available on fungi and microbial processes along elevation gradients is primarily from temperate areas and very few from tropical regions. This study documents changes in fungal and bacterial diversity, and abundance and composition of microbial functional groups along a subtropical elevation gradient.

Sharon Cantrell Short-Term Completed 2003 to 2004
180 Canopy Trimming Experiment (CTE) Microbial diversity DNA data

Hurricanes are common disturbances in the Caribbean region that affect tree distribution, species diversity and biomass in forests. Little is known of how microbial communities in soil and litter are affected by natural or anthropogenic disturbances. The objective of our study was to determine the relative abundance and diversity of microorganisms in leaf litter at different stages of decomposition, and the effect of canopy opening and debris addition or removal.

Results: Leaf mass loss was slowest in the treatment with canopy trimming and debris removal. Canopy opening was associated with lower litter moisture, lower fungal connectivity between litter layers and slower mass loss after three months. Addition of green leaves increased moisture, and frequently accelerated mass loss of the senesced leaves below them at 17, 28 and 40.5, but not 53 weeks. After 28 weeks, mass loss showed a significant treatment interaction, and was concordant with fungal connectivity between litter cohorts. TRFLP profiles of the 16S rDNA digested with MnlI and fungal ITS digested with HaeIII shows that the microbial communities at 17, 28 and 53 weeks were highly divergent among treatments (Sorensen index of similarity). In comparisons of green versus senesced leaves within treatments, bacterial communities’ differed somewhat, fungal communities differed strongly, but mass loss did not differ. Conclusions: Microbial community changes through time can be related to microclimate and the availability of labile compounds. Fungi appeared to control the succession of microorganisms in decomposing leaves.

Sharon Cantrell Short-Term Completed 2006
188 Biodiversity and metacommunity structure of rocky intertidal invertebrates in some coastal ecosystems in Puerto Rico

The goals of this study were to determine the relative importance of environmental (wave power density, wave height) and habitat (e.g., algal cover, slope, complexity of rock surfaces) factors associated with the structure of local assemblages at multiple shore heights and the regional metacommunity of mobile invertebrates on oceanic rocky intertidal habitats. These characteristics and abundances of 41 species of invertebrate were estimated at 10 plots at each of three tidal heights at each of ten sites on the shoreline of Puerto Rico.

Christopher P. Bloch Short-Term Completed 2009
189 Wood to Soil 0-10 cm data and Wood to Soil 10-20 cm data to detect the imprint of decaying logs (30-80 cm diameter) from two hurricane cohorts (Hugo, 1989, and Georges, 1998)

Many trees fell during Hurricanes Hugo (1989) and Georges (1998) in Puerto Rico. A debris removal experiment suggested that coarse woody hurricane debris slowed canopy recovery by fueling microbial nitrogen immobilization. We analyzed C, N, microbial biomass C and root length in paired soil samples taken under versus 20-50 cm away from large trunks of two species felled by Hugo and Georges three times during wet and dry seasons during the two years after Georges. Data on soil P and other nutrients have not yet been analyzed. Soil microbial biomass, C and N were higher under than near logs of both age cohorts. Frass from wood boring beetles may induce the early effects. Root length was greater under logs at 0-10 cm depth during the dry season, and away from logs in the wet season, but varied independently of microbial biomass. Thus decaying wood can provide resources exploited by tree roots. Percent soil C and N were significantly higher under than near logs in both the 0-10 and 10-20 cm samples. Microbial biomass C varied significantly among seasons at 0-10 cm depth but differences between positions (under vs away) were only suggestive. Surface soil on the upslope side of the logs had significantly more N and microbial biomass, likely from accumulation of leaf litter above the logs on steep slopes. This study shows that C and N accumulate significantly more in soil under than near decaying logs, even in logs that had only decayed for 7 months, and thus contributes to soil heterogeneity. Tree roots track and exploit resource and nutrient hotspots as they change locations between seasons, so the soil heterogeneity in soil fertility is important for forest productivity.

D. Jean Lodge Short-Term Completed 1999 to 2001
191 Luquillo Understory invertebrates Sticky Trap Samples

Studies of arthropod assemblages in the fossil record can provide information on how assemblages have changed over evolutionary time. Studies at the LEF provide a unique opportunity to compare extant assemblages to those inferred from fossil amber deposits in the Caribbean. Poinar and Poinar (1999, The Amber Forest: A Reconstruction of a Vanished World, Princeton University Press) compiled data on inclusion of arthropod taxa in Dominican amber, representing a tropical hardwood forest from 25 mybp. Their reconstruction of a Caribbean arthropod assemblage from a Miocene Era tropical hardwood forest generally resembled canopy arthropod assemblages from the extant tropical hardwood forest at the LEF, suggesting that forest arthropod assemblages in the Caribbean may have changed relatively little over this long time period.

Sticky traps, designed to resemble resin globules that eventually could become amber, were coated with adhesive and placed on lower tree boles or on logs at one non-gap site at the LEF for 5 days during June 2004, January and July 2005, July 2006 and July 2007 (total 35 samples).  Samples were dominated by Diptera (89% of specimens), with phorids representing 60%, mycetophilids 16%, dolichopodids 4%, sarcophagids 2%, cecidomyiids and chironomids 1% each, and other Diptera 5%.  Other collected taxa included Hymenoptera (6% of specimens), with chalcidoid wasps 4%, little fire ant (Wasmania auropunctata) 1% and other Hymenoptera 1%; Coleoptera (2% of specimens), with curculionids 1% and other Coleoptera 1%; and a variety of other insects, spiders and mites representing 3%.  Two small Anolis lizards and a small Eleutherodactylus frog also were captured.  Arthropod composition in sticky traps from the LEF and in Dominican amber were similar.

Timothy D. Schowalter Short-Term Completed 2004 to 2007
195 Elevational gradients of walking stick (Lamponius portoricensis) abundance

Abundance data were collected for Lamponius portoricensis from a mixed forest transect and from a palm dominated transect set along an elevational gradient in the Sonadora watershed. Each transect ranged from 300 m to 1000 m in elevation, with elevational strata located at 50 m intervals and 10 plots per stratum. No palm dominated forest could be located at 700 m in the watershed, resulting in 15 strata (150 plots) along the mixed forest transect and 14 strata (140 plots) along the palm forest transect.

The data set includes 3 files that contain abundance data for walking sticks (Lamponius portoricensis) along an elevational gradient within the Sonadora River watershed. Two files (1 and 2) contain data from the mixed forest transect but differ in the year during which they were collected (2007 and 2008). The third file (3) contains data from a palm forest elevational transect from 2008, for which all sites were located in palm dominated forest in the same watershed. Note: Plots at 250 m of elevation were only sampled during 2007, no palm dominated forest could be located at 750 m of elevation; that elevation is omitted from the palm transect.

Michael R. Willig Short-Term Completed 2007 to 2008