Project Title Abstract Contact Related non-meteorological Data Sets (if not a climate data set)
Anole Population Dynamics The population activity, abundance, density, and spatial distribution of anoline lizards (genus Anolis) were investigated in tabonuco rain forest of the Luquillo Mountains, Puerto Rico. A summary of the aspects of anole biology relevant to food web structure and organization in tabonuco forest were developed from these studies. The anole activity in different habitats was studied in relation to the changes in canopy structure before and after Hurricane Hugo (September 1989). The drastic reduction in canopy structure immediately following the hurricane confined anole activity to the lower few meters of the forest. Anolis stratulus, a canopy species, apparently responded to changes in microclimate. Relative abundance estimates based on vertical transect surveys were A. stratulus (82%), A. gundlachi (11%), and A. evermanni (7%). Vertical surveys documented that A. Douglas Reagan
Avian populations Long-Term Monitoring The project is part of the study of the resilience of populations after multiple disturbances. This study uses long-term population measurements of key species as a baseline to evaluate changes in populations in response to disturbance. The distribution of counts at 40 points in the Luquillo Forest Dynamics Plot allows correlation of population changes at each point with changes in plant and animal species and abundance at the same point. Robert B. Waide
Biodiversity and metacommunity structure of rocky intertidal invertebrates Coastal ecosystems are complex and species rich, but are vulnerable to degradation from a variety of anthropogenic activities. Nevertheless, information on intertidal community composition in the Caribbean Basin and at other oceanic sites is lacking. Such information is essential to developing a more comprehensive understanding of rocky intertidal systems and their responses to global change. 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. Christopher P. Bloch, Brian Klingbeil
Bisley Experimental Watersheds (BEW) The BEW is a long-term study area that encompasses a total of 13 ha.  For the past 30 years the forest composition and nutrient contents have been monitored by the US Forest Service and LUQ collaborators. In addition, data is also collected on the watershed exports (Heartsill-Scalley et al., 2007, 2011) and its relation to the history of disturbance.  Contact Information: Grizelle Gonzalez, Whendee Silver, Lawrence L. Woolbright, Michael R. Willig
Bisley Vegetation Plots Relationships between landforms, soil nutrients, forest structure, and the relative importance of different disturbances were quantified in two subtropical wet steepland watersheds in Pueno Rico. Ridges had fewer landslides and treefall gaps, more above-ground biomass, older aged stands, and greater species richness than other landscape positions. Ridge soils had relatively low quantities of exchangeable bases but high soil organic matter, acidity and exchangeable iron. Valley sites had higher frequencies of disturbance, less biomass, younger aged stands, lower species richness and soils with more exchangeable bases. Soil N, P, and K were distributed relatively independently of geomorphic setting, but were significantly related to the composition and age of vegetation. On a watershed basis, hurricanes were the dominant natural disturbance in the turnover of individuals, biomass, and forest canopy. However. Grizelle Gonzalez
Bromeliad Invertebrate Diversity in Dominica A study of the bromeliad invertebrate fauna in forests at three elevations in Dominica, as part of cross site studies on bromeliad invertebrates in different tropical localities. Barbara A. Richardson, Michael J. Richardson
Bromeliad Invertebrate Diversity in the LEF Tank bromeliads form complex, but discrete, microcosms whose biological, physical and chemical parameters can be sampled in their entirety. Plants impound canopy litter and throughfall water, and form a microhabitat for mainly detritivorous animal communities. This study of their fauna provided a natural way to examine diversity, and also the relationship between diversity and habitat parameters at different elevations in the LEF. Barbara A. Richardson, Michael J. Richardson
Canopy Structure There are two main goals in this project. One one-time goal was to measure the dimensions of gaps present at El Verde research area, and the other continuing goal is to record changes in three dimensional canopy structure in three one- hectare sized plots, one each in tabonuco, colorado, and cloud forests. Nickolas Brokaw
Canopy Trimming Experiment (CTE) General description of Experiment and Projects: Hurricanes are important drivers of periodic disturbances on tropical forests of the Luquillo Mountauns. The immediate impact of this disturbance is on the canopy biomass which is redistributed from the canopy compartments to the detrital pool of the forest floor hence creating a wide opened canopy.  The Canopy Trimming Experiment (CTE) is a long-term experiment designed for two purposes: 1) to decouple the effect of canopy disturbance (e.g., increasing light levels, temperature, moisture, etc.) from those of increased detrital inputs on rates of germination, growth, survival, detritus processing, nutrient cycling, soil conditions, and trophic structure, and 2) to increase the frequency of simulated hurricane effects above background levels to once every six to ten years. Climate change models predict increased frequency and intensity of Caribbean hurricanes (Emmanuel 1987, Goldenberg et al. Sharon Cantrell, Grizelle Gonzalez, D. Jean Lodge, William H. McDowell, Barbara A. Richardson, Joanne M. Sharpe, Aaron Shiels, Timothy D. Schowalter, Whendee Silver, Michael R. Willig
Community Composition of Litter Invertebrate A study of the litter invertebrate fauna in litter from palm and non-palm canopies in each of the three main forest types in the LEF was undertaken to distinguish between the effects of elevation and of litter quality and quantity on the composition and biomass of the litter invertebrate community. Michael J. Richardson, Barbara A. Richardson
Community Composition of Plants The composition of plant communities changes with elevation in the Luquillo Experimental Forest. 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. Twenty-four permanent vegetation plots, each 50m by 20m are being established in the LEQ, with eight plots each along three rivers, the Sonadora, Icacos, and Mamayes. The plots are being established at every 100m in elevation, starting at 200m above sea level. All woody, free-standing stems greater than 1cm dbh are being marked, identified and mapped into 5x5 subquadrats. We anticipate 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 LEQ. Jess Zimmerman
Community Ecology of Land Snails Terrestrial gastropods and walking sticks were sampled at 36-40 points on the grid at the Bisley Watersheds to investigate long-term population and community dynamics and response to disturbance. Terrestrial gastropods and walking sticks were sampled at 40 points on the Luquillo Forest Dynamics Plot at El Verde twice annually from 1991-2002 to investigate long-term population and community dynamics and response to disturbance. Densities: Densities of invertebrates and apparency of plant species are estimated to investigate the effects of disturbance on long-term population dynamics, habitat associations, and spatial distributions. Habitat: To investigate habitat associations of terrestrial invertebrates, apparency of 17 plant groups (species, genera, families) from 0-3 m from the ground was estimated at 36 points on the grid at Bisley Watersheds 1 and 2 in 1994 and 1999. Michael R. Willig, Christopher P. Bloch
Community Ecology of Streams Snails Diadromous fauna, migrating between marine and coastal streams is dominant in the neotropics. However, the factors controlling their population distribution and size are poorly understood. The migratory snail Neritina virginea (Gastropoda: Neritidae), abundant in estuaries and coastal rivers in the Caribbean, was studied to understand those factors. The objectives of the study were three-fold: 1) to identify the factors controlling the distribution of diadromous fauna at different spatial scales, 2) to determine patterns and causes of massive upstream migrations and their importance for population persistence, and 3) to integrate this knowledge into conservation strategies for migratory species and stream management plans. Effie A. Greathouse
Diatom Population Dynamics Monthly collections of benthic diatoms are made at four sites in the Rio Mameyes of northeastern Puerto Rico. The sites range from an unpolluted closed canopy headwater stream within the National Forest, to a small, highly polluted coastal plain tributary that drains a golf course and surrounding suburban development. Diatoms are collected by cleaning a standardized area of randomly selected rocks from each site. The identification of the composition and abundance of diatoms in each site will be used to identify species and communities that reflect water quality and community response to floods, low flows, and water pollution. Brynne Bryan
Differential Abundance of Microbial Functional Groups along the Elevation Gradient from the Coast to the Luquillo Mountains Soil fungal communities respond to multiple abiotic and biotic factors that change along elevation gradients. This study documents changes in fungal and bacterial diversity, and abundance and composition of microbial functional groups along a subtropical elevation gradient. The elevation gradient is located in eastern Puerto Rico and is composed of five forest types each with characteristic vegetation. Soil samples were collected every three months from March 2003 thru March 2005. Soil fungal and bacterial communities were analyzed using fatty acid methyl esters (FAME) and TRFLP profiles. Diversity in this elevation gradient is higher at mid-elevations. Most G negative and G positive bacterial FAME were positively related to soil pH in MLR models, lower pH in mid-elevation forest soil may suppress bacteria favoring fungi. Sharon Cantrell
Earthworm Population Dynamics Plant communities may impose strong control on soil fauna populations. We compared and examined patterns of earthworm abundance, species composition, and distribution pattern of earthworms in tree plantations and secondary forests of Puerto Rico. Our results indicate that variation in plant species composition and soil properties between plant communities can trigger differences in earthworm abundance and distribution pattern within a tropical wet forest. Xiaoming Zou
Ecological studies of dams and migratory fauna The ecological roles of diadromous fauna (freshwater shrimps, fishes, and snails) in Puerto Rico were studied in the context of examining consequences of their loss from streams above large (height >15 m) dams. Four sub-projects were conducted: Effie A. Greathouse
Effects and Recovery from Poisoning Quebrada Sonadora was poisoned with chlorine bleach 140 m upstream from the bridge of Road 186 in the LEF causing massive mortality of freshwater shrimps over a ~500 m reach (300 m a.s.l. , Fig. 1). The poisoning was discovered on 12 March 1999 and was estimated to have occurred on 10 March, based on the state of decay of thousands of dead shrimps observed along the river. No carcasses of Sicydium plumieri were observed. While no bleach bottles were found at the site of this poisoning, bleach bottles have been found at other stream poisonings documented in the LEF, and locals report that swimming pool tablets are also sometimes used in illegal chlorine poisonings. Chlorine is known to display rapid volatilization, transformation, and flushing in lotic waters; thus, LEF chlorine poisonings are pulse disturbances. When the poisoning was discovered, the benthos in pools of the poisoned reach was visibly and dramatically different than the pool benthos upstream. Catherine Pringle
Elevational Gradients of Gastropod Biodiversity Elevational gradients are useful for assessing the manner in which animal species respond to environmental variation. Changes in elevation result in predictable changes in abiotic factors (temperature, precipitation) as well as in plant community composition and physiognomy, and may do so within a relatively small geographic area, minimizing the role of biogeographic or historical mechanisms in molding differences in animal species composition among sites. Paired elevational transects (250 m to 1000 m) in the Sonadora River watershed were sampled at 50 m intervals to decouple underlying environmental gradients that are associated with changes in elevation and that are hypothesized to structure animal communities. Michael R. Willig
Experimental Food Web Manipulation Results of an experimental manipulation of the understory food web by controlling densities of Anolis lizards and Eleutherodatylus frogs and measuring the response of arthropods and plants (in terms of herbivory). These manipulations were performed by constructing exclosures that controlled the entrance and exit of anoles and coquies. Paul Klawinski
Fern Population Dynamics Ferns are an important part of the understory of many tropic forests, yet nothing is known about their leaf turnover rates, hence their contribution to the litter layer and overall functioning of the forest ecosystem. This long-term project addresses that question by marking and monitoring each leaf produced by over a thousand individuals representing over 20 different species. Plants and their leaves were observed at four month intervals for ten years starting in September 1991 (Phase 1) and then at one year intervals for an additional ten years starting in January 2001. Seasonality in leaf and spore production, as well as effects of drought and hurricanes are noted. Defoliation experiments with several species are being conducted to determine the limits of disturbance effects. Joanne M. Sharpe, Leslie Finical
Flooded forest plot sampling in the Amazon Sampling of plots in three major forest types that differed by flooding duration after 4 years of regeneration showed: (1) common species exist between wet forests and their gaps and between wet and very wet gaps, (2) tree richness is maximum in dry forest and minimum in very wet gaps except in the wet gaps that show the second highest number of species, (3) there were less stems in gaps compared to forests and less stems in forests as flooding increased, except again in the wet gaps, and (4) dominance-diversity curves have more dominance by single species in the dry gap plots compared to other gaps and in dry forest compared to other forests. In general while some aspects of structure such as tree stem density is largely determined by tree-fall gap dynamics, tree composition is determined by flooding regime. Randall W. Myster
Fresh Water Biannual Monitoring The LTER is conducting annual monitoring of Algae, Chlorophyll a, benthic organic matter, and benthic inorganic matter in order to document baseline stream characteristics. These data may be used to examine effects of disturbances such as hurricanes on stream ecosystems. Catherine Pringle
Fresh Water Shrimp population dynamics Spatial and temporal patterns of abundances for coexisting species: different intensities and frequencies of disturbances can alter spatial and temporal patterns of abundances for coexisting species. To determine if these different hydrologic regimes altered distributions of populations, we compared shrimp densities during different periods of time. There were significant differences in the relationships between locations of stream pools along an elevational gradient (300 to 470 m) and the abundances of two species of shrimp (Atya lanipes and Xiphocaris elongata) during the following three periods: pre-Hurricane Hugo (20 mo), post-Hurricane Hugo (50 mo), and low-flow (12 mo). Mechanisms that likely cause different patterns of distribution (See Abstract) include avoidance of predators coupled with active preference by prey species for pool habitats with low frequency of washout by storm flows, and with sufficient storage of food resources (microbially conditioned leaf detritus). Todd Crowl, Mark Pyron, Karen M. Buzby
Frog population dynamics El Verde Station, located in the tabonuco forest zone on the NW side of the Luquillo Experimental Forest (LEF), has hosted numerous scientific efforts since the 1960s. Thus, a great deal of information exists concerning anuran populations at the site over the past 30 years. Although past surveys did not use consistent techniques, they clearly document the general status of the anuran community of the area. I began working at El Verde in the 1970s and have collected data on the anuran community primarily in the 1980s and 1990s. Until recently, these surveys also lacked a consistent sampling protocol, although they clearly document declines in species richness in comparison to earlier records. Lawrence L. Woolbright
Graduate Student's River Education Program The River Education Program (Luquillo-LTER)is a portal to information about the natural resources of El Verde, Luquillo Experimental Forest, and El Yunque National Park. By reporting on what has been learned from research and monitoring in these areas, we hope to increase public awareness of new findings and encourage studies that will help guide management decisions. NOTE: A web site was developed by O. Perez-Reyes at: Omar Perez-Reyes
Herbivory Long-term experiments associated with herbivory, a process which under certain circumstances may be an important regulator of detrital processing, has started at El Verde only since 2002. In addition to continuing long-term vegetation measurements will be conducted to determine long-term patterns of herbivory in two ways. As in most tropical forests, herbivores mainly eat young leaves (Coley & Barone 1996), which flush during May and June in the tabonuco forest or following disturbance (Angulo-Sandoval & Aide 2000). We will measure percent herbivory on new leaves of focal species marked each year in May and June. The second measurement will be of inputs of green leaf litter and insect frass to the forest floor. These measures will be used to gauge the changes in rates of herbivory during recovery from disturbance, with the ultimate goal of evaluating the role of herbivory in succession. Maria del Pilar Angulo
Influence of Decapods on Ecosystem Processes Three experiments were performed to study the influence of decapods on ecosystem processes. In the first one (catalogued as LTERDBAS #104) the hypothesis that differences in macrobiotic assemblages can lead to differences in the quantity and quality of organic matter in benthic depositional environmentsamong streams in montane Puerto Rico was tested. The experimental results were 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. Catherine Pringle
Invertebrate diversity in Heliconia flower bracts at El Verde This study complemented the work on bromeliad microcosms. It was carried out to compare the abundance and diversity of the invertebrate fauna supported by the accumulated fluid and organic matter in Heliconia bracts with that of the aquatic component of the bromeliad microcosm. Barbara A. Richardson, Michael J. Richardson
Land Use 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. Natural pasture that had cows and horses grazing until early 1996. No planted grasses, although some grasses seeded naturally because of the effect of the couse and horses. Those grasses are in the percent cover data set. Randall W. Myster
Landslide Removal Experiment The LRE experiment is a series of vegetation removals on 10 landslides designed to determine what mechanisms drive landslide succession. Three types of removals were conducted: a) removal of Gleicheniaceae ferns (GLE): landslides ES9, ES13, J3, and MY3 (as with my other work, ES stands for slides in the Espiritu Santo drainage, J is for Jimenez, MY is for Mameyes, and RB is for Rio Blanco).b) removal of pioneer woody plants (PIO): ES3, MY6, RB10, RB11c) removal of Cyathea tree ferns: RB1, RB2 On each landslide there are two removal plots and two control plots as follows: Plot 1: Control: ES9, ES13, MY3, RB10, RB2; Removal: J3, ES3, MY6, RB11, RB1 Lawrence R. Walker
Landslide Revegetation Landslide are among the most severe rainforest disturbances (Garwood et al. 1979, Hubbell & Foster 1986, Sousa 1984, Waide & Lugo 1992, Walker et al. in press), generating extreme abiotic spatial gradients (Fernández & Myster 1995) and exposing soil and parent material (Guariguata 1990). Landslides contain patches of vegetation surrounded by a matrix of soil or bare substrate (Dalling 1994, Myster & Fernández 1995). In addition, they often undergo recurrent localized disturbance either by resliding or by treefall at the edge of the landslide (Hartshorn 1980), thereby adding new plant preopagules, soil or organic material after the initial slippage. These landslide feature, coupled with interactions between patches of similar soil or vetetation (including seed dispersal, shading, litter deposition and vegetative reproduction), strongly suggets that landslide are a patch-dynamic system (Hupp 1983, Pickett & White 1985). Lawrence R. Walker, D. Jean Lodge, Aaron Shiels
Leaf litter inputs into Prieta B and Gatos streams This is a long-term monitoring of leaf litter inputs into Prieta Stream, arm B, and Gatos stream. The monitoring is conducted using litter traps similar tho those used in other LTER project. Baskets are suspended over the channel and are emptied every other week. All material is dried and identified. Alonso RamIrez
Litterfall production along a tropical upper elevation gradients We collected litterfall every two weeks from 12 forested sites in Pico del Este. Our goals are to determine patterns in litterfall production along the elevation gradient. Whendee Silver
Long-Term Elevation Plots We seek to link our conceptual understanding of tabonuco forest derived from long-term experiments and measurements with knowledge of changes in disturbance patterns and driving variables along an elevation gradient in the Luquillo Mountains.  By comparing emergent ecosystem properties along this gradient, we focus on general properties that underlie the dynamics of ecosystems. In these long term plots we monitor key biota in spatially explicit manner at coarse time scales while more sensitive climatic and ecosystem/biogeochemical variables are monitored frequently (intradaily to monthly) in a more spatially coarse manner.  Contact Information: Jess Zimmerman, Sharon Cantrell, Michael R. Willig, Todd Crowl, Lawrence R. Walker, D. Jean Lodge, Aaron Shiels, Whendee Silver, Grizelle Gonzalez, Alonso RamIrez, Jude Jardine
Long-term Intersite Decomposition Experiment (LIDET) The LIDET experiment is designed to test the effects of substrate quality and macroclimate on long-term decomposition and nutrient release dynamics of fine litter.   Although other factors, such as the decomposer biota, may also influence these long-term dynamics, we felt that substrate quality and macroclimate would explain the largest proportion of the variation and would be the easiest to extrapolate geographically. The role of the decomposer biota is tested indirectly by the LIDET experiment, however, as the litter used was not native to the sites.   If there is a large interaction between substrate quality and decomposer biota, then some species of litter may decompose faster or slower than generally expected at some of the sites. D. Jean Lodge
Lotic Intersite Nitrogen eXperiment 2 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. William H. McDowell
Lotic Intersite Nitrogen eXperiment I 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
Luquillo Forest Dynamics Plot (LFDP) The processes that determine the plant species diversity and structure of tropical forest are still uncertain despite many years of investigation. A tropical forest characteristically has few common species and many rare species, with conspecifics often widely distributed throughout the forest. The potential for inter and intra-specific interactions are numerous, and it is difficult to determine which factors maintain species diversity or how rare species survive in the population. Factors that we believe contribute to tropical forest structure and composition include the physical environment and past history of the forest, species-specific physiological requirements for light, nutrients and water necessary for growth, survival and reproduction, and pathogens and herbivores. Jess Zimmerman, Jill Thompson, Nickolas Brokaw, Robert B. Waide, James Aaron Hogan
Managing freshwater inflow to estuaries in northeast Puerto Rico: ecological and institutional consideration Dissertation research examining the ecological importance of freshwater inflow to estuaries in northeast Puerto Rico . Part 1 (Chapter 1) includes a comparison of historical (1977) and current (2004) fish community data in the Espiritu Santo estuary. Part 2 (Chapter 2) includes a stable isotope and gut content study of the contribution of freshwater inflow to estuarine fishes in the Espiritu Santo and Mameyes estuaries. Catherine Pringle
Meteorology and Hydrology at Bisley Several meteorological parameters are being measured at Bisley since 1993. Correlations between elevation and stream-runoff and rainfall, elevation and air and soil temperature, and between trhoughfall and vegetation types have been found. These relationships are used in hydrologic and nutrient budgets as well as in environmental models. Rainfall and Stream-runoff Grizelle Gonzalez
Meteorology at El Verde Rainfall and temperature have been measured at the El Verde Station since 1964, twenty two years previous to LUQ LTER 1. In McDowell and Estrada-Pinto (1), the collection procedures, the daily raw precipitation data from 1964 to 1986, and some summary statistics of the precipitation data covered on that period of time were reported. Meteorological sensors were installed at the El Verde Field Station's flat concrete rooftop, 3 m above the ground surface at an elevation of 350 m asl after the September 1989 (Hugo) hurricane. Since 1995, rainfall and temperature data since 1975 and sensors data since 1990 from the above records are being published on the LUQ LTER Web site. Alonso RamIrez, Robert B. Waide
Meteorology-Puerto Rico During LUQ LTER 1 (from 1988 to 1994) several meteorological data sets where obtained from other agencies for comparison. In 1993, historical daily precipitation and temperature data were obtained from the United States Department of Commerce NOAA NCDC from 5 stations, four of which are located at the East and South of the El Yunque Mountain (Fajardo, Río Blanco Lower and Upper, Pico del Este), and another at the North West (Río Grande). Historical streamfall data from the USGS were also obtained, but not summarized. These data can be obtained from the Puerto Rico USGS Web site at Douglas A. Schaefer
NADP Precipitation Data We report here the chemistry of weekly wet-only rainfall from the Luquillo Experimental Forest (LEF) NADP station (code PR20) for the period February 1985 through January 1996. Our station was knocked out by Hurricane Hugo in September 1989, and not reestablished until May 1991. The station remains in active service to the present. Data from 1997on is missing on this site. Visit the NADP. NTN web site at : to get the data. In overview, our site has more annual rainfall than any other in the NADP network, but in general that rain is less concentrated than that falling in the continental U.S. That means rain in the LEF is less acidic and deposits less nitrogen and sulfur than in the industrial northeast. Alonso RamIrez
Nutrient Cycling in Tabonuco Forest  Understanding the long-term impact of deforestation on ecosystem structure and function of tropical forests may aid in designing future conservation programs to preserve biodiversity and sustain ecosystem productivity. We examined forest structure, tree species composition, litterfall (fine and coarse) due to Hurricane Hugo and subsequent fine annual litterfall inputs, litterfall rate, and leaf litter decomposition. The experiment was initiated by the MRCE (Minortity Research Centers of Excellence) program, and continued by the LTER. In addition to measuring nutrient fluxes from litterfall and decomposition, we measured KCl-extractable soil nitrogen in ammonium and nitrate forms to determine the effects of complete fertilization and removal of hurricane debris. History of litterfall, decomposition and soil nitrogen availability studies (MRCE experiment) at the Luquillo Experimental Forest (LEF): D. Jean Lodge, Xiaoming Zou, Kristiina Vogt, Daniel Vogt, Thomas Siccama, Alan Covich, Frederick Scatena (In Memorium)
Phenology Flowering phenology was added to LUQ site monitoring program after the occurrence of Hurricane Hugo in 1989, which provided an immediate test of the monitoring program developed under the initial proposal. Seasonal rhythms of flowering and fruiting are an important component of the community dynamics of tropical forest and can be a critical determinant of the dynamics of consumer populations. Jess Zimmerman
Pre Hurricane Cecropia Survey The goal of this project was to locate and characterize the sites where Cecropia schreberiana saplings and seedlings occur. I made a one-time survey of about 35 ha of tabonuco forest near El Verde Research Station, in 1989 before Hurricane Hugo. What little Cecropia regeneration I found was in tree fall gaps, or in open areas along streams. Nickolas Brokaw
Pre-Hurricane Cecropia Survey The goal of this project was to locate and characterize the sites where Cecropia schreberiana saplings and seedlings occur.   I made a one-time survey of about 35 ha of tabonuco forest near El Verde Research Station, in 1989 before Hurricane Hugo.   What little Cecropia regeneration I found was in tree fall gaps, or in open areas along streams. Nickolas Brokaw
Precipitation and Stream Chemistry Soil organic matter content (SOM) and C:N ratios of the litter (Weaver et al. 1973, Zou et al. 1995) and SOM (Silver et al. 1999) increase with elevation and are expected to influence stream chemistry (Aitkenhead & McDowell 2000). Linking stream chemistry to characteristics of watershed soils and vegetation (litter quality, soil C:N, soil C and N standing stocks) can be done within the timeframe of the current funding request. Rain, throughfall, and stream water are collected weekly at 18 LEF sites. These data cover the period from 1988 onwards. Earlier rain and stream water chemistry data are in the files from William McDowell. William H. McDowell
Prieta stream - Discharge and water level at pool 0 This is a long-term monitoring of water discharge and water level at Prieta Stream. The monitoring point is located at Pool 0, which is the same location where we sample stream chemistry. Alonso RamIrez
Riparian Carbon and Nitrogen Dynamics 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. William H. McDowell
Seedling and Sapling Dynamics Studies of seedlings and saplings are and have been conducted on several landslides and plots on the LEF. The primary purposes are to study seedling recruitment and seedling and sapling growth and the effect of hurricane disturbance (specifically Hugo) on these processes as related to the degree of canopy disturbance, and the temporary reduction in shade from the defoliation of the canopy under distinct soil conditions. 9Ha Study Nickolas Brokaw, Douglas Reagan
Soil Carbon and Nutrients in the Luquillo Experimental Forest (LEF) In this study, we examine the spatial variability of soil carbon, nitrogen and phosphorus in the Luquillo Experimental Forest (LEF) using a spatially explicit version of the CENTURY biogeochemistry model. We took soil samples from 119 locations in the Luquillo Mountain during the summer of 1998 and 1999. Then we compared the simulated soil C, N and P pools with observed values as a way to validate our simulation results. Charles A.S. Hall
Soil Nutrient Dynamics in Bisley Soils and forest floor were sampled quantitatively from a montane wet tropical forest in Puerto Rico to determine the spatial variability of soil nutrients, the factors controlling nutrient availability, and the distribution of nutrients in soils and plants following Hurricane Hugo. Whendee Silver
Soil Organic Matter Dynamics in Tabonuco Forest In this project we try to find out the relationship between the primary production and the soil organic carbon fractions in the tabonuco forest, a plantation and a secondary forest in Guzman. Xiaoming Zou
Streamflow in the Luquillo Experimental Forest (LEF) The US Geological Survey has monitored daily average streamflow (in cubic feet per second; CFS) at 19 streams in or near the Luquillo Experimental Forest starting in 1945 (Table 1). Twelve streams are reported here. This summary includes monthly summaries of that data set through 30 September 1994. More recent data are available from the USGS Streamflow Web site. Douglas A. Schaefer
STREAMS Project at La Selva Biological Station, Costa Rica The STREAMS Project at La Selva Biological Station, Costa Rica (owned and operated by the Organization for Tropical Studies, OTS) was established in 1985. Before this program, little was known about the biogeochemistry, structure, and function of Central American streams. Scientific understanding of neotropical streams has been primarily based on research conducted in South America on the Amazon (and to a lesser extent, the Orinoco). Results of the STREAMS Project comprise one of the few longterm datasets on stream solute chemistry and ecology in primary lowland rainforests of Central America. The project encompasses four areas: (1) linkages between stream ecology and biogeochemistry (e.g., Pringle 1991; Pringle and Triska 1991; Pringle et al. 1993, Triska et al. 1993; Duff et al. 1996; Genereux and Pringle 1997, Pringle and Triska 2000, Triska et al. 2006a,b, Ramirez and Pringle 2006, Ramirez et al. 2006, Stallcup et al. Catherine Pringle
Dynamics of Stream and Riparian Ecosystems Urban activities and related infrastructure alter the natural patterns of stream physical and chemical conditions. According to the Urban Stream Syndrome, streams draining urban landscapes are characterized by high concentrations of nutrients and ions, and might have elevated water temperatures and variable oxygen concentrations. Here, we report temporal and spatial variability in stream physicochemistry in a highly urbanized watershed in Puerto Rico. The main objective of the study was to describe stream physicochemical characteristics and relate them to urban intensity, e.g., percent impervious surface cover, and watershed infrastructure, e.g., road and pipe densities. The Río Piedras Watershed in the San Juan Metropolitan Area, Puerto Rico, is one of the most urbanized regions on the island. The Río Piedras presented high solute concentrations that were related to watershed factors, such as percent impervious cover. Alonso RamIrez
El Yunque Chronosequence Project The El Yunque Chronosequence plots consist of four sites, El Verde 1 (EV1), Sabana 1 (SB1), Sabana 2 (SB2), and Sabana 3 (SB3), which are located at the edges of El Yunque National Forest at sites to the south of El Verde and Sabana Field Stations.  The plots represent a range of successional stages representing areas in agriculture or recently abandoned in 1936 but reforested after 1950, and areas in agriculture or recently abandoned in 1977 and reforested since that time.  They range in size from ~0.5 to 1 ha, vary in elevation from ~150m to 550m a.s.l. and span a wide range of ages and land use histories (Table 1). Plot Name Size Age Maria Uriarte, Jess Zimmerman
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. Michael R. Willig, Steven J. Presley
Invertebrates of Luquillo Invertebrates are an important component of tropical forest ecosystems, accounting for 70-80% of species.  They respond to environmental changes and have important effects on ecosystem processes through their consumption of plant material, contribution to litterfall and augmentation of throughfall nutrients.  Studies of invertebrates at Luquillo have addressed arthropod responses to disturbances (hurricanes and droughts) and long-term changes in environmental conditions, and arthropod effects on foliage removal and nutrient fluxes. Timothy D. Schowalter
Research in Luquillo LTER Schoolyard project: Description For nearly 20 yr, the US Forest Service and the University of Puerto Rico-Río Piedras have collaborated to develop K-12 curriculum in science and mathematics throughout Puerto Rico. These efforts led to the development of the LUQ Schoolyard LTER program that now involves high schools in four rural municipalities. Self-motivated teachers from each of these schools, with the assistance of their students, have established long-term plots on public and private lands near their schools to study forest structure and dynamics. In some schools, these investigations have had outstanding results, with teachers publishing in a peer-reviewed journal (Acta Científica, Vol. 13, 1999) and attending national conferences. Noelia Baez Rodriguez, Steven McGee
Schoolyard research in a secondary forest localized in the kart zone in the municipality of Florida, Puerto Rico: Description In 1999, a science teacher of the Juan Ponce de Leon High School in Florida-Puerto Rico, Elliot Lopez, and some students, establish a research area in a secondary forest localized in the kart zone in the municipality of Florida, with the assistance of the International Institute of Tropical Forestry. This zone has a high diversity of species. The research area (2000 m²), denominated Mogote Cuba, provides an idyllic area to develop special studies since it is the habitat of some species that are not common in other places like Coccoloba pubescens. Other trees species present are Dendropanax arboreus, Alchornea latifolia, Persea americana, Ceiba pentandra , Adira inermis, Calophyllum calaba, Zanthoxylum martinicense, Nectandra coriacea,Guarea trichiloides, Trichillia pallida and Pimenta racemosa. The Puertorrican giant green lizard (Anolis cuvieri) is one of the reptiles present in that forest. Elliot Lopez
Schoolyard research in Dry Scrub Forest Plot of Guánica State Forest: Description <p>The purpose of this investigation is to establish a database as part of a long-term ecological research at the dry scrub forest plot in the <span class="style3">Guánic</span>a State Forest of Puerto Rico. This investigation started in 2009 as part of the Luquillo LTER Schoolyard Program.</p> Glenda Lee Almodovar Morales
Schoolyard research in the Naranjito Secondary Forest: Description A secondary forest localized in the Anones Ward in a coffee plantation abandoned in the 1950’s in whose borderline is with the ground of the Francisco Morales High School of Naranjito. This private property, which consists of about 48 acres, belongs to Francisco Ortega Cosme. Today part of the farm is dedicated to the commercial cultivation of plantain. The good relations between the Ortega Cosme family with the high school and the community contribute to share part of the farm to develop diverse projects that deals about environmental health and conservation education. Between the special interest that represent the research area is vecinity of it to the school and to the urban zone of the town, the presence of a ravine and the fact that the dominant specie, Spathodea campanulata, is invasive specie. Glenda Lee Almodovar Morales
Schoolyard research in the secondary forest La Torrecilla, Barranquitas: Description During the years of 1986 and 1987, we selected a private area in the Forest “La Torrecilla”, located at the Barrio Barranquitas, for the development of a long-term study with the help of the International Institute for Tropical Forestry.Our study area is located at the Barrio Barrancas of Barranquitas at 3,093 feet above sea level. The area has been classified as a secondary forest in the past because it was used for agriculture since the XIX Century until 1940, to cultivate coffee. In our forest, one of our main water source originates: The Manatí River. The Forest is the lung which efficiently purifies our air. Diana Gonzalez
Wood to Soil Carbon & Nutrients This study was designed to detect the imprint of decaying logs (30-80 cm diameter) from two hurricane cohorts (Hugo, 1989, and Georges, 1998) on soil carbon, nutrients and microbial biomass C. Quantification of root length at 0-10 cm depth was added after the first log was sampled. Volumetric soil cores were taken under the logs at two depths, 0-10 and 10-20 cm. Paired samples were taken away from the logs on the same date within 50 cm of the under-log samples, and 20-50 cm away from the log drip line to reduce background variation in soils. Samples were collected in: April 1999 dry season (0.6 and 9.6 years after Hurricanes Georges and Hugo, respectively); January 2000 end of wet season; September 2000 wet season (1.1 and 11 years after Hurricanes Georges and Hugo, respectively). Two pairs of samples were collected on each date from each log, one pair in the uphill direction and the other pair in the downhill direction. D. Jean Lodge, Grizelle Gonzalez