A DATA SET is a series of observations collected by the same methodology. Each data set should have documentation sufficient for someone unfamiliar with the research to replicate the study. Data sets may be broken into subsets (data files) that are discrete in space and time, in that order. The documentation for a data set should include all spatial and temporal subdivisions of the data.

(Data, Abstract, Methods, Variables)

NOTES:

• Add rows to tables or lines to paraghaphs as you need them for entering your data.
• Contact emelendez@lternet.edu, if you have any question.

PERSON(S) COMPLETING THIS FORM: E-MAIL ADDRESS:

DATA SET IDENTIFIER: Litterfall of the tabonuco forest before hurricane Hugo

PROJECT TITLE: Nutrient Cycling in Tabonuco Forest (MRCE/LTER Litterfall Nutrient Fluxes, and Extractable Soil versus Microbial Biomass Nitrogen)

PROJECT DESCRIPTION: 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):

The Minority Research Centers of Excellence (MRCE) experiment was designed originally to determine whether forest productivity was limited by nutrient availability, genetic constraints or climatic variables along a steep environmental gradient in the Luquillo Mountains of Puerto Rico. Comparisons were made between dwarf forest at 500 m elev. and tabonuco forest from 300-400 m elev. There were two main experiments in the original design: 1) forest fertilization (complete versus none); 2) transplant experiments using common gardens at high and low elevation, with and without wind protection at high elevation. In addition, phenology of leaves was studied in the dwarf forest to determine the longevity of leaves in the canopy.

Hurricane Hugo struck in September 1989, following a year of pre-treatment measurements and just as the forest plot fertilization experiments were to begin, and deposited a year and a half of annual above ground litter inputs of phosphorus on the forest floor in green leaf litter (Lodge et al. 1991).  As phosphorus is thought to be the most limiting element, this necessitated the addition of a hurricane debris-removal treatment as a second type of control in the lower elevation tabonuco forest. Furthermore, the hurricane changed the nature of the study into one of looking at changes in forest composition and the recovery of forest productivity in response to fertilization and hurricane debris-removal. Seedling, sapling, herbaceous plant, and fern responses, as well as measurements of light availability and canopy closure were added to the originally planned measurements of tree diameter growth, leaf litter production, and fine root production and turnover. Funding for continued studies of the MRCE plots ended in 1998, but they were of such great value as a long-term experiment that they were incorporated into the LTER program. Another hurricane in 1998 (Hurricane Georges) presented an opportunity to look at the effects of removing only the woody debris (in new plots) versus removing all hurricane debris.

The leaf decomposition experiment was originally designed to examine short-term disappearance of foliage from three important montane species: Prestoea montana (R. Grah.) Nichols, Dacryodes excelsa (Vahl.), and Cyrilla racemiflora. Hurricane Hugo (August, 1989) provided a unique opportunity to study effects of this type of natural disturbance on decomposition. The study was repeated in 1990 as part of the LTER, with some changes in the design that allowed for comparisons of short -term foliar litter biomass and nitrogen dynamics: (1) among the three species, (between the colorado and tabonuco forest types, (3) between riparian and upland sites, and (4) between pre- and post-hurricane environments.

LTER CORE AREAS: (Annotate all that apply)

Primary Productivity

Disturbance Patterns

LEF LTER 1 RESEARCH TOPIC: (Annotate all that apply)

Litter breakdown

We define a data file as a component of a data set. A data set can have only one data file or more. Basically, different data files have different data structures or format.
DATA SET FILES (SUBSETS):

Data File No.	Data File Identifier	On-Line Filename	Starting Date	Periodicity of sample	End Period
1	Mean Monthly leaffall rate of eight common species before Hugo	litttab1.txt	November 1980	biweekly	October 1981
2	Monthly separated leaffall rate of eight common species before Hugo	litttab2.txt	November 1980	biweekly	October 1981
3	Monthly separated ( by litterfall type) leaffall rate before Hugo	litttab3.txt	November 1980	biweekly	October 1981
4	Monthly separated (all months) leaffall rate before Hugo	RateByMonth.txt	November 1980	biweekly	October 1981

RESEARCH LOCATION: A 1 ha plot (100 x 100 m) was randomly established in two sites: a mid-successional forest (MSF) and an adjacent mature tabonuco forest (MTF) in the Luquillo Experimental Forest of Puerto Rico

INVESTIGATORS:
PRINCIPAL INVESTIGATORS E-MAIL address

Xiaoming Zou

xzou@lternet.edu

OTHER RESEARCHERS E-MAIL address

CONTACT PERSONS E-MAIL address Phone Number (Include area code)

Xiaoming Zou

xzou@lternet.edu

(787) 764-0000. Ext: 2868

SOURCE OF FUNDING (SPONSOR): NSF-LTER

DATA SET ABSTRACT: 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.

DATA SET METHODS:
Forest structure and species composition

A 1 ha plot (100 x 100 m) was randomly established in each of the MSF and MTF in 1980. Within each plot, twenty circular subplots (113 m2) were randomly located. All trees greater that or equal to 0.1 m in DBH (diameter at breath height) in each subplot were identified and the DBHs were recorded.

Litterfall and ground litter biomass

Twenty 1 m2 baskets lined with 1 mm2 mesh fiberglass screen were randomly placed in each 1 ha plot at 1 m above ground. Litterfall was collected biweekly for 1 yr between November 1980 and October 1981. All litter samples were separated into leaves, flowers, fruit, wood, and miscellaneous materials (mostly bark), oven-dried at 70°C for 72 hrs, and weighed. Ground litter was collected from 0.25 m2 subplots in both the dry season (March, 40 subplots) and the wet season (September, 20 subplots) randomly located in each of the 1 ha plots. Each sample was separated into wood and miscellaneous categories, oven-dried at 70°C for 72 hrs, and weighed.

Leaf decomposition

A total of 140 litterbags were constructed among which 70 litterbags were filled with fresh leaves collected from the MSF and 70 from the MTF (Blair et al., 1990). These fresh leaves represented the tree species composition in natural litterfall in April at both sites. The species composition of litterfall was determined using leaffall in the 1-m2 randomly placed baskets in each plot. Fresh leaves were collected for each forest within 24 hours of senescence in May and sorted by species. Leaves of the 13 most common species from each forest, representing 82-91% of the total fresh leaf mass, were placed in 1-mm2 mesh fiberglass screen bags (0.2 by 0.25 m) in proportion to their biomass in litterfall. Leaves of the remaining 25 species were put in a miscellaneous category and randomly selected to obtain a total of 10-g fresh leaf material (4.6 g mean oven-dry mass) in each bag.

For each leaf type, 35 litterbags were placed equally in 5 randomly selected subsites in the 1 ha plots where leaves were collected. In order to separate the effects of leaf chemistry on leaf decomposition from those of biotic and abiotic environmental conditions between the two forests, the other 35 litterbags for both leaf types were together placed in a 10 x 10 m plot in the MTF at five randomly selected locations. The 1 ha plots covered an area with heterogeneous geographical locations including ridges and valleys, whereas the 0.01 ha plot was located on a ridge top and upper slope position. One randomly selected litterbag was collected after 0, 7, 14, 28, 60, 120, and 300 days in the field at each site from each plot. There were 2 (leaf types) x 2 (incubation sites) x 5 (replicates) x 7 (collections) = 140 litterbags.

Small roots which had entered the litter bags were carefully removed in the laboratory. The remaining litter in each bag was oven dried at 70 °C for 72 hours and weighed to determine dry mass loss. Dry litter was then ground with a Wiley mill through a 0.85 mm (20 mesh) stainless steel sieve. One gram of the ground leaf material from each litterbag was digested with H2O2 and concentrated HNO3 (Luh Huang and Schulte, 1985) before analyzing for P, K, Ca, and Mg content with an atomic absorption and emission spectrophotometer. Total C and N in leaf material were analyzed by direct combustion in a C-H-N analyzer (Carlo-Erba Model 1106).

Data analyses

Basal area, tree density, and leaffall for each species were calculated for each forest. Total litterfall rate and ground litter biomass of all species were also calculated for each forest. The analysis of variance (ANOVA) was employed to test the differences in basal area, tree density, leaffall rate, and ground litter biomass between the forests or the seasons (SAS, 1987). Leaf decay rates were calculated using a single exponential model Mt = M0e-kt, where Mt was the remaining mass of leaf materials in a litter bag at time t and M0 was its initial mass. Slope k was obtained using linear regression after taking the natural logarithms of the equation. Multivariate tests were used to examine differences in k values between the two forests and between sites (SAS, 1987). The significance level was set at a = 0.05.

Percentage of initial weight remaining was calculated using oven-dried weight. Percentage of initial element remaining in litterbags was obtained by multiplying the ratio of total element at time t (t = 0, 7, 14, 28, 60, 120, and 300 days) to that at time 0 by 100. Total element content in a litterbag was calculated as the product of element concentration and the oven-dry weight. Differences in elemental concentrations between forests and among decomposing dates were tested with ANOVA. Where significant differences were obtained by ANOVA, Bonferroni t-test (SAS Inc., 1987) was used to compare these differences in elemental concentrations. The significance levels for ANOVA and Bonferroni t-test were both set at à = 0.05. Plots of residuals vs. predicted values indicated that no variables significantly violated the homogeneity assumption, with the exception of K concentrations. A non-parametric analysis was employed by ranking K concentrations prior to performing ANOVA and Bonferroni t test.

REFERENCES:
Blair, J.M., Parmelee R. W. and Beare, M. H., 1990. Decay rates, nitrogen fluxes, and decomposer communities of single- and mixed-species foliar litter. Ecology, 71: 1976-1985.

Luh Huang, C. Y. and Schulte, E. E., 1985. Digestion of plant tissue for analysis by ICP emission spectroscopy. Comm. Soil Sci. Plant Anal., 16: 943-958.

SAS Inc., 1987. SAS Guide for personal computers. 6th edition. Cary, North Carolina, USA.

Odum, H. T. and Pigeon, R. F. 1970. A tropical rain forest: A study of irradiation and ecology at El Verde, Puerto Rico. U.S. Atomic Energy Commission, National Technical Information Service, Springfield, Virginia, USA.

Ewel, J. J., and Whitmore, J. L., 1973. The ecological life zones of Puerto Rico and the U. S. Virgin Islands. U.S.D.A. Forest Service Research Paper ITF-18, 71 pp.

Brown, S., Lugo, A., Silander S. and Liegel, L., 1983. Research history and opportunities in the Luquillo Experimental Forest. USDA Forest Service General Technical Report SO-44, 128 pp.

Huffaker, L., 1995. Soil survey of the Caribbean National Forest and Luquillo Experimental Forest. USDA Forest Service, Washington D.C. (in press).

CROSS-REFERENCES (other data sets related to this one): LTERDBAS#51: MRCE/LTER Soil and Microbial Biomass Nitrogen; LTERDBAS #93: Litter decomposition in tabonuco forest before Hugo; LTERDBAS #94: Litterfall of the tabonuco forest before Hurricane Hugo; LTERDBAS #95: Litterfall along topographic gradients at lower Bisley; LTERDBAS #111: Litterfall in tabonuco (subtropical wet) forest in the Luquillo Experimental Forest, Puerto Rico (MRCE Litterfall data); LTERDBAS #115: Short-term disappearance of foliar litter of three tree species native to rain forest of Puerto Rico

SAMPLE LOCATION: ITES, Soil Laboratory

STORAGE SITES: ITES, Data Manager's File DM-002 , Drawer #1

INVESTIGATOR'S ASSIGNED KEYWORDS: forest recovery, leaf decomposition, secondary forest, tabonuco forest

LEF LTER OFFICIAL KEYWORDS (See table): EL VERDE, TABONUCO, DECOMPOSITION, LITTER FALL, SECOND FOREST, TREES, PEER REVIEWED JOURNAL

PUBLICATIONS:
Zou, X., C. Zucca, R. B. Waide, and W. H. McDowell. 1995. Long-term influence of deforestation on tree species composition and litter dynamics of a tropical rain forest in Puerto Rico. Forest Ecology and Management 78:147-157. (Abstract)

DISSEMINATION: UNRESTRICTED

REASONS TO RESTRICT DATA IN THIS DATA SET BEYOND ITS TWO YEAR POLICY PERIOD*:

*WILL HAVE TO BE APPROVED BY LTER PRINCIPAL INVESTIGATORS: N. BROKAW, A. LUGO

SITES DESCRIPTIONS: This study was conducted in the Luquillo Experimental Forest (LEF) at the El Verde Field Station (18°20'N, 65°49'W) in Puerto Rico. The research area was located in lower montane rain forest (Odum and Pigeon, 1970, Ewel and Whitmore, 1973), where the mature forest is typically dominated by tabonuco trees (Dacryodes excelsa Vahl.). Elevation of the tabonuco forest ranges between 300-600 m. Mean monthly temperature varies from 20.8-24.4°C with a mean annual precipitation of 3456 mm (Brown et al., 1983). Although there is no obvious dry season in the area, a period of reduced rainfall occurs between January and April. Soils were dominated by Zarzal series that are deep Oxisols of volcanic origin (Huffaker, 1995).

Geographical positional system (GPS) Coordinates for each location:

location	latitude	longitude
MTF = mature tabonuco forest
MSF = mid-successional forest

VARIABLES (ATTRIBUTES)

FILE NAME OR #ABOVE (all in which the variable appears)	1	1	1	2, 3, 4	2, 3, 4	2
ABBREVIATION (as it appears on the data file)	Species	MSF_g-m2-yr	MTF_g m-2-yr	MONTH	YEAR	DATE
NAME OF VARIABLE	Scientific name	litterfall by species at mid-successional forest	litterfall by species at a mature tabonuco forest	Month of collection.	Year of collection	Date of collection
DEFINITION OF VARIABLE	scientific name of eight common species in a mid-successional forest (MSF) and a mature tabonuco forest (MTF) in Puerto Rico. No data are missing in this field.	Annual leaffall rate (standard error) of the eight common species in a mid-successional forest (MSF) in Puerto Rico. No data are missing in this field.	Annual leaffall rate (standard error) of the eight common species in a mature tabonuco forest (MTF) in Puerto Rico. No data are missing in this field.	Month of collection. No data are missing in this field.	Year of collection. No data are missing in this field.	Date of collection (in mm/dd/yyyy). No data are missing in this field.
UNIT		gramsPerMeterSquaredPerYear	gramsPerMeterSquaredPerYear
PRECISION
RANGE OR LIST OF VALUES
DATA TYPE	alphanumeric	alphanumeric	alphanumeric	alphabetic	integer	date
MISSING DATA CODES

VARIABLES (CONTINUES)::

FILE NAME OR #ABOVE (all in which the variable appears)	2	2	2	2	2	2	2
ABBREVIATION (as it appears on the data file)	PLOT3MTF-LEAF_G-M2-D	PLOT3MTF-FLOWER_G-M2-D	PLOT3MTF-FRUIT_G-M2-D	PLOT3MTF-WOOD_G-M2-D	PLOT_3MTF-MISC_G-M2-D	PLOT4MSF-LEAF_G-M2-D	PLOT4MSF-FLOWER_G-M2-D
NAME OF VARIABLE	Weight of leaves of eight common species from a mature tabonuco forest plot 3	Weight of of flowers of eight common species from a mature tabonuco forest plot 3	Weight of fruits of eight common species from a mature tabonuco forest plot 3	Weight wood of eight common species from a mature tabonuco forest plot 3	Weight of miscelaneous material of eight common species from a mature tabonuco forest plot 3	Weight of leaves of eight common species from a mid-secondary forest plot 4	Weight of flowers of eight common species from a mid-secondary forest plot 4
DEFINITION OF VARIABLE	Weight of leaves from twenty 1m2 baskets from plot 3, baskets lined with 1 mm2 mesh fiberglass screen, randomly placed in each 1 ha plot at 1 m above ground from which litterfall was collected biweekly for one year. No data are missing in this field.	weight of flowers from twenty 1m2 baskets from plot 3, baskets lined with 1 mm2 mesh fiberglass screen, randomly placed in each 1 ha plot at 1 m above ground from which litterfall was collected biweekly for one year. No data are missing in this field.	weight of fruits from twenty 1m2 baskets, baskets lined with 1 mm2 mesh fiberglass screen, randomly placed in each 1 ha plot at 1 m above ground from which litterfall was collected biweekly for one year. No data are missing in this field.	weight of wood from twenty 1m2 baskets, baskets lined with 1 mm2 mesh fiberglass screen, randomly placed in each 1 ha plot at 1 m above ground from which litterfall was collected biweekly for one year. No data are missing in this field.	weight of miscelaneous material from twenty 1m2 baskets, baskets lined with 1 mm2 mesh fiberglass screen, randomly placed in each 1 ha plot at 1 m above ground from which litterfall was collected biweekly for one year. No data are missing in this field.	Weight of leaves from twenty 1m2 baskets from plot 4, baskets lined with 1 mm2 mesh fiberglass screen, randomly placed in each 1 ha plot at 1 m above ground from which litterfall was collected biweekly for one year. No data are missing in this field.	weight of flowers from twenty 1m2 baskets from plot 4, baskets lined with 1 mm2 mesh fiberglass screen, randomly placed in each 1 ha plot at 1 m above ground from which litterfall was collected biweekly for one year. No data are missing in this field. No data are missing in this field.
UNIT	grams SquareMeter per Day	grams SquareMeter per Day	grams SquareMeter per Day	grams SquareMeter per Day	grams SquareMeter per Day	grams SquareMeter per Day	grams SquareMeter per Day
PRECISION
RANGE OR LIST OF VALUES
DATA TYPE	decimal	decimal	decimal	decimal	decimal	decimal	decimal
MISSING DATA CODES

FOR DATA MANAGER USE ONLY

DATE OF LAST REVIEW: 3 May, 2009
DATE OF LAST ENTRY: October 1981
STAGE OF DATA SET MANAGEMENT (dates):
RECEIVED: October 10, 1996
CATALOGUED: May 5, 1997
ON-LINE: May 6, 1997
REVIEWED BY RESEARCHER: May 5, 1997
FILING MEDIA:
NAME OF DOCUMENTATION FILE : LEFDS197.FM*
NAME OF DATA FILE: litttab1.txt, litttab2.txt, littab3.txt RateByMonth.txt
NAME OF ON - LINE CATALOG: LEFDSET1
RECORD #: 97
DOCUMENT TYPE: magnetic media - paper
PRIORITY TO BE ENTERED: N/A 

Rev. date of this form: 8 June 2001