DATA SET IDENTIFIER: Seedling and sapling dynamics of treefall pits and undisturbed florest floor in El Verde, Puerto Rico.

PROJECT TITLE: Seedling and Sapling Dynamics

PROJECT DESCRIPTION: 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

The primary purpose of this study is to look at seedling recruitment, and the growth of seedlings and saplings as it relates to the degree of canopy disturbance caused by Hurricane Hugo. Although all trees down to 1-cm dbh will eventually be identified and measured for the separate 16-ha grid project, the smallest trees will not be measured for at least a year, and seedling will not be included in the 16-ha grid program. The seedling/sapling plots in the 9-ha grid will allow us to follow early responses of seedlings and saplings to increased light. Tree maps for the 16-ha grid which will encompass the 9-ha grid) will eventually be used to determine the proximity of seed-source trees to each plot.

Treefall Pits Study

In this study, I compared seedling and sapling dynamics in soil pits and undisturbed forest floor, were both environment has experienced a temporary reduction in shade from the defoliation of the canopy during Hurricane Hugo (September 1989) but had soil conditions that were distinct. Soil pits were chosen as the microsite within the treefall gap most likely to differ in soil characteristics from the adjacent forest and most likely to alter plant establishment patterns. Soil mounds, important sites of establishment in some temperate forests (Webb 1999), erode quickly under the high rainfall conditions in Puerto Rico and were not considered in this study. I asked the following questions: (1) how does the soil physical environment differ between the soil pit and the forest floor?; (2) do tree species that have N-fixing symbionts influence soil nutrients or species composition of colonizers?, and (3) what are the consequences of uprooting and defoliation for populations of seedlings and saplings and for tree recruitment?

LTER CORE AREAS: (Annotate all that apply)

Disturbance pattern

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

Disturbance regime

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	cation analysis	tipcation.txt	May 1991	every 5 months, approxly.	May 1992
2	seedling numbers	tipalldate.txt	May 1991	every 5 months, approxly.	May 1992

RESEARCH LOCATION: A 70-ha research forest near the El Verde Station in the LEF.

INVESTIGATORS:

PRINCIPAL INVESTIGATORS E-MAIL address

Lawrence Walker

walker@lternet.edu

OTHER RESEARCHERS E-MAIL address

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

Lawrence Walker

walker@lternet.edu

(702)895-3196

SOURCE OF FUNDING (SPONSOR): NSF-LTER

DATA SET ABSTRACT: 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.

DATA SET METHODS: All trees used in this study were uprooted during Hurricane Hugo (18 Sep 1989), providing an unique opportunity to compare treefalls of identical age. My study area was in the forest that experienced the least of the damage (9% of all trees uprooted). A total of 27 uprooted trees (x = 16.6 ± 2.6 m tall) were chosen from two tree species with symbiotic N-fixing bacteria (Edmistein, 1970), Inga laurina (Fabaceae; N = 4) and Ormosia krugii (Fabaceae; N = 9), and one tree species without simbiont Casearia arborea (Flacourtiaceae; N = 14). I observed live nodules on roots of the first two tree species but N-fixation was not measured.

One plot was placed in the center of the mineral soil oil of each pit ("pit plot"), and one plot (of equal size) in the undisturbed forest floor ("forest floor") 2-5 m from the edge of the floor pit in a haphazardly chosen direction (excluding the area under the uprooted pit). The forest plots were selected to be outside the vertical extension of the canopy gap created by the treefall (Brokaw 1985) but still within the presumed zone of influence of roots and nodules from the target tree. The understory in the forest plots was largely undisturbed by the hurricane.

One sample of surface mineral soil (6 cm diameter x 5 cm deep) was collected from each 0.5-m² plot in July 1990 (10 mo after Hurricane Hugo). Mineral soils were sampled after the removal of the O1 and O2 organic horizons in the forest and any miscelaneous organic debris in the pit. Upon ignition at 490°C for five hours soils were then passed through a 0.15 mm (100 mesh) sieve and analized for the total N using a modified Kjeldahl method to include nirtrate and nitrite (Page 1982) and for total P (Luh Huang and Schulte 1985). Exchangeable ions were extracted using either 2N KCL (Al, Ca, Mg) or Olsen-EDTA (Fe, Mn, K) and analized with a Beckman plasma emission spectrometer (Hunter 1974).

Measurements of saplings, seedlings, and ground cover were made in the 0.5-m² plots in pits and adjacents forests seven times between May 1991 and May 1992, at 8, 13, 18, 22, 25, 30, and 32 months after Hurricane Hugo. At each visit, all woody saplings (10 - 100 cm tall; excluding vines) in each plot were identified and permanently labeled; all woody seedlings (<10 cm tall) were counted and their subsequent survivorship recorded (live = green leaves present).

REFERENCES:
Brokaw, N.V.L. 1985. Gap-phase regeneration in a tropical forest. Ecology 66:682-687.

Edmistein, J. 1970. Survey of mychorrhiza and nodules in the El Verde Forest. Pages F15-F20 in H.T. Odum and F. Pigeons, editors. A tropical rain forest: a study of irradiation and ecology at El Verde, Puerto Rico. N.T.I.S., Springfield, Virginia.

Hunter, A.H. 1974. International soil fertility evaluation and improvement. Laboratory procedures. Department of Soil Science, North Carolina State University, Raleigh, North Carolina.

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

Soil Survey Staff. 1995. Order I soil survey of the Luquillo Long-term Ecological Research grid, Puerto Rico. USDA-NRCS.

Webb, S.L. 1999. Distubance by wind in temperate zones forests. Pages 201-236 in L.R. Walker, editor. Ecosistems of disturbed ground. Elsevier, Armsterdam, The Netherlands.  

CROSS-REFERENCES (other data sets related to this one):LTERDBAS 37: Regeneration after Hurricane Hugo, woody species > 10 cm tall (9Ha grid, El Verde) (9Ha Plots Small Data Set); LTERDBAS 38: Regeneration after Hurricane Hugo, woody species > 1 m tall (9Ha grid, El Verde) (9Ha Plots Large Data Set); LTERDBAS 39: Regeneration after Hurricane Hugo woody species > 1m tall (9ha grid, El Verde)(Wood fall from Hurricane Hugo 9Ha Grid) (9Ha Plots Wood Data Set); LTERDBAS 40: Regeneration after Hurricane Hugo woody species > 1m tall (9ha grid, El Verde) Percent cover below 3m (9 ha grid, El Verde); LTERDBAS 113: Seedling and sapling dynamics of treefall pits and undisturbed florest floor in El Verde, Puerto Rico

SAMPLE LOCATION:

STORAGE SITES (of data files): ITES, Data Manager's File DM-002 , Drawer #4

INVESTIGATOR'S ASSIGNED KEYWORDS: Cecropia schreberiana; Dacryodes excelsa; hurricane; nitrogen fixation; soil nutrients; treefall; tropical rainforest

LEF LTER OFFICIAL KEYWORDS (See table): LEF, TABONUCO, NITROGEN, HURRICANE, TREEFALL, TREES, PEER REVIEWED JOURNAL

PUBLICATIONS:
Walker, L.R. 2000. Seedling and sapling dynamics in treefall pits in Puerto Rico1. Biotropica 32(2):262-275.

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: J. ZIMMERMAN, A. LUGO , D.J. LODGE

SITES DESCRIPTIONS: The 70-ha forest near El Verde station is a subtropical wet forest dominated by Dacryoides excelsa (tabonuco; Burseraceae) and Prestoea montana (sierra palm; Arecaceae). At 350 to 400 m elevation the forest receives a mean annual precipitation of 3460 mm and the mean monthly temperatures range between 21° and 25° C. The soils at El Verde are a complex of upland Utisols and Oxisols (Zarzal-Cristal complex; Soil survey Staff 1995) and are mostly well-drained clays and silty clay loams.

Geographical positional system (GPS) Coordinates for each location:

location	latitude	longitude
Near the El Verde Station	18°19 N	65°49 W

VARIABLES (ATTRIBUTES):

FILE NAME OR #ABOVE (all in which the variable appears)	1,2	1	1	1	2	2
ABBREVIATION (as it appears on the data file)	spp(1),saplspp(2)	trmt	Site	{ ca, p, fe, mn, al, mg, k}	Habitat	{date1=May 91, date2=Oct 91,  date3=Mar 91,  date4=Jul 91,  date5=Oct 92,  date6=Mar 92,  date7=May 92}
NAME OF VARIABLE	Sappling species	Treatment	Site of study	Cations measured	Habitat studied	Numbers of seedlings in each plot
DEFINITION OF VARIABLE	Tree species treated and analized. A total of 27 uprooted trees (x = 16.6 ± 2.6 m tall) were chosen from two tree species with symbiotic N-fixing bacteria (Edmistein, 1970), Inga laurina (Fabaceae; N = 4) and Ormosia krugii (Fabaceae; N = 9), and one tree species without simbiont Casearia arborea (Flacourtiaceae; N = 14)	Forest understory and soil pits created by the uprooting of 27 trees during Hurricane Hugo	Code assigned to the study area in relation to the tree species studied	Nutrient level of the tree studied (all analyses were done at the USFS lab in Rio Piedras)	Habitat studied in the 0.5-m² plots in pits and adjacents forests	Numbers of seedlings in each of the 27 plots (tree species combined for this data set)
UNIT				mg/g
PRECISION				.01
RANGE OR LIST OF VALUES	1 = Ormosia; 2 = Casearia; 3 = Inga	1 = pit; 2 = forest	1-9 (9) Ormosia trees that fell over in Hurrican Hugo; 1-14 (14) Casearia trees; 1-4 (4) Inga trees;		1 = pit; 2 = forest	0,…
DATA TYPE	alphanumeric	integer	integer	real	integer	natural
MISSING DATA CODES	N/A	Always present	Always present	Always present	None	None

COMPUTATIONAL METHODS:

Variable Name	Formula
None

DATE OF LAST REVIEW: Jan 23, 2006
DATE OF LAST ENTRY: May 2000
STAGE OF DATA SET MANAGEMENT (dates):
RECEIVED ENTERED: Nov 2000
FILED ON-LINE Feb 28, 20001
REVIEWED BY RESEARCHER
FILING MEDIA:
NAME OF DOCUMENTATION FILE: lterdb113.doc,.htm
NAME OF ON - LINE CATALOG: LTERDBAS
RECORD #: 113
DOCUMENT TYPE: magnetic media (only)
PRIORITY TO BE ENTERED: N/A

Rev. date of this form: 25 January 2001