Luquillo Data Sets By Insertion Order

Circular plot counts are used to measure relative numbers of birds over time and between sites. The duration of each count is 10 minutes. During this period, all birds heard or seen are recorded on a data sheet in one of two categories: 1) within 25 m of the observer (< 25 m) and 2) further than 25m from the observer (> 25 m). Records are further broken down into birds only heard (H on the data sheet) and birds observed (recorded as estimated distance from the sampling point in meters; see sample data sheet). Counts are begun as soon after dawn as possible and conclude before noon. Census points are at least 60 m apart within the grids. A complete list of the grid points where counts are taken is found in the data. Originally counts were conducted three times a year.

The overall height and the presence of vegetation in different height intervals above ground is recorded above points on a 5 x 5 m grid in three hectare-sized plots in the Luquillo Experimental Forest, Puerto Rico. One plots each is in tabonuco forest (350 m elevation), colorado forest (650 m) and cloud forest (1000 m). The first records were made shortly before Hurricane Hugo, in 1989. Post hurricane measurements have been made five time to six time in each plot, the most recent been in 1998 for all plots. The results show the damage to forest structure wreaked by Hurricane Hugo, steady recovery of forest structure after Hugo, minor damage by Hurricane Hortense in 1996, and resumption of recovery after Hortense. Maximum canopy height and the vertical distribution of vegetation in the forests are returning to pre-hurricane Hugo values.

Here we use permanent plot data sampled from 16 landslide to documents temporal successional pathways in landslide patches (without the use of a chronosequence, cf. Guariguata 1990) and address the following questions: (1) What are the successional pathways of landslide and what species define them? How much pathway variation of individual plots is there within these landslides? (2) How similar are pathways among landslide? Is there any evidence that, with time, landslides either converge to a common vegetative enpoint or slow in the rate of successional change?

The purpose of this study is to document the recovery of vegetation on new landslides in the Luquillo Experimental Forest.

Daily emperature has been measured at the El Verde Field Station since 1975 (see methods). Monthly averages have been calculated. Maximum values for maximum temperature were recorded from May to October with a range from 29 to 30 and peaks of 29.7 Centigrade in October. The months of October through December show the most dramatic increase, specially December (see chart). Highest average maximum temperatures during these years were recorded in 1998 and 1999 (See chart). Max monthly temperatures appear to be increasing from this years on.

Rainfall has been measured at the El Verde Field Station since 1964. McDowell and Estrada-Pinto, 1988 presents a description of the collection procedures, raw data from 1964 to 1986, and some summary statistics for this period of record. Precipitation for this period showed some seasonality in monthly means, with a peak in May. Monthly averages for the period of 1975 to current chart can be found at this site. The highest values for the monthly averages for the period of 1975 to 2000 are from August to December with a low in October and November the highest. In this period the highest amount of total annual rainfall was in 1998 with 5293.61 mm and the minimum in 1994 with 1402.87 mm.

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

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.

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.