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SPATIAL VARIABILITY IN SPECIES COMPOSITION IN NEOTROPICAL MONTANE TREE COMMUNITIES

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abstract
A plot network was used to look at changes in stand–level characteristics, diversity, and floristic composition across the elevational gradient and at tree line. Thirty –six 0.1–ha tree plots were installed (1) along three different elevational transects in tropical montane cloud forest (TMCF) between 1500 and 3600 m and (2) across a ∼ 40 km landscape transect near tree line above 3200 m in southeastern Peru. Stand variables were correlated with explanatory variables such as geographic distance, environmental variables as aspect, slope, potential solar radiation (PSR), and carbon&ndash6;nitrogen soil content to examine the variation explained by environmental variation in addition to elevation (temperature). Results show a total of 435 species across the elevation gradient and 121 in the landscape sample near Andean treeline. At mid elevation plots (1600 — 2900 m) Cyatheaceae and Melastomataceae were the most abundant families. The plots near treeline (above 3200 m) were similar in their composition at family and genus level but distinct at the species level, with Melastomataceae being the family with most individual trees and Asteraceae the most species–rich family. In both the elevational transects and the landscape–level within–elevation transect, geographic distance between plots had no correlation with floristic similarity. Elevation was correlated with tree community composition and diversity for all plots, but the strength of the trend changed between elevational transects, indicating the importance of landscape heterogeneity. Correlations with environmental variables (aspect and slope) showed no relationship with either species richness or diversity. However there was a significant relationship with potential solar radiation (PSR). In this study elevation was the main factor that influenced the floristic composition and diversity across the elevational gradients, even across small elevation changes near tree line. Potential solar radiation had significant effects on species richness in both the elevational transects and the landscape sample near Andean treeline. These results indicate an important role of PSR. More empirical and experimental data are needed to fully understand the effect of PSR on plant communities in these montane forests. Future studies should incorporate additional explanatory variables such as disturbance (both anthropogenic and natural), cloud regime and a broader array of soil nutrients.
subject
montane forest
tree communities
contributor
Garcia Cabrera, Karina (author)
Silman, Miles R (committee chair)
Browne, Robert A (committee member)
Smith, William K (committee member)
date
2012-01-18T09:35:33Z (accessioned)
2012-07-18T08:30:15Z (available)
2011 (issued)
degree
Biology (discipline)
embargo
2012-07-18 (terms)
identifier
http://hdl.handle.net/10339/36437 (uri)
language
en (iso)
publisher
Wake Forest University
title
SPATIAL VARIABILITY IN SPECIES COMPOSITION IN NEOTROPICAL MONTANE TREE COMMUNITIES
type
Thesis

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