Regional variation in Caribbean dry forest tree species composition

Janet Franklin,David W. Steadman,Humfredo Marcano-Vega,Ethan H. Freid,Julie Ripplinger

doi:10.1007/s11258-015-0474-8

Abstract

How does tree species composition vary in relation to geographical and environmental gradients in a globally rare tropical/subtropical broadleaf dry forest community in the Caribbean? We analyzed data from 153 Forest Inventory and Analysis (FIA) plots from Puerto Rico and the U.S. Virgin Islands (USVI), along with 42 plots that we sampled in the Bahamian Archipelago (on Abaco and Eleuthera Islands). FIA data were collected using published protocols. In the Bahamian Archipelago, we recorded terrain and landscape variables, and identified to species and measured the diameter of all stems ≥5 cm at 1.3 m height in 10 m radius plots. All data were analyzed using clustering, ordination, and indicator species analysis at regional and local scales. Regionally, the largest cluster group included over half of all plots and comprised plots from all three island groups. Indicator species were native Bursera simaruba (Burseraceae) and Metopium toxiferum (Anacardiaceae). Species composition was similar to dry forests throughout the region based on published studies. Other groups we identified at the regional scale consisted of many Puerto Rico and USVI plots that were dominated by non-native species, documenting the widespread nature of novel ecosystems. At the local scale the Bahamian data clustered into two main groups corresponding largely to the two islands sampled, a pattern consistent with the latitudinal aridity gradient. Bahamian dry forests share previously undocumented compositional similarity with native-dominated dry forests found throughout the Caribbean, but they lack extensive post-disturbance novel dry forests dominated by non-native trees found in the Greater Antilles.

Highlights

Understanding regional variation in plant community composition is required in an era of global change because ecosystem processes and services depend on taxon-specific responses to climate change, land use change, novel species combinations, and altered disturbance regimes (Sala et al 2000; Tylianakis et al 2008)
Other groups we identified at the regional scale consisted of many Puerto Rico and U.S Virgin Islands (USVI) plots that were dominated by non-native species, documenting the widespread nature of novel ecosystems
We addressed the first question by analyzing Forest Inventory and Analysis (FIA) data available from the U.S Department of Agriculture (USDA) Forest Service for Puerto Rico and the U.S Virgin Islands (USVI) in conjunction with comparable plot data we collected on Bahamian islands

Summary

Introduction

Understanding regional variation in plant community composition is required in an era of global change because ecosystem processes and services depend on taxon-specific responses to climate change, land use change, novel species combinations, and altered disturbance regimes (Sala et al 2000; Tylianakis et al 2008). Patterns of diversity and composition of Neotropical dry forests have been broadly described (Gentry 1995), and ecological attributes of Antillean (Lugo et al 2006) and south Florida, US (Gillespie 2006) dry forests have been reviewed. Dry forests have been studied on individual islands within the Caribbean region, a comprehensive, quantitative analysis of Caribbean dry forest composition is lacking. Dry forest communities in some parts of the Caribbean, such as the Bahamian Archipelago, are not well studied (Carey et al 2014).

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Results

Conclusion