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J.O. López-Martínez et al. 2010. Ecological factors influencing beta diversity at two spatial scales in a tropical dry forest
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Ecological factors influencing beta diversity at two spatial scales in a
tropical dry forest of the Yucatán Peninsula
J. Omar López-Martínez * , J. Luis Hernández-Stefanoni & Juan Manuel Dupuy
Centro de Investigación Científica de Yucatán A.C. Unidad de Recursos Naturales,
Calle 43 # 130. Colonia Chuburná de Hidalgo. C.P. 97200, Mérida, Yucatán, México
Abstract
Understanding the ecological factors determining beta diversity at different spatial
scales is relevant for ecological theory and for conservation and management. We analyzed the
relationship of beta-diversity and environmental and spatial variables at two spatial scales. We
identified vegetation classes based on a supervised classification, determined species
composition, and obtained soil samples from a total of 276 sites in 23 sampling landscapes.
Using vegetation classes and FRAGSTAT, we calculated patch-type metrics in each landscape.
Spatial dependence was included in the models using PCNM. Partial CCA and RDA were
performed to partition variation. Soil properties, stand-age, landscape metrics and site PCNMs
were used at the local level, while landscape metrics and landscape PCNMs were used at the
landscape level. At the local level, space was the most important variable related to variation in
species composition (48.87%), whereas at the landscape-level, landscape-metrics explained
most (50%) of the variation in species composition.
Keywords: Beta diversity; CCA; forest succession; landscape patterns; RDA; spatial
dependence
1. Introduction
Beta diversity refers to variation in species composition among sites within a
geographic area (Legendre et al. 2005). It could be determined by different habitats along an
environmental gradient, or by geographic distance within seemingly uniform habitats. In the
latter case, beta diversity reflects spatial isolation among species (Halfter 1998). Beta diversity
allows us to understand how species habitats are distributed, it is also an important component
in biodiversity conservation planning and management (Halfter 1998).
Factors affecting species turnover and the scale at which they operate have been debated
for a long time in ecology. Two of the main causal factors of beta diversity are: 1) limitation in
the dispersal capacity of species that are demographically and competitively equal (neutral
theory, Hubbell 2001). 2) Environmental conditions as a determinant of species presence and/or
abundance (niche theory, Grubb 1977).On the other hand, it is important to note that factors
affecting species turnover may vary among spatial scales (Garcia 2006).
The aim of this study was to analyze the relative importance of environmental
heterogeneity, stand age, landscape structure and spatial dependence on species turnover of a
tropical dry forest at two different spatial scales.
* Corresponding author.
Email address: jmartinez.omar@gmail.com
Forest Landscapes and Global Change-New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.