Abstract Detail

Ecological Section

Toledo, María [1], Williams Linera, Guadalupe [2].

Climate effect on vegetation structure and tree diversity along an entire elevation gradient in central Veracruz, México.

Climate has been studied as an important factor to explain changes in vegetation structure, species richness and composition along elevation gradients. If climate does not change randomly along elevation gradients and climate variables can predict diversity patterns, then, the species richness gradient is essentially a climate gradient. The objective of this study was to determine the ecological significance of the relationship between climate, vegetation structure and tree diversity in an entire elevation gradient (140-4000 m) in central Veracruz, México. We selected 15 sites along the gradient. In each site ten 10 x 10 m plots were established and all trees > 5 cm dbh were counted, measured and identified. For each site, 19 climate variables were extracted from WorldClim database. Ordination and the selection of significant climate variables were performed using Canonical Correspondence Analysis (CCA). CCA suggested three groups of sites explained by precipitation of the coldest quarter of the year (PPcold) and mean temperature of the warmest quarter of the year (Twarm). The sites along the gradient were ordered as dry forest (140-780 m) related with Twarm, an ecotone (986 m), and both montane cloud forest (1275-2650 m) and coniferous forest (3020-4000 m) related to PPcold. [G1] Dominant families varied along the gradient: Fabaceae was dominant in dry forest, Fagaceae and Lauraceae in the cloud forest, Pinaceae was monodominant in the coniferous forest. Species richness, basal area and density were related to elevation, PPcold and Twarm using lineal and polynomial regressions; the best model was selected using Akaike Information Criteria. Along the whole gradient, species richness, basal area, and PPcold were best fitted with a second order polynomial model, Twarm decreased linearly; but density did not show a significant relation with elevation. Both species richness and basal area were positively correlated with PPcold and negatively with Twarm. Species richness peaks at mid elevation and is related to the part of the gradient where precipitation is the highest and seasonality (measured and coefficient of variation) is less variable during the year (the cloud forest region). We conclude that change in species composition and types of vegetation are determined by climatic drivers.

Broader Impacts:

1 - Universidad Nacional Autónoma De México, Facultad De Ciencias, Rosa Estrella No. 10, Ciudad De México, N/A, 01470, Mexico
2 - Instituto de Ecología A.C., Ecología Funcional, Carretera antigua a Coatepec 351 El Haya, Xalapa, Veracruz, 91070, México

Keywords:
Elevation gradients
Communities
climate
Vegetation types
Tree diversity.

Presentation Type: Oral Paper:Papers for Sections
Session: 10
Location: Ascot/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 2:15 PM
Number: 10004
Abstract ID:184
Candidate for Awards:Ecological Section Best Graduate Student Paper