Plant species richness and diversity along an altitudinal gradient in the Sierra Nevada, Mexico

Abstract

This article presents an analysis of plant species richness and diversity and its association with climatic and soil variables along a 1300‐m elevation gradient on the Cerro Tláloc Mountain in the northern Sierra Nevada in Mexico. Two 1000‐m2 tree sampling plots were created at each of 21 selected sampling sites, as well as two 250‐m2 plots for shrubs and six 9‐m2 plots for herbaceous plants. Species richness and diversity were estimated for each plant life form, and beta diversity between sites was estimated along the gradient. The relationship between species richness and diversity and environmental variables was modelled using simple linear correlation and regression trees. Species richness and diversity showed a unimodal pattern with a bias towards high values in the lower half of the elevation gradient under study. This response was consistent for all three life forms. Beta diversity increased steadily along the elevation gradient, being lower between contiguous sites at intermediate elevations and high – the species replacement rate was nearly 100%– between sites at the extremes of the gradient. Few species were adapted to the full spectrum of environmental variation along the elevation gradient studied. The regression tree suggests that differences in species richness are mainly influenced by elevation (temperature and humidity) and soil variables, namely A2 permanent wilting point, organic matter and horizon field capacity and A1 horizon Mg2+.

Diversity and distribution patterns of ferns and lycophytes in a cloud forest in Mexico

“…It is widely accepted that the diversity of plant species decreases as elevation increases; however, such a decline is not necessarily linear, since there are more species at intermediate elevations (Rahbek, 2005;Sánchez-González & López-Mata, 2005). In the specific case of ferns and lycophytes (Pteridophytes), some studies confirm the unimodal response in species diversity (Kluge, Kessler, & Dunn, 2006;Watkins, Cardelu, Colwell, & Moran, 2006).…”

“…In the present study, the total richness along the elevational gradient was 78 species of ferns and lycophytes; however, the richness and diversity values of both taxonomic groups showed no significant relationship (P < 0.05) with respect to elevation (Figure 2). This contrasts with the results of other investigations that refer to a unimodal response (Rahbek, 2005;Sánchez-González & López-Mata, 2005;Sang, 2008;Zhu, Jiang, Liu, Xiong, & Kang, 2007) or, less commonly, positive or negative responses between elevation and species richness, for different groups of plants and ecosystems (Rahbek, 2005;Slik et al, 2009). It is important to note that elevation is an environmental mes más frío (TMMF), rango anual de la temperatura (RAT = BIO5-BIO6), temperatura media del trimestre más húmedo (TMTH), temperatura media del trimestre más seco (TMTS), temperatura media del trimestre más cálido (TMTC), temperatura media del trimestre más frío (TMTF), precipitación anual (PA), precipitación del mes más húmedo (PMH), precipitación del mes más seco (PMS), estacionalidad de la precipitación (EP), precipitación del trimestre más húmedo (PTH), precipitación del trimestre más seco (PTS), precipitación del trimestre más cálido (PTC), precipitación del trimestre más frío (PTF).…”

“…Es aceptado ampliamente que la diversidad de especies de plantas decrece conforme la altitud incrementa; sin embargo, tal disminución no es lineal necesariamente, puesto que hay mayor número de especies en altitudes intermedias (Rahbek, 2005;Sánchez-González & López-Mata, 2005). En el caso específico de los helechos y licopodios (Pteridofitas), algunos estudios confirman la respuesta unimodal en la diversidad de especies (Kluge, Kessler, & Dunn, 2006;Watkins, Cardelu, Colwell, & Moran, 2006).…”

“…The relationship was estimated using parametric (linear regression analysis) and nonparametric (regression trees) methods with the STATISTICA version 7 data analysis software system (StatSoft Inc., 2004). Regression trees do not make a priori assumptions about some sort of association between the variables studied and facilitate the interpretation of their relationships, which is not achieved if linear statistical models are used (Sánchez-González & López-Mata, 2005).…”

Study on Diversity of Undergrowth Plant Community in Cibagou Nature Reserve

“…However, there are many studies have shown that the temperature and humidity of the elevation in the range has most species survival conditions, thus presents the species richness increased with altitude showed a trend of unimodal curve change [17] [18], namely lower after rising first. Grytnes [19] found that high species richness values appeared at an altitude of 1500 -2500 min the Himalayas or Nepal.…”