Elevational Species Richness Patterns Emerge From Multiple Local Mechanisms in Himalayan Woody Plants

Abstract

We compared woody plant species distributions across nested spatial scales (local scale to entire Western Himalaya) and explored landscape scale patterns in detail to obtain inferences about the elevational gradient in species richness. Distribution data were compiled for 1100 species in the Western Himalaya, and primary data, comprising 123 species and 47 000 individuals, were collected for a landscape. Correlates of diversity were examined for the five spatial scales, and for different biogeographic groups at the landscape scale. The results indicate multiple mechanisms both within and across scales. At the landscape scale, though the mechanisms explaining unimodal species richness patterns were hard to separate, the underlying correlates of biogeographic groups were more distinct; temperate species richness followed mid‐domain model predictions, and showed a nonlinear relationship with temperature, whereas tropical species richness tracked temperature and area. Simulations demonstrated that models with varying assumptions, while resulting in monotonic, unimodal, or multimodal patterns at local scales, could all lead to unimodal patterns at regional scales when multiple local replicates are aggregated, with a peak in the major ecotone. The turnover or successive accumulation of marginal species in ecotones potentially explains the mid‐elevational peak in this zone. Landscape scale primary data on distribution and abundance could therefore be critical to understanding key aspects of macroecological patterns.

Altitudinal Gradient Affects on Trees and Stand Attributes in Mount Ciremai National Park, West Java, Indonesia

“…This finding was in accordance with the theory that the number of woody species in tropical forests tends to decrease with increasing altitude and latitude (Rahbek, 1995;Aiba and Kitayama, 1999;Givnish, 1999;Acharya et al, 2011;Kraft et al, 2011). Forests at higher elevations tends to have less species number because they have smaller species pools reflecting more severe past disturbance (Aiba et al, 2005;Oommen and Shanker, 2005). The decline in species richness due to higher altitudes in Mount Ciremai National Park (Fig.…”

Environmental Drivers of Patterns of Plant Diversity Along a Wide Environmental Gradient in Korean Temperate Forests

“…Many previous studies have been restricted to the use of only species richness as a surrogate of biodiversity at each elevational band in their analyses without using other valuable diversity indices, such as the mean number of species and beta diversity. This is because these studies used interpolated species richness as modified from distributional records with secondary data sources, such as the literature [32]. Therefore, our study benefited from exploring the elevational patterns and the drivers with additional valuable diversity indices as related to an empirical data source; these data were collected at a regional scale and were analyzed by comparing the results with many previous studies using secondary data from the literature.…”

Structure, Composition and Diversity of Forest Along the Altitudinal Gradient in the Himalayas, Nepal

“…The results of this study also reflect this general trend found in plant diversity of mountain forests in Himalaya. Oommen and Shanker (2005) provided evidence for different mechanisms along spatial scales and explained a mechanism based on the investigations on woody plant diversity in the Indian Western Himalaya. They revealed that the species with high tolerance to climatic variability had followed mid-domain model predictions, and showed a nonlinear relationship with temperature, whereas tropical species richness tracked temperature and area.…”