How communities assemble is a central and fundamental question in ecology. Recently, the integration of functional trait and phylogenetic information into biodiversity studies provide new insight into assembly processes. The Himalayan Mountains, which are the highest mountains in the world, have extremely high mountain ecosystems (mountains with altitude higher than 5000 m), and are considered as the one of the world's biodiversity hotspots. With one of the longest elevation gradients, Himalayan Mountains provide an ideal system for exploring species distribution pattern along elevation gradient.
Figure 1 Map of the study area showing the 36 transects distributed in 12 bands with increments of 300 m. The letter correspond to the vegetation zones showing in the right side: (a) evergreen broadleaf forest; (b) coniferous and broadleaf mixed forest; (c) dark coniferous forest; (d) shrub and grass; (e) alpine tundra with sparse grass.
Researchers from the Institute of Zoology, Guangdong Academy of Sciences, East China Normal University and University of Toronto conducted taxonomic, functional and phylogenetic avian diversity along a 3600-m elevational gradient in the central Himalaya, China. A total of 151 breeding resident birds were recorded during the wet season in period 2012-2013. Species richness, functional diversity and phylogenetic diversity all showed hump-shaped patterns, however, the elevation bands where they peaked were almost similar. Richness-controlled functional diversity (indicated by SES.FD) decreased with increasing elevation, whereas richness-controlled phylogenetic diversity (indicated by SES.PD) showed Mid Valley patterns (lowest values of the diversity metric occurred at mid elevations). The functional structure of bird communities was more clustered relative to source pools (i.e. species more similar to one another) across the elevation gradient, suggesting abiotic or habitat filtering likely governed the assembly processes. However, phylogenetic structure was more clustered relative to source pools at mid-elevations and more overdispersed (i.e. species are less related) at low and high elevations.
Taken together, our study demonstrated contrasting elevational patterns assessed from functional and phylogenetic measures and highlighted the necessity of considering multiple measures of biodiversity when assessing community structure. With regard to conservation suggestions, mid-elevation areas often received extensive attention due to its rich diversity. However, this study found that high-elevation areas still have high phylogenetic diversity and are also worth of attention, especially these high-elevation areas are more sensitive to climate change, and will undergo a severe impact in the future when exposed to climate change scenarios. We conclude that for a better understanding of the patterns and causes of elevational diversity gradients, there is a strong necessity of integrating multiple facets of biodiversity in inferring assembly processes.
Figure 2. Elevational patterns of bird species richness, functional diversity (FD), phylogenetic diversity (PD) and its standardized effect size (SES.FD and SES. PD) along a 3600 m elevational gradient in the central Himalaya, China. The black, solid line refer to the best fitted line using polynomial regression analyses.
This work entitled “Elevational patterns of bird functional and phylogenetic structure in the central Himalaya” was published in the journal Ecography. Dr. Zhifeng Ding, who is from Institute of Zoology, Guangdong Academy of Sciences, was the first author. This work was supported by National Natural Science Foundation of China, and GDAS' Project of Science and Technology Development.
How to cite: Ding, Z., Hu, H., Cadotte, M.W., Liang, J., Hu, Y. and Si, X. (2021), Elevational patterns of bird functional and phylogenetic structure in the central Himalaya. Ecography, 44: 1403-1417.