Direct and indirect effects of environmental factors, spatial constraints, and functional traits on shaping the plant diversity of montane forests

Abstract

Understanding the relative importance of the factors driving the patterns of biodiversity is a key research topic in community ecology and biogeography. However, the main drivers of plant species diversity in montane forests are still not clear. In addition, most existing studies make no distinction between direct and indirect effects of environmental factors and spatial constraints on plant biodiversity. Using data from 107 montane forest plots in Sichuan Giant Panda habitat, China, we quantified the direct and indirect effects of abiotic environmental factors, spatial constraints, and plant functional traits on plant community diversity. Our results showed significant correlations between abiotic environmental factors and trees (r = .10, p value = .001), shrubs (r = .19, p value = .001), or overall plant diversity (r = .18, p value = .001) in montane forests. Spatial constraints also showed significant correlations with trees and shrubs. However, no significant correlations were found between functional traits and plant community diversity. Moreover, the diversity (richness and abundance) of shrubs, trees, and plant communities was directly affected by precipitation, latitude, and altitude. Mean annual temperature (MAT) had no direct effect on the richness of tree and plant communities. Further, MAT and precipitation indirectly affected plant communities via the tree canopy. The results revealed a stronger direct effect on montane plant diversity than indirect effect, suggesting that single-species models may be adequate for forecasting the impacts of climate factors in these communities.The shifting of tree canopy coverage might be a potential indicator for trends of plant diversity under climate change. S U PP O RTI N G I N FO R M ATI O NAdditional supporting information may be found online in the Supporting Information section.How to cite this article: Li T, Xiong Q, Luo P, Zhang Y, Gu X, Lin B. Direct and indirect effects of environmental factors, spatial constraints, and functional traits on shaping the plant diversity of montane forests.

Spatial heterogeneity of tree diversity response to climate warming in montane forests

“…Of course, there are differences in the upward migration of trees species among the four mountains, which may be due to more than just different warming rates, for example, topographic, plant species composition, soil organic matter content, and microbial properties (Mayor et al., 2017). Warming would direct and indirect affect trees migrating along elevations (Li, Xiong, Luo, Zhang, et al., 2020), which could disrupt the functional properties of montane ecosystems (Svenning & Sandel, 2013) and result in periods of disequilibrium where range shifts may be compensated for by species from lower latitudes and faster population turnover (Lenoir et al., 2008).…”

“…The most prevalent ecosystems are cold and warm temperate coniferous forests or broad‐leaved mixed forests with more than 800 wild vertebrates and 4,000 wild vascular plants in those four mountains (Dakhil et al., 2019; Li, Xiong, Luo, Zhang, et al., 2020; Sichuan Vegetation Cooperation Group, 1980). In terms of trees species abundance, the plants in the study area mainly consist of Abies sp., Picea sp., Betula sp., Tsuga sp., and Sabina sp.…”

“…This is particularly true since species also differ in their abundances, functional traits, distributions, and habitat associations at various scales (Baltzinger et al., 2011; Li, Xiong, Luo, Zhang, et al., 2020). Nevertheless, this spatial variation in plant diversity responses to climate change still remains relatively unknown, particularly for montane forest ecosystems (Li, Xiong, Luo, Zhang, et al., 2020).…”

“…The Giant Panda National Park (GPNP) with a total area of 27,000 km 2 (over 80% of the area is mountain region) in China was established in 2017. The ambition of the GPNP to preserve the Giant Panda habitat is self‐evident (Li, Xiong, Luo, Zhang, et al., 2020). However, the GPNP management plan does not provide clear measures to mitigate climate change (Sichuan Provincial Government, 2017).…”

“…Since most organisms, at both fine and coarse spatial scales, differ significantly in their response to climate change, large spatial scale models cannot reliably determine the impact of altered climates on vegetation (Milad et al, 2011;. This is particularly true since species also differ in their abundances, functional traits, distributions, and habitat associations at various scales (Baltzinger et al, 2011;Li, Xiong, Luo, Zhang, et al, 2020).…”