Climatic and Catchment-Scale Predictors of Chinese Stream Insect Richness Differ between Taxonomic Groups.

Jonathan D Tonkin,Peter Haase,Qinghua Cai,Deep Narayan Shah,Sonja C Jähnig,Mathias Kuemmerlen,Fengqing Li

doi:10.1371/journal.pone.0123250

Abstract

Little work has been done on large-scale patterns of stream insect richness in China. We explored the influence of climatic and catchment-scale factors on stream insect (Ephemeroptera, Plecoptera, Trichoptera; EPT) richness across mid-latitude China. We assessed the predictive ability of climatic, catchment land cover and physical structure variables on genus richness of EPT, both individually and combined, in 80 mid-latitude Chinese streams, spanning a 3899-m altitudinal gradient. We performed analyses using boosted regression trees and explored the nature of their influence on richness patterns. The relative importance of climate, land cover, and physical factors on stream insect richness varied considerably between the three orders, and while important for Ephemeroptera and Plecoptera, latitude did not improve model fit for any of the groups. EPT richness was linked with areas comprising high forest cover, elevation and slope, large catchments and low temperatures. Ephemeroptera favoured areas with high forest cover, medium-to-large catchment sizes, high temperature seasonality, and low potential evapotranspiration. Plecoptera richness was linked with low temperature seasonality and annual mean, and high slope, elevation and warm-season rainfall. Finally, Trichoptera favoured high elevation areas, with high forest cover, and low mean annual temperature, seasonality and aridity. Our findings highlight the variable role that catchment land cover, physical properties and climatic influences have on stream insect richness. This is one of the first studies of its kind in Chinese streams, thus we set the scene for more in-depth assessments of stream insect richness across broader spatial scales in China, but stress the importance of improving data availability and consistency through time.

Highlights

Describing and explaining large-scale patterns of species richness has long been a focus of ecological and biogeographical research [1,2,3]
Streams provide unique testing grounds for biodiversity assessments at large spatial scales due to their similarity in local habitat conditions globally [5], in addition to the fact that factors such as climate may operate on running water systems in a different manner to terrestrial ecosystems [6]
The only land cover variable to have a strong input in the models was percentage of catchment in broadleaf tree cover (Figs 3 and 4)

Summary

Introduction

Describing and explaining large-scale patterns of species richness has long been a focus of ecological and biogeographical research [1,2,3]. Streams provide unique testing grounds for biodiversity assessments at large spatial scales due to their similarity in local habitat conditions globally [5], in addition to the fact that factors such as climate may operate on running water systems in a different manner to terrestrial ecosystems [6]. Factors that influence and control the biodiversity of stream insects vary greatly and differ with scale [5,7], such as present and past land use [8,9], productivity [10], climate change [11], the flow regime [12], and temperature [13]. What remains clear is that our understanding of large-scale biodiversity patterns and their drivers is very much incomplete [7]

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Conclusion