Elevation dependence of climate effects on ecosystem multifunctionality states over the Qinghai-Tibet Plateau

Abstract

The multiple functions and services provided by ecosystems that linked human-being are under threat with the global environment changes. Large-scale research of ecosystem multifunctionality (EMF), which include AN, AP, AK, CEC, SOM, SMC, SMN, AGB BGB and other indicators, can help us excavate ecosystems more comprehensively and strengthen protection awareness of biodiversity, but it remains scarce, especially for the Qinghai-Tibet Plateau (QTP). In this paper, evaluating EMF by the three calculation approaches–average approach, single threshold approach, and principal component analysis, we presented the spatial pattern of EMF over the QTP. We found that three approaches undergone the coincident spatial variation characteristic, with a decreasing gradient from southeast to northwest. Although the EMFs of forests (geometric mean of three indexes = 0.37) and alpine meadows (geometric mean of three indexes = 0.29) were significantly higher than those of alpine steppe (geometric mean of three indexes = 0.16) and alpine desert steppe (geometric mean of three indexes = 0.12) ecosystems, the EMFs jointly exhibited an inverted U-shaped distribution with altitudinal gradient in all ecosystems. For the correlation between EMF and precipitation, which first increases and then decreases along altitudinal gradient, with a turnaround around 4000–5000 m. Nevertheless, the correlation between EMF and temperature, which universally increases with altitudinal gradient. Our results emphasize that gradient change of EMF is attributed to elevation dependence of climate change throughout the QTP, and understanding transformation threshold that is beneficial for the protection and sustainable development of ecosystems.