Climatic change controls productivity variation in global grasslands.

Qingzhu Gao,Yue Li,Mark W Schwartz,Hasbagan Ganjurjav,Xin Ma,Wenquan Zhu,Xiaobo Qin,Yunfan Wan,Matthew A Williamson

doi:10.1038/srep26958

Abstract

Detection and identification of the impacts of climate change on ecosystems have been core issues in climate change research in recent years. In this study, we compared average annual values of the normalized difference vegetation index (NDVI) with theoretical net primary productivity (NPP) values based on temperature and precipitation to determine the effect of historic climate change on global grassland productivity from 1982 to 2011. Comparison of trends in actual productivity (NDVI) with climate-induced potential productivity showed that the trends in average productivity in nearly 40% of global grassland areas have been significantly affected by climate change. The contribution of climate change to variability in grassland productivity was 15.2–71.2% during 1982–2011. Climate change contributed significantly to long-term trends in grassland productivity mainly in North America, central Eurasia, central Africa, and Oceania; these regions will be more sensitive to future climate change impacts. The impacts of climate change on variability in grassland productivity were greater in the Western Hemisphere than the Eastern Hemisphere. Confirmation of the observed trends requires long-term controlled experiments and multi-model ensembles to reduce uncertainties and explain mechanisms.

Highlights

Primary production and its trends are important indicators of ecosystem function[1]
The largest trends of decrease in the model-driven net primary production (NPP) values were found for the Mongolian Plateau, the Midwestern USA, and in mid-eastern South America, while the largest trends of increase were found for the Qinghai–Tibetan Plateau, the high-latitude regions, and central Africa (Fig. 1B)
Tremendous progress has been made in recent years in detecting changes in regional terrestrial ecosystems, based on long-term observational and remote sensing series data[25,26,27,28,29]

Summary

Introduction

Primary production and its trends are important indicators of ecosystem function[1]. Many studies have documented that ecosystem primary production is sensitive to climate change, and is simultaneously responsive to many other non-climate factors in the world[2,3,4]. The gaps in knowledge have led to questions about how to detect and identify the impacts of climate change on the variability of grassland productivity at the global scale, relative to the effects of non-climate factors. We applied the climate-driven Miami Model to simulate the potential net primary production (NPP) of the global grassland ecosystem; this model estimates NPP strictly as a function of temperature and precipitation. This process enabled us to identify the contribution of climate to NPP, and demonstrated the integrated and overlapping impacts of climate factors on productivity change.

Methods

Results

Conclusion