A global-drive analysis of ecosystem respiration in the Arctic and Third Pole

Abstract

Terrestrial ecosystem respiration is an important component of the global terrestrial carbon cycle. The special environment of low temperatures in the Arctic and Third Pole makes ecosystem respiration extremely sensitive to the response of climate change. Therefore, understanding the response of Arctic and Third Pole (Tibetan Plateau) ecosystem respiration to individual global environmental drivers is critical for predicting future climate change caused by global warming. However, current studies have not systematically reported on the relative contributions of rising CO2 concentrations, nitrogen deposition, land-use change, and climate change, which are global change factors with multi-year trends and interannual variability, to ecosystem respiration in the Arctic and Third Pole. Here, we used multiple multi-scenario models of vegetation dynamic process model from 1901 to 2010, and divided each environmental driver, each season into long-term trend and interannual variability components by using a novel variance decomposition method. Our results showed that (1) ecosystems autotrophic respiration and heterotrophic respiration in Arctic and Third Pole are relatively low, which remains within 110 g C m−2 in both the Arctic and the Tibetan Plateau; (2) ecosystem respiration tends to increase in all scenarios, and the increase rate has accelerated significantly since 1980. The interannual variability of climate change contributes the most to the variability of ecosystem respiration, up to 52 % and 63 % in the Arctic and Tibetan Plateau, respectively. Both the multi-year trend and interannual variability of increasing atmospheric CO2 concentration contribute to the increase in ecosystem respiration, with relative contributions of 28 % and 32 %, respectively. (3) In the Arctic and the Tibetan Plateau, which are sensitive to temperature and short-wave radiation, summer is the key seasonal component controlling ecosystem respiration, and the contribution of this season (including long-term trends and interannual variability) to annual ecosystem respiration in the Arctic and the Tibetan Plateau is 64 % and 45 %, respectively. Our study bridged the gap in understanding the response of cold ecosystems to global changes at high altitudes and high latitudes, which provides a methodological reference for future accurate prediction of global environmental drivers of cold ecosystem respiration.