Status: this discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The manuscript was not accepted for further review after discussion.
A temperature threshold to identify the driving climate forces of the respiratory process in terrestrial ecosystems
1School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediat ion Technology, Sun Yat -sen University, Guangzhou 510275, China
2College of Environmental Science and Engineering, Peking University, Beijing 100871, China
3Institute for Environment and Sustainability, Climate Risk Management Unit, European Commission, Joint Research Centre, Ispra 21027, Italy
4Institute of Ecology, University of Innsbruck, Sternwartestr 15, Innsbruck 6020, Austria
5Institute for Mediterranean Agricultural and Forest Systems, National Research Council, Ercolano (Napoli) 80040, Italy
1School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediat ion Technology, Sun Yat -sen University, Guangzhou 510275, China
2College of Environmental Science and Engineering, Peking University, Beijing 100871, China
3Institute for Environment and Sustainability, Climate Risk Management Unit, European Commission, Joint Research Centre, Ispra 21027, Italy
4Institute of Ecology, University of Innsbruck, Sternwartestr 15, Innsbruck 6020, Austria
5Institute for Mediterranean Agricultural and Forest Systems, National Research Council, Ercolano (Napoli) 80040, Italy
Received: 06 Aug 2017 – Discussion started: 21 Aug 2017
Abstract. Terrestrial ecosystem respiration (Re) is the major source of CO2 release and constitutes the second largest carbon flux between the biosphere and atmosphere. Therefore, climate-driven changes of Re may greatly impact on future atmospheric CO2 concentration. The aim of this study was to derive an air temperature threshold for identifying the driving climate forces of the respiratory process in terrestrial ecosystems within different temperature zones. For this purpose, a global dataset of 647 site-years of ecosystem flux data collected at 152 sites has been examined. Our analysis revealed an ecosystem threshold of mean annual air temperature (MAT) of 11 ± 2.3 °C. In ecosystems with the MAT below this threshold, the maximum Re rates were primarily dependent on temperature and respiration was mainly a temperature-driven process. On the contrary, in ecosystems with the MAT greater than 11 ± 2.3 °C, in addition to temperature, other driving forces, such as water availability and surface heat flux, became significant drivers of the maximum Re rates and respiration was a multi-factor-driven process. The information derived from this study highlight the key role of temperature as main controlling factor of the maximum Re rates on a large fraction of the terrestrial biosphere, while other driving forces reduce the maximum Re rates and temperature sensitivity of the respiratory process. These findings are particularly relevant under the current scenario of rapid global warming, given that the potential climate-induced changes in ecosystem respiration may lead to substantial anomalies in the seasonality and magnitude of the terrestrial carbon budget.
This study highlight the key role of temperature as main controlling factor of the maximum respiration rates in most terrestrial ecosystems, while other driving forces reduce the maximum respiration rates and temperature sensitivity of the respiratory process. These findings are particularly relevant under the current scenario of rapid global warming, given that the potential climate-induced changes in ecosystem respiration may lead to substantial anomalies in terrestrial carbon budget.
This study highlight the key role of temperature as main controlling factor of the maximum...