Abstract

Allelua Niyokwizera, Yiqi Luo, Etienne Tuyishimire, Aneesh Kumar Chandel and Lifen Jiang*

Understanding the long-term effect of temperature increases on soil respiration remains difficult to date. To the best of our knowledge, there is a paucity of literature on how soil respiration responds to long-term temperature increases in field experimental studies. A 17-year field study was conducted in a tallgrass prairie in Oklahoma, USA, to assess how soil respiration would respond to temperature rises in long-term warming and to investigate the underlying mechanisms regulating soil respiration in this ecosystem. Moreover, to mimic the traditional method of collecting hay in this region, a further step known as the clipping treatment was put into place. We measured soil respiration rates, Net Primary Production (NPP), and environmental variables, including air and soil temperature and soil moisture. Our results showed that warming significantly enhanced soil respiration in both clipped and unclipped plots. Soil respiration was primarily controlled by temperature. Under all treatments, the responses of soil respiration to temperature were nonlinear, increasing with temperature first until reaching the optimum temperature and then declining at high temperatures. Furthermore, it was found that warming-induced changes in soil respiration were significantly and positively correlated with changes in Aboveground NPP (ANPP) due to warming, which was dominated by the changes in ANPP of C3 species rather than C4 species. Belowground NPP (BNPP) and soil moisture did not have a significant effect on soil respiration. Our findings suggest that the ongoing climate change will keep stimulating soil respiration in tallgrass prairie ecosystems, which would exacerbate climate change, and this needs to be further investigated on a broader spatial scale.