Impacts of passive experimental warming on daytime and night-time respiration in a semi-natural grassland
Abstract. Soil respiration (SR) is the largest source of CO2 released from the terrestrial ecosystem. It is greatly influenced by soil carbon pool, climate warming and daily fluxes i.e., daytime (DT) and night-time (NT) temperatures. However, there are hardly any studies relating to the effects of passive experimental warming on Ecosystem respiration (ER) and SR during DT and NT. We conducted a simulated warming experiment using passive Open Top Chamber (OTC) in a semi-natural grassland of Doon Valley, in the state of Uttarakhand, India. OTCs showed an increase in DT and NT soil temperatures. SR and ER were measured within OTC as well as outside using LI-8100A Automated Soil CO2 Flux System. We found that SR and ER increased under passive experimental warming by 38.66 % and 20.35 % during DT, and 38.8 % and 12.41 % during NT respectively. SR/ER ratio increased under passive warming treatment during DT and NT, indicating SR as the major contributor to ER. Temperature-respiration showed a positive relationship under ambient and warming conditions. Q10 analyses revealed that respiration rates are sensitive to passive warming, especially during the NT. This study addresses the crucial gap of monitoring NT respiration in addition to DT respiration to estimate the CO2 efflux and its response to passive experimental warming.
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