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Response of Rhizospheric and Basal Soil Respiration to Changes in Soil Moisture and Temperature under Different Irrigation Phases in Arid Cotton Field in Northwestern China
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DOI：10.1134/S1064229325602598.png)
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Abstract
En 中文
Understanding the response of rhizospheric respiration (from roots, mycorrhizal hyphae and associated microbes) (R-r) and basal soil respiration(from decomposers) (R-b) to environmental variables (soil temperature (T-s) and soil moisture (M-s)) is critical for ecosystem C budget research, as these two components represent the major source of soil respiration. To study the different effects of T-s and M-s on R-r and R-b, six plots, three under the crown of cotton and three on the bare land were built in one of cotton fields at the Aksu National Experimental Station of Oasis Farmland Ecosystem on April 5, 2012. Based on the difference of soil respiration between cotton plots and bare plots, the components of soil respiration, R-r and R-b were divided. Then, the responses of R-r and R-b to soil temperature and moisture were analyzed, respectively. The results showed that. (1) During the whole experimental period, the variation in R-r was more strongly influenced by M-s (R-2 = 0.6065) than by T-s (R-2 = 0.0023), whereas R-b exhibited higher temperature sensitivity (Q(10) = 2.291) than R-r(Q(10) = 0.844). (2) During active irrigation phase, both R-r and R-b decreased with increasing M-s but showed only a weak relationship with T-s. (3) During the post-irrigation phase, the temperature responses of both R-r and R-b were well characterized by Q(10) models, whereas their relationships with M-s followed parabolic trends. Our results demonstrate three key findings: (1) R-b and R-r shown significantly divergent responses to T-s and M-s; (2) while R-b displayed higher temperature sensitivity (Q(10)) than R-r, both were strongly regulated by M-s, with supra-optimal soil moisture levels (e.g., from irrigation or heavy precipitation) disrupting thermal control of respiration; (3) M-s exerted threshold-dependent effects on both R-r and, with R-b's threshold (approximated field capacity) being substantially higher than R-r's. These findings underscore the necessity of integrating the differential responses of R-r and R-b to T-s and M-s into ecosystem models to enhance projections of soil carbon cycling under future climate scenarios.
Keywords:
global warming
green gas
canopy gap
CO2 concentration
CO2 diffusion
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