Abstract
The contributions of heterotrophic respiration (RH) to total soil respiration (RS) for the non-growing season, growing season, and annual period are 84.8%, 60.7%, and 63.3%, respectively.Few studies have partitioned RS into its rhizospheric (RR) and heterotrophic components throughout the year in northern forest ecosystems. Our objectives were to quantify the contributions of non-growing season and heterotrophic respiration. We conducted a trenching experiment to quantify RR and RH in a temperate deciduous forest in Northeast China over two years using chamber methods. Temperature sensitivities (Q10) for RS and for RH were both much higher in the non-growing season (November to April) than those in the growing season. The Q10 for RS was higher than Q10 for RH in both seasons, indicating a higher temperature sensitivity of roots versus microorganisms. Mean non-growing season RS, RH, and RR for the two years were 94, 79 and 14 g carbon (C) m−2, respectively, which contributed 10.8%, 14.5%, and 4.5% to the corresponding annual fluxes (869, 547 and 321 g C m−2 year−1, respectively). The contributions of RH to RS for the non-growing season, growing season, and annual period were 84.8%, 60.7%, and 63.3%, respectively. Using the same contribution of non-growing season RS to annual RS, to scale growing season measurements, to the annual scale would introduce significant biases on annual RH (−34 g C m−2 yr−1 or −6%) and RR (16 g C m−2 yr−1 or 5%).We concluded that it was important to take non-growing season measurements in terms of accurately partitioning RS components in northern forests.
Highlights
Soil respiration (RS ) is estimated to be 83–108 Pg carbon (C) yr−1 globally [1,2,3], which consumes67%–88% of the terrestrial gross primary production (123 Pg C yr−1 ) [4]
Soil respiration is overwhelmingly comprised of heterotrophic (RH ; respiration by microbes and soil fauna) and rhizospheric (RR ; respiration by roots, their associated mycorrhizal fungi, and other micro-organisms directly dependent on labile carbon compounds leaked from roots) components [8,9,10]
Zhang et al [52] verified that changes in photosynthesis drive the seasonal soil respiration–temperature hysteresis relationship, with numerical models and 129
Summary
Soil respiration (RS ) is estimated to be 83–108 Pg carbon (C) yr−1 globally [1,2,3], which consumes. 67%–88% of the terrestrial gross primary production (123 Pg C yr−1 ) [4]. RS is potentially an important positive feedback for climate warming [5,6,7]. RS plays an essential role in global carbon cycling. Partitioning RS is an important step for assessing plant physiology, C allocation, ecosystem C balance, and the climate feedback potential of changes in RS [5,15,16,17]
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