Patterns of SOC and soil 13C and their relations to climatic factors and soil characteristics on the Qinghai–Tibetan Plateau
Background and aims
SOC inventory and soil δ13C were widely used to access the size of soil C pool and to indicate the dynamics of C input and output. The effects of climatic factors and soil physical characteristics and plant litter input on SOC inventory and soil δ13C were analyzed to better understand the dynamics of carbon cycling across ecosystems on the Qinghai-Tibetan Plateau.
Field investigation was carried out along the two transects with a total of 1,875 km in length and 200 km in width. Sixty-two soil profiles, distributed in forest, meadow, steppe, and cropland, were stratified sampled every 10 cm from 0 to 40 cm.
Our result showed that SOC density in forest and meadows were much higher than in steppe and highland barley. In contrast, δ13C in forest and meadow were lower than in steppe and highland barley. Soil δ13C tended to enrich with increasing soil depth but SOC decline. SOC and δ13C (0–40 cm) were correlated with different climatic factors in different ecosystems, such that SOC correlated negatively with MAT in meadow and positively with MAP in steppe; δ13C correlated positively with MAT in meadow and steppe; and δ13C also tended to increase with increasing MAT in forest. Of the variation of SOC, 55.15 % was explained by MAP, pH and silt content and 4.63 % was explained by the interaction between MAT and pH across all the ecosystems except for the cropland. Meanwhile, SOC density explained 27.40 % of variation of soil δ13C.
It is suggested that different climatic factors controlled the size of the soil C pool in different ecosystems on the Tibetan Plateau. SOC density is a key contributor to the variation of soil δ13C.
KeywordsSoil organic carbon Soil δ13C Climate factors Soil characteristic Qinghai-Tibetan Plateau
We thank three anonymous reviewers for the constructive comments on an early version of the manuscript. This research is supported by the State Key Basic Research Development Project (Grant No. 2010CB833503), CarboEast Asia: Capacity building among China Flux, Japan Flux, and Ko Flux to cope with climate change protocols by synthesizing measurement, theory, and modeling in quantifying and understanding of carbon fluxes and storages in East Asia (Grant NO. 31061140359), the Cooperation Project of MOST (Grant NO. 2010DFA22480), and Key Projects of Chinese Academy of Sciences (Grant No. KZCX2-YW-QN301).
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