青藏高原高寒草甸不同土层土壤有机碳分解温度敏感性及其驱动机制
毕业论文关键词：温度敏感性；土壤有机碳分解；不同土层；高寒草甸
The Temperature Sensitivity and Mechanisms of Soil Organic Carbon Decomposition with Depth in Alpine Meadow of Tibet Plateau
Abstract： In terrestrial ecosystems, especially in the Tibet Plateau, which is sensitive to climate change, a slight change in soil carbon stock can cause significant changes in CO2 concentration in the atmosphere and may have an important feedback on global warming and further aggravate the global warming. However, there was little research on the temperature sensitivity of deep soil organic carbon（SOC）decomposition. We selected two typical soils of Kobresia humilis meadows and Potentilla fruticosa shrubs in the alpine meadow of the Tibet Plateau, and cultured for 120 days at 15 ℃ and 25 ℃. The soil respiration was measured in different time. The temperature sensitivity and its driving mechanism of SOC decomposition in different soil layers were studied by combining the soil basic physical and chemical indexes, microbial index and root biomass. Three kinds of methods were used to calculate the temperature sensitivity of soil organic carbon decomposition to find the most suitable method to evaluate temperature sensitivity of soil organic carbon decomposition. We concluded that soil instantaneous respiration corrected by soil carbon content increased with soil depth, and was related to soil microbial metabolic quotient. Which indicated that the decomposition of soil organic carbon in different soil layers was positively correlated with the total amount of soil microbes. Moreover, we found that there was a difference in the total amount of decomposed soil organic carbon between the two soil types during the 120-day , but it was independent of the cultured temperature. There was no difference in the results of the three evaluat ion methods, but the temperature sensitivity of soil organic carbon decomposition decreased with the increase of soil depth, indicating that the surface soil to the global warming is more easily decomposed, thereby exacerbating the feedback to global warming. This result is of guiding signif icance for predicting the balance of carbon in alpine meadows on the Tibet Plateau under the condition of future global warming. Key words: Temperature sensitivity；Soil organic carbon decomposition；Different soil layers；Alpine meadow
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