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
时间:2019-08-04 14:40 来源:毕业论文 作者:毕业论文 点击:次
| 摘要：陆地生态系统中，存储了大量土壤有机碳的青藏高原对于气候变化异常敏感，因而土壤碳库比较微小的变动也会引起大气中 CO2浓度巨变，并会对全球变暖产生重要的反馈作用，并且这种现象会进一步加剧全球气候变暖。然而关于深层土壤有机碳（SOC）分解的温度敏感性的相关研究较少，因此本实验选取青藏高原高寒草甸生态系统中两种典型植被——矮嵩草（Kobresia humilis）草甸和金露梅（Potentilla fruticosa ）灌丛的土壤，分别在室内 15℃和 25℃下培养 120 天，测定不同时间的土壤呼吸。结合土壤基础理化指标和微生物指标、根系生物量，研究不同土层 SOC 分解的温度敏感性及其驱动机制；同时应用三种计算土壤有机碳分解的温度敏感性的方法，寻求更加合适的表达以及评价土壤有机碳分解的温度敏感性的方法。研究得出，通过土壤碳含量校正过的土壤瞬时呼吸随着土壤深度的增加而增加，同时与土壤微生物呼吸商有关。说明不同土层土壤有机碳的分解与其中土壤微生物的总量呈现正相关。而且我们发现在 120 天培养周期内，被分解的土壤有机碳总量在两种土壤类型之间存在差异，但是其与培养温度无关。三种评价方法计算的结果没有差异，然而土壤有机碳分解的温度敏感性均随着土壤深度增加逐渐降低。表明表层土壤在全球变暖的背景下更易分解，从而加剧土壤有机质分解对于全球变暖的响应。结果对于预测未来气候变暖条件下青藏高原高寒草甸不同土层碳的平衡具有一定的指导意义。 38006 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 (责任编辑：qin) |