全球变化下地上/地下枯落物输入变化对森林土壤碳氮储量及水文过程的影响研究

Change in temperature, carbon dioxide concentration and precipitation patterns that are predicted under scenarios of global climate change and anthropogenic activity will have profound effects on species diversity and forest productivity, resulting in quantity alteration of detritus inputs to soils. These changes of litters and underground roots can thus influence decomposition of soil organic carbon, nitrogen, other soil nutrients and hydrologic process. However, the long-term dynamic effects of litter input changes on forest soil carbon and nitrogen storage and hydrological processes are not clear. In order to realize the effect of alterations in forest detritus inputs on dynamics of carbon, nitrogen and hydrologic process, the Pinus yunnanensis forest in central Yunnan province, southwestern China is taken as a case study. The detritus input and remove treatment (DIRT) experiment were used to estimate the effect of forest detritus input alterations on soil. Dynamics of soil carbon organic concentration, nitrogen and other soil nutrient concentration, runoff and sediment yield of detritus input and remove treatments were obtained based on the field monitoring and lab experiments. And situ test were carried out and three key soil processes in forest soil be focused, including (a) the carbon transfer from litters to soil, (b) the nutrient decomposed from litter to soil, and (c) the soil erosion and hydrologic process of detritus input and remove treatments for realizing the mechanism of alterations in forest detritus inputs influence soil organic carbon stocks, soil nitrogen storage and hydrologic process. It is believed that the findings and the approach proposed in this study will provide more interesting and useful hints to support effective forest litter management. Further, the findings of the research will provide theoretical basis for prediction of carbon and nitrogen stocks and hydrologic alternation in future forest.

在全球气候变化背景下，气候变暖、温室气体CO2浓度的升高和全球降雨量的重新分配改变了森林生态系统的生物多样性和森林生产力，从而导森林地上/地下枯落物输入发生变化。这种地上/地下枯落物输入变化对森林生态系统土壤有机碳的形成、土壤养分元素的供应和森林水文过程能都产生了重要的影响，但枯落物输入变化对森林土壤碳氮储量和水文过程的长期影响还不清楚。本研究以滇中高原云南松林为研究对象，基于枯落物添加和去除（DIRT）实验，通过对不同枯落物处理土壤碳氮储量、养分元素含量和产流、产沙量的动态监测，以及对枯落物分解过程中的碳转化过程、养分释放过程和水文关键过程的原位实验和室内分析，揭示枯落物输入变化对森林土壤碳氮储量和水文过程的影响及机制。研究结果可为全球变化条件下森林枯落物经营、管理以及未来森林碳氮储量和水文变化及其对气候变化反馈作用的科学预测提供理论依据。

在全球气候变化的背景下，气候变暖、温室气体CO2浓度的升高和全球降雨量的重新分配改变了森林生态系统的生物多样性和森林生产力，从而导致森林枯落物输入量发生变化。并且，随着人类活动影响加剧，如收获林下枯落物、枯落物计划烧除、人工攫取森林有机质亦使枯落物输入量发生改变。这种地上/地下枯落物输入变化使森林土壤地表覆盖层和地下根系周转量发生了重要的变化，进而对对森林生态系统土壤有机碳的形成、土壤养分元素的供应和森林土壤水文特征能都产生了重要的影响。本研究以滇中高原云南松林为研究对象，基于枯落物添加和去除（DIRT）实验，采用原位枯落物分解袋法对对不同枯落物输入条件下土壤枯落物分解过程进行了研究，在此基础上，采用定位观测和室内分析的方法，对不同枯落物输入条件下土壤呼吸、土壤碳、氮储量及土壤水文特征进行了研究，揭示了枯落物输入变化对森林土壤碳氮输入-释放及土壤水文特征的影响及其机制。研究结果可为全球变化条件下森林枯落物经营、管理以及未来森林碳氮储量和水文变化及其对气候变化反馈作用的科学预测提供理论依据。