【作者】 张旭辉；

【导师】 潘根兴；

【作者基本信息】 南京农业大学 ， 土壤学， 2005， 博士

【摘要】 土壤碳库为地球表层系统中最大的碳储库。土壤中的有机碳库对于温室效应与全球气候变化有着重要的控制作用。水稻土是我国特殊的人为湿地土壤,面积2987万公顷,生产着我国1/4的粮食,其在农业生产中占有举足轻重的地位,因此本研究提出土壤升温下水稻土活动性碳的变化及其环境效应,为阐明水稻土活动性碳的变化特点与陆地碳循环的关系、水稻土对全球变化的响应提供科学资料,并期望为我国水稻土持续利用战略的选择提供科学依据。不同轮作制度及土地利用方式亦影响着土壤有机碳的固存,因此本研究还针对淮北地区不同轮作制度及土地利用方式的旱地土壤的有机碳在土壤中的分配特点及动态变化进行了分析,以期为我国农业土壤固碳特点提供科学资料。 本文研究了不同轮作制度下淮北白浆土有机碳固存与分配、以及多年生叶用银杏种植对黄潮土有机碳变化的影响,并重点研究了土壤升温对水稻土有机碳的矿化和CO₂呼吸排放的影响。其主要结果如下: 一.不同发生起源的水稻土有机碳对土壤升温的响应 1、供试水稻土的平均矿化速率及其对温度的响应相对于自然森林土壤和草地土壤要小,这从一定程度上佐证了我们对中国水稻土有机碳近年来持续增长具有固碳潜力的发现。 2、水稻土的碳矿化速率及Q₁₀值随土壤类型和N素水平的不同而不同,而N素水平的高低影响着土壤有机碳的动态和CO₂的释放,这在全球变暖趋势和中国水稻土壤的化肥N素的高投入下显得尤为重要。 3、从土壤有机碳矿化动态可以指示出水稻土可矿化有机碳的四个不同分解阶段,在实验室培养条件下,快速降解的碳库虽然量小但却显著的响应于升温效应。 二.不同肥料处理水稻土有机碳对升温的响应及其田间土壤呼吸的日变化特点 1、黄泥土水稻土在水分饱和条件下的矿化特征表明其对升温的不敏感性,这进一步说明其对全球变暖响应的惰性,因此.亦表明其具有一定的固碳能力 2、太湖地区的黄泥土在非植稻季节春秋两季的日排放量分别介于更多还原

【Abstract】 The soil carbon pool is the biggest one in the earth surface system and the soil organic carbon （SOC） plays an important role in global carbon cycling. The global warming induced from the greenhouse effect and its impact on the terrestrial ecosystems is the focus on the international circles of geology, ecology, and environmental sciences, which is the key project in the frame of the Global Carbon Project, PAGES, IHDP and GCTE et al. Soils contain about 1500Pg （lPg=lGt=10¹5g） of organic carbon worldwide, which is about three times the amount of carbon in vegetation and twice the amount in the atmosphere. Soil carbon mineralization and the CO2 evolution has been paid attention due to its important effects on the global carbon cycle and terrestrial ecosystems.This paper deals with the effect of different crop rotation systems on the aggregates and their SOC accumulation in Paludalfs in North Huai Region; the effect of the cultivated leaf-harvesting Ginkgo on the SOC dynamics; and especially researches the effect of soil wanning on the SOC mineralization of the various paddy soil. The main results showed as follows:1. Organic Carbon Mineralization and CO2 Evolution of Paddy Topsoil and the Temperature Dependencea. The mean C mineralization rate of these paddy soils studied and the temperature dependence was relatively small compared to those of natural forest soils and grassland soils. This may support our previous finding of the SOC enhancement in paddy soils of China.b. C mineralization and O₁0 of paddy soils varied with soil type and soil N status. The labile C plays an important role in the mineralization of SOC in paddy soils while N bioavailability, to a lesser degree, also influence the C mineralization and the temperature dependence.c. Furthermore, our data here indicated that there was different sub-pool ofmineralizable C in the paddy soils which had different accessibility to mineralization and the response to wanning. When addressing the C mineralization and the CO2 evolution of paddy soil, labile C should be paid much attention and further study needed for modeling the response of paddy soils to global warming in the context of C mineralization and the temperature dependence.2. Response of the SOC of paddy soils with various fertilizer treatments on warming and daily variation of CO2 evolution in the fielda. The SOC of Huangnitu paddy soil in Tai Lake region is not sensitive to soil warming.b. Daily amount of soil respiration in spring and autumn are ranged from 271.78 to 409.17 mgC-CO2.m^-2.d^-1 and 197.26 to 336.72 mgC-CO₂.m^-2.d^-1. These data are much smaller than those in other lituratures.c. The daily amount of flux under the treatment of only applied inorganic fertilizer increase by 71% than of organic-inorganic fertilizer at most, which indicated long-term only application of chemical fertilizer may lead to significant increase of CO2 emissions and not be favor of carbon sequestration.3. Dynamics of SOC under the various crop rotation and land utilizationa. There is a signicfice in the particle size distribution, SOC contents and the natural abundance of ¹3C in these aggregates of Paludalfs under different crop rotation systems in North Huai region. Young carbon derived from corn tended to be accumulated in the coarse fractions as revealed by heavier stable carbon composition in those from deep layer under the rotation system containing corn crop.b. Land utilizatioin may affect the dynamics of SOC seriously.The effect of the cultivated leaf-harvesting Ginkgo on the SOC dynamics were studied. The results showed that when the agricultural soil （wheat） changed to the economic forests （Ginkgo）, the content of SOC decreased yearly. Soil carbon should be paid attention in the research of global change as well as reclaiming soil fertility and food quality.更多还原