中文摘要：

利用LI-6400便携式光合作用测量系统和LI-6400-09土壤呼吸室,对不同地形和不同植被条件下土壤呼吸速率及其影响因子进行测定。结果表明：科尔沁沙地土壤呼吸速率日变化均表现出上午逐渐增大,下午逐渐减小、凌晨最小的趋势。沙地土壤呼吸变化具有明显的空间异质性,土壤呼吸由大到小变化依次为：背风坡（1.95±0.21μmolCO2.m-2.s-1）〉坡顶（1.05±0.14μmolCO2.m-2.s-1）〉迎风坡（0.74±0.08μmolCO2.m-2.s-1）〉丘间低地（0.62±0.09μmolCO2.m-2.s-1）。沙地土壤呼吸与植物生长条件具有密切关系,狗尾草（0.86±0.11μmolCO2.m-2.s-1）〉小叶锦鸡儿（0.69±0.06μmolCO2.m-2.s-1）。土壤呼吸日变化速率与空气温度呈正相关,与空气相对湿度呈负相关关系,并且与土壤温度呈指数相关。沙丘内部不同地形、植被的Q10差异不大。

英文摘要：

Soil is a major C pool,and it has a close link with atmospheric and biotic pools.Soil respiration is an important component in carbon cycle of terrestrial ecosystem.Soil respiration is the sum of heterotrophic respiration（soil fauna,bacteria and fungi） during decomposition of organic matter,and autotrophic（root） respiration.As an index of the metabolic activity of heterotrophic microbes and plant roots,soil respiration shows spatial heterogeneity.On a global scale,soil respiration showed a clear zone characteristic from tundra to equatorial ecosystems;soil respiration also showed a significant spatial variation under different vegetation,soil texture and land-using patterns and other factors in small-scale topography.In the desert,there is big variation in sand dune terrain conditions by the impact of changes in different parts of soil moisture,soil temperature,vegetation diversity,community appearance and characteristics of vegetation conditions.The previous study was emphasized on the effect of desertification on soil respiration and carbon balance studies,whereas spatial heterogeneity of soil respiration and its mechanism was inadequate.And studies for the quantitative assessment of soil respiration which reveals desertification of terrestrial ecosystem carbon cycle and its effect on global climate change has an important significance.In order to understand the controlling environmental factors of soil respiration in sand land,we studied daily variation of soil respiration and its relationship with air temperature,air humid and soil temperature in Horqin Sand Land.By using LI-6400 portable photosynthesis apparatus connected to soil chamber,soil respiration and environmental factors under different sand dune terrains（low land,windward slope,the top of the dune,leeward slope） and different vegetation conditions（Caragan microphylla and Setaria virdis） of the dune in a sand dune were measured in August 2010,with related affecting factors analyzed.The result indicates that the diurnal trend soil res