Studies On Soil Respiration Under Differernt Land Use Types In Wufendi Gou Basin Of Huangfuchuan Region

Huangfuchuan watershed is located in the middle of the farming-pastoral zone in Northern China. It is a part of Warm-temperate typical steppe zone, and is sensitive to climate and land use changes. In this study, the main vegetation community and difiFerent land use type soils in Wufendi gou basin of Huangfuchuan watershed was selected to analyze the variation of soil respiration and water& temperature effect, study the influences of artificial activities on soil respiration, by using "LI-8100 Automated Soil CO₂ Flux System" to measure soil CO₂ flux in situ, combining with soil microorganism respiration soil microorganism relevant indexes and soil physical & chemical property indexes. The main results are as follows:The daily dynamics of soil CO₂ flux in Wufendi gou basin Huangfuchuan watershed changed with the differences of day and night environment, and the degree of change depended on soil moisture, soil temperature and their collocation. Under the moderate soil water condition, there was a biggish change and the change of soil CO₂ flux in 24 hours showed an obvious single-peak curve varying little during the night and noticeably in the daytime, which reached maximum value from 12:00 to 16:00 and minimum value at about midnight; under the condition of drought, the degree of change was smaller and there was a peak in the forenoon or after a short-term precipitation. The CO₂ flux under different land use types had comparatively obvious space-time differences. In the summer and autumn, the maximum of diurnal mean CO₂ flux all occurred in Form. Hippophae rhamnoides, and the minimum in sandy land. The order of soil CO₂ flux was: cropland > forest > grassland > sandy land.There was the maximum value of soil microorganism respiration intensity in cropland except marsh; the maximum contents of soil organic carbon, microbial biomass carbon and extractable carbon all occurred in cropland, too. The soil metabolic quotient in marsh was the highest, the second was in scrub forest and those in arbor forest,grassland and cropland were lower. On the whole, it was concluded that cropland,grassland and arbor forest were generally in order, but environmental constraints to a certain degree happened in scrub forest, and marsh environment was not stable indicated by high metabolic quotientThe data testified that soil water content and temperature had interaction on soil respiration.