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The Influence of Vegetation Restoration and Re-vegetation on Soil Organic Carbon Stocks in the Hilly Loess Plateau

Author: WangZheng
Tutor: LiuGuoBin；XuMingXiang
School: Northwest University of Science and Technology
Course: Ecology
Keywords: Soil organic carbon Vegetation restoration Loess Hilly Region Soil respiration Seasonal changes
CLC: S714
Type: Master's thesis
Year: 2011
Downloads: 102
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Abstract

The hilly area of ??the Loess Plateau, returning farmland to forest / grass vegetation restoration of regional land use / cover had a significant impact, direct impact on the ecosystem carbon cycle and greenhouse gas emissions. Vegetation restoration of the environmental effects of the key scientific issues and assessment needs of the national ecological construction effect, the research for the study area in the Loess Hilly Region, to study the different vegetation restoration on soil organic carbon (SOC) sequestration spatial and temporal variation explore vegetation restoration the SOC library component and the dynamic changes of soil respiration and its influencing factors. Provide a basis for assessing regional vegetation restoration of soil carbon sequestration effect, understand the variation of the regional soil organic carbon pool. Study made the following main conclusions: 1) the type of vegetation recovery and restore the life of significant soil carbon sequestration effect, better than the long-term effects of artificial bushes and trees woodland soil carbon sequestration on the land abandonment and natural grass; vegetation to restore soil carbon sequestration effect spatial differences. Vegetation restoration in the short term (0-10/15yr), the fastest accumulation of natural shrub land SOC density (SOCD) (0.93 t · hm ^{-2 · yr ^{-1 ) artificial trees, artificial shrub, fallow and natural grassland SOCD no significant increase. The vegetation restoration 20/25yr, artificial trees, shrub land SOCD annual accumulation rate was significantly increased to 0.53-0.66 t · hm ^{-2 yr ^{-1 , significantly higher than the abandonment land and natural grass. The Vegetation Restoration is the dominant factor in the small watershed SOCD space redistribution. SOC content in soil profiles and reduce the surface layer (0-5cm) SOC closure the most significant, is also sensitive layer SOC changes. Terrain of SOC accumulated significant impact which aspect SOC closure greatest impact, followed by slope position, slope less affected. 2) SOC stratification ratio (stratification ratio of SOC, SR) is indicative of the Loess Hilly Region vegetation restoration valid indicators of changes in soil carbon sequestration effects and soil quality, SR (0-5/20-30cm) gt; 2 vegetation restoration key indicators of soil quality improvement process. The SR and SOCD with the lives variation consistent, organic matter, total N and available N with vegetation restoration years changes with SR. The SR indicates differences in SOC closure of different vegetation types and soil quality, artificial trees, shrubbery the SR (0-5/20-30) and SOCD, organic matter, total nitrogen, available nitrogen was significantly higher than that of abandoned land. Sloping land into terraced fields or orchards, SR interference by farming, did not change significantly. SR (0-5/20-30cm) was significantly associated with the the SOCD and soil quality indicators. 3) artificial arbores on the deep (50-200cm) soil SOC reserves significantly improved. 2m soil SOC reserves than 1m the soil SOC storage is about 1/3 higher. The deep SOC reserves in the reconstruction of 15-24yr have significantly improved. 9-34yr reconstruction 2m soil SOC reserves significantly increased up to 43.02 t · hm ^{-2 than the 1m soil high 8.36 t · hm ^{-2 . Estimating the area of ??vegetation to restore soil carbon sequestration effect, if you only consider the 1m soil SOC reserves will be seriously underestimated the effect of the vegetation to restore soil carbon sequestration. 4) the different seasons of the amount of soil respiration significant differences in the non-growing season soil respiration is an important part of the soil carbon; seasonal variation of the temperature of soil respiration to play a leading role, while the total soil respiration of different vegetation types mainly by the easy oxidation SOC and microbial biomass carbon content. And sunny 9 years of plantation (ch9h), the shady slope 9 years plantation (ch9y) and Sunny 25 years of plantation (ch25) the non-growing season soil respiration rate 0.20-0.49μmol · m ^{-2 · s ^{-1 , significantly lower than the growth season, but still had a high proportion (10-18%) of the growing season respiration rate. The temperature of the main factors of the seasonal variation of soil respiration, moisture, easily oxidized SOC and microbial biomass carbon changes from the regulation change on soil respiration season. The ch25 easily oxidized SOC and microbial biomass carbon content significantly to higher than ch9h and ch9y led to the ch25 total soil respiration rate was significantly higher than ch9h and ch9y. 5) plantation land the SOC library component has certain seasonal dynamics, this dynamic change of temperature, moisture and other environmental factors are closely related. Decreased SOC content in the growing season, the opposite seasonal changes and soil respiration. The higher content of microbial biomass carbon ease the oxidation SOC in the spring and autumn, summer and winter in a lower value, medium temperature and moisture conditions are conducive to the propagation of microorganisms ease of oxidation of the formation of the SOC. The strong correlation between SOC content and SOC active component content, the main part of the seasonal variation of the SOC library may be the active component of the SOC, soil surface 0-5cm soil carbon release level.}}}}}}}}

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