| With Concentration of CO2 increasing and greenhouse effect caused by it, all countries and social public is paying more and more attention to carbon cycling. Therefore, global climate change has become focus on the study of carbon cycling. However, soil carbon pool is playing a very important role in the process of global carbon cycling. It is well known that, soil carbon is losing greatly caused by serious soil structure damage and soil quality decreasing because of soil erosion. So vegetation restoration of eroded soil has potential of carbon sequestration and soil quality improvement and soil and water conservation. In the south of Jiangxi Province, a great deal of studies on soil and water conservation and ecology has been conduct in the eroded soil. But, the study of carbon sink has not been emphasized so that the role of soil organic carbon has not been definite. In the thesis, the effect of vegetation restoration on soil organic carbon (SOC), soil Oxidizing organic carbon (OOC), soil dissolved organic carbon (DOC), soil microbial biomass carbon (MBC), litter return organic carbon and fine foot return organic carbon has been studied. Major conclusions were summarized as follows:(1) There was a distinct increase of soil organic carbon content after vegetation restoration in eroded degraded red land. Different restoration patterns soil organic carbon content as follows:TR (11.8g/kg)>MM (9.64g/kg)>GL (8.88g/kg)>GJ (7.87g/kg) >FY (6.00g/kg), compared with HD (3.25g/kg), Which was 3.63 times,2.97 times,2.73 times,2.42 times and 1.85 times. Several restoration patterns soil organic carbon content in profile, layers of soil organic matter content decreased with the soil depth and individual-level is also a slight rise. In 0～20 cm soil, five restoration patterns soil organic carbon content account for more than 50% of the whole soil profile, there was a certain table cohesion and there was little change below 20cm the soil layers.By analysis of variance show:five restoration patterns and HD soil organic carbon content all reached a significant difference level (P<0.05).(2) There was a distinct increase of soil active organic carbon content after vegetation restoration in eroded degraded red land.Five restoration patterns soil EOC content range of 2.04-3.93 g/kg.Compared with HD, GJ、GL、FY、MM and TR soil EOC content had respectively increased by 2.63g/kg、2.59 g/kg、1.54 g/kg、2.75 g/kg and 3.43g/kg.The order between the content of Five restoration patterns soil WSOC was: TR>MM>FY>GL>GJ, which were 3.83 times,2.63 times,2.1 times,1.48 times and 1.41 times compared with HD.Soil MBC content had a same trend with WSOC content, which were 7.15 times,5.21 times,4.76 times,4.73 times and 3.56 times compared with the content of HD soil MBC.Vegetation restoration had a significantly improved the active soil organic carbon content, but had little change the trend of layers of soil organic matter content decreased with the soil depth.Variance analysis showed that:five restoration patterns and HD soil EOC content,MBC content all reached a significant difference level (P<0.05)(3) There was a distinct increase of litterfall organic carbon content after vegetation restoration in eroded degraded red land. For different tree species composition, litterfall are very different in different recovery mode, and show in the order:MM>GL>FY>GJ. In different recovery mode, leaf litter was the most important component of litterfall, and it accounted for more than 65% of theirselves. The litter falls of the four recovery mode showed evident seasonal dy-namics, GL and FY showed double peak type, peak appears in April and December; MM was the triple peak type,and there was a maximum in March; GJ showed single peak type, and peaked in May. In different recovery mode, the amount of litterfall organic carbon return was MM>GL>FY>GJ, and each litterfall components return as follow:leaves>branches>fruit.(4) There was a distinct increase of fine root organic carbon content after vegetation restoration in eroded degraded red land.As a whole of fine root biomass of four recovery patterns all had a increase compared with the HD. Fine root biomass of different restoration patterns had a significant difference and all mainly distributed in the the surface layer (0～10cm). The fine root biomass of HD and GJ changed significantly in the vertical direction, but GL slightly. Fine root biomass under different recovery mode show a seasonal variation and generally show a single peak. Among them the single peak of GJ is most obvious and it appears in July. MM’s fine root biomass more than HD of each month, but their trends almost the same and the single peaks appear in December and May, respectively. Changes in the fine root of GL and FY are both gentle, their range between 203.6～371.26 kg/hm2 and 532.55-771.18 kg/hm2, respectively. The amounts of fine root organic carbon restitution under every mode are GJ>FY>MM>GL and 7.52、1.95、5.28、 2.09 times of HD. |
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