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Difference analysis of soil organic carbon pool in different forestlands returned from farmlands in karst gorge area |
Tang Fukai1, Cui Ming1, Zhou Jinxing1, Yan Shuai1, Ding Fangjun2, Lü Xianghai3 |
1. Research Institute of Desertification, Chinese Academy of Forestry ,100091, Beijing,China; 2. Guizhou Academy of Forestry,550005, Guiyang,China; 3. China International Engineering Consulting Corporation, 100048, Beijing, China |
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Abstract To determine the effects of different forestlands returned from farmlands on soil organic carbon and carbon pool management level in karst areas, soil organic carbon (SOC) contents, density and carbon management index ( ICM ) under six different land-use types, including conventional farmland (CT), abandoned farmland ( AF), farmland returned to plantations of Dodonaea viscosa ( DV), Zanthoxylum scandens (ZA), Toona sinensis (TS) and Vernicia fordii (VF), were studied in Huajiang gorge area of Guizhou Province. The results showed that: 1) compared with farmland, total organic carbon (TOC) content and density of lands converted from farmlands increased significantly (P<0.05). TOC in 0 -20 cm layer ranged from 13.00 -34.07 g/kg, with farmland the lowest while Toona sinensis the highest. TOC density in soil profile presented a trend of TS> VF>AF>DV>ZA >CT. 2)Both TOC content and TOC density decreased with the increase of soil depth in all land-use types. TOC contents in 0 -20 cm soil were 1.11 -1.37 times as high as the cross-sectional mean value, while SOC density in 0 -20 cm deep soil accounted for 35.68% -46.45% of the entire section, showing an obvious table cohesion. 3) Taking farmland as a reference, ICM of all the other four converted lands were obviously greater than 1 except for Z. scandens. Vegetation recovery can effectively improve soil carbon pool management level, with T. sinensis and V. fordii having the highest efficiency. In addition, the change of LOC/ TOC ratio had the same tendency as the variation of TOC content. RL/ T can be used as an important indicator to reflect the level of carbon management. In summary, returning farmland to forests has the potential of expanding capacity of carbon pool and improving soil quality; therefore, we should pay attention to selecting suitable restoration modes, increasing vegetation cover as well as reducing human disturbance.
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Received: 25 September 2013
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