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福建省长汀县河田镇是我国南方红壤区水土流失最严重的地区之一。通过对长汀河田严重侵蚀地采取乔灌木混交治理近 2 0a后林分N、P养分循环的研究 ,结果表明 ,乔灌木混交林乔木层地上各组分的N、P含量大小均为叶 >皮 >枝 >干 ,根系的N、P含量则随径级的减小而增大 ,乔灌木混交林各组分的N、P含量均比对照的高。混交林林分的N、P总累积量达339.2 0 0和 2 .0 88kg hm2 ,分别是对照的 1 0 0 .6倍和 69.6倍 ,其乔木层的N、P积累量分别占林分的 93.0 %和 93.6% ;乔灌木混交林苔藓层的养分积累量高于草本层和灌木层。乔灌木混交林的N年存留量、归还量和吸收量分别是对照的 33.6、2 5 .9和 30 .3倍 ,而P的则分别是对照的 81 .4倍、35 .9倍和 63.4倍 ,乔灌木混交林中乔木层、灌木层、草本层和苔藓层等在N、P养分循环中发挥较好的作用 ,对退化土壤肥力恢复起到十分积极作用。
Hetian Town, Changting County, Fujian Province is one of the areas with the most serious soil erosion in the red soil areas of southern China. The results showed that the contents of N and P in each component of arbor layer in the mixed forest of trees and shrubs were in the order of leaf> shrub> The content of N and P in roots and roots increased with the decreasing of diameter class. The content of N and P in each component of the tree and shrub-and-tree mixed forest was higher than that of the control. The total N and P accumulation in the mixed forest stands was 339.2 0 0 and 2.08 kg hm2, respectively, which were 100.6 and 69.6 times of the control, respectively. The N and P accumulation in the tree layer was 93.0% and 93.6% respectively. The nutrient accumulation in the moss layer of the mixed forest was higher than that of the herb layer and the shrub layer. The annual, return, and uptake rates of N trees, shrubs and mixed forests were 33.6, 25.9 and 30.3 times that of the control and 81.4 times, 35.9 and 63.4 times of the control respectively The tree layer, shrub layer, herb layer and moss layer in the mixed forest of shrub and shrub played a good role in N and P nutrient cycling and played a very positive role in the restoration of degraded soil fertility.