We investigated the changes of soil nutrients and plant communities in the artificial sand fixation forests of Caragana korshinskii with different ages. The results showed that soil organic carbon and soil total nitrogen contents increased with the stand ages, and were significantly higher in 40 and 50 year-old than other ages. Soil organic carbon and total nitrogen contents recovered much faster in the surface layer (0-10 cm) than in others. Soil nutrient stoichiometric ratios (C:P, N:P) in the 0-10 cm soil layer differed significantly among different stand ages. With the increases of stand age, C and N contents in C. korshinskii leaves increased significantly, and reached the maximum at 50 year-old. Leaf P content increased first and then decreased, being maximum at 18 year-old. Leaf C:N first increased and then decreased, being maximum at 12 year-old. The contents of photosynthetic pigments and leaf C:P and N:P decreased first and then increased, being minimum at 18 year-old. C. korshinskii was mainly influenced by N availability before 40 year-old, but mainly limited by P after. The species number, density, and vegetation cover of annual and perennial herbaceous plants increased with stand ages, and the community shifted from a simple shrub plant community to a complex shrub-herb community. The biomass of C. korshinskii and herbaceous plants increased significantly with stand age, and had a significant positive correlation with the contents of soil organic carbon, total nitrogen and N:P.
以晋西北丘陵风沙区不同林龄(6、12、18、40和50年)柠条锦鸡儿人工林为研究对象,分析其土壤养分和植物群落变化特征。结果表明: 土壤有机碳和全氮随着林龄的增加而增加,在40和50年时养分含量显著高于其他林龄,且土壤表层(0～10 cm)有机碳和土壤全氮恢复远快于其他土层,表层土壤养分计量比C∶P、N∶P在不同林龄间存在显著差异。随着林龄的增加,柠条锦鸡儿叶片C、N含量显著增加,在50年时达到最大值;叶片P含量先增加后减少,18年时达到最大值;叶片C∶N先增加后减少,12年时达到最大值;而光合色素含量、C∶P、N∶P均先减少后增加,18年时为最小值。林龄小于40年的柠条锦鸡儿主要受土壤N的影响,大于40年主要受P限制。柠条锦鸡儿林下一年生和多年生草本植物种类数量、密度、盖度均随林龄增加而增加,植物群落逐渐由简单的灌木向复杂的灌草群落演变。柠条锦鸡儿与草本植物生物量随着林龄的增加显著增加,且均与土壤有机碳、全氮含量和N∶P呈显著正相关关系。.
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