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    不同恢复年限侵蚀红壤生态化学计量特征

    Ecological stoichiometry characteristics of eroded red soil in different restoration years

    • 摘要: 为了解侵蚀红壤碳、氮、磷分配格局及化学计量特征,本文在长汀县侵蚀红壤区选取不同恢复年限(2、13、30、33 年)、立地条件相近、样地情况基本一致的马尾松林作为研究对象,以未治理侵蚀地(CK1)和次生林(CK2)为对照,对其土壤总有机碳、全氮和全磷质量分数及其化学计量比的特征进行测定和分析。结果表明:1)随恢复年限的增加,土壤总有机碳和全氮质量分数呈线性增加,土壤全磷质量分数无显著变化,恢复2 ~ 33 a 的马尾松林土壤总有机碳、全氮和全磷质量分数仍显著低于CK2 土壤,表明土壤肥力的恢复是一个漫长的过程。2)土壤C:N、C:P、N:P随恢复年限的增加呈上升趋势,恢复2 ~33 a 的马尾松林土壤C:N 逐渐趋向CK2。3)土壤C:N 和C:P 与土壤总有机碳质量分数呈正显著相关,土壤N:P 与全氮质量分数呈显著正相关,土壤N:P 与全磷质量分数相关性不显著,表明侵蚀退化红壤恢复过程中,土壤化学计量比主要受土壤碳和氮质量分数的控制,暗示着侵蚀红壤现阶段的植被恢复对N 素的响应比对P 素的响应更敏感。

       

      Abstract: Background Large areas of degraded lands have been restored in red soil regions of south China since 1980s, which provides tremendous ecological and economic services such as soil and water conservation, carbon sequestration and environment protection. Some problems such as soil degradation,soil and water loss and tree disease decline, however, also appeared after several decades of ecological restoration due to lack of knowledge about soil characteristics, which seriously threatens the stability and sustainability of plantation. The contents of carbon, nitrogen, and phosphorous are important indexes of forest management, which respond positively to the environmental conditions. In recent years, the ecological stoichiometry has received considerable attentions. However, few studies have been reported about the patterns of soil stoichiometry across ecological restoration. Methods We took Pinus. massoniana woodlands as research objects, and determined the content variations of total organic carbon (C), total nitrogen (N), and total phosphorous (P) in soil, as well as ecological stoichiometric ratios across different ecological restoration years at 6 sites. Six P. massoniana woodlands were the ones restored by 0 year (CK1), 2 years, 13 years, 30 years, 33 years, and secondary forest (CK2), respectively. Those study sites were expected to be distinguished at the level of ecological restoration years along the typical eroded red soil region in Hetian town, Changting County, Fujian Province. Results 1) The contents of C and N in soil increased in the restoring process of degraded red soil. However, the P content was not considerable changed. The soil C, N and P contents in the forest of restored 2-33 years were still significantly lower than those in CK2. 2) The ratios of C:N, C:P and N:P tended to increase with the restored years increasing, especially soil C:N ratio of restored 2-33 years was approaching to those in CK2. 3) C content and C:N, C content and C:P, N and N:P all were in positive correlation, but P content had no significant correlation with N:P. Conclusions Soil C, N and P contents were out of balance in the non-restored eroded red soil (CK1). Despite some areas have been restored for 30 or 33 years, the nutrient contents still were lower than those in secondary forest (CK2). In other words, the typical eroded red soil restoration is a long-term process. Moreover, soil stoichiometry ratios were mainly restricted by soil C and N contents in the restoring process of degraded red soil. It suggests that a vegetation recovery is more sensitive to N than to P at this typical eroded red soil region. Thus, this study will help to reveal the nutrient cycling of P. massoniana woodlands by combing with stoichiometric characteristics of soil C, N, and P comprehensively and systematically. Therefore, it is very important to guide the ecological restoration of eroded red soil,and further improving the productivity of forest system should be carried out.

       

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