滇中本地和外来植物群落对紫色土理化性质的影响

在同一"气候-母质"条件下,本文研究了滇中飒马场流域4种处于不同演替阶段的本地植被群落和1种外来植被群落对酸性紫色土理化性质的影响。结果表明:随着灌草丛、云南松、针阔混交林到次生常绿阔叶林的本地植物群落演替过程,土壤的容重、pH、水溶性盐阳离子含量明显降低,而土壤粘粒、水解性酸、活性铝、有机碳、全氮含量显著增加,同时表层土壤有机碳和全氮占其剖面总含量的比例有降低的趋势。次生常绿阔叶林土壤0~150 cm土层的有机碳、全氮贮存量比灌草丛土壤的分别高出35 Mg hm-2和1.2 Mg hm-2,而其pH则比灌草丛土壤的低0.33。这反映出酸性紫色土的富铝化过程、生物富集过程和粘化过程随着植被演进而加强。桉树林土壤有机碳、全氮贮量和pH分别为93.04 mg hm-2、2.45 mg hm-2和4.49,与针阔混交林土壤的有机碳、全氮贮量和pH没有显著差异,但是其水解性酸度和活性铝含量均显著高于针阔混交林土壤的,表明长期种植桉树有加速土壤酸化的可能。

Impacts of Native and Exotic Vegetation Types on a Cambisols Properties in the Mid-Yunnan Plateau

The long term impacts of native and exotic vegetation were investigated on soil physico-chemical properties(1.5 m depth of soil profiles).The experiment site,established in a degraded Aci Pup Udic Cambisols of the mid-Yunnan plateau of China(25°24′09″N,101°28′18″E),contained five vegetation types,including one exotic,Eucalyptus smithii forest(EF),and four native vegetation: shrub land(SL),Pinus yunnanensis forest(PF),semi-natural Keteleeria evelyniana and Pinus yunnanensis forest(SNF),natural secondary forest of Keteleeria evelyniana and Cyclobalanopsis glaucoides(NSF).With the vegetation succession from shrub land to natural secondary forest,soil bulk density,pH,soluble salt content decreased,but the contents of clay,total acidity,active aluminum,organic carbon and total nitrogen increased significantly.The highest soil organic carbon(SOC) and total nitrogen(TN) measured under NSF were 121 and 2.96 mg C hm-2,respectively,whereas under SL,those were 86 mg C hm-2 and 1.76 mg C hm-2 respectively.Therefore,there is evidence suggesting that pedogenic processes of allitication,humification and argilication of the Cambisols were intensified following the forest succession.Soil pH,SOC and TN of EF were 4.49,93.04 Mmg C hm-2 and 2.45 mg C hm-2 respectively,and were not significantly different from those of the SNF soil.However,higher content of soil total acidity and active aluminum of EF soil indicated that the plantation of Eucalyptus smithii might have accelerated soil acidification.