【摘要】 为了解常绿阔叶林退化对土壤碳库和养分库的影响,采用空间代替时间的研究方法,以常绿阔叶林顶级群落为参照,选择了次生常绿阔叶幼年林、次生针阔混交林、次生针叶林、灌丛和灌草丛代表不同的退化类型,分别对其土壤氮磷养分库、碳库进行了调查和分析。结果表明:土壤氮库贮量从大到小依次为,成熟常绿阔叶林、次生常绿阔叶幼年林、灌丛、次生针叶林、灌草丛和次生针阔混交林;土壤总磷含量也是在成熟林最高,次生针阔混交林和次生针叶林的总磷含量显著高于次生常绿阔叶幼年林和灌丛;土壤有机碳含量从高到低依次为:成熟常绿阔叶林,次生针叶林、次生常绿阔叶幼年林、灌丛、灌草丛和次生针阔混交林;土壤铵态氮在成熟林、灌丛和灌草丛的库容量最大,其次分别为次生幼年常绿阔叶林、次生针阔混交林,最小的为次生针叶林;硝态氮则在灌草丛的库容量最大,其次分别为次生针叶林、次生针阔混交林和成熟林针叶林,最小的为次生常绿阔叶幼年林和灌丛。统计显示,常绿阔叶林退化不仅导致土壤有机碳库含量的显著下降,也使得土壤氮磷养分库含量显著下降。可以认为,砍伐导致的大量生物量输出和森林管理措施的影响,植物种类组成的改变,土壤物理性质的改变以及养分和有机碳的主要生物化学转化环节发生改变是导致此类变化的主要因素,常绿阔叶林顶极群落土壤是该地区土壤的最大养分库和碳库。更多还原

【Abstract】 Evergreen broad-leaved forest(EBLF),covering a lot of area in China,is the zonal vegetation type in subtropical area.However, under long-term human disturbances,this forest is shifting to include much more degraded area dominated by secondary forests,shrub and grassland.Unfortunately,forest nutrients dynamics remain poorly qualified,despite the growing view that these processes might be extremely important in helping us understand changes of biogeochemical cycle in the context of the global change(particular in the change of land use),and shedding light on the conservation and restoration of EBLF.To understand the impacts of the degradation of EBLF on soil carbon and nutrient pools,we chose mature EBLF as the reference climax forest,and secondary and young evergreen broad-leaved forest,secondary conifer and evergreen broad-leaved mixed forest,secondary coniferous forest,shrubs and grassland to represent different degradation stages in Tiantong National Forest Park.After examining soil nutrients and carbon pools,we obtained the following results and conclusions:(1) Soil total N stocks displayed the following order: mature evergreen broad-leaved forest > secondary and young broad-leaved forest > shrub > secondary coniferous forest > grassland > secondary conifer and broad-leaved mixed forest;(2) soil total P is in the order: mature evergreen broad forest > secondary coniferous forest > secondary conifer and broad-leaved mixed forest > secondary and young broad-leaved forest > grassland > shrub;(3) soil organic carbon is in the pattern of mature evergreen broad forest > secondary coniferous forest > secondary and young broad-leaved forest > shrub > grassland > secondary conifer and broad-leaved mixed forest;(4) stock of soil NH+4-N displayed an "U" shape in the series of EBLF degradation;and(5) stock of soil NO-3 was highest in the grassland than other degraded types,in which significant differences were not found.These results suggested that soil carbon and nutrients pools decreased gradually during degradation of EBLF.The mature EBLF can be considered as a major carbon sink and a huge nutrient pools in this region.更多还原