长江中游黄壤低丘区植被的退化特征研究——以浠水县为例

Studies on features of degenerate vegetation in yellow soil and low hill in the Middle Yangtze River:An example of Xishui country

以湖北省浠水县为例,采用以空间系列替代时间系列的方法,选取长江中游黄壤低丘区不同程度退化植被类型如天然林(石栎)、人工林(杉木、马尾松、毛竹)、灌丛次生林等,以荒裸地为对照,开展植物群落结构、生产力及功能退化特征对比研究。结果表明:(1)退化植被的群落外貌特征为群落层次减少,荒裸地和灌草地都缺乏乔木层,群落内多是阳性喜光植物;林分郁闭度降低,植被覆盖率降低。(2)随着植被退化程度的加深,生物多样性Shannon-Wiener指数的变化趋势为由小到大再变小,均匀度指数Simpson的变化趋势为由大变小再变大。(3)就土壤容重而言,石栎林<杉木林<灌草地<荒裸地,土壤孔隙度状况为马尾松林>灌草林>石栎林>荒裸地,不同退化程度森林类型土壤含水量、最大持水量、最小持水量变化趋势均为马尾松林土壤水分状况最好,其次是灌草林,然后石栎林、杉木林、毛竹林差别不大,荒裸地最差。(4)植被的退化影响土壤养分含量变化,本次调查中,荒裸地的土壤有机质含量为0.97%、全氮含量为0.06%,均明显低于其他森林生态系统,而全钾和全磷含量较为稳定。

By the method of replacing time series with spatial series, selecting natural forest of Lithocarpus glaber, artificial forest of China fir and Pinus massoniana and mao bamboo, bush secondary forest etc. as studying objects, taking bare and wasteland as the control, the comparative studies of vegetation community structure, productivity and function degenerative character were carried out in Xishui Country, Hubei, which locates at the yellow soil of low hill area in the Middle Yangtze River. The results are as follows： （1） the features of the degeneration vegetation community were the community level reduced, the barren space and shrub-land lacked of tree layer, there were mainly heliophile, and the forest crown density reduced, the vegetation coverage receded. （2） the Shannon-Wiener index of biodiversity changed from small to big and then to small with the increase of vegetation degeneration, and the evenness index changed from big to small and then to big. （3） ranked the rate of volume-mass of soil ranked as Lithocarpus glaber〈Cunminghamia lanceolata 〈shrub-land〈barren space; the porosity ranked as Pinus massniana 〉shrub-land〉Lithocarpus glaber〉barren space; the soil moisture and the max and min soil moisture changedas the order： Pinus massniana〉shrub-land^Lithocarpus glaber〉barren space. （4） the soil nutrient contents were afected by the degenerate degree of vegetation, the content of organic matter in the barren space was 0.97 % and the T-N was 0.06%, which was evidently lower then the other ecosystem＇s, but the K and T-P contents was very steady.