内蒙古羊草草原退化系列上群落生物量组成特征的研究

通过对羊草草原退化系列上四个退化梯度植物种类组成、不同生活型和水分生态型的绝对和相对生物量以及群落的多样性指数的比较发现,随着退化程度的增强,物种的数量逐渐减少.禾本科在群落中的作用逐渐下降,而其它科,尤其是菊科的作用逐渐增大.群落科组成的多样性随着群落的退化先降后增,水分生态类型的多样性则逐渐下降.旱生植物的生物量逐渐增加,其作用随着群落的退化也逐渐增强,整个群落逐渐向旱生方向发展.多年生根茎禾草在群落中的生物量逐渐降低.群落生活型组成的多样性先降后增.在重度退化群落,多年生根茎禾草和多年生丛生禾草的相对生物量均有所下降,小半灌木和多年生草本的相对生物量有所升高,四种植物在群落中优势度较为平均,打破了原生群落中多年生丛生禾草和多年生根茎禾草占优势的局面.

The Study on Characteristics of Biomass Composition of Natural Leymus chinensis Steppe on a Deteriorated Series in NeiMongol

It is compared that the floristic composition,and relative biomass of different life forms and different water-ecotypes on four deteriorated communities of natural Leymus chinensis steppe.The characteristics of community biodiversity were examined as well.With the deterioration of the steppe,the number of the species decreased gradually.The function of Gramineae decreased,and the function of the others,especially Compositae,increased gradually.The diversity index of floristic composition decreased at the beginning of deterioration and then increased.And the diversity index of water-ecotype of community increased gradually.With deterioration,the biomass of xerophilous plant increased and its function also increased.The community became more xerophilous.The diversity index of life forms decreased at first and then increased.The biomass of perennial rhizome grasses decreased gradually.The relative biomass of perennial rhizome grasses and perennial bunch grasses was lower in the heavy-deteriorated community than in other communities.The relative biomass of small semi-shrubs and other perennial grasses increased.The dominances of these four life forms were about the same.The situation that perennial rhizome grasses and bunch grasses dominate the community changed.