高寒草甸不同草地类型功能群多样性及组成对植物群落生产力的影响

The effects of differences in functional group diversity and composition on plant community productivity in four types of alpine meadow communities

对不同类型草地功能群多样性和组成与植物群落生产力之间的关系进行了探讨。结果表明 :(1)在矮嵩草(Kobresiahumlis)草甸和金露梅 (Potentillafroticosa)灌丛中 ,豆科植物的作用比较明显 ,而其他功能群植物的作用较弱。 (2 )在藏嵩草 (Kobresiatibetica)沼泽化草甸和小嵩草 (K .pygmaca)草甸中 ,虽然杂类草、C3 植物和莎草科植物功能群的生产力占群落初级生产力的比例较大 ,但二者在统计上没有显著性差异 ,这表明群落生产力除受物种多样性的影响外 ,也受物种本身特征和环境资源的影响 ,更主要的是受到功能群内物种密度和均匀度的影响 ,即功能群组成比功能群多样性更能说明对生态系统过程的影响。 (3)不同类型草地群落植物功能群盖度与群落初级生产力呈显著的线性相关。 (4 )不同类型草地群落生产力与功能群内物种数的变化均表现为单峰曲线关系 ,即功能群内物种数处于中间水平时 ,群落生产力最高。

The relationship between species diversity and ecosystem function is one of the core problem of biodiversity research, and productivity is an important modality of ecosystem function. The species diversity of natural communities is often strongly related to their productivity. The grassland is an important component of terrestrial ecosystems and plays a significant role in the biodiversity and ecosystem function. Understanding of how to use natural vegetation to restore deteriorated grasslands is critical for protection of grassland ecosystems. Moreover, the relationship between species richness and productivity relies on scales. At some scales, productivity affects diversity, and at other scales, species diversity also affects productivity. Thus, it is necessary to know the relationship between plant functional diversity and productivity in different grassland types. In 2003 the differences in plant functional diversity, functional composition and productivity in different grassland types of alpine meadow were analyzed. Humans are modifying both the identities and the numbers of species in ecosystems. However, the impacts of such changes on ecosystem processes are still controversial. The effects of functional diversity and composition on plant community productivity were analyzed in four types of alpine meadows. The research results show:(1) the effects of the legume functional group on productivity was greater than other functional groups in Kobresia humlis meadow and Potentilla froticosa shrub. (2) Although the biomass of forbs, C 3 plants and sedge functional groups account for higher proportion of community productivity in Kobresia pygmaca meadow and K. tibetica swamp meadow, differences were not significantly different, indicating that the factors influencing community productivity were not only species diversity, but also the identity of species present and environmental resources. These factors were in turn mainly affected by species diversity and evenness among functional groups. That is, differences in functional group composition have a larger effect on ecosystem processes than functional group richness alone. (3) A significant correlation was found between the coverage per functional group and the primary productivity of communities in the four types of alpine meadows. (4) Changes in productivity with number of species per functional group showed a unimodal pattern, such that the maximum community productivity occured at an intermediate level of number of species per functional group.