科尔沁沙地植物多样性对生产力的影响及分布格局

Influence upon productivity and biodiversity patterns by plant species diversity on Kerqin Sandy Land

采用种丰富度和以Shannon-Wiener指数为计算方法的功能多样性和组成多样性为指标,探讨了植物多样性对科尔沁沙地草场生产力的影响以及其分布格局特征。结果表明,科尔沁沙地植被不同的物种多样性指数对系统生产力的影响以组成多样性最大,功能多样性次之,植物种丰富度最小。在小尺度上,组成多样性只存在一种格局且具有分形结构,其格局对干扰过程反应不明显;功能多样性有多种格局存在,对多种干扰过程反应敏感。从提高沙地草场生产力和增强系统的稳定性角度出发,草场改良的依据应建立在种的引进和引进种所产生的组成多样性上。

Plant species diversity, being divided into species richness, functional diversity, and composition diversity, and its influence upon grassland productivity and distribution pattern of the plant diversity had been studied with Shannon- Wiener index method. The results showed that the composition diversity exerted the greatest influence upon the productivity of the grassland systems, the functional diversity had less impact upon the productivity and the species richness had the least influence upon the productivity in Kerqin sandy land. For the composition diversity, the system productivity increased with the diversity while the diversity indices changed form 0.5 to 1.1, the climax productivity reached 336g/m2 when the diversity index was 1.1. In addition, the increase of functional diversity alto induced the system productivity enhancement, when the diversity index was 0.9 the productivity rose to maximum value as 299g/m^2. Moreover, when the diversity indices were more than 0.9 the productivity descended gradually. On a small scale, the composition diversity existed only one kind of distribution pattern and had the fractal structure, which indicated the pattern of vegetation composition diversity was not sensitive to different disturbing processes. On the contrary, the functional diversity bore several patterns and was sensitive to such different disturbing processes. The changing traits of lacunarity curve illustrated that the functional diversity was higher aggregation （curve slope is sharp） when the analysis scales were less than 15. Reversely, the aggregation of functional diversity was lower （curve slope is flat） when analysis scales were more than 15. In order to promote the productivity of the sandy grassland and enhance the stability of the sandy land ecosystem, the grasslands improvement should be based upon the introduction of the different plant species and the consequent composition diversity formed by the introduced plant species.