Influence Of Community Plant Diversity And Density On Soil Resistance In Songnen Grassland

In the past decades, due to irrational land uses, overgrazing and steppe-croplandconversion，steppe degradation widely occurred and inverse succession emerged inSongnen grassland. Degradation belongs to desertification. Soil erosion is the keydriving force that leads to desertification. Desertification performances for manyaspects, for example, the quality and number of communities’ decrease; the structureof communities is damaged; the function of communities can’t be played; theproduction of grassland and ecosystem biodiversity’s decrease. By this token，to studythe factors that influence soil resistance of Songnen grassland is so important.By field investigation, field sampling and lab analysis, the following results wereobtained:1. Our vegetation survey indicates that plant diversity reached1in the pioneerstage, increased to about5in the transitional stage, and decreased to1again in theclimax stage. The key vegetation type of pioneer stage is Chloris virgata.Leymuschinensis and other kinds of plant compose the key vegetation type of transitionalstage. The key vegetation type of climax stage is Leymus chinensis.2. The rich plant diversity systems generated higher soil resistance (with lowerSDR) in soils than the poor plant diversity systems.3. Community plant density always affected soil resistance with significance.Higher plant density means higher soil resistance.4. Plant diversity and density both affect soil resistance in the Songnen grasslandecosystem. But the plant density may contribute more to the soil resistance than thecommunity plant diversity in the grassland.