The Effects Of Flaveria Bidentis Invasion On Soil Microbial Communities, Enzyme Activities And Nutrients

The effects of exotic species Flaveria bidentis invasion on soil microbial communities, enzyme activities and nutrients had been studied to reavel the mechanism of Flaveria bidentis invading farmland and barren land successfully. The results are as follows:1. Available N, P, K at the root rhisphere of Flaveria bidentis were significantly higher than the control. Soil microbial communities were also higher than the control, the more closer to root, the more numbers of microbial communities. Compared to cultivated land, Flaveria bidentis had a bigger lifting capacity at non-cultivated land. Soil enzyme activities were significantly higher. The closer to root, the higher enzyme activities. pH values were significantly higher than the control. In Flaveria bidentis root surface at non-cultivated land and cultivated land, the contents of available nutrients were 6.88、2.64、4.44 and 13.78、7.56、5.31 times as that at nude land respectively; the numbers of cultivable actinomycetes, bacteria and fungi in root surface were 21.40, 13.23, 6.67 and 9.27, 2.15, 2.24 times as that at nude land respectively; The alkaline phosphatase, acid phosphatase, urase, dehydrogenase, invertase activities were 19.44, 5.39, 1.64, 1.74, 4.62 and 2.26, 3.45, 1.53, 0.95, 4.89 times as that at nude land respectively which can indicate that bacteria were so active.2. The invading of Flaveria bidentis significantly reduced root available nutrients, the numbers of microbial communities and soil enzyme activities at the root surface of nearby maize. The contents of available nutrients at non-interactional root surface were 64.70%, 80.71%, 63.54% of that at interactional root surface.3. Both field and laboratory tests confirmed that the total P at root rhisphere of Flaveria bidentis and maize reduced significantly but the available P increased significantly, suggesting that root secretion or (and) the microbial communities nearby roots have the ability of translating sparingly soluble phosphate into soluble phosphorus.4. The total nutrients in the organs (leaves, stalks, grains, roots) of Flaveria bidentis were significantly lower than in maize, this maybe one of the important reasons of Flaveria bidentis can live in barren land.