Effects Of Rice-duck Intergrowth On Biodiversity Of Benthic Animals In Paddy Water

With the expending area of rice-duck intergrowth, the theory of rice-duckintergrowth increasingly becomes focus. In order to study the change of benthicanimal's biodiversity in paddy and measure method. This trial through designeddynamic experiment of rice-duck intergrowth and experiment of different numberducks. We expected finding the dominant factors which effect the change of benthicanimal's biodiversity in paddy's water environment and confirming reasonable numberof ducks. The results as follows:1 The number of benthic animal kinds descent as raising ducks in paddy. Themore ducks in paddy, the more degree of descent, especially in tillering stage andripening stage. The total number of benthic animal descent comparing general paddy.The descend degree was big in anterior stage and small in late stage. The difference ofsuperiority population was not evident in anterior stage and evident in late stage. Thereason was that the superiority degree of Branchiura was more and more evident. Inthe general paddy, the superiority population was more and more not evident and thecomposition of every kinds was equality.2 The benthic animal's biodiversity in rice-duck intergrowth was increasing inanterior stage and fall in late stage. The correlative coefficient was high betweenShannon-Wiener index and Simpson index, reach 0.96, which were the ideal methodsto measure and estimate the benthic animal's biodiversity in paddy. But, the Marglefindex was not reasonable.3 The numerical value of DO and COD was increasing. The numerical value oftotal N was also increasing except in ripening stage. The effect of pH was not evident.The relativity between DO and Shannon-Wiener index orSimpson index was best, reach 0.72. So we could apply DO estimating benthicanimal's biodiversity in paddy cursorily.4 In order to protect benthic animal's biodiversity in paddy, reduce disturbingducks' normal activity and confine casting food in anterior stage; keep high level ofwater and casting enough food in late stage; extract ducks early in ripening stage. Weshould limit raising the number of ducks in paddy which the best number was aboutper 180 ha.