Competitive Relationship Of Dominant Species In The Loess Plateau Cai Song Community

It is imperative under the situation to accelerate the recovery and restoration of degenerative ecosystem on the Loess Plateau, because the ecosystem is seriously degraded due to soil and groundwater depletion. The vegetation was the foundation of changing ecological environment and improving the positive ecological cycle. Pinus tabulaefirmis f shekanensisrao was an ecological forma group of Pinus tabulaeformis in the Loess Plateau, have more excellent characters than P.tabulaeformis. The research of P. tabulaefirmis f. shekanensisrao provide important theory basis for protecting to superior tree species and reconstruction the ecological system of the regions.Based on comprehensive study to the P. tabulaefirmis f. shekanensisrao community, selected the P. tabulaefirmis f. shekanensisrao and Q. liaotungensis as the superiority species of P. tabulaefirmis f. shekanensisrao community for the research. We propose a new parameter namedⅣ(Individual Vantage); Then, CII competition index base on theⅣwas put forward and; Finally, the new competition index CII was applied to analyze the competition between P. tabulaefirmis f. shekanensisrao and East-Liaoning oak. The result showed that:the method of using the DBH to describe the situation of the whole tree growth lack enough basis of ecology and create the error in the research. The comparison and analyze imply that the new competition indexⅣand CII not only overcomes the shortcoming of using the DBH to describe the situation of the whole tree growth, but also counting simple and convenient. Thus,Ⅳand CII are superior to CID, and applicable for dominant tree species competition analysis. The analysis showed that:1. Analysis of the spatial distribution pattern of P. tabulaefirmis f. shekanensisrao and Q. liaotungensis by the way of Variance/mean. The analysis showed that, P. tabulaefirmis f. shekanensisrao and Quercus liaotungensis forests is aggregated distribution, P. tabulaefirmis f. shekanensisrao and Q. liaotungensis of interspecific competition is still fierce, and did not meet the relative stable communities' state. And the interspecific competition of P. tabulaefirmis f. shekanensisrao is more fierce than Quercus liaotungensis.2. We propose a new parameter named Individual Vantage (Ⅳ) for effective measure tree growth situation and more accurate quantitative trees competition between strength. We measure the competition ability of P. tabulaefirmis f. shekanensisrao and Quercus liaotungensis by the ways of the index of IV and APA. The results can be shown as follows:(1) The index of Individual Vantage is an equally effective index compared to APA; (2) There are 4 stages in the compare of the competition ability of P. tabulaefirmis f. shekanensisrao and Quercus liaotungensis:in the scales of 2.5cm