Interspecific Relationship Of The Taxus Cuspidata

Taxus cuspidata is a tertiary relic species which distributes in Northeast China.It is also class I national protected and endangered species.Based on field investigation about Japanese yew population and communities in Muling Nature Reserve of Heilongjiang Province,the relationship between Japanese yew and other tree species was analysed using quantitative ecology.The interspecific interactions including intraspecific and interspecific competition, interspecific association,interspecific covariation,interspecific segregation and niche of species in T.cuspidata community.In intra-interspecific competition aspects:the intraspecific and interspecific competition intensity were quantitatively analyzed using Hegyi single tree competition index model.In interspecific association aspects:using X~2-test,the association coefficient(AC) and point correlation coefficient(Φ);In interspecific covariation aspects:using Pearson's correlation coefficient and Spearman's rank correlation;In interspecific segregation aspects:using interspecific separation index;In niche aspects:examining species-specific niche breadths(Levins) and overlaps(Pianka) of main species in tree and shrub layers.The results showed:Study on the natural population ecology of Japanese yew will be helpful to reveal its endangered mechanism,and it is greatly important in theory and applied values on conservation,plantation and restoration of the population effectively.This study revealed corresponding regulations about the scalar and stucture characteristics,intraspecific and interspecific competition,community characteristics,reproductive and tree-ring characteristics of Japanese yew population.The results showed:1) The intraspecific competition of Japanese yew population was weak,accounting for 5.88 percent of total competition,and the main stress to the Japanese yew population came from interspecific competition,which accounted for 94.12 percent of the total.The main competitors were Abies nephrolepis,Tilia amurensis and Acer mono.2) At 5m×10m,10m×10m and 10m×20m size quadrates,the multi-interspecies association index(V_R) were below 1(negative correlation).The association was significantly in 5m×5m and 10m×10m sampling area.But in 10m×20m sampling area,the association was no significant.In 20m×20m sampling area,the association was positive correlation,but no obvious.Based upon a series of techniques includingχ~2 test,association coefficient and connection coefficient,the species-pairs of significant association was increasing with the sampling plots enlarged.In different sampling area,species-pairs of weakly association occupied more than half.The species-pairs of negative association were more than that in positive association.The association between T.cuspidata and other species:In 10m×10m sampling plots,T.cuspidata and Ulmus laclnlata were significant positive association,In 20m×20m,T.cuspidata and T. amurensis were significantly positive correlation.3) The Spearman's rank correlation results obtained were basically with Pearson's correlation coefficient results.T,cuspidata and Suringa reticulate were significant negative covariant.T. cuspidata with Sorbus alnfoilaboth were positive covariant.Through segregation index andχ2 test,it was showed that most of the species pairs were positively segregated,some species-pairs were randomly segregated,and only a few species pairs were negatively segregated and T.cuspidata and Betula platyphylla,T.cuspidata and S.reticulata were positively segregated;other species were randomly segregated with T.cuspidate.4) Under all environments,T.cuspidata and T.amurensis in upper overstory were the greatest of all the species investigated.The niche breadth of Acer ukurunduense and Pinus koraiensis in succession layer were greater.In addition,T.cuspidata and T.amurensis's niche breadth were less succession layer.In upper overstory niche overlaps of A.tegmentosum,T.amurensis, A.ukurunduense,A.nephrolepis with that of T.cuspidata were very high.In succession layer, niche overlaps of Picea asperata and A.nephrolepis with that of T.cuspidata were greater than that of all the species investigated.