Interspecific Segregation in Carpinus cordataCommunities in Lishan Nature Reserve,Shanxi

Interspecific relationships are an important element affecting community structure and function.To explore the pattern of interspecific segregation in Carpinus cordata communities,40 quadrates were investigated in Lishan Nature Reserve,Shanxi,with a distribution map drawn for all trees and shrubs with the DBH≥5 cm for tree or basal diameter for shrubs.The nearest neighbors of each individual were identified using nearest neighbor method.The interspecific segregation for all species in these communities was studied by using the χ²-test,an N×N nearest-neighbor contingency table and a 2×2 nearest-neighbor contingency sub-table.Based on the value to divide S index,interspecific segregation indicated that there were 349 species-pair positive segregations,90 species-pair negative segregations,and 507 species-pair random segregations,accounting for 36.89%,9.52%,and 53.59%,respectively.The semi-matrix showed that the dominant species often showed positive segregation,and had a stronger viability and competitiveness,such as Carpinus cordata,Carpinus turczaninowii,Acer mono and Acer grosseri.The dominant and companion species usually showed negative segregation,with fewer individuals and lower coverage,such as Abelia biflora,Ribes mandshuricum and Rosa bella.The result of the χ² test for the N×N nearest-neighbor contingency table indicated that 44 species in the communities demonstrated mosaic distribution and overall non-segregation.Moreover,the results of species segregation indicated that the Carpinus cordata communities were in the early stage of succession,which was consistent with the fact that the communities were unstable due to the disturbance of natural rock collapse and human activities.