关键词: 天然绿色棉, 天然绿色棉, 远缘杂交, 定向选育

Abstract: The herbage species under artificial Pinus tabulaeformis forests in Chengde ciunty were regarded as the main study object in this paper,and the interspecific relations of 595 pairs of species were studies byχ2-test,Pearson’s correlation coefficient and Spearman’s rank correlation coefficient.The results indicate that(1) In showing the associations of the species,Spearman’s rank correlation coefficient test is more sensitive thanχ2-test and Pearson’s correlation coefficient test.(2)The number of negative correlation pairs of species are more than positive correlation; the pr oportion of significant and very significant pairs of species is low;it means that most species are not closely related with each other and independently distributed and the communities are in the phase succession.(3)The positive correlations between species-pairs are the indication of niche overlap and owe to the similar biological adaptability; The negative correlations between species-pairs are the results of niche separation.