Comparative Study on Rainforest Species Association in Different Altitude in Mountain Diaoluo of Hainan

In order to assess the relationships of species interaction changes with the height of elevation,species association in the two different altitude tropical rainforests in Diaoluo Mountain of Hainan Island was studied.Several indices of the tree layer in the oak nuturd sewndary forests in Diaoluo region were analyzed,including relative aboundance(RA),relative dominance(RD),relative frequency(RF),and important value(IV),Based on 2×2 contingency tales of species presence or absence data,statistical methods including analysis of species association and χ2 test were applied.The results showed that: 1)The test revealed that all tree species in different altitude tropical rainforests showed a significant pattern of positive association;2)The proportion of species pairs showed no associations in different altitude tropical rainforests though χ2 test on 20 species forming 190 species pairs;3)The proportion of the no associations species in the lowdown rainforest was higher than the tropical mountain rainforests with the increase of the altitude and the proportion of the positive and negative association was lower than the tropical mountain rain forest with the increase of the altitude.