Habitat And Scale Dependence Of Interspecific Association In Gutianshan Subtropical Forest Communities

Interspecific association refers to the interrelationship between different species in the same spatial distribution.It is usually used as a basis for community classification and be an important indicator and evaluation criterion in the study of plant interrelationships in ecosystems.It is of great significance for understanding species coexistence,population distribution and dynamic succession in communities.Since the last century,the analysis methods of interspecific associations have been supplemented and improved many times,and have been widely used in ecology,botany,zoology and other fields.However,the current measurement of interspecific associations is often only an external description of the inter-species relationships among communities,and only the status of community dynamic succession or the results of competition among plants are obtained.The formation mechanism and process of interspecific associations are not clear.Based on the survey data of the 5 hm~2 subtropical evergreen broad-leaved forest community in Gutianshan,Zhejiang Province,the study specifically analyzed the overall connectivity and paired species connectivity of the community’s interspecific association by variance ratio method and Spearman rank correlation coefficient.Analyze the basic situation of the interspecific association of forest communities in Gutianshan.On this basis,the change trend of interspecific association in the three habitats and the three scale interaction factors is compared through boxplots to explore the habitat and scale dependence of the interspecific association in Gutianshan forest communities.The study contributes to understanding the interspecific relationship of 5hm~2 fixed plot in Gutianshan.It provides theoretical and data support for the study of species coexistence and community succession on subtropical evergreen broad-leaved forests.The main results and conclusions are as follows:(1)The basic situation of the interspecific association of the forest community in Gutianshan:At the scale of 20 m×20 m,the variance ratio method showed that the multi-species interspecific association(VR value)was 1.619(>1),indicating that the overall interspecific relationship in the community showed a significant positive correlation.The results of Spearman rank correlation coefficient analysis showed that among the 66 species pairs composed of 12 dominant species in the community,there were 42 pairs of positive associations and 24 pairs of negative associations,and the positive-negative association ratio was 1.75:1.In terms of the significance of the results,a total of 29 species pairs showed significant or extremely significant associations,of which there were 6 pairs of extremely significant positive associations and only 1 pair of extremely significant negative associations.In the results of the study,the number of species pairs with positive association was more than that of negative association species,and the number of extremely significant positive association species pairs was much more than that of extremely significant negative association species,and the overall relationship between multiple species was significantly positive association,indicating that the forest community in Gutianshan is in the development trend was relatively stable at the scale of 20 m×20 m,the inter-species relationships of the community tended to coexist positively,and the community structure was stable and in a positive succession stage.(2)Habitat dependence of interspecific associations of forest communities in Gutianshan:In the study,the interspecific association strength values in different habitats at three scales of 10 m×10 m,20 m×20 m and 40 m×40 m were represented by boxplots.The results showed that,regardless of the sampling scale,the interspecific association strength of paired species in the forest community of Gutianshan decreased with the increase of altitude.From the significance of the results,except that the results between the H2 habitat and the H3 habitat at the scale of 40 m×40 m were not significant,the other inter-group relationship results were extremely significant,indicating that the interspecific association of the community in the subtropical evergreen broad-leaved forest has a significant habitat dependence,and the higher the altitude,the weaker the interspecific association strength of the community.(3)Scale dependence of interspecific associations of forest communities in Gutianshan:In the study,the interspecific association strength values at different scales in three habitats of low altitude valley(H1),mid altitude hillside(H2)and high altitude ridge(H3)were represented by boxplots.The results showed that:in the H1 habitat and the H2 habitat,the interspecific association strength of the paired species in the Gutianshan forest community increases with the increase of the scale;in the H3 habitat,there is no significant relationship between the strength of interspecific association in the community and scale.From the significance of the results,in the H1 habitat and the H2 habitat,the interspecific association results of the community at the three scales were all pairwise significant;in the H3 habitat,except for the results at the 10 m×10m scale and the 40 m×40 scale,which were mutually significant,and the results among the other groups were not significant.This indicated that in the subtropical evergreen broad-leaved forest,the scale dependence of the interspecific association of the community was related to altitude.In the middle and low altitudes,the larger the scale,the stronger the interspecific association of the community;in the high altitude,there was no obvious scale effect.To sum up,the study found that the forest community in Gutianshan developed relatively stable;the interspecific association of the community had a strong habitat dependence,and the interspecific association strength decreased with the increase of altitude;the scale dependence of the interspecific association of the community was difference at different altitudes.The interspecific association strength of the community increased with the increase of scale at low altitude and middle altitude,but there was no obvious scale effect at high altitude.In addition,after comprehensively considering the effects of habitat and scale,the study believes that when conducting interspecific association studies on a large sample of subtropical evergreen broad-leaved forest,the middle altitude hillside habitat at the scale of 20 m×20 m is the most likely to detect the community interspecific association.The results of the study provide a certain reference value for the study of the influencing factors and mechanism of interspecific association of woody plants in Gutianshan.In the long run,it will provide a reference for the study of the succession dynamics of plant communities in subtropical evergreen broad-leaved forests.