Study On Interspecific Affinity Of Cephalcia Kunyushania And Plant Species Of Natural Forests In Kunyushan

The research of interaction between insects and forestry system is always the hot spot of forestry pest management. It can provide cornerstone to forestry pest sustainable management theory. In the process of the study,the information for distribution patterns,stand conditions and biological characteristic are of great help. O nly by knowing more details can we improve the forest ecological pest management(EPM) methods and production practices.In community ecology study, the relations and interaction between species runs throughout the performance as a main direction,which was called “inter-specific affinity”,including “inter-specific association” and “inter-specific correlation”. The former depicted the spatial coexisting patterns of different species in a certain region,as a binary qualitative analysis method;and the latter described quantitative relations between different species in the same environment. Both of them were based on biological diversity researches. Forest pest management or regulation is an important ecosystem service provided by biodiversity,especially by plant diversity.This study was conducted in the 50 permanent plots set by Kunyushan Ecosystem Station and to use Kunyushan web-spinning sawfly- host system as a model. The main contents are as follows:(1) Analysis of inter-specific association between Cephalcia kunyushanica and 57 Tree layer plants and 195 understory plants,in species pair form and in entirety form;(2) Comparison of mass of insect larvae sampled from different kind hosts,and comparison of Shannon-Wiener index of 2008,2012 and 2014;(3) Analysis the quantitative relations of host density and insect ecological density;(4) Select representative stand on the base of insect density,proportion of non- hosts as models.The main results are as follows:(1) Based on sample-circle(sample-quadrat) method and the 2×2 contingency table of species presence/absence data collected from 50 permanent plots in K unyushan region,the VR analysis,?2-test,association coefficient,Ochiai association index,Dice association index,point correlation coefficient,Cramer index,as well as percentage co-occurrence,were used in quantitative analysis of the inter-specific correlation of Cephalcia kunyushanica(the defoliator) occurrence and adjacent plant occurrence. The result of ?2-test indicated that there was a significant positive correlation of overall association existing among Cephalcia kunyushanica and other 57 Tree layer plants(195 neighboring understory plants,as well) at the 0.01 level. Furthermore, the insect showed extremely significant positive inter-specific correlation relations to 11 species including Carex rigescens respectively at the 0.01 level,while negative ones to 16 species including Carex siderosticta respectively at the same level. The insect also showed extremely significant positive inter-specific correlation relations to Pinus densiflora(P<0.01) and P. thunbergii(P<0.05) respectively,while negative ones to Hovenia acerba(P<0.01) and Populus ussuriensis(P<0.05) respectively.(2) An unequal number of mature larvae were collected from each host species,so we used a single- factor nonhomogeneous method to analyze the variance in larval mass among host species of Pinus. That revealed no significant difference in the mass of larvae among the seven hosts;The mean value of Shannon-Wiener indexes of the 32 plots(No. 1-40) in the 2008(The value was 0.9201) was almost the same with that in the year 2013(The value was 0.8961),without significant difference in statistics,and the same trend for that of other 7 p lots(41-50) in 2012 and 2013,which implied that this kind dominant leaf eating insect species have no significant influence on the species-richness of the 39 plots,where host pines were distributed.(3) C lassify the 39 plots into two tpyes,one is “pure host plot”,and the other is “host-non-host plots”. Use Pearson correlation analysis with larval density as a dependant variable. There was no significant relationship between sawfly larval density and the number of hosts in host- non- host mixed plots in the years 2013 and 2014(R22013 =0.001,R22014 =0.026). However,the results of Pearson correlation between sawfly larval density and the amount of hosts in “pure host” stands showed an interesting relationship trend: insect density decreased linearly with increasing host-plant density on ln- ln axes,no matter in the year 2013 or the year 2014. This relationship was significant( R22014=0.290,R22013=0.542,|t2014|>|t(0.05,17),|t2013|>|t(0.05,17),so both P <0.05). That revealed the resource dilution effect for Cephalcia kunyushanica.(4) No. 32 plot was selected as the representative stand for its suitable non- host density,plantation density and distribution patternsThe research also disscussed the characteristic, function and limitation of each association index, and potential co-coperation between Cephalcia kunyushanica and other organism during the succession of Kunyushan forestry system, as well as non-biotic factors’ action on the defoliating insect.