| Quercus variabilis is one of the most widely distributed native tree species in my country,and it is also a dominant tree species for vegetation restoration,making a huge contribution to protecting the ecological environment.However,most of the cork oak forests in China are residual secondary forests and artificial forests.There are problems such as reduced productivity,single tree species and unstable ecosystems,which provide conditions for the invasion of pests and diseases.The invasion of pests affects the health problems of cork oak forests and causes serious economic losses.A large number of studies have shown that there are many factors that affect the occurrence of forest pests.Site conditions,meteorological factors,human factors and forest stand structure will all have an impact on the occurrence of forest pests.However,there are few studies on the impact of leaf-eating pests in variabilis oak forests.Therefore,in this study,the pure forest of Quercus variabilis and the mixed forest of Quercus variabilis and Platycladus orientalis were studied.40 plots of the pure forest of Quercus variabilis and the mixed forest of Quercus variabilis and Platycladus orientalis were set up in Qingliangsi forest area in Dengfeng City,Henan Province.Starting from the perspectives of site conditions,stand structure,and understory vegetation diversity,using a combination of field surveys and indoor analysis experiments to explore the relationship between these factors and the degree of damage by leaf-eating pests,through a comparative analysis of pure oak forests and The difference in the degree of damage of leaf-eating pests in the mixed forest of Quercus variabilis and Platycladus orientalis leads to the following main conclusions:(1)Different site factors have different effects on the damage degree of leafeating pests in pure forests and mixed forests.Altitude,litter thickness and litter coverage are significantly positively correlated with the damage degree of pure forest and mixed forest leaf-eating pests(P<0.05);slope and the degree of pure forest leafeating pest damage are significantly positively correlated(P<0.05),while the slope has no significant correlation with the damage degree of leaf-eating pests in mixed forests(P>0.05);different slope orientations are significantly related to the degree of damage of leaf-eating pests in pure and mixed forests(P<0.05).It is semi-sun>sunny slope>shady slope;different soil texture has a significant correlation with the damage degree of leaf-eating pests in pure forest and mixed forest(P<0.05),and the damage degree is loam>sandy soil.(2)The influence of different forest factors on the damage degree of leaf-eating pests in pure forest and mixed forest is inconsistent.Stand density,canopy density,stand age,average plant height,average diameter at breast height,and average undershoot height are significantly positively correlated with the damage degree of leaf-eating pests in pure and mixed forests(P<0.05);crown width and pure forest The damage degree of leaf-eating pests showed a very significant positive correlation(P<0.01),and the damage degree of leaf-eating pests in mixed forests showed a very significant negative correlation(P<0.01).(3)Pure forests and mixed forests have different levels of damage under different site conditions and stand structures.Regardless of changes in altitude,slope orientation,canopy density,forest age and tree height,the damage of leaf-eating pests in mixed forests is always greater than that of pure forests;when the slope is less than 35°,the mixed forest suffers severely,and when the slope is greater than 35°,the pure forest suffers Severe;when the litter thickness is less than 2 cm,the pure forest leafeating pests are more harmful;when the thickness is greater than 2 cm,the mixed forest leaf-eating pests are more harmful;when the litter coverage is less than 50%,the pure forest and the mixed forest eat There is no obvious difference in the damage degree of leaf pests.When it is greater than 50%,the damage degree of pure forest leaf-eating pests is higher than that of mixed forest;when the soil texture is loamy,the mixed forest suffers severely,and when the soil texture is sandy soil,the damage of pure forest is high.When the stand density is less than 1500 plants/hm2,the pure forest suffers severely;when the density is greater than 1500 plants/hm2,the mixed forest suffers severely;the diameter at breast height is less than 9 cm,the pure forest suffers severely,and the mixed forest suffers severely if the diameter is greater than 9 cm;When the height is 2 m,the pure forest suffers severely.When the height is greater than 2 m,the mixed forest suffers severely;when the crown width is less than 4 m,the mixed forest suffers severely,and when the crown width is greater than 4 m,the pure forest suffers severely.(4)Shrub coverage has a significant positive correlation with pure forest leafeating pest damage(P<0.05),and a significant negative correlation with mixed forest leaf-eating pest damage(P<0.05);Shannon-wiener index of shrub layer There is a very significant negative correlation with the damage degree of leaf-eating pests in pure forests and mixed forests(P<0.01);the Simpson index of shrub layer has a very significant negative relationship with the damage degree of leaf-eating pests in pure forests(P<0.01),and it has a significant negative correlation with the damage degree of leaf-eating pests in mixed forests(P<0.01).There is no significant correlation between the damage degree of leaf-eating pests(P>0.05);the Pielou uniformity index of the shrub layer has a significant positive correlation with the damage degree of leaf-eating pests in pure and mixed forests(P<0.05);the Margalef richness index of the shrub layer There was no significant correlation with the damage degree of leaf-eating pests in pure forests(P>0.05),and a very significant positive correlation with the damage degree of leaf-eating pests in mixed forests(P<0.01).(5)Herbal coverage was significantly positively correlated with the damage degree of leaf-eating pests in pure and mixed forests(P<0.05);the Shannon-wiener index of the herb layer and the degree of leaf-eating pest damage in pure and mixed forests were both extremely significantly negative Correlation(P<0.01);the Simpson index of the herb layer has a very significant negative correlation with the damage degree of leaf-eating pests in pure forests(P<0.01),and a significant negative correlation with the damage degree of leaf-eating pests in mixed forests(P<0.05)There is no significant correlation between the Pielou uniformity index of the herb layer and the damage degree of leaf-eating pests in pure forests and mixed forests(P>0.05);the Margalef richness index of herb layer has a very significant negative correlation with the degree of damage of leaf-eating pests in pure forests(P<0.01),and there was a very significant negative correlation with the damage degree of leaf-eating pests in the mixed forest(P<0.01). |
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