Effects Of Landscape Features And Stand Factors On Poplar Canker

Poplar canker(Cytospora chrysosperma)has been severely damaging the healthy development of poplar plantations in China.The features of the surrounding landscapes and local conditions can both influence poplar canker occurrence and spread.Based on the investigation of the occurrence of poplar canker in Karamay City and Manas County of Xinjiang Uygur Autonomous Region,this paper used general linear models(GLMs)and general linear mixed model(GLMMS)to analyze the influence of landscape patterns and stand characteristics in different landscape scales,as well as landscape complexity and stand factors in different soil physical and chemical properties on poplar canker.Designed to identify potential drivers of canker occurrence and severity,to analyze its prevalent landscape ecological process,and provide theoretical basis for rational allocation of landscape patterns to effective control poplar canker.The main results are as follows:(1)There was no significant relationship between poplar canker incidence and diameter at breast height,tree height,as well as crown cover.The incidence of pure forest was higher than that of mixed forest,and the higher the planting density,the higher the incidence.Canker incidence correlated positively with the proportion of dead trees with cankers but occurred irrespectively of the proportion of dead trees not infected with canker.And canker incidence correlated negatively with the number of poplar scale insects.(2)The canker incidence was higher in less vigorously forests stands;forestlands that had been irrigated 2-3 times in the growing period of trees had a lower incidence than forestlands that had not been irrigated.(3)The canker incidence had significant positive relationship with the Shannon diversity index which was the diversity of major pests of poplar,and correlated significantly negatively with the proportion of non-poplar hosts and elevation.And the canker incidence of Populus nigra had positive relationship with the height of first live branch.(4)Compared with 500 m and 1000 m landscape scales,the correlation between 250 m landscape scale and poplar canker was most significant.And in the landscape scale of 250 m,the canker incidence had a positive correlation with landscape diversity,and negative correlations with landscape connectivity and landscape complexity.Taking the sample plots as the center and dividing the landscape scale of 250 m,the incidence of poplar canker in Manas County was lower than that in Karamay City under the same landscape structure.Soil conditions in the same study area,the canker incidence in the sample plots with simple landscape structures was higher than that in the forest lands with complex landscape structures.