Study On The Relationship Between Landscape Patterns And The Spread Ofpine Wilt Diseasein Yichang, Hubei Province

Landscape patterns have significant and complex effects on a variety of ecological processes, including the flow of matter and nutrients and the distribution and movement of species. To explore the impacts of regional habitat differences on the occurrence and spread of forest diseases and insect pests, we focused on the pine wood nematode reported in Yichang in the Yiling district of Hubei Province. Usingforest inventory vector data collectedby theForestry Survey and Planning Institute of Hubei and census data of pine wilt disease in the Yiling district from 2007 to 2012 takenby the Station of Pest and Disease Control and Quarantine, we examined the effects of forest landscape pattern on pine wilt disease as predicted by landscape ecology theory.The main results were as follows:(1)The percentageof pine forest landscape patch area, the average patch size, and the degree of natural connection and polymerization of patches were all positively correlated with pine wilt disease morbidity. Analysis of the granularity of the pine forest landscape demonstrated that the proportion of area composed of small- and middle-patch sizes was negatively correlated with pine wilt disease morbidity, whiletheproportion of huge-patch and super-patch sizes was positively correlated.(2)The patches’ number of pine forest landscape, the average patch size and the degree of polymerization of patches in Successive-infected villages were all greater than Occasional-infected villages’ when the villages’ total area were larger than 1500 ha. There was no significant difference among other landscape indices. These results reflected that the fragmentation of pine forest landscape could promote the spread of pine wilts disease. (3) The intensity of human activity, which can interfere with the landscape, was also positively correlated with pine wilt disease morbidity. (4) At landscape level, as edge density and Shannon’s diversity index increased, pine wilt disease morbidity increased. The contagion index, in contrast,was negatively correlated with pine wilt disease morbidity, as was the area-weighted mean patch fractal dimension. (5) The Successive-infected villages’ landscape diversity and landscape fragmentation were generally greater than Occasional-infected villages’ and the Successive-infected villages’landscape shape was more complex than Occasional-infected villages’. These results suggest that landscape heterogeneity would facilitate the spread of pine wilt disease.Thus, using theanalysis of landscape patterns at the town and village level, we can infer that, in the Yiling district, a forest landscape composed of small pine forest patches with a low aggregation index and low degree of fragmentation of the entire landscape can prevent the spreadofpine wilt disease to some extent. The findings of this study can be used as a reference to aid the prevention and control of pine wilt disease in the Yiling district.