Preliminary Research Of Factors That Influence The Occurence And Spreading Of Pine Wilt Disease In Dinghai District Zhoushan City In Zhejiang Province

Pine wilt disease is the cancer of pine trees.The biology relationship with Bursaphelenchus xylophilus(pathogeny eelworm),Monochamus spp.(vector) and Pinus spp.(host) forms the infection cycle of pine wilt disease which is complexed and results in the features of pine wilt disease,spreading repidly,more routes of transmission,wider suitable regions and so on.At the present,the research about pine wilt disease from the scale of landscape,using mensurable and synthesized way are little,so this article is creative in research approach and research angle.In this text,my study locations is Dinghai district Zhoushan city in Zhejiang province. According to the comparing analysis and detrended canonical correspondence analysis in this paper,the natural environment is the dominating factors,dispersal by human beings and artificial control follows.Beacause artificial regulations or measures are taken and man-made interference are less in Ding hai district.Relative air humidity is the most important factor to the epidemic situation of pine wilt disease,mainly effects from April to August.Days of precipitation in April,Sunshine condition,air temperature in May,amount of precipitation in July and wind speed in August are key factors for the epidemic situation of pine wilt disease,and it is probable to related to their biological characteristics.Wind speed and sunshine condition are possible the major factors that affect pine trees going through the winter.It's useful to predict the epidemic situation of pine wilt disease if focus on the climte condition in those key months. Artificial rain during the emergence of Monochamus alternatus may slow down the epidemics.Landscape pattern influence the spread of pine wilt disease,and the process change the landscape pattern.On one side,landscape diversity,the area/shape of pine forest patches and distance/connectivity among pine patches make for the differences of the outbreak and degree of pine wilt disease.On the other side,After the disturb of pine wilt disease,the degree of landscape fragmentation is deeper.The survival pine patches has such features:the mean area is smaller,the shape are more regular,the inner habitat area is smaller,the corridors and conection among pine patches are cut off.The succession and regeneration of pure pine woods are speeded up.Therefore,pine wilt disease are less likely to or never occur again.Though the influnence of human elements is weaker,the effect still can't be underrated.Partly because effective artificial measures are taken cause the results.Forest conservation is one of effective measures.In this foundation of non-entry,white muscardine fungi and traps are used to defend Monochamus alternatus.This measures restrict the epidemic situation of pine wilt disease.In addition,more professionals for preventing are needed,the supervision and quarantine of pine wood transportation still should be focused on.It is necessary to set warning signs and isolations between the boundary of orchard and pine forest to prohibit non-professional persons from entry.