| This study aimed at control of major forest diseases(FD)and insect pests(IP)and improvement of forest health for providing technical support of forest health maintenance and improvement in Da Xing,an Mountains.Six major FD/IP including Dothistroma pini Hulbary,Dendrolimus superans(Butler)Strobilomyia spp.,Coleophora dahurica Falkovitsh and Ips subelongatus Motschulsky were selected for research.According to FD/IP situations in 27 tree farms of 5 forestry bureaus(Amuer forestry bureaus?Huzhong forestry bureaus?Songling forestry bureaus?Tahe forestry bureaus?Tuqiang forestry bureaus from 2008 to 2011 and based on surveys of FD/IP affected forest signatures as Altitude distribution?Forest type distribution?Slope aspect?Slope position?Soil type?forest origin?DBH?canopy density and stand age of these forestry bureaus the relations between these signatures and FD/IP affections were statistically analyzed.(1)Da Xing'an Mountains area Dothistroma pini Hulbary is 110 small class,93 of these small class is in 400m?780m altitude interval,which accounting for 84.45%.Forests of Xing'an Rhododendron Xing'an larch forest type group,Xing'an Rhododendron birch forest type group and Slope modified larch forest type group are affected by plant diseases and insect pests more seriously of 78 small class,which accounts for 70.91%of totality.Dothistroma pini Hulbary occurs frequently in east,west,southeast and southwest,accounting for 72.72%of the totality.Plantations incidence 6.08 times that of the natural forests.In the small class with 0.3?0.65 canopy density,Dothistroma pini Hulbary with occurrence of 88.19%in all disease.Dothistroma pini Hulbary infected index significantly negative correlate with slope(P<0.01),and positivly with canopy density(P<0.05).(2)Cydia zebeana Ratzebury infected 93 small class,in 400m?630m altitude interval.Forests of Xing'an Rhododendron Xing'an larch forest type group,Xing'an Rhododendron birch forest type group and Slope modified larch forest type group are affected by plant diseases and insect pests more seriously of 65 small class,which accounts for 69.89%of totality.Southern slope incidence 2 times that of the north slope,the infected forestry canopy density range is relatively concentrated in 0.4?0.7,accounting for 87.10%of all disease.Plantations incidence 3.84 times that of the natural forests.Infected forestry DBH mainly concentrated in the range of 0 to 16 cm,which accounts for 93.55%of the forest.Cydia zebeana Ratzebury canopy density is 20.83±3.76 highest in the forest of 16cm DBH?(3)Strobilomyia spp.infected 61 small class,in 400m?625m,45 small classes in 400m?630m are infected,which accounts for 73.77%.Forests of Xing'an Rhododendron birch forest type group,grass Xing'an larch forest type group and Slope modified larch forest type group are affected by plant diseases and insect pests of 39 small class,which accounts for 63.93%of totality.Southern slope incidence 3.86 times that of the north slope.Plantations incidence 3.17 times that of the natural forests.The infected forestry canopy density range is relatively concentrated in 0.3?0.75,and the infected forestry are concentrated in the density range of 0.4?0.7,accounting for 93.44%.The Strobilomyia spp.infected index significantly correlate with slop and canopy density.(4)Coleophora dahurica Falkovitsh infected 26 small class,in 420m?750m,17 small class in 400m?630m are infected,which accounts for 65.38%.Forests of Xing'an Rhododendron Xing'an larch forest type group,Xing'an Rhododendron birch forest type group and Slope modified larch forest type group are affected by plant diseases and insect pests of 16 small class,which accounts for 61.54%of totality.Plantations incidence6.06 times that of the natural forests.The infected forestry canopy density range is relatively concentrated in 0.4?0.6,accounting for 92.31%.The density of insects significantly correlates with average tree height and DBH of arbor.(5)Ips subelongatus Motschu lsky infected 53 small class,in 420m?1100m.Forests of Xing'an Rhododendron birch forest type group,pinus pumila Xing'an larch forest type group,Ledum palustre Xing,an larch forest type group and Bryophyta Xing'an larch forest type group are affected by plant diseases and insect pests of 46 small class,which accounts for 86.79%of totality.East slope incidence 3.625 times that of the west slope.Plantations incidence 5.73times that of the natural forests.The infected forestry canopy density range is relatively concentrated in 0.3?0.6,accounting for 77.36%.The infected forestry DBH is concentrated in10?13cm,accounting for 88.68.(6)In this research,large sample sampling survey is used to analyze 23 typical forest types in Da Xing'an Mountains with the method of mathematical statistics.575 forestry samples were chose to calculate Simpson index mean and variance.Forest types with serious plant diseases and insect pests are Xing'an Rhododendron Xing'an larch forest type group,Xing'an Rhododendron birch forest type group and Slope modified larch forest type group.Simpson index are 0.6292±0.0838,0.5692±0.0495,0.5492±0.1409,accounting for 13.13%of Slope modified larch forest type group,17.51%of Xing'an Rhododendron birch forest type group,and 43.78%of Xing'an Rhododendron Xing'an larch forest type group,which all belonged to the low Simpson index forestry.(7)According to the samples taken from Amuer Forestry Bureau area of the Da Xing'an Mountains in northern China from 2008 to 2011,the sampled fields were all subjected to the interference by external uncertainties.Through field survey and fixed location observation,we calculated the infection index and Simpson diversity index by means of mathematical statistical analysis.Therefore,the relationship between forest biodiversity and the external interference factors could be analyzed.When the Simpson index of the disease infected field and the infection index were fltted,the following equation was obtained,y=0.0022x2-0.1422x+2.7906,and the correlation coefficient R2=0.7267.When the infection rate of pest sample and Simpson index were fitted,y=0.0007x2-0.1174x+5.6639 was obtained and R2=0.8096.The results indicated that there was difference in woody plant diversity with different types of forest species composition.If the forest woody plant diversity was higher its corresponding ability on resistance to the damage of plant diseases and insect pests was higher.(8)In this report we analyzed the relationship between the plant diversity index(D)and the canopy,insect pest infection rate and disease index.Our results showed that there was no simple mathematic relationship between woody plant diversity and the anti-interference of disease and insect pest.However,our results showed that the sample plots with higher plant diversity index had less disease and insect pest damages.If the overall forest community stability was higher it was favorable to the forest system recovery and regeneration after the disturbance by disease and insect pest.Woody plant diversity is the necessary conditions for the forest community stability. |
PDF Full Text Request