| Aquilaria sinensis is the rare and protected trees of China,but there is a few wild A.sinensis and most of them is artificial growing.Because of the increasing plating area of A.sinensis, disease and insect pest has became a serious problem, extremely impair the forest health of A.sinensis. Ecological control is a effective way of reduction the diseases and insect pests of A.sinensis, which has profound significance to the ecological development of Hainan province.Then,it also offer the essential scientific basis to the A.sinensisartificial cultivation and breeding.In this study,39 sample plots were set up in Hainan province.We investigated theA.sinensis diseases occurrence〠distribution stand structure factor and understory vegetation species diversity, this reseaichaboutA.sinensis plantations will from different stand types, different stand structure factor, understory vegetation species diversity of angles to explore the relationship between the factors and pests 。 The main results are as follows:(1)The impact of the different forest types on the disease and insect pest of the Hainan A.sinensis plantations.Based on A.sinensispure forestsand mixed forests survey, study 1-3 years,4-6 years,7-9 years,10-12 years of pure and mixed forests in the incidence of pests and diseases. The results show that as the growth of age, the disease and insect pest of A.sinensis plantations present upward trend.During all the age period, compared the A.sinensispure forests, the disease and insect pest of Aquilaria sinensis mixed forests are relatively slightly.Six different mixed patterns during the age period of 7 to 9 years are selected, which are A.sinensis+Kahaya seegalesis;A.sinensis+Hevea brasiliensis;A.sinensis+Homalium hainanense;A.sinensis +Santalum albunsis+sinensis+Dalbergia odorifera;A.sinensis+Dimocarpus longan +Areca catechu, the mixed modesremarkable influenced the incidence and the disease index.The rate of the disease and insect pest from high to low is A.sinensis +Dimocarpus longan+Areca catechu;A.sinensis+Hevea brasiliensis; A.sinensis +Santalum album.;A.sinensis +Homalium hainanenseGagnep;A.sinensis+Kahaya seegalesis;A.sinensis+Dalbergia odorifera. The disease and insect pest of A. sinensis. andKahaya seegalesisare the slightest, mixedforests is a effectively way on decrease the occurrence of the the disease and insect pest.(2) The impact of the different stand structure to the disease and insect pest of the Hainan A.sinensis plantations.By doing the correlation analysis, multiple comparisons about 39 standard ground. It presents that the stand density remarkable influenced the incidence and the disease index(r=0.826,P<0.01; r=0.725,P<0.01), the insect bites rate was positive correlationabout stand density r (r=0.366,P=0.022); The coverage significantly influenced the incidence and disease index(r=0.888,P<0.01; r=0.822,P < 0.01), the insect bites rate was positive correlationabout stand density (r=0.397,P=0.012); The crown diameter remarkable influenced the incidence, the disease index and the insect bites rate(r=0.757,P<0.01; r=0.733,P<0.01; r=0.573,P <0.01); The diameter at breast height remarkable influenced the incidence and the disease index(r=0.708,P<0.01; r=0.737,P<0.01), the insect bites rate was positive correlationaboutthe diameter (r=0.353,P=0.027); The tree height remarkable influenced the incidence, the disease index and the insect bites rate(r=0.618,P<0.01; r=0.624,P< 0.01; r=0.519,P< 0.01); Proposed prediction model of A.sinensisPlantation incidence is established. Y (incidence)=-0.481++0.002X1+0.678X2+0.019X3 Xi:stand density X2:coverage X3:diameter at breast height According to the F test, this predict model could reach the extremely remarkable level. (R2=0.887, F=7.588, df=35, P<0.01).(3) The impact of the different understory vegetation diversity to the disease and insect pest of the Hainan A.sinensis plantations.By investigated the understory vegetation of the 39 A.sinensis plantations test plot.Analyze the relationship between herb cover, Shannon-Wiener index, Simpson index, Pielou index, Margalef index index and pest.The results show that all indices associated with theinsect pest was not significant, correlation between disease incidence and disease index is as follows:the herb cover was significantly positively correlated with the incidence and the disease index(r=0.717,P<0.01; r=0.595,P< 0.01); Shannon-Wiener index was significantly negatively correlated withthe incidence and the disease index(r=-0.609,P <0.01; r=-0.607,P<0.01); Pielou index was significantly negatively correlated withthe incidence and the disease index(r=-0.689,P<0.01; r=-0.678,P<0.01); Margalef index was significantly negatively correlated withthe incidence and the disease index(r=-0.623,P<0.01; r=-0.652,P<0.01); Simpson index was significantly negatively correlated withthe incidence and the disease index(r=-0.614,P<0.01; r=-0.590,P<0.01)。... |
