Diversity Of Microorganism And Insects, Invasive Risk Of Anoplophora Glabripennis In Natural Forest Of Populus Euphratica In Tarim, Xinjiang

The effect of species and diversity of dendrocola fungi, soil microorganism and insects, and invasive risk of Anoplophora glabripennis on ecosystem health in Populus euphratica forests was studied systematically. The main results were as follows:1. Forty-one species of fungi were isolated and identified from leaves, branches and stems of P. euphratica, in which 1 species belonged to Zygomycotina, 3 species belonged to Ascomycotina, 1 species belonged to Basidiomycotina and 36 species belonged to Deuteromycotina. 20 species of fungi were obtained from leaves. The species of fungi on different shape of leaves were similar. 33 species of fungi were obtained from branches. The species and quantities of middle-aged P. euphratica were apparently more than that of younger and mature P. euphratica. 31 species of fungi were obtained from stems, and the species quantities were increased with the tree age. 297 strains endophytic fungi were isolated from P. euphratica, which were identified belonging to 7 orders, 22 genera, and 35 species. There were 160 strains endophytic fungi isolated from stems which belonged to 35 species. And 103 strains, 24 species endophytic fungi were isolated from branches. 31 strains, 12 species were isolated from leaves of P. euphratica.The result of analysis to diversity in dendrocola fungi community of P. euphratic showed that diversity and evenness of foliage habiting fungi of needle leaves were the highest. The indices of diversity of fungi on branches were the highest on middle-age P. euphratic, lesser on mature and least on younger P. euphratica. According to the orderliness what the more the diversity and evenness of fungi, the less the probability of disease occurrence, the probability of disease occurrence on middle-age P. euphratica forests was least. Therefore it was healthier than other P. euphratica forests.2. There were evident differences in the microorganism biomass and composition rates of four kinds of natural P. euphratica forests in Xinjiang, and the dominant and special microorganism existed in all different layers of soil section. The vertical distribution showed that the microorganism biomass decreased with the increase of soil depth and the population of microorganism was the least in 31-40 cm depth of soil. The microorganism consisted of bacteria, which were the chief content and distributed widely, and actinomycetes as well as fungi, which were scarce in some layers of soil section. Aspergillus was the dominant genus among the 11 genera of fungi isolated from soil in the different ageP. euphratica forests.3. The insect resource was very abundant in P. euphratica forests. There were 141 species collected which belonged to 12 orders, 61 families. Among them 90 species were pests, 32 species were natural enemies (predacious and parasitical insects) and other insects included 19 species.Four functional groups of insect communities were divided according to nutritional relation of insect communities in P. euphratica forests. The species and individuals of phytophagous community were more abundant than natural enemy community and other insect community significantly, and it was dominant community in P. euphratica forests. Diversity and evenness of predacious community were highest in 4 functional groups of insect communities. Among different insect communities, Coleoptera and Lepidoptera were dominant orders whole year. The insect was very abundant in the middle-age P. euphratica forests, and there were 107 species collected which belonged to 11 orders, 52 families in it. 76 species were collected in younger P. euphratica forests which belonged to 10 orders, 45 families. And there were 58 species in mature P. euphratica forests which belonged to 11 orders, 30 families. But there was only one genera isolated in effete P. euphratica forests. Therefore, it indicated that the control effect of natural enemies was very weak. When the firestorm of pests happened, excessive man-made control measure would make the the ecosystem become more and more weaker.4. Apocheima cinerarius was the most important and dangerous pest species. It could be as bioindicator for assessment of forest ecosystem. The investigation of larval density indicated the ratio of harmed trees was up to 100%. The quantities of larval were little higher in the middle-aged forests than that in the younger and mature forests. A. cinerarius was favor of the imitative leaves of P. euphratica as food.5. Anoplophora glabripennis would damaged in P. euphratica if the bark thickness was less than 7mm. Forecasting A glabripennis 'harm choice to P. euphratica according to variance of bark thickness, we found the appropriate bark thickness to A. glabripennis' oviposition was conformed to bark thickness of younger P. euphratica. The younger P. euphratica was much easier to be damaged, and the damage height was extended to all stem. And the heights were over 3 meter and 4 meter for middle-aged and mature P. euphratica respectively.6. The insect-resistance of 9 species trees in Xinjiang was identified. The resistant sequence from high to low was: Morus alba Linn., Elaeagnus angustifolia Linn. > Populus euphratica Oliv., Ulmus densa Litv., Populus alba var. pyramidalis Bunge., Ulmus pumila Linn., Populus nigra var. thevestina (Dode) Bean. > Acer negundo Linn., Salix matsudana Koidz., Salix matsudana f. umbraculifera Rehd. Based on the emergence holes, A. glabripennis was one generation in one year in Bayingolin Mongolia Autonomous district of Xinjiang Province. It could finish one generation on P. euphratica. So it indicated that A. glabripennis was dangerous to P. euphratica potentially.