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Plant,Arthropod Diversity And Forest Health Evaluation In Aershan Forestry Area,Inner-Mongolia

Posted on:2013-02-26Degree:DoctorType:Dissertation
Country:ChinaCandidate:J LiFull Text:PDF
GTID:1113330371974467Subject:Forest Protection
Abstract/Summary:PDF Full Text Request
Aershan forestry bureau, located in the northeast part of Inner-Mongolia, is an important reserve area of man-made forests of northeastern China. This area is also the key part of ecological shelter system of Daxinganling, which is critical for the ecological security of northern China.The Siberian moth, Dendrolimus superans (Butler) is the primary pest of this forest area, especially in the man-made forests. This pest has an intermittent outbreak interval of about ten years, and it is considered as a serious threat to the man-made larch forests of this area. However, there are no previous studies on forest biodiversity or ecosystem health in this area.There are various factors affecting forest health, including biological disasters, natural disasters (such as fire and acid rain) and man-made interferences. But as to Aershan area, the forests were mainly affected by biological disasters, especially by siberian moth, larch bark beetle and gypsy moth. The present study covers forests belonging to different types and forest farms in Aershan forest area. Plant communities were identified and analyzed by traditional methodology of community ecology. The arthropod communities were collected.identified and analyzed by manual collection, window traps and light traps. Besides.the forest health was evaluated by constructing evaluation indices based on the main forest pests and forest in this region.The main results and conclusions are as follows:1. The species composition and diversity patterns of plants were systematically examined in the present study.Totally 102 plant species, belonging to 71 genus and 33 families were recorded in Aershan.Arbors, shrubs and herbs had 8,9 and 85 species, respectively.In terms of number of individual, Compositae (12 genus,21 species), Rosaceae(11,13), Ranunculaceae (4,7), Ericaceae (4,5) and Papilionaceae (3,5) were the dominant groups while occasional groups included Equisetaceae, Cheiropleuriaceae, Violaceae, Papaveraceae, Onagraceae and Pyrolaceae, most of which had only one species recorded.In terms of importance values,the trees Dahurian larch (Larix gmelinii(Rupr.)Rupr.) and Japanese white birch (Betua platyphylla Suk.) were the dominant populations in arbor layer while the dominant populations in herb layer included Carex chingannensis L., Lolium perenne L., Fragaria orientalis (Glehn) Juzep., Equisetum palustre L., Geranium dahuricum DC. and Galium boreale L., The shrub layer did not have obvious dominant populations because of low variation and nonuniform distribution pattern. However, common populations were Prunus asiatica L.and Malus bauata Jusepczuk.In terms of niche breadth, except for the two dominant tree species (Larix gmelinii (Rupr.) Rupr. and Betula platyphylla Suk.) in this area. Car ex chingannensis L.. Lolium perenne L., Fragaria orientalis (Glehn) Juzep., Equisetum palustre L., Geranium dahuricum DC. Galium boreale L., Artemisia sacrorum Leded., Spiraea pubescens Turcz., Filipendula intemedia (Glehn) Juzep. and Spiraea salicifolia L. were dominant populations with large niche breadth. This populations also showed broad distribution areas and high environmental adaptability.In terms of different forest types, natural forests showed obvious advantages both in forest biodiversity and distribution of dominant populations.2. The species composition, diversity pattern, nutrition level and guilds were systematically examined in different levels.166 species of arthropods were recorded, belonging to 87 families and 15 orders.In terms of number of species, Lepidoptera (13 families,43 species), Coleoptera (21,33),Diptera (11,20), Hymenoptera (11,17), Orthoptera (5,17), Hemiptera(4,10),Homoptera (4,7) and Neuroptera (3,6) were defined as the dominant groups.They included the most abundant populations of this area, while only rare species were found in Phasmatodea, Ephemeroptera, Odonata, Trichoptera, Mantodea, Raphidiodea, and some species belonging to Arachnoidea representing the rare groups. The natural, man-made and volcanic forests (a special natural forest) recorded 91,66 and 30 species, respectively.Great differences were found in the arthropod community collected by different methods. As to the window traps,60 species were recorded, most of which belonging to Coleoptera, Hymenoptera and Diptera. As to the light traps,86 speices (mainly belonging to Lepidoptera, Coleoptera, Hymenoptera, Diptera) were recorded. As to manual collection,44 speices (mainly belonging to Orthoptera, Coleoptera, Homoptera and Lepidoptera) were recorded.99 species were recorded in natural forest while 66 and 30 species were recorded in man-made and volcanicforests. Variation were found in the species richness and diversity of arthropods by different collection methods.86 guilds were recorded in the present study, window trap, light trap and manual collection found 39.51 and 24, respectively. In the dominant guilds, Loxostege sticticalis L., Chilo suppressalis (Walker), Lymantria dispar L., Choristoneura luticostan, Carabidae, Formicidae and Sigara substriata Uhler were classified as phytophagous guilds. Parasitical guilds included Ichneumonidae. Braconidae and Pteromalidae. Predatory guilds included Formicidae, Ephemeridae, Chrysopidae,Myrmeleontidae, Aslidae, Mantodea, Odonata while Staphylinidae, Muscidae and Silphidae belonged to saprophagic guilds. In addition, four families of the spider group were also classified as predatory guilds. The natural forests had obvious advantages over man-made forests in terms of the distribution and diversity of nutrition level and number of guilds.3. The optimal mixed proportion of larch and birch for the enrichment and increase of biodiversity was examined.The biodiversity was greatly influenced by mixed proportion of the two tree species since it determined the canopy structure, which was critical for the forest light environment. In addition, the arthropods (especially the phytophagous species) were mainly affected by the neighbouring plants. Based on the thinning caused composion gradient of the two tree species. We examined the plant and arthropod diversity along a tree mixture gradient, caused by thinnings of the two tree species or natural factors. We concluded that a composition ratio of between 5:5 and 7:3 is most favourable for the enrichment of forest biodiversity and for improving of forest health level.4. An index system of forest evaluation against biological disasters was constructed.Based on the historical data and our investigations on the forest pests in this region, the natural forests in Aershan area were well managed, healthy and seldom affected by biological disasters. Meanwhile, the man-made forests were easily affected by biological disasters because of uniform stand structure and unstable ecosystem. This can be well proved by the fact that only the man-made forests were damaged by the outbreak of the Siberian moth in 2001-2002.Based on the diversity evaluation system and the analysis of factors affecting forest health, an index system including structure, function and disturbance level of stands were built to evaluate the forest health status of different forest types in Aershan. The forest health degree had five levels including excellent (8-10), healthy (6-8), relatively healthy (4-6), unhealthy (2-4) and morbid (0-2). The results showed that the average health index of the Aershan forest was 5.43, which was classified to relatively health level. Forests of four farms, Detingde, Yiminhe, Chaiheyuan and Sangduer in headwater were classified as healthy. The proportion of natural forests in the farms was 93%,61%,41% and 63%, respectively. The historical data showed that none of them were affected by forest pests since 2000.Three farms (Yiershi, Aershan and Lixin) were on unhealthy level, all of which were classified as reserving headwaters forests. The proportion of natural forest of the three farms were 55%,57% and 83% and thay were heavily damaged by forest pests in recent more that ten years (mainly included siberian moth, gypsy moth, larch pine beetle, long horn beetle, disease and rodent). Seven farms (Chaihe, Guerban, Suhuhe, Jinjianggou, Nangou, Tianchi and Xingan) were relatively healthy, Tianchi and Xingan forest farms were volcanic forests, but the other five ones were headwaters forests. The proportions of natural forests of the seven forest farms were 70%,39%,42%,75%,68%,71% and 63%, respectively. Only Chaihe, Guerban and Suhuhe forest farms were slightly and discontinuously affected by the Siberian moth, forest bark beetles, deseases and rodents according to the historical records.In summary, except for the effects of edge effect (Chaihe farm), manual interferences (Yiershi, Aershan and Lixin farms) and natural disasters (Xingan and Chaiheyuan farms seriously burned in 1998), the results based on the evaluation index system in the present study were consistent with those based on the composing of natural forests and the historical data of forest pests in Aershan area. The forest health status can well be reflected by the present indices system and classified management practices can be put forward based on this knowledge.
Keywords/Search Tags:Aershan, Dendrolimus superans, Plant, Arthropod, Diversity, Forest health evaluation
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