Plant Community Succession Research Of Resuming Ecosystem In Peak Cluster Depression

It is a difficult work to restore and rebuilt a continuable ecosystem in Peak Cluster Depression .There is a serious rock desertification because peak cluster depression short of soil while still afford many people. It becomes the neediest area with brittle ecosystem in karst area. Vegetation restoration is a chief task when rehabilitate ecosystem. Following restoration ecology principle and vegetation succession rule, combining natural and manpower restoration is a effective technique of rebuilding such degradation ecosystem. Systemic research on plant community succession plays an important role in karst ecosystem restoration research and practice. For research the succession character and the relationship between plant community and environment. I did several field investigations by karstology and field ecology methods and used taxology, quantitative ecology, vegetation ecology, microbiology and etc to research plant community succession systemically in Nongla peak cluster depression restoring ecosystem from following standpoints: flora, group, community, agrology, microbiology and so on. Comprehensive analysis include: species composition, space structure, classification and ordination, biodiversity, community connection, soil microbe, etc. At the same time I investigate environment of plant community in detail and analyze dominant environment factors in PCA for the first time. At last, I integrate various research results of peak cluster depression from 70s to now then analyze the character and trend of south sub-tropic peak cluster depression in order to provide scientific theory for vegetation restoration and ecosystem rehabilitation of degraded ecosystem in karest area.List the main points of the research below:1. After identifying all species there are 398 species among 20 samples which At last range them into 10 associations combining community characters. Sum up 4 synthetic environment factors which can reflect sample surroundings by PCA from 10environment factors of 20 samples. They are restoration condition factor, human-soil disturb factor, landform factor, slope-rock factor. the result of DCA and DCCA is accord to the result of TWINSPAN and DCA ordination plot is close to DCCA ordination plot. Both CCA and DCCA show that restoration condition factor and human-soil disturb factor are main influence factors of community distribution, landform factor and slop-rock factor take the second place. Integrating the result of environment factor PCA ,it obviously shows that restoration time, artificial disturb, lithology, slope position these 4 factors play more important role than rock bare rate, slope grade, direction and other factors in community distribution. DCCA is the best ordination way in researching karst vegetation especially in peak cluster depression because DCCA can well reflect community distributing by environment grads and list them at succession sequence. TWINSPAN, environment factor PCA, DCA, CCA and DCCA work together which can show vegetation characters respond the change of environment and their interrelation commendably.2. Plant communities in Nongla peak cluster depression are plotted out 5 restoration stages based on restoration conditions and result of quantity ecology research. They are restoration prophase, restoration prometaphase, restoration metaphase, restoration after-metaphase, restoration anaphase. Biodiversity of arbor layer changes linearly with the development of restoration while shrub layer and grass layer present complicated non-linearly change. Pa,Ga and H change consistently. From restoration prophase to restoration after-metaphase: shrub layer> grass layer>arbor layer, diversity between shrub layer and grass layer is small. Diversity between shrub layer and arbor layer decreases with restoration progress. Species of grass layer reduces sharply during restoration anaphase, show that: shrub layer> arbor layer >grass layer .specie and individual number of plant community in south sub-tropic peak cluster depression will increase sustaining with restoration process, but species and individual number under arbor layer will decrease after increasing when arbor layer Correlation analysis of 5 biodiversity indexes indicate: the mean difference of Pa and Ga,H and Pa,H and Ga,Jsw and H is significant at the 0.01 level, the mean difference Pa and Jsw is significant at 0.05 level. Community collectivity biodiversity show that: Pa,Ga,H and Jsw have similar change trend, but D is different from other 4 indexes. In restoration process, restoration time and artificial disturbance influence community biodiversity more efficiently than lithology, rock bare rate, slope and other environment factors. Community biodiversity is a reasonable quantify index to research plant community restoration succession.3. In peak cluster depression ecosystem, bacteria is the dominant genus of soil microbe, actinomycete less, epiphyte least .The number of soil microbe showed as surface layer>middle layer>under layer; soil microbe composition changes with the improvement of soil environment aroused by Vegetation .Compared microbe species and quantity in different succession stages, they are very different. In surface layer, the order is that tree stage>shrub stage>young tree stage>shrub and grass stage>grass stage; in middle layer, the order is that shrub stage>young tree stage>tree stage>shrub and grass stage>grass stage. Meanwhile, in under layer, the order is that: shrub stage>tree stage>young tree stage. Soil environment decide species and number of soil microbe. The species and numbers of soil microbes have positive correlation with soil organic carbon, effective nitrogen and soil gap degree while they have negative correlation with pH value, content of MgO and Al2O3. long -term succession ,soil microbes gradually adapt alkaline soil which full of calcium in karst ecosystem ,so it is able to bear a certain extent of alkalescence.4. There are 2 damaged types called Structure-damaged type and landscape-damaged type in peak cluster depression. Both secondary progressive succession and farm are main restoration types. We fractionize 10 kinds based on vegetation and environment: bare rock, barren, tussock, secondary brushwood, secondary shrub, secondary young forest, secondary climax forest. According to conditions and characters of nature restoration, farm and material landform, I summarize restoration and succession trend of Nongla peak cluster depression. Integrating past research results I conclude generic characters of restoration and succession community in peak cluster depression and draw the relationships among main restoration succession communities which I investigated in NongLa. The restoration prevailing climax of peak cluster depression is a typical climate-landform-soil succession climax. Species adapt special karst surrounding so that the whole plant community shows characteristics of karst area.