A Preliminary Study On Structure And Stability Mechanism Of Casuarinas Plantation Ecosystem In Coastal Sandy

Coast protection forest is a kind of production system for harmonization relationship of human being and nature. Coast protection forest function are including of storm protection, sand-binding, storage water, soil and water conservation, improve ecological environment, reduce natural disaster ,safeguard and promotion industrial and agricultural production. Coast protection forest has an important meaning for high quality environment to human. Since its introduction, Casuarina equisetifolia, because it has characteristics in resistance to drought, anti-barren, to bear salt alkaloid and anti-sandstorm, has become the main protective plants species in the southeast coastal zone of our country. At present, with only one chief constructive species in the coast protection forest ecosystem, there are many problems in the ecosystem, such as unitary composition plants species, simple stand structure, incompatible layout caused low ecology protection function , low biodiversity and unstable ecosystem. Therefore, construction by biology stable guarantee ecology stable coast protection forest ecosystem with Casuarinas as one of main tree species, combining with other trees species, complexing ecosystem structure, enhancing Casuarinas plantation ecosystem stability, is the core question to the southeast coast area protection forest construction .This thesis was studied on typical Casuarinas plantation ecosystem in Fujian Province coastal area. The research primary coverage are investigation to the Casuarinas plantation ecosystem composition structure (producer, consumer, disintegrator as well as non-biological part), study in biodiversity and wind-resistance, drough-resistance, anti-insect pest's aspects conducts and so on, and compare Casuarinas plantation ecosystem with the Litsea glutinosa secondary forest ecosystem in biodiversity, the findings mainly listed as follows:(1)The structure composition of Casuarinas plantation ecosystem mainly included producer, consumer, disintegrator as well as non-biological part, Casuarinas primarily take the most large number of the producer, next ones are the plant of Pinaceae,Mimosaceae,Myrtaceae and so on ,which are afforested mixing Casuarinas. Besides, there are 56 plants species were found in Casuarinas plantation. The consumers include 86 species insect, 13 species birds, 4 species Reptiles, 9 species Mammal, 4 species Amphibian. The disintegrator aspect separately conducts the research edaphon in 16 year and 25 year old Casuarinas plantation, including three groups edaphon and five kind of function bacteria. The non-biological part mainly elaborated the research meteorological factor and soil factor.(2) Conducts the biodiversity research to the Casuarinas shelterbelt forest and the back edge forest, and it is found that all the biodiversity indexes are increasing with Casuarinas forest growth in shelterbelt forest, but there is not the same tendency in the back edge forest. At the same time, we investigate the biodiversity of three pieces of secondary forest in three villages nearby the Casuarinas plantation, and found that Litsea glutinosa(Lour.) C. B. Rob.) is the dominant plant species in all the secondary forst ecosystems. The average number of botanical species in respective type places of forest is 5.67 in the Casuarinas shelterbelt forest, 8.33 in the back edge forest, 27.33 in the Litsea glutinosa secondary forest. All the biodiversity indexes, Simpson index, Shannon-Wiener index, evenness index(jsw), evenness index(jsp),of Litsea glutinosa secondary forests are higher than theirs in Casuarinas plantation.(3)From wind-resistance, drought-resistance, anti-insect pest aspect to carry on the elaboration to resistivity stable mechanism of Casuarinas plantation forest ecosystem. It is found that Ping18, Yue501, Hui1 are high wind-resistance, drought-resistance strains, Taishan and C1 are high anti-insect strains. The difference is remarkable of Casuarinas resistance of Anoploplora chinesia(Forster) in different geographical positions, site condition, preparation of land way, cultivation management measures and so on. And the stable regulation mechanism of Four Position One System and Three-combination were stated with selection of high anti-strain, to increase the individual heredity diversity, to increase the species diversity, to increase the ecosystem diversity as well as the landscape diversity, improves the stand structure composition, optimize disposition and the spatial arrangement, enhances the resistivity stability of Casuarinas plantation ecosystem.(4)To study Casuarinas plantation ecosystem's resiliency stability by investigation and found that the Mountain-Casuarinas have the strongest ability of root sprouts to renew, and it shows that the stump plant density and the biomass presents increases first then reduces while the degree of old and degeneration of the plants strengthens. It was considered as one of nature repair quick way that root sprouts the tiller to renew to the Mountain-Casuarinas old age and degenerated stand.(5)The ecosystem hierarchical structure, the species diversity, the resistance index, plant insect pest and disease condition, self-renewal ability, the system productive capability, the shade density, the degree of soil restoration to constitute of ecosystem stability evaluating indicator system to appraise the stability of the Casuarinas plantation ecosystem and the Litsea glutinosa secondary forests ecosystem respectively. As result, the Casuarinas plantation ecosystem integrated stability index is 0.50, the integrated stability rank belongs medium. The Litsea glutinosa secondary forest ecosystem integrated stability index is 0.83, the integrated stability rank belongs superiority. Finally, the biodiversity mechanisms, the produce-consume- decompose food chain mechanism, the artificial regulative stability maintenance mechanism were proposed as the Casuarinas plantation ecosystem stability mechanism.