Research On The Reconstruction Technology Of Daxie Island’s Low-quality And Benefit Forests

The research place is in Daxie Island (Daxie Development Zone). Due to the historical reasons and special geographical conditions, there still existing a large number of low-quality and benefit forests. In order to ameliorate the appearance of the forest landscape, to improve the forest’s ecological function and to achieve the goal that is to build an island which is ecological landification and a livable seaboard city, it urgently needs a set of reconstruction technologies that can quickly renovate and recovery the low-quality and benefit forests. This research investigates and analyzes the major types of low-quality and benefit forests in Daxie Island. According to the biological features of tree species and the growth of major tree species, this thesis screens out the superior tree species suitable for survival which is transformed by low-quality and benefit forest. Renovating and transforming two common types of degenerate forests, this thesis concludes the transformation methods and techniques of the main low-quality and benefit forests in Daxie Island. Main results are as follows:1) According to the site factors, it was divided into14kinds of site types. In accordance with superior tree species classification, this thesis uses principal component cluster analysis to divide the phytobiocoenose of Daxie Island into four appearance types which are Shrub,Scrub-grassland,Secondary broad-leaved forest, Secondary coniferous forestand and Secondary mixed needle, and16kinds of community types. Species richness ranged between6.0and15.3which reflect the results of special geographical conditions and relatively serious human interference cause certain impacts on species richness.2) Adopting comprehensive factor classification method to combine the site type and community type to classify and name the low-quality and benefit forests in Daxie Island. Based on the criteria for low-quality and benefit forests in Technical Specification for the Improvement of Low-quality and Benefit Forest published by State Forestry Administration, Daxie Island can be totally divided into16kinds of low-quality and benefit forests in which secondary broad-leaved forest type is the most widespread, followed by coniferous and mixed forest.3) Choose12kinds of superior broadleaf tree species to have a sapling growth volume comparison. The experiment indicates that among these12kinds of tree species,11kinds of them survival rate are over90%, with only Castanopsis’survival rate less than85%.5aRaw pinus elliottii with an average tree height of4.5m and average diameter of9.45cm growth volume ranking the first among12kinds of trees, while Castanopsis’ growth is the slowest(5a Raw pinus elliotti average tree height and average diameter are just2.1m and1.05cm). Through analyzing the comparative test of forestation in sunny slope and shady slope, most tree species can grow well in both sunny and shady slope in their young period. Neolitsea sericea’s growth condition in shady slope is better than that in sunny slope while, sweetgum and Pinus Elliottii Engelm’s growth advantage in sunny slope is more obvious. Overall, the above-mentioned tree species, as long as be chosen right and follow the principle of suitable for place and tree, can be used as an renovate pioneer tree species in low-quality and benefit forests’ renovation.4) After having transformation test on two major low-quality and benefit forest communities, the results showed that:①fter doing the thinning replanting transformation to pinus massoniana forest (eight of Loose yelin and two of Broad-leaved forest), new planted Schima superb and Chinese sweet gum grow well.6years later species structure adjusts to six of Loose yelin and four of Broad-leaved forest, crown density reached0.8. Replanted and reserved tree species grow rapidly, stand density highly improved and volume increased by86.7%which is obviously higher than the growth rate of control plot. In transformation plots stand litter weight and water holding function improved significantly. The water holding capacity of the soil is also greatly enhanced, stand water conservation function improved tremendously.②fter transforming the Quercus acutissima-Schima superba low-quality and benefit forest whose crown density is about0.6. Forest community structure changed obviously, oak’s importance value in transformation plot decreased obviously while the proportion of young hardwood saplings’ importance value rise above40%rapidly. Through the contrast test in A transformation plot (without thinning fostering) and B transformation plot (after thinning fostering, annual stand crown density at0.4and0.5). We can find that secondary broad-leaved forest with a medium crown density can totally adopt the transformation method which is fostering after forestation. However, we need to select shade-tolerant tree species or species of shade-tolerant in seedling period, and do the light thinning timely3-5years after seedling growth. Deforest upper nontarget zone’s tree species gradually, in order to make renovate tree species grow rapidly and have new forest community succession.5) Through the research, this thesis concludes the transformation methods and techniques of the main low-quality and benefit forests in Daxie Island.