Study On The Ecology Characteristics Of Chinese Fir Forest Community With Natural-approximate Ecological Restoration Mode

Ecological problems of Plantation have always been the focus and hot issues of research by scientists at home and abroad.Chinese fir recommended as one of the most important planting tree species in southern China.The serious decline of site and productivity which caused by successive plantation had restricted sustaining development of Chinese fir artificial forestry and the ecological commonweal plantation.So,based on the new theories and methods about plantation advanced by arborists at home and abroad, this paper studied on ecological resume and regeneration according to natural-approximate theory and practice about the forest ecosystem management,and tried to give a comprehensive and profound research on compositions,configurations,functions and the dynamic processes of different ecosystem regeneration models,based on the two natural-approximate ecosystem regeneration models(the old-growth Chinese fir model and abandoned natural regeneration model).The paper provided scientific guidance and theory to containable development of plantation with different ecosystem resumes and regeneration models.The results were as follows:(1)The old-growth Chinese fir community had formed a multilayer and richness in species physiognomy by prolonging the rotation and natural resume.Density of the existing tree layer is 1477 plant·hrn^-2and the stand volume was 435.95 m³Â·hm^-2.Now,density of Chinese fir was 662 plant·hm^-2,with 88.9%of total volume.There were 28 broadleaf tree species which had enriched the composition in species. Aspects and locations affected on the density and growth of species obviously.There were a lot of regeneration seedlings under this layer which include 38 species with 8185 plant·hm^-2total.These seedlings offered optimum provenance for regeneration of the old-growth Chinese fir,however there was no discovery of the Chinese fir seedlings' regenerated.The DBH current increment,height current increment,volume current increment and their annual increments showed all increasing prophase and decreasing anaphase with ages.(2)The total biomass of the old-growth Chinese fir community was 254.456 t·hm^-2,and biomass of tree layer occupied most proportion of 97.06%,which dominated obviously,next was the shrub layer,the herbage layer and the litter layer had a small percentage.The biomass of stem was the biggest proportion, with 67.58%;the next was root,bark,brand and leaf.The biomass appeared high in the middle and low on the both ends of height and DBH distribution,which was the highest distribution in 20-25m of height classes and 20-25cm of DBH classes.Biomass of tree layer centralized in only few dominance species, Chinese fir accounted a largest proportion,with 82.21%,the next were Schima superba and Castanopsis fargesii,respectively 9.65%and 3.53%of total biomass of the tree layer.(3)Distribution of individual number and species of the tree layer in height and DBH had similar characteristics basically,with species number decreased as the tree height and DBH increasing,while individual number showed the bimodal curve as the height and DBH increasing,which related to the broad-leaves trees' regeneration.The old-growth Chinese fir community had high density,specie number and individual number of the tree layer and under layer had the proportional relationship.(4)There were totally vascular plants of 63 family,103 gene and 128 species in old growth Chinese fir community.There were 29 species in tree layer,and the important value of the Chinese fir accounted 47.86%.There were 56,35 and 33 species respectively of shrub layer,herbage layer and liana layer. Oreocnide frutescens accounted the biggest important value in shrub layer as such Allantodia hachijoensi in herbage layer and Tetrastigma hemsleyanum in liana layer.Aspects and locations had a very obvious effect.Phanerophytes bud accounted for 68.75%,representing the overwhelming majority.The species composition and the spectrum of middle and small leaves have dominated the most with 86.72%. Pan-tropical of general area-types of spermatophyte occupied a dominant position and these were similar with the old-growth Chinese fir community in Ancaoxia.(5)The old-growth Chinese fir community was a high diversity,and the Shannon-Wiener diversity had reached 3.86.The diversity and the uniformity index showed the trend of shrub＞liana＞herbage＞tree layer.The difference of diversity was obviously,the effect of aspect and slope on diversity was obvious in this community,especially on the ecological advantages index,which will be different as different indexes.There were differences in VSI and HHI of each aspect which showed southwest＞southeast＞north as a whole.It has indicated that there was a more complex level of the vertical and horizontal direction of branches level in the southwest slope and it had a higher diversity.(6)Through analyzing the spatial pattern of the community,the results showed that tree species had a random distribution with 41.38%.There was notable association only between Schima superba and Enrya nitida by X² test.There were 281 species pairs showing negative coefficient,occupied 59.85%.There were only few species with a lager niche width index,and the niche overlaps between species were generally lower.These characteristics reflected that the community was still in the prophase of regeneration.(7)The soil porosity conditions,soil moisture and soil nutrients were all good,and the soil fertility was improvement.Aspects have obviously influenced on each soil fertility index.And the index decreased with soil depth increasing.(8)The old-growth Chinese fir community was not yet in unstable condition analyzed by M.Godron method,but more stabled than plantation of 15-year-old.(9)Nowadays,the growth and biomass of tree in plantation were better than that in abandoned natural regenerated model.However,the plantation was a model with single structure and very few numbers of species(only 5);the community structure was more complex in the abandoned natural regenerated model, composed with 22 species of abandoned natural regenerated community of high density.Particularly,the litter biomass was bigger than that in abandoned plantation,because of the difficulty in decomposing in litter which would be detrimental to nutrient cycling of plantation community(10)The individual number and species number showed single-peak curve on the height distribution of the two models.The density and species showed a trend of decreased with the DBH increasing in abandoned plantation model.The density and species all showed single-peak curve with each character.But different with each other。(11)There were great differences in species composition of tree layer and shrub layer in the two models.There were 22 and 30 species of tree layer and shrub layer respectively in abandoned models composed 5 and 20 of that in plantation.The R,diversity and evenness index in abandoned models were all higher than that in plantation,especially in tree layer.Chinese fir occupied the biggest important value on 51.07%in plantation community composed that was Phyllostachys heterocycla,(31.35%).Under layer, Maesa japonica was the biggest important value.And the general area-types spermatophytes of the two models were similar. (12)There were different in soil moisture and soil pore space of two modes,especially the top soil. The soil physical structure in plantation was better than that in abandoned modes because of human activities.The soil chemical properties in the organic matter,organic carbon and total N content,were improved obviously in abandoned models,particularly soil surface(0-20cm).