Study On Community Structure Of Dominant Species Of Protection Forest In Beijing Mountainous Area

Construction of protection forest is not only the core of forestry construction in spacious region, also the important component of eco-environment construction. The construction of protection forest in Beijing has already been the principal issue that matters the enhancement of capital people's living standard, development of economy and improvement of eco-environment. The structure of protection forest is the key factor that effects directly on the exertion of protection benefits, while protection forest management mainly aims at the regulating and controlling its structure and maintaining it optimal. Therefore, based on the study on the plant flora, species diversity of community, spacial structure of community and spacial distribution pattern of populations in protection forest, the differences of structure among protection forests were analyzed and the spacial structure characteristics of dominant community were posted. Subsequently, by structurized forest management, species component of dominant community, competition and spacial distribution pattern of population in protection forests were designed and adjusted in Beijing mountainous area in order to design optimal spacial structure of protection forest in stand scale and improve the shelter efficiency which can be used for guiding the sustainable management of protection forests.24 hectare-level plots in 13 nature reserves and forestry centre were set in Beijing mountainous area. Based on the individual spacial position information of dominant community, the spacial structures of community and distribution pattern of populations were then analyzed by applying nearest neighborhood stand structure unit and point pattern analysis approach. Subsequently, by applying the factors of spacial structure including uniform angle index, mixing and neighborhood comparison , the community structure of dominant species was adjusted. The main results are stated respectively as following.(1)The dominant community of protection forests in Beijing mountainous area included 454 fascicular plant species (including planting species), belonging to 86 families and 261 genera. In addition, there were 4 exotic species belonging to 2 families and 4 genera and 450 wild species belonging to 85 families and 257 genera. The families of wild fascicular plants distributed in world were the most, while ones in temperate zone were the least. However, the temperate characteristics of the plant genera were very distinct. Not only the genera endemic to china were the least, but also the endemic characteristics of plant were not showed. The life form of wild plants in Beijing mountainous area was dominated by phaenerophytes which account for 48.45% of total species. While hemicryptophytes were 30.67% of wild species. The first year-herbaceous plants, geophyte and chamaephytes were relative little and were 12.00%, 6.00% and 2.89% respectively.(2) The community floristics of dominant species in protection forests was very excessive. The difference of its component was not only rather great, its component with the same stand type was also different drastically. The stand density of different dominant species was different dramatically and the stand density of natural Pinus tabulaeformis Carr forest of 1821No./ hm2 was the largest in Songshan Nature Reserve, while Juglans mandshurica Maxim forest in Baihuashan Nature Reserve with the least stand density of 606 No./ hm2. Furthermore, the difference of the total basal area at breast height was very great. The total basal area of 29.959 m2/hm2at breast height of Quercus liaotungensis forest in Baihuashan Nature Reserve was the largest, while the Castanea mollissima forest was with the least total basal area of 5.094 m2/hm2at breast height resulted from young stand age. The analysis on the diameter at breast height and height of protection forests shows that the dominant species were mainly in inverse J-type distribution, normal school, single peak or multi-peak distribution. Simultaneously, the total volumes of natural stand were more than artificial ones due to small stand density or poor site conditions of partial natural stand. The volume of Larix principis-rupprechtii forest was the most resulted from its faster growth, great stand density and rich site conditions.(3) The community species diversities of different dominant species were abundant, while species richness indices and diversity indices changed very drastically in community gradient. The species richness indices in herb layer were higher than that in shrub and arbor layers. On the whole, herb layer>shrub layer>arbor layer. The distribution law of the species evenness indices with different growth type in community gradient was not obvious. On the whole, the species evenness indices in herb layer were more than that in shrub and arbor layers.(4) The analysis on the community spacial structure of dominant species in Beijing mountainous areas protection forests shows that not only the mixing of protection forests was on the low side at large, but also the mixing difference was rather great among communities of dominant species. The Populus davidiana Dole forest and Tilia mongolica forest in Wulingshan forestry centre were natural secondary mixing forests. Therefore, their growth situations were very well with great mixing. The stand mixing status of natural Platycladus oreintalis Franco stand, natural Quercus dentate Thunb forest and Castanea mollissima plantation were not very well because their mixing was rather low. The analysis on the neighborhood comparison shows that the forests polarization among natural Pinus tabulaeformis Carr, Platycladus oreintalis Franco, Betula davurica Pall, Quercus, Quercus liaotungensis, Quercus dentate Thunb, Populus davidiana Dole and Juglans mandshurica Maxim forest was very distinct. Relative to the spacial structure unit, forests distribution with different neighborhood comparison was rather regular and niche polarization was also very notable. The analysis of the uniform angle index shows that the community distribution pattern of dominant species was contagious distribution, while sectional individuals of natural forest or artificial forest with low stand density were in random distribution, but the level distribution pattern of only minor plantation was regular distribution.(5) The level distribution pattern of the major populations in the community of dominant species in protection forests changed obviously along with the scale and was mainly in aggregated distribution. But the aggregated degree, dimensions and scale of the major populations were different as a result of different stand type. The relationship of the main populations in the community of protection forests was mainly negative association. The species-pairs with positive inter-specific relationship were very rare. Moreover, the competition among the major populations was very drastic, while the competition among major populations of plantation was more drastic than that of natural forest.(6) The individuals distribution pattern of community of the dominant species in different development stages changed complicatedly along with the scale in Beijing mountainous areas protection forest. And the distribution pattern of mature trees was mainly in random distribution, besides that of middle-aged trees in aggregated distribution and that of saplings in aggregated distribution or random distribution. The relationship among individuals in different development stages was mainly negative association. The species-pair of negative association at the significant level accounted for 43.5% of total species-pair, while the species-pair in positive correlation was only one pair. The negative correlation between middle-aged trees and saplings, between middle-aged trees and mature trees were very significant, while the correlation between saplings and mature trees was rather weak.(7) The water resource conservation capacity of most natural forests was more than plantation in protection forests. The water conservation capacity of Larix principis-rupprechtii forest was the most in plantation. While the water conservation capacity of Betula dahurica forest in Baihuashan Nature Reserve, Pinus tabulaeformis and Quercus mongolica forest in Songshan Nature Reserve were rather low in natural forests.(8) The level distribution pattern, species composition and competition of Pinus tabulaeformis, Platycladus orientalis and Larix principis-rupprechtii forest were firstly adjusted and their management effects were also evaluated. The Results shows that, by spacial structure adjustment of community, not only the nourishment space of reserved forests was expanded and the competition pressure of forests was decreased, but also the mixing conditions were improved resulting in well spacial conditions for the growth of reserved forests.