Abstract
From Jan. 2013 to Nov. 2018, we carried out the investigation on vegetation studies in the ecological monitoring programs, Shenzhen and totally researched 170 plant communities of mountain areas etc., few areas of street regions and parks etc., for communities’ structural characteristics and plant diversity. We comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level and the main affected factors. We also researched and analyzed these communities’ structural characteristics and pant diversity, comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level, the main affected factors; researched and analyzed the relationship between plant community structure characteristics with the absorbing ability to PM2.5 pollutants. The result showed that the structure and plant diversity of natural forest were obviously better than artificial disturbed forest or artificial forest, the semi-natural forest was the middle level of the forests, In the indices of height, DBH, coverage and crow width etc. of tree layer, natural forests and semi-natural forests were obvious higher than that of artificial disturbed forest or artificial forest; in some forests of artificial disturbed forest or artificial forest, though their richness indices of family and genus were a slightly higher, but this contribution was majorly due to herb layer plants, and some shrub layer plants. Analyzing three kinds of communities, the number of tree layer species of natural forest was the largest, and their every α-diversity index value was the highest; these characteristics values of semi-natural forest were second, artificial disturbed forests or artificial forests were the lowest; in shrub layer, and herb layer, few α-diversity indices of artificial disturbed forest or artificial forest were a slightly higher than that of some natural forests, but the integral values of the diversity indices of natural forest and semi-natural forest were obviously higher than the former. The research showed that in the artificial disturbed forest or artificial forest, because there have some little scale clearing areas, so some pioneer plant species could enter the community and formed a temporarily increase of species diversity, however, these species major were some shrub and herb plants; but tree layer possessed obviously more, even surpassed several ten times biomass than shrub and herb layers. Therefore, the respects of maintain ecosystem stability and other ecological efficient have major and dominated position and so on; and then this community can be natural recovery and succession, those forementioned new entire plants shall withdraw from the community and are replaced by the original plants of the community; but this process has already caused the ecological efficient loss and ecosystem unstable. Above research results are better evidence and theory reference to the argument problems on that are natural forest and natural restoration forest biodiversity higher? or is artificial forest biodiversity higher? and or is more artificial disturbed forest higher? Our researches showed that used random investigation method set quadrats, and combined typical investigation method, the structural indices in the all layer of community and all diversity indices of tree, shrub and herb layers and the integral values were similar, same or usually these indices in the community which set 600 m2, 800 m2 total quatrat area were higher (α-diversity) than that of more than 3000 m2, 4000 m2 or 7000 m2, even more than 17,000 m2 total quadrat area of communities. These lots of researches further proved that according to minimum area method for vegetation survey, in subtropical region, using random investigation method combined with typical investigation set 400 m2 or 400 m2 - 500 m2 total quad<span
Highlights
Research results are better evidence and theory reference to the argument problems on that are natural forest and natural restoration forest biodiversity higher? or is artificial forest biodiversity higher? and or is more artificial disturbed forest higher? Our researches showed that used random investigation method set quadrats, and combined typical investigation method, the structural indices in the all layer of community and all diversity indices of tree, shrub and herb layers and the integral values were similar, same or usually these indices in the community which set 600 m2, 800 m2 total quatrat area were higher (α-diversity) than that of more than 3000 m2, 4000 m2 or 7000 m2, even more than 17,000 m2 total quadrat area of communities. These lots of researches further proved that according to minimum area method for vegetation survey, in subtropical region, using random investigation method combined with typical investigation set 400 m2 or 400 m2 - 500 m2 total quadrat area in a community is correct, or 510 - 600 m2 quadrat is more stability to the investigation of plant community
1) In aspect of plant community structure, Shenzhen, the order from better to weak is that natural forest > semi-natural forest > artificial forest or artificial disturbed forest; in most of natural forests or semi-natural forests, the indices of height, coverage, DBH, crow width and density etc. in tree and shrub layer are higher than more other region, even some natural forests of other regions (Zhu et al, 2004; Burton et al, 2005); even these main indices of communities are higher than that of some natural forest of tropical region (Li et al, 2008)
These research results proved that the plant diversity of natural forest or long time natural restoration forest is obviously higher than artificial forest or more artificial disturbed forest (Huang et al, 2016a; Huang et al, 2016b; Liang et al, 2016)
Summary
In former, about the vegetation structure of Shenzhen and plant diversity have carried out some researches, Liu et al (2007) investigated to Acacia mangium plantation in Phoenix Mountain; Liu et al (2010) carried out research to the structure of community of Danan Mountain; Zhang et al (2007) carried out study on diversity of Syzygium odoratum community in Dapeng Peninsula, Shenzhen; Kang et al (2005) made investigation about plant type and community characteristic in Bijiangshan Park, Shenzhen; Wang et al (2003) researched on the species diversity and succession situation of natural forest communities in Nanshan District of Shenzhen. We focus on introducing a part of the research situation of the communities. These researches are importantly significant and theory reference to exploring the status of ecosystem structure, tracking monitoring the change trends of these biological characters and factors, and plant ecology, phytogeography, ecological monitoring research, and the strategy draw up on optimization of local ecosystem protection
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