| The entire altitude of Seda County is more than 4000 meters,which belongs to the plateau hilly area.The cold climate has created a special geographical environment in Seda County,and it also makes the forest tree germplasm resources in Seda County more vulnerable.This study takes the geographical distribution of forest tree germplasm resources in Seda County as an example.Based on the survey of natural geography,the characteristics of forest tree germplasm resources,the life style and distribution pattern of forest tree germplasm resources,and environmental factors,this study further Using DCA and RDA ranking to analyze the geographical distribution of forest tree germplasm resources in Seda County and the relationship between the diversity of forest tree germplasm resources and topographic,soil,climate and other environmental factors,aiming to reveal the geographical distribution characteristics and environmental factors of forest tree germplasm in Seda County Relationship,correctly understand the geographical distribution characteristics of forest tree germplasm resources and the fragility of the growth environment of Seda County in the plateau hilly area,and provide constructive suggestions for the future protection and development of ecological diversity of forest tree germplasm resources in Seda County.The research results are as follows:(1)The general situation of the composition of forest germplasm resources in Seda County.The forest germplasm composition in Seda County is relatively simple.According to statistics,there are 134 forest germplasms,including 46 genera in 26 families.Among them,gymnosperm forests contain 14 genera of 2 families,5 genera,and angiosperm forests contain 120 genera of 24 families,41 genera.The dominant families and dominant genera of forest tree germplasm in this area are not obvious,and the overall performance is that the content of the number of families is large,and the number of genera and species is relatively small.The proportion of single families and genera is large,and the percentage of families and genera with a small number of species is also high,which proves that the forest germplasm resources in Seda County have a long history in the flora.The dominant families in Seda County account for a relatively small amount,the species richness is relatively poor,and the occurrence of drought-tolerant,salt-tolerant,wind-eroded and sand-burden forest trees is relatively high.Due to the current status of water and soil habitats and the heterogeneity of manmade destruction,the dominant forest tree species appeared in an aggregated distribution,but the forest tree germplasm resources in each zone were still not abundant enough.The above conditions can prove the fragile growth environment of forest tree germplasm in Seda County.(2)According to Wu Zhengyi et al.'S systematic classification of vegetation life forms in China,the forest life forms in Seda County are divided into 3 types,which can be divided into 3 categories and 6 sub-categories,and shrubs> trees> vines.There are 95 species of shrubs,33 species of trees,and 6 species of liana.According to the statistical analysis of the forest germplasm in Seda County,the statistical analysis of the families and genera included in the study area,the families and genera of the research area are mostly distributed in the two regions of the pantropic and northern temperate zones.In the conservation center of germplasm resources,plant genera and species differentiation also come from these two types of families.Overall,the forest germplasm resources in Seda County are still temperate.(3)Looking at the structure from the vertical distribution composition and horizontal distribution range of forest trees in Seda County,the number of species showed an increasing trend with decreasing altitude,that is,the higher the altitude,the fewer the forest germplasm types;The concentrated distribution area of forest germplasm resources in Seda County accounts for 14.93% of the total species in Seda County.From Jiaxu Township to the west or east,the species diversity of forest germplasm is less,In terms of the distribution of seed resources,the forest germplasm resources of Jiaxu Township are the gathering points of Seda County County.(4)The richness of forest tree germplasm resources is the focus of the forest community composition.The forest tree germplasm sample plots in Seda County are roughly divided into A,B,C,D,E,5 plot groups,along the first axis and the second axis.The aggregation distribution is not obvious.The results of DCA analysis show that the distribution of forest germplasm resources in Seda County is mostly dominated by factors,reflecting the characteristics of plateau hilly areas.Moreover,this study found that the richness index of the tree germplasm resources in the sunny side of Seda County is lower than that in the shaded side,which may be due to the increase in the tree spacing reducing the species diversity of trees,shrubs,and vines.These factors mainly affect the species diversity of forest tree germplasm through the effects of sunlight intensity,slope,and terrain.(5)The RDA analysis ranking chart can intuitively reflect the relationship between different environmental factors and soil nutrients.It can be seen that TN(Total N)has the strongest influence,which indicates that soil N nutrients have a very important influence on the growth of forest tree resources in Seda County.There is a significant positive correlation between TN(total nitrogen)and the importance of arbor species,shrubs,and vine species.This indicates that the area of Seda County has a high soil N content,and the plant growth status is good,indicating that soil TN(total Nitrogen)is the dominant factor affecting the growth of forest germplasm resources in Seda County.At the same time,the bulk density and gravel content are significantly negatively correlated with the important values of shrub species,which indicates that the forest growth is better in areas with low bulk density and gravel content.(6)Over the years,the county committee and county government of Seda County have attached great importance to investing a lot of manpower and material resources in afforestation,tending management,and mountain closure forestation.Through analysis,it can be seen that the forest tree germplasm resources in Seda County have caused The fragile site conditions of this kind of forest tree germplasm resources can only carry out the restoration and reconstruction of vegetation to re-cover the vegetation,and only after the restoration of basic soil fertility can better protect the surrounding forest tree germplasm.When restoring and rebuilding,it is necessary to pay attention to the choice of restoration species,the order of introduction of species,the combination of species,the conditions of the planting area and the choice of suitable planting time.In the future,it is a trend to ecologically restore forest germplasm resources in Seda County,reduce human interference,and cooperate with the development of the tertiary industry. |
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