| Dasiphora is composed of two species,Dasiphora fruticosa and Dasiphora glabra.Dasiphora is a typical deciduous shrub in the alpine region in shanxi,located in sub-alpine shrub meadow,gap of Larix principis-rupprechtii,hillsides and rivers at high altitude.Dasiphora fruticosa community appeared between 1900~2600m,Dasiphora glabra community appeared between 1700~2400m in Shanxi.Dasiphora fruticosa and Dasiphora glabra having ecological value of reviving vegetation,keeping water and improving soil conditions,which plays a very important role in the protection of ecosystems of the Shanxi region.In this paper,based on the field survey,the community characteristics of Dasiphora fruticosa and Dasiphora glabra were systematically and comprehensively studied from the community ecology point of view,including the community structure,composition,areal types,classification,species diversity,interspecific association and so on.The purpose of this study is the analysis of the ecological relationships between plant communityand environment,and to provide some theory bases that could be applied in the ecological protection and afforestation in Shanxi.The results show that:(1)Two species of Dasiphora communities characteristics in every study regions: Dasiphora fruticosa community distribution range of Mount Hengshan,Mount Wutai,Mount Luya and the Pangquangou,there were27,61,57 and 73 species;Dasiphora glabra community distribution range of Mount Luya,Pangquangou,Hongya Canyon,Mount Lingkong and Mount Xingtang and Mount Lishan,there were81?119?16?50?137and 36 species.Two species of Dasiphora communities distribution type of families in every study regions cosmopolitan elements predominate among them.Community physiognomy was characterized mainly by phanerophytes.(2)Two species of Dasiphora communities characteristics in Shanxi: 142 quadrat were set up and investigated in the field show there were totally 330 species belonging to 195 genera of 56 families in two species of Dasiphora communities;The flora of 195 seed plants founded in the community was classified into 15 areal types and 5 subtypes;Community physiognomy was characterized mainly by phanerophytes.(3)Age class structure of the studied areas and the twopopulations of Dasiphora in Shanxi: a larger percentage of Dasiphora fruticosa population clusters in Mount Hengshan and Mount Wutai are middle-aged,suggesting that the populations are in a stable development stage;the majority of Dasiphora population clusters in Tianchi and Pangquangou are in age I and a good percentage of the clusters are in age II.The seedling amount is large,suggesting that the populations are in the growing stage and good growing status.There are many old-aged clusters and few seedlings in the Haodifang Forest Farm of Lingkong Mountain,suggesting that the populations are declining and tend to develop toward high latitude areas;a larger percentage of Dasiphora glabra population clusters in Mount Wutai,Mount Luya,Haodifang Forest Farm and Mount Xingtang are middle-aged,suggesting that the populations are in a stable development stage,and Li Mountain is not suitable for the growth of Dasiphora glabra due to the low latitude and high temperature;age class structure of the two populations of Dasiphora in Shanxi: the majority of the Dasiphora glabra populations within the studied areas are young or middle-aged and just a few are old-aged,suggesting that the Dasiphora glabra populations are in the growing stage.As an alpine shrub distributed at high latitudes,Dasiphora glabra suffers certain but very limited human disturbance.The middle-aged individuals asa result get to develop stably.Overall,Shanxi Dasiphora glabra populations are in the growing stage;the development is good and the development potential is great.The majority of the Dasiphora fruticosa populations within the studied areas are young and just a few are old-aged,Overall,Shanxi Dasiphora fruticosa populations are in the growing stage,the development is good.(4)Two species of Dasiphora communities classification and diversity in Shanxi.By using TWINSPAN theory,this result divided Dasiphora fruticosa community into 8 association,divided Dasiphora glabra community into 11 association.Four diversity indices were applied to analyze the species diversity characteristics of two species of Dasiphora communities.richness index,species diversity index,Simpson index and evenness index.The results showed that different communities and the type of species diversity index have obvious difference,if in the moderate water and light conditions of the habitat,community has higher species diversity than the other.Species diversity and its function system are studied,the results indicates that the numbers of richness degree index,species diversity degree index and uniform degree index of two species of Dasiphora communities plot samplings showing that they are more herb layer than shrub layer.From the change in species diversity with changing altitudegradient,the ecological Simpson index did not differ by elevation gradient,and other indexes were basically consistent,with increasing altitude,the 4 diversity indexes for community?for the shrub and herb layers increased with increasing altitude.(5)Community biomass: Research in the studied area of Tianchi Luya Mount indicates that species with big importance value usually has high above-ground biomass,while species with small importance value has low above-ground biomass;shrub-layer biomass of Dasiphora fruticosa and Dasiphora glabra community>litter biomass within the community>herb-layer biomass,and the litter amount of the Dasiphora fruticosa community is significantly larger than the Dasiphora glabra community;the fresh weight of all parts of a species is basically 10 times its dry weight,and the saturated fresh weigh of leaf is higher than the fresh weight;F-test with biomass models shows that the regression correlation between the biomass of each component and the measurement factor is high significant;the significance is verified by all models.(6)Interspecific association: ?2 test with 142×34 contingency table were used to analyze the interspecific association among 578species-pairs of 34 dominant species of two species of Dasiphora communities.Pearson's correlation coefficient and Spearman's rank correlation coefficient were also applied to calculatecorrelations between species.The results showed that 232 and 273species-pairs were positively correlated,while 321 and 282species-pairs had negative correlations,based on Pearson ' s correlation coefficient test and Spearman ' s rank correlation coefficient test,respectively,and the numbers of positive correlated species-pairs were nearly equal to the negatives.The results showed that two species of Dasiphora communities was developed in more stable with the time. |
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