Habitat Association And Indication Of Bryophytes In A Subtropical Forest Of Eastern Guangdong

Although the bryophytes are small in size,they are of great importance in maintaining biological diversity,conserving soil and water,and are highly sensitive to environmental changes,which can reflect the dynamic characteristics of forest community habitats.Studying the habitat association and indication of bryophytes is of great significance to the maintenance of biodiversity and the construction of bryophytes plant communities,and it is of great importance to study the indication of bryophytes to environmental change under the background of global climate warming.In this study,the bryophytes community in the Guangdong Kanghe Provincial nature reserve was studied,and 6 hm~2 permanent plots were used for the investigation of bryophytes.The topographic factors such as elevation,slope and aspect of each sample were investigated and recorded,and the smoothness of each sample was calculated.The elevation,slope,aspect and the smoothness are divided into different grades.In order to explore the relationship between bryophytes and habitats,we used various nonparametric analysis methods to study the relationship between bryophytes community and changed habitats.The differences of bryophytes communities in different types of forest,elevation gradients,slopes,aspect and degrees of smoothness were analyzed.The effects of habitat heterogeneity on the coverage and diversity of bryophytes were revealed,and the response and indication of the bryophytes plant communities to the habitat changes were demonstrated.The main conclusions of this thesis are as follows:(1)There are 47 species of bryophytes(including 3 varieties)in the plot,including 15species of liverworts,belonging to 7 families and 11 genera,and 32 species(including 3varieties)of mosses,respectively,belonging to 18 families and 25 genera.The species of bryophytes in the plot are mainly tropical and subtropical,the dominant phenomenon is not prominent,and the dominant families and genera are not obvious.The Kurzia gonyotricha,Chiloscyphus latifolius,Pseudotaxiphyllum pohliaecarpum and Fissidens laxus occupy a dominant position in the plot.In addition,in the sample scale,the Simpson index,evenness and Berger-Parker dominance index of bryophytes are stronger than the plot scale,which indicates that bryophytes have stronger response to sample size.(2)Multi-response permutation procedures(MRPP)showed that the species composition of bryophytes was significantly different from forest types in general.But pairwise comparison detected that the species composition of the liverworts was found to be mainly in the difference of stand type III and other two kinds of stands,while the species composition of mosses had no significant difference between stand type II and III.It reflects the different responses of liverworts and mosses in different forest types.There was no significant difference in species richness,Menhinick index,Simpson index,evenness index and Berger-Parker dominance index among different forest types in bryophytes community.(3)There were significant differences in the composition of bryophytes in different elevation gradients.At different altitude gradient,the species composition of bryophytes shows a certain degree of asymmetry,that is,relatively few species occupy relatively more resources,and the asymmetry of bryophytes community at low altitude is weakest.In the three-level elevation gradient scheme,it was found that there were no significant differences between the species richness,the Simpson index,evenness of bryophytes and elevation gradient.The species richness and diversity index of the bryophytes in the four-level elevation gradient and five-level elevation gradient were significantly different at each elevation level.But there was no significant difference in evenness between different elevation levels.(4)The species composition,species richness,Menhinick index,Simpson index,evenness index and Berger-Parker dominance index of liverworts and mosses were not significantly different between aspects,which indicated that the effect of aspect to bryophytes was small.The species composition of liverworts and mosses showed significant difference in different slope overall;the slope has obvious influence on the Menhinick index,the Simpson index and Berger-Parker dominance index of the liverworts,but had no significant effect on the species composition,species richness,Menhinick index,Simpson index,evenness and Berger-Parker dominance index of mosses.There are significant differences between species richness,the Menhinick index and the Simpson index of liverworts and mosses in different degree of smoothness;the evenness index and Berger-Parker dominance index of mosses have significant difference in different degree of smoothness,but there is no significant difference between the evenness index and Berger-Parker dominance index of the liverworts.(5)The results of random forest analysis showed that the influence of the degree of smoothness and potential direct light incident radiation(PDIR)on the coverage,richness,Simpson Index,evenness and Berger-Parker dominance index of liverworts and mosses was higher,which showed that the impact of the smoothness and PDIR on the bryophytes was greater,as the important environmental factor limiting the growth of bryophytes.Habitat factors,such as slope and altitude,also had different effects on bryophytes diversity index,which showed that the diversity of bryophytes was not influenced by single factors but by multiple factors.(6)The indicator analysis showed that there were differences in the indicators of bryophytes under different habitats,and some bryophytes could indicate different habitat conditions at the same time.Pseudotaxiphyllum pohliaecarpum has significant indication effect on the 2nd elevation gradient,the 3rd slope grade and 1th smoothness level.Thuidium pristocalyx and Plagiochila flexuosa have the remarkable indication to the 1th elevation gradient and the 2nd smoothness level.Kurzia gonyotricha can significantly indicate the habitat conditions of the 4th elevation gradient and the 3rd smoothness level.Rhynchostegium pallidifolium has a significant indicating effect on the 1th elevation gradient,sunny aspect and 2nd smoothness level.Sematophyllum subpinnatum,Homalia trichomanoides var.japonica,and Spruceanthus polymorphus have the good indication function to the sunny aspect and the 2nd smoothness degree.The above conclusions showed that the community structure,species diversity and distribution characteristics of bryophytes are obviously related to forest types,elevation,slope,smoothness level in subtropical forests.At the same time,bryophytes had a certain indicating effect on these habitat factors.This study provides data support and theoretical guidance on species diversity protection,survival strategy,community construction mechanism,resource utilization of bryophytes.