Elevational Patterns Of Bryophyte Diversity In West Tianmu Mountain Of Zhejiang Province

Biodiversity is the foundation of life on earth,providing a variety of ecosystem services which are vital to the current and future human well-being.The destruction of global biodiversity and the deterioration of ecological environment are gradually disintegrating the life support system on the earth,threatening the stability of ecological system and the survival and development of all mankind.The explanation of the distribution patterns and causes of biodiversity is the basis of biodiversity conservation research,and the altitude gradient can provide an important platform for studying biodiversity conservation because of the huge environmental changes within a short distance.However,due to the differences in the sampling gradient and the resolution of the sampling data,the elevational patterns of species diversity were diversified.Bryophytes are extremely sensitive to environmental changes and have a wide distribution range,so they may become the most ideal group for studying the elevational patterns of species diversity,exploring investigation methods and analyzing causes.Due to the wide variety of bryophytes,small individuals,high cost of field collection and difficulty in classification and identification,the research of bryophyte diversity patterns and the protection of bryophytes had become the most vital but weakest link in biodiversity conservation.In this paper,the West Tianmu Mountain Nature Reserve in Zhejiang Province,located in the eastern subtropical zone of China,was selected as the research area.Gradient plots were set up at different altitude to investigate.Two sampling methods were adopted: floristic habitat sampling method and subplots sampling method.Based on the diversity and microclimate monitoring data,the altitude gradient distribution patterns of bryophyte diversity in Mt.Tianmu were analyzed,and the potential factors of its distribution pattern were explored.In addition,it was proposed to explore a set of reasonable and reference survey methods through the study of bryophytes in Mt.Tianmu,to provide a basis for subsequent surveys,and finally to provide a unified survey specification to conduct an altitude gradient survey of bryophytes and understand the change of bryophyte species diversity along the altitude gradient and the driving factors behind it.The main research results of this paper were as follows:1.In this study,37 plots were investigated for the first time,and then 12 plots were investigated again.A total of 48 species of bryophytes belonging to 146 genera and 56 families were obtained,including 112 species of liverworts belonging to 32 genera,16 families and 296 species of mosses belonging to 114 genera,40 families.There were 5dominant families of liverworts,accounting for 46.88% and 73.21% of the genera and species of liverworts respectively.There were 11 dominant families of mosses,accounting for 53.51% and 67.23% of the genera and species of mosses.The floristic components of the dominant families and genera were consistent with their geographical areas.5 endangered species in China were found,namely Lejeunea pallide-virens?Neckera perpinnata?N.laevidens?Glyphomitrium minutissimum and Regmatodon longinervis.One new record species in China was found: Spruceanthus planifolius;2.The contribution rate of bryophyte species collected in this study to the total bryophyte species in Mt.tianmu reached 68.11%,which was higher than the sum of several study in history.By analyzing the inventory incompleteness of the number of specimens and bryophyte species,the sample coverage rate obtained by different groups and different sampling methods were close to 1;The average slope of the species accumulation curve was less than 0.1 when the number of samples reached 90%-100%.It indicated that this study had high sufficiency.After fully sampling the epiphytic bryophytes in 12 of 37 plots,22 species of bryophytes were newly found,with an average increase of about 2 species in each plot,indicating that the diversity would be further improved with the increase of sampling intensity.3.By comparing different sampling methods and results,it was found that the combination of SPS and FHS could obtain higher diversity of bryophytes.Among them,the diversity of bryophytes investigated by FHS was higher than that of SPS,but SPS can find more small individuals.Through the analysis of different elevational coverage,sampling interval and density of parallel plots,it was found that incomplete sampling coverage had obvious influence on the elevational patterns of bryophyte diversity.Compared with mosses,the elevational pattern of liverworts was more affected by elevational sampling interval.The diversity of bryophytes at an altitude section can be reflected when the number of parallel plots was 2-3.4.By analyzing the relationship between bryophyte diversity and altitude in 17 sample plots,it was concluded that the elevational pattern of bryophyte diversity was atypical hump-shaped pattern,and the diversity increased with the increase of altitude,and peaked at the middle altitude(about 700-1000 m),and then gradually decreased,while there was an upward trend at high altitude.Liverworts and mosses showed different patterns.The pattern of moss was almost the same as the bryophytes,but the pattern of liverworts showed a typical hump-shaped pattern,and peaked at an altitude of about 1000-1300 m.Otherwise,the elevational pattern of epiphytic bryophyte diversity was hump-shaped,and the peak appearred in the middle-high altitude of 1100-1300 m.The elevational pattern of epiphytic mosses was similar to that of bryophytes,but the elevational pattern of epiphytic liverworts gradually increased with altitude and showed a slight downward trend at high altitude.By analyzing the altitude distribution range of bryophytes,it was found that 78.01%of species were narrow distributed,of which 37.23% were only distributed below the median altitude,and 29.79% were only distributed above the median altitude.The narrow taxa of liverworts tended to distribute at higher altitude,among which 34.72%of liverworts only distributed above the median altitude,while the narrow taxa of mosses tended to distribute at lower altitude,and 40.48% of mosses were only distributed below the median altitude.It showed that mosses were dominant in the low altitude and liverworts were dominant in the middle-high altitude.In addition,there were only 22 species(7.80%)of bryophytes whose altitude distribution range were more than 1000 m,and 142 species(50.35%)of bryophytes whose altitude distribution range were less than 100 m,which indicated that there were fewer wide-range species and more narrow-range species of bryophytes in Mt.Tianmu.The presence-based and abundance-basedd dissimilarity measures in species composition showed similar patterns along the altitude gradient,that is,taxonomic ?diversity of bryophytes,liverworts and mosses all increased as elevational distance increased.However,the value of ? diversity was greater than 0.5,indicated that the species composition differed greatly even between two plots adjacent to the altitude.5.The results of Pearson correlation and spatial linear model all proved that factors such as stand basal area,slope,average temperature during the growth period,average relative air humidity during the growth period,aspect and the richness of woody plants were identified as the drivers of epiphytic bryophyte diversity,which reflected the driving role of microhabitat in the diversity and distribution of bryophytes.However,liverworts and mosses were affected by different factors.Average temperature during the growth period,average relative air humidity during the growth period and aspect had significant effects on the species richness of liverworts,while stand basal area,slope and aspect had a significant impact on the richness of mosses.The results of Mantel test and db RDA proved that the ? diversity of epiphytic bryophytes was significantly related to the elevational distance,and relative air temperature and humidity had a greater impact on the composition of bryophytes,which was closely consistent with the physiological characteristics of bryophytes that were sensitive to temperature and humidity.6.Through the analysis of the trunk distribution characteristics of epiphytic bryophytes,it was found that the epiphytic bryophytes and mosses had the highest diversity at the base of the trunks(0.3 m above the ground),while the diversity of liverworts was the most abundant at 1.1 m.In addition,the epiphytic bryophytes had the highest cumulative absolute coverage at the base of the trunks(0.3 m above the ground).The species diversity and coverage of bryophytes distributed in the northfacing direction were higher than those in the south-facing direction,which indicated that the epiphytic bryophytes tended to grow on the cool and moist base and shady side of the tree.