| Orchids is one of the most abundant and most highly evolved families of angiosperms;it has a wide distribution and regularity,strict environmental requirements,a strong dependence on ecosystems,and a certain role in indicating biodiversity.The Beipan River Basin is an important monsoon intersection area.It is also an interlaced zone in different forest areas.Combined with typical karst landscapes,the habitat conditions are extremely special.Wild Orchids are abundant in resources.However,the intensity of rocky desertification in this area is high,and the market for wild Orchids is serious.At the same time,there is a large gap in the species of Orchids involved in counties(districts)in the river basin,and the resource background is unclear.This paper takes the orchid family in the middle and lower reaches of the Beipan River as the research object and studies on the Species Composition,Flora Characteristics,Community Species Diversity,Distribution Characteristics and Threats of Orchids in the Research Area.improves the background of orchid resources in the study area and understands the distribution pattern of Orchids in the study area.,to reveal the special transitional characteristics of the study area and the distribution of orchid species,provide a certain reference for the protection and utilization of Orchids in the study area.The main results are as follows:(1)A total of 49 genera and 163 species(including variants and variants)of Orchids were found in the study area;of which 6 new record genera and 33 new record species;Two species,Habenaria furcifera and H.rostrata,were newly recorded in Guizhou Province.There are 27 species of threatened grades that are above endangered(EN),accounting for 16.56% of the total species;single genera have a high proportion,with 22 genera,accounting for 44.9% of the total genera.(2)Compared with the neighboring neighbors,the number of genera and species of Orchids in the study area is not significantly different from that of other adjacent regions except for a certain gap with the northern region;The species ratio in the study area was higher than that in the adjacent peripheral areas,and the germline differentiation degree was large.The similarity of the genus is greater than the similarity of the species,and the genus similarity level is similar to the north region except that the similarity level is not similar to the middle similiarity,and is similar to the other neighboring regions.The similarities of the species are all medium dissimilar and the similarity coefficient is low.(3)The distribution frequency of Orchid species in the study area was relatively low,with 69 species occurring between 1 and 5,accounting for 77.53% of the total surveyed species.The species diversity of the orchid communities where the orchid family is located is the most abundant at the altitude of 1100-1300 m.With the change of altitude,the dominant species of the Orchids plant communities are not obvious,and there is little difference in the number of individual species between the communities.(4)The genus and species of Orchids in the study area are rich in composition.The floral types of genus can be divided into 11 distribution types and 5 distribution variants.The floral types of species can be divided into 7 distribution types and 3 distribution variants.The R/T values of genus and species were 3.18 and 7.43.The genus and species of tropical nature clearly predominate.A total of 45 species used the study area as one of the natural distribution marginal areas(boundaries),accounting for 27.78% of the total species.(5)With the increase of altitude,the species number of Orchids increases first and then decreases,and the species is most abundant at the altitude of 900-1100 m.Endangered(EN)and critically endangered(CR)species occur mainly in the elevation range of 500-1100m;Orchid species are most abundant in the 1100-1300 m elevation range.Plant species in Orchids have large gaps and low similarity in species distribution among different slopes,aspect,slope position,community height,and niche habitat type.The area where the Orchids plants are densely distributed is the junction of Qinglong and Guanling and the whole of Wangmo County.Critically endangered(CR)grade species are mainly distributed at the junction of Qinglong and Guanling,while endangered(EN)grade species are mainly distributed at the junction of Qinglong and Guanling and the junction of Guanling,Xingren and Zhenfeng.(6)Adaptation types are diverse,including 75 species of diurnal Orchids,80 species of epiphytic Orchids and 8 species of saprophytic Orchids;according to the TWINSPAN cluster,the orchid families in the study area can be divided into 18 adaptation types;in combination with the CCA ordination map,the vast majority of species of the same adaptation type are concentrated in similar areas.Altitude,community height and topography are the three environmental factors that affect the distribution of Orchids.(7)Orchids are highly disturbed by human activities.There are 63 species of medium disturbance,accounting for 70.78% of the Orchids plants.Habitat degradation or loss is serious.The40.65% of the study area is rocky desert area,and 68 species are distributed,accounting for 76.4% of the Orchidaceae plants.The Junction of Qinglong county and Guanling County,Wangmo County,Zhenfeng county at the junction,The junction of Zhenfeng county and Guanling County.The priority species are in 19 species: Bletilla striata,Paphiopedilum malipoense,Dendrobium nobile,Anoectochilus xingrenensis,Dendrobium scoriarum,Cleisostoma rostratum,Paphiopedilum bellatulum,Eulophia zollingeri,Pelatantheria rivesii,Oberonia myosurus,Bletilla formosana,Geodorum eulophioides,Oberonia ensiformis. |
