| Subgen.Brachypetalum belongs to the Orchidaceae Paphiopedilum,which has high ecological significance and ornamental value.At present,due to the serious theft of the population and the remote growth,this group of plants is extremely endangered.At present,the habitat characteristics and protection status of this group of plants are not clear,which limits further scientific research and implementation of protection measures.This study reveals the habitat characteristics of subgen.Brachypetalum from different angles,and analyzes its protection status and vacancies in combination with investigation,which has important guiding significance for the protection and research of Subgen.Brachypetalum.The habitat characteristics of this group of plants were revealed from the aspects of wild population resource distribution status,habitat characteristics,soil nutrients,soil fungal community structure and protection effect analysis.The following main results are obtained.(1)A total of 194 natural distribution points of subgen.Brachypetalum were investigated.Paphiopedilum micranthum was the most widely distributed with the largest number of distribution points,Paphiopedilum wenshanense had the least number of distribution points,and Paphiopedilum armeniacum had the narrowest distribution range.The distribution of resources in each distribution point of the subgen.Brachypetalum is uneven.The number of plants in most distribution points is less than 100,and the number of plants in a few distribution points is more than 300.The geographical distribution is mainly concentrated in 22°to 29°,longitude 98°to110°,the northernmost distribution point is in Daozhen County,Zunyi City,the westernmost distribution point is in Gaoligong Mountain,Nujiang River,Yunnan Province,the southernmost distribution point is in Chongzuo,Guangxi Province,the easternmost distribution point is in Guilin,Guangxi Province.The dense distribution area is in the southwest of Guizhou,southeast of Yunnan and the junction of Guizhou and Guangxi.The altitude distribution range is from 100 m to 2000 m.The distribution altitude of Paphiopedilum wenshanense and Paphiopedilum armeniacum is higher,the distribution altitude of Paphiopedilum concolor and Paphiopedilum emersonii is lower,and the distribution altitude of Paphiopedilum micranthum is the widest.(2)The geomorphological types of the growth of subgen.Brachypetalum are mainly karst landforms,and some grow in normal landforms.The slope of the habitat is usually controlled by the topography,and the slope range is large,from gentle to steep.The slope of the distribution points in the karst area is mostly large,while the slope of the distribution points in the normal landform is relatively slow,and the slope is mainly in the west and northwest.It often grows at the root of large trees,or in negative terrain such as rock crevices and stone troughs,which is conducive to soil deposition and water retention.The soil layer of the habitat is shallow and discontinuous.The soil is composed of humus soil or limestone and dolomite sedimentary soil,which causes the plants of the subgenus to often exist in the form of aggregation or dispersion to adapt to topographic changes.The community type of the habitat is mainly subtropical evergreen and deciduous broad-leaved mixed forest,and the main tree species of the community in which the habitat is located are mostly common tree species in the area.(3)The habitat soil of the subgen.Brachypetalum was determined by experiments.It was found that the habitat soil nutrient content was rich,but it fluctuated greatly with different distribution points.One-way analysis of variance showed that there were differences in soil chemical properties and enzyme activities among the seven subgen.Brachypetalum plants.The contents of soil total nitrogen,total potassium,alkali-hydrolyzable nitrogen and available potassium were not significantly different due to species differences,while the contents of soil total phosphorus,organic matter,alkali-hydrolyzable nitrogen,available phosphorus,invertase and cellulase were significantly different(P≤0.05).(4)The soil fungal communities in the habitat of subgen.Brachypetalum are mainly Basidiomycota and Ascomycota,and the fungal functional groups are mainly symbiotic fungi,saprophytic fungi and pathotrophic fungi.There were significant(P≤0.05)differences in alpha diversity and beta diversity among the species of the subgenus.Although the species composition of soil fungi in the habitats of the subgenus was similar,the community structure of soil in the interspecific habitats was significantly different.Lsfe analysis with 4 as the threshold screened out 10 biomarkers in the soil of Paphiopedilum micranthum habitat,5 biomarkers in Paphiopedilum wenshanense,3 biomarkers in Paphiopedilum concolor,only two biomarkers in Paphiopedilum malipoense,5 biomarkers in Paphiopedilum bellatulum,and 6biomarkers in Paphiopedilum emersonii.CCA analysis showed that climatic factors,geographical factors,habitat factors,climatic factors,soil physical and chemical factors and soil enzyme activities all had an impact on the soil fungal community structure in the habitat of subgen.Brachypetalum,but the interpretation rate was low,and some of them were not revealed.It may be caused by the biological habits between species,among which climatic factors have the highest interpretation rate(20.96%).Spearman correlation analysis showed that 7 dominant fungal groups were significantly positively or negatively correlated with soil nutrient factors.(5)The Max Ent model predicted the suitable area of subgen.Brachypetalum,and found that the high suitable area was 19328km~2,the middle suitable area was111335km~2,and the low suitable area was 202143km~2.Using Arc GIS10.2 mask extraction technology,the protection rate of high suitable area was only 2.04%,the protection rate of middle suitable area was 2.88%,and the protection rate of low suitable area was 3.81%.Among the 194 distribution points investigated,191 were threatened to varying degrees.The threat factors were mainly from human factors and natural factors.Human factors were mainly human-destroyed vegetation,and natural factors were mainly habitat degradation.The protection rate of the distribution points of subgen.Brachypetalum was only 34.54%.The study also investigated 19 research units to carry out ex-situ conservation of subgen.Brachypetalum.The ex-situ conservation of Paphiopedilum micranthum was the largest,and the conservation of Paphiopedilum wenshanense was the least.The number of conserved plants was about144,787,which effectively supplemented the population resources of subgen.Brachypetalum.This study systematically revealed the habitat characteristics of Subgen.Brachypetalum,and analyzed its conservation status.The results showed that Chinese Paphiopedilum broad subgenus was mainly distributed in the junction of Guizhou and Guangxi and the southern region of Guangxi,among which,P.concolor had the lowest altitude,P.armeniacum had the highest altitude,and P.micranthum had the widest altitude and distribution range.There are differences in the habitat characteristics of each species in soil physical and chemical properties,soil enzyme activities and soil fungal community structure.At the same time,there are some similar habitat characteristics,such as topography and niche types,etc.The study predicts the suitable range of the current subgenus Brachypetalum,and analyzes the in situ protection,ex situ protection,threatened factors and degree.The results showed that the area of high suitable area was 19328km~2,the area of medium suitable area was111335km~2,and the area of low suitable area was 202143km~2.Using Arc GIS 10.2 mask extraction technology,the proportion of high suitable area included in the protected area was only 2.04%,medium suitable area was only 2.88%,and low suitable area was only3.81%.It was found that only 34.54%of the distribution sites of the subgenus broadleaf were included in the protected areas.The overall protection rate of natural distribution sites was only 34.54%,and the lowest protection rate of Paphiopediopedium was only23.38%.Among the 194 distribution sites of subgenus Brachypetalum,191 sites were threatened to varying degrees,and the threat factors mainly came from human factors and natural factors.The human factors were mainly vegetation destruction,and the natural factors were mainly habitat degradation.According to the survey,19 research units carried out ex situ conservation of the subgenus Brachypetalum,with the most effort in the ex situ conservation of P.micranthum sclerophyllum and the least in the conservation of P.wenshanense,with the number of conserved plants being about144787,which effectively added the population resources of the subgenus Broadleaf.This study provides a reference for the study and scientific protection of subgenus Brachypetalum species. |
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