Geographical Distribution Pattern Of Wild Rhododendron In China And Evaluation Of Ornamental Value Of Wild Rhododendron In Guizhou Province

Based on a large number of literature and specimen data,the species list of wild Rhododendron in China was established by means of mathematical statistics and GIS spatial analysis.To establish the geographical distribution database of wild Rhododendron in China.The database information is further filtered,sorted and summarized to improve the accuracy of data.The species diversity and geographical distribution pattern of wild Rhododendron in China at different scales were studied according to different geographic accuracy and data matching.Based on the vertical distribution data of wild Rhododendron in Guizhou Province,the vertical distribution pattern of wild Rhododendron in Guizhou Province was discussed,and the similarity of wild Rhododendron in different altitudes was analyzed.Through analyzing the ornamental characteristics of Rhododendron in Guizhou Province,the evaluation model of ornamental value was established,and 158 species distributed in Guizhou were selected.The aim is to provide theoretical basis for the conservation and utilization of germplasm resources in the future.The main findings are as follows:(1)According to statistics,China is rich in wild Rhododendron resources.In addition to Xinjiang Ningxia and other arid and desert areas,the provincial administrative regions have wild distribution.Seven subgenera,734 species(including subspecies and variants)were recorded,including 464/203 endemic species in China/provincial level.Yunnan Province(390 species)is the first in species richness and specificity at the provincial level.Located in Yunnan Province,Gongshan County(134 species)ranks first in species richness at the county level.The distribution pattern of all species and endemic species of Rhododendron is basically the same at the provincial level,with the Himalayas and Hengduan Mountains as the biaxial,gradually spreading to the edge.The richness pattern of endemic species has obvious gradient change and shrinks to the southwest,and the central range of the Hengduan Mountains gradually narrows to the southwest.Based on species richness and geographic distribution database,21 hot counties were obtained by screening algorithm,representing 75% of the total wild population in China.Most of these hotspots coincide with global biodiversity hotspots.Comparing the species similarity coefficients between different provinces,the maximum was Hunan Province and Jiangxi Province.The minimum values are Tibet Autonomous Region and Guangdong Province.(2)A total of 158 species(including subspecies and variants)in six subgenera of Rhododendron.were compiled from field surveys combined with literature,and a search list was produced.48 species of Rhododendron.were found in the wild in Guizhou Province.By analyzing the vertical distribution pattern in Guizhou,it was found that they are mainly distributed in the1400-1700 m vertical altitude range.In terms of resource richness,the Subgen.Hymenanthe,Subgen.Rhododendron and Subgen.Tsutsusi have a clear advantage at the data level.In general,the distribution of subgenera is richer in the lower and central altitudes.(3)Based on the analysis of the factors affecting the assessment of the ornamental value of wild Rhododendron species in Guizhou Province,four standard layers and 18 evaluation factors were selected to construct an evaluation system for the ornamental value of wild Rhododendron species in Guizhou Province,through which the wild Rhododendron species distributed in Guizhou Province were evaluated and selected.The evaluation results of the 158 species of Rhododendron were divided into three levels,with the maximum value of 4.017,the minimum value of 3.056 and the mean value of 3.5518.Among them,Rhododendron delavayi,R.liliiflorum,R.decorum R.stamineum and R.simsiiare the five highest rated species in this evaluation,analysing the high scoring factors and geographical distribution of high scoring species based on the results of the evaluation.Combining the actual situation with the evaluation results,this evaluation system basically reflects the actual ornamental value of wild Rhododendron species.The complex field environment and geological landforms have created such rich species resources in China,and the transition and uniqueness of the flora is of great research value.Therefore,for Rhododendron,which has a wide distribution area,a changeable living environment,a complex group structure and a variety of species,the geographical distribution information of different scales should be sorted out to deeply understand its distribution pattern and rules.The analysis of its ornamental characters and the evaluation of its ornamental value will provide some reference for the future research on germplasms resources and the introduction and application of the species.