An Adaptive Evaluation Of Seven Rare And Endangered Woody Plants Under Ex-situ Conservation

Biodiversity conservation has become a global strategic task,especially in the background of serious destruction of the ecological environment and the extinction or on the edge of extinction of a large number of species.The protection of rare and endangered plants is particularly important.The assessment of ex-situ conservation of rare and endangered plants helps to understand the limitations of ex-situ conservation work,and improves the quality of ex-situ conservation work and adjusts daily management measures.It also provides theoretical references and guiding for the conservation and introduction of plants,and the work of returning to nature.The plant leaf functional traits,nutrient resorption efficiency,and ecological stoichiometric characteristics are the consequences of plant adaptation to the environment.At the same time,they vary with changes in environment and are widely used in plant adaptation strategies.In this study,the ex-situ conservation populations(Wuhan Botanical Garden,Chinese Academy of Sciences,Xianning Jiugongshan Nature Reserve)and wild populations(Wufeng houhe Nature Reserve and Nanjing Mufu Mountain)of seven species of rare and endangered woody plants were regarded as study subjects which were Davidia involucrata,Tetracentron sinense,Tapiseia sinensis,Pterostyrax psilophyllus,Dipteronia sinensis,Sinojackia xylocarpa and Cercidiphyllum japonicum.The differences in plant leaf functional traits,ecological stoichiometric characteristics and nutrient resorption efficiency between different populations and their relationship with environmental factors were explored to evaluate the adaptive evaluation of ex-situ conservation of seven rare and endangered woody plants.The main results were as follows:(1)The seven rare and endangered woody plant species showed certain differences in the ecological stoichiometric characteristics of ex-situ conservation populations and the nutrient content of the leaves did not show consistency with the soil nutrient contents.Phosphorus might be limiting element.The Botanical Garden population of Cercidiphyllum japonicum and the Jiugongshan population of Sinojackia xylocarpa had higher nitrogen use efficiency,and the Houhe population of Dipteronia sinensis and the Jiugongshan population of Davidia involucrata had lower phosphorus use efficiency.(2)There were differences in nutrient resorption efficiency between ex-situ conservation populations and wild populations.The specific manifestations were that the ex-situ conservation populations of Cercidiphyllum japonicum and Davidia involucrata had lower nitrogen recovery efficiency.There were significant differences in phosphorus resorption efficiency among different populations of Dipteronia sinensis,Tetracentron sinense,Tapiseia sinensis,Davidia involucrata.The ex-situ conservation populations of Dipteronia sinensis and Tetracentron sinense showed higher carbon accumulation.The wild population of Davidia involucrata had a more obvious trend of calcium resorption.The old leaves of wild populations of Dipteronia sinensis accumulated more magnesium element.The kalium resorption efficiency showed a wide range of changes among the five species except for Dipteronia sinensis.(3)The differences in functional traits between wild populations and ex-situ conservation populations indicated their adaptation strategies to the environment.The Botanical Garden population of Cercidiphyllum japonicum and the Houhe population of Tapiseia sinensis might be affected by local light resources which changed the leaf size.The Jiugongshan population of Dipteronia sinensis,the botanical garden population of Tapiseia sinensis,the botanical garden population of Cercidiphyllum japonicum,and the Nanjing population of Sinojackia xylocarpa might adapt to the local environment through a lower growth rate.There was a significant difference in the dry matter content among different populations of Cercidiphyllum japonicum,Dipteronia sinensis and Pterostyrax psilophyllus,indicating its different ability to resist physical insults.Based on the above results,we found that the overall seven rare and endangered woody plants had been growing well at ex-situ conservation sites,and the ex-situ conservation work had been successful to a certain extent.There were differences between wild and ex-situ conservation population in plant leaf functional traits,ecological stoichiometric characteristics and nutrient resorption efficiency,indicating that the management measures need to be improved after ex-situ conservation.