Climatic Limitations Of Cinnamomum Camphora And Cunninghamia Lanceolata Based On Leaf Economic Spectrum And Plant Water Strategy

As typical subtropical plants,Cinnamomum camphora and Cunninghamia lanceolata are important economic tree species in China.Global climate change,especially the frequent occurrence of extreme climate events,has led to changes in the geographical distribution of the above two species,so that its impact on the physiological and trait functions,economic spectrum and survival strategies of Cinnamomum camphora and Cunninghamia lanceolata can be identified,which can provide basic information for the biogeographical distribution of tree species and ecosystem functions in subtropical regions.Therefore,in order to explore the limitations of climate change on the geographical distribution of camphor and Chinese fir,this study collected the geographical distribution of Cinnamomum camphora and Cunninghamia lanceolata in subtropical regions and the limiting climatic factors on the geographical distribution of Cinnamomum camphora and Cunninghamia lanceolata.The indicators of economic traits and hydraulic traits were determined;the climate limiting factors were analyzed from the two aspects of plant water strategy and "leaf economic spectrum";we carried out quantile regression analyses on the relationship between the 5th quantile,median,and 95th quantile of annual mean temperature,warmth index,annual precipitation coldest monthly minimum temperature and economic traits and hydraulic traits.We conducted our research by studying the climatic limitations of plants,identifying and analyzing the environmental survival strategies of Cinnamomum camphora and Cunninghamia lanceolata in subtropical regions.Below are key research findings:1)According to the contribution rate of climatic factors,we determined the main climatic factors affecting the geographical distribution of Cinnamomum camphora and Cunninghamia lanceolata.The main climatic factors affecting Cinnamomum camphora:average temperature,warmth index,annual precipitation,minimum temperature of the coldest month.The contribution rates of climatic factors are 49.23%,27.77%,12.92%,5.47%,respectively,and the total contribution rate reached 95.39%.The main climatic factors affecting Cunninghamia lanceolata:annual precipitation,warmth index,annual average temperature,minimum temperature of the coldest month.The contribution rates of climatic factors are 45.50%,27.98%,18.70%.4.74%,respectively,and the total contribution rate reached 96.92%.In the context of global climate change,it has guiding significance for subtropical plant niche expansion.2)In terms of economic traits,Cunninghamia lanceolata has higher leaf dry matter content and lower specific leaf area than Cinnamomum camphora.It is found that Cunninghamia lanceolata has stronger adaptability and resource acquisition ability than Cinnamomum camphora.From the perspective of hydraulic properties,the branch embolism resistance,wood density,and water potential at leaf loss point of Cinnamomum camphora are more drought-resistant than those of Cunninghamia lanceolata.Generally speaking,the environmental adaptability and the resource acquisition ability of Cunninghamia lanceolata is stronger,and the drought tolerance of Cinnamomum camphora is better.3)We analyzed the trade-off relationship between the economic traits of Cinnamomum camphora and Cunninghamia lanceolata to find out the leaf economic spectrum of plants in this area,and carried out correlation analysis between economic traits and climatic factors.The response mode of leaf dry matter content and climate factors MAT,MAP,WI,MTCM are a bilateral restriction mode.The response mode between specific leaf area and climate factors MAT,MAP,WI is a unilateral restriction mode.And the response mode with climate MTCM is a horizontal mode.Leaf dry matter content has a more obvious response to climate factors than specific leaf area,and it can better predict the distribution range of Cinnamomum camphora and Cunninghamia lanceolata.4)We analyzed the trade-off relationship between the hydraulic traits of Cinnamomum camphora and Cunninghamia lanceolata to find out the water use strategy of plants in this area,and conducted correlation analysis between hydraulic traits and climatic factors.In the research on climate limitation of plant water strategy,it is found that P50S,Ψtlp and WD are responsive to climatic factors.The responses ofΨtlp and WD to climatic factors are more obvious,and the response mode of Ψtlp to MAT and MTCM is a bilaterally limited mode,which is more sensitive to the climatic factor of temperature due to the dual constraints of extreme high temperature and the coldest month’s minimum temperature.The response mode of WD,MAT,and MAP is a unilateral restriction mode,which is limited by hydrothermal conditions,and its distribution range can be predicted more accurately based on this trait.The distribution range of camphor and fir under the current climate scenario and the main climatic factors limiting their distribution were obtained in the results of this study,and the climatic limiting factors from the plant physiological level were analyzed to make the predictions more accurate.This study provided a scientific theoretical basis for the current and future planning and planting of Cinnamomum camphora and Cunninghamia lanceolata in China.