The Study On Leaf Functional Traits Of Different Dominant Species In Tianlaochi Catchment In The Upper Reaches Of Heihe River

As an important part of the ecosystem,plants can adapt their environment and participate in the material and energy cycle through various ecophysiological characteristics,especially,leaf functional traits have play important role in indicating the stability of the ecosystem and global climate change.Tianlaochi catchment in the upper reaches of Heihe River was selected as our study area.The LA,SLA and LWC of dominant species in different slope directions and different elevation gradients in the basin were measured by leaf area and leaf water content,and their changes with slope direction,elevation and time were analyzed.Through studying the functional traits of plant leaves in different environments,we can analyze the differences among these traits,and understand the ecological adaptability and survival strategies of plants to the environment.From the study,results are as follows:(1)In the study area,the SLA of Picea crassifolia varied from 60.98 cm²·g^-1 to325.36 cm²·g^-1,the variation range of LWC was 53.63%?86.65%.The variation range of LA in Caragana jubata was 0.27 cm² to 0.85 cm²,the SLA of Caragana jubata varied from 142.42 cm²·g^-1 to 291.94 cm²·g^-1,the variation range of LWC was64.97%?80.01%.The SLA of Sabina przewalskii ranged from 42.94 cm²·g-¹ to 76.08cm²·g-¹,the variation range of LWC was 49.26%?67.46%.The variation range of LA in Dasiphora fruticosa was 0.13 cm² to 1.02 cm²,the SLA of Dasiphora fruticosa ranged from 117.24 cm²·g^-1 to 281.67 cm²·g^-1,the variation range of LWC was47.76%?71.34%.LA of Caragana jubata growing on shady slope was higher than that LA of Dasiphora fruticosa growing on sunny slopes.With the increase of the elevation gradient,the LA and SLA of the dominant species in the both shady and sunny slopes of the catchment showed a decreasing trend,and the LWC of the dominant species except for Picea crassifolia showed a decreasing trend.The change range of SLA with elevation on shady slope was significantly higher than that on sunny slope.The SLA values of Picea crassifolia and Caragana jubata were lower than that the SLA values of Sabina przewalskii and Dasiphora fruticosa.The variation of SLA values of species on shady slopes was more regular than that of species on sunny slopes.The change range of LWC about Picea crassifolia with elevation was significantly higher than that of shrub species,however,the change range of LWC about Sabina przewalskii was contrary,indicating that there were abundant living resources in the sunny slope of the catchment.Meanwhile,Picea crassifolia growing in the shady slope was more sensitive to the hydrothermal changes of elevation gradiens.(2)During the growing season in the study area,the variation range of LA in Caragana jubata growing on shady slope was greater than that of Dasiphora fruticosa growing on sunny slope.With the time increase,the LA of dominant species in the shady and sunny slope of the catchment showed a increasing trend,the LWC showed a decreasing trend,the SLA of all species showed a trend of increasing at first and then decreasing.Except for Caragana jubata at the elevation of 3100 m?3300 m,the leaf functional traits of all species changed stably in the late growth season.The variation of LWC in different growth stages of species on the shady slope was more obvious than that on the sunny slope,and the peak time of SLA of species on the shady slope was earlier than that of species on the sunny slope,implying that the growth period of Sabina przewalskii and Dasiphora fruticosa growing on the sunny slope was longer than that of Picea crassifolia and Caragana jubata on the shady slope.The SLA of the two herbaceous plants growing on the sunny slope was lower than that of Polygonum viviparum growing on the shady slope.(3)The change amplitude and rate of SLA and LWC of Picea crassifolia along different elevations were much higher than those of other dominant species.The change amplitude of Caragana jubata at different elevations was smaller but the change fluctuation was larger.The change amplitude of SLA of Sabina przewalskii and Dasiphora fruticosa at different elevations was smaller.Among the change rate of SLA,that of Sabina przewalskii was the least.Therefore,it can be deduced that the growth rate of Sabina przewalskii is the slowest among the selected dominant species.We compared the varible coefficients(CV)of leaf functional traits,the order of CV(LA)was Dasiphora fruticosa>Caragana jubata,the CV(SLA)was in the order of Picea crassifolia>Caragana jubata>Sabina przewalskii>Dasiphora fruticosa,and the CV(LWC)was in the order of Sabina przewalskii>Picea crassifolia>Caragana jubata>Dasiphora fruticosa.(4)The relationship between leaf functional traits was analyzed qualitatively,and the results showed that tree species with small SLA but large LWC could survive in the environment with big hydrothermal condition different,while shrub species with small LWC would develop a survival strategy with small LA and SLA in order to adapt to harsh environment.On sunny slopes with abundant light resources,high temperature and high evaporation,trees and shrubs would form leaf functional traits with large LA and SLA but small LWC to adapt to the environment,while herbages growing in shade environment will adapt to cold and humid environment by increasing LA,SLA and LWC.Leaf functional traits can reflect the environment of species growth,and express survival strategies due to long-term adaptation in the special environments.We could understand the habitat different by analyzing the differences of plant leaf functional traits in different elevation gradients,aspect.We hope the results could provide theoretical guidance for the selection of species in the ecological restoration in the study area,and provide data support for the region ecological research model performance,and also lay the foundation of predicting the distribution pattern of functional type of vegetation under climate change in the future.