Variation In Carbon Isotopic Composition And Elements Of Different Geographic Populations Of Caragana Jubata And Its Response To Environmental Changes

Climate change,characterized by climate warming and changes in precipitation patterns,has severely affected the key processes and functions of the terrestrial ecosystem.Water and nutrients are the two essential elements for plant growth,which contribute to the normal growth and physiological functions of plants.Climate change will affect the utilization of water of individual plant.At the same time,the acquisition and regulation of nutrients will also have a significant impact.In the context of climate change,how plants and soils adapt to the effects of environmental changes is critical to our understanding of terrestrial ecosystems in response to climate change,especially in the sensitive areas like high-altitude areas.Therefore,in order to analyze the response of high-altitude areas to climate change,this study took Caragana jubata,a leguminous shrub which distributed in high-altitude mountainous areas in China as the object.We collected the leaf and soil samples of C.jubata of 35 geographic populations in different environmental conditions,the carbon isotope composition(?13C)and the content of carbon(C),nitrogen(N),phosphorus(P),calcium(Ca),magnesium(Mg),potassium(K),sodium(Na),iron(Fe),manganese(Mn),copper(Cu)and zinc(Zn)were examined in both leaves and soils.We aimed to explore the carbon cycle,water and nutrient utilization of C.jubata,to reveal its response to environmental changes,and to illustrate the key factors which affect carbon cycle,water and nutrient utilization of C.jubata,the results will provide data support in understanding the environmental adaptation of C.jubata.The main results are as follows:(1)The value of soil 813C was significantly higher than leaf ?13C of C.jubata.Soil ?13C was significantly correlated with leaf ?13C,and decreased initially then increased with increasing leaf ?13C,which meant soil organic C was closely related to leaves.The enrichment rate of 13C in soil decreased firstly and then increased with increasing leaf ?13C.Leaf and soil ?13C were positively correlated with altitude,which indicated that the water use efficiency of leaves was increased with increasing altitude,and the decomposition rate of soil organic C increased with altitude.Leaf ?13C was mainly affected by temperature,and soil ?13C was affected by both temperature and water.(2)The content of leaf N was high and significantly correlated with several elements,which reflected the importance of N in N2-fixing plants.Leaf C:N and C:P were positively correlated with altitude,leaf N,P,Mg,K,Na and Mn content were negatively correlated with altitude,leaf C content was increased initially and then decreased with altitude.Leaf C,P,Cu and Zn content,and leaf C:P were mainly affected by temperature;leaf N,Ca,Mg,K,Na and Mn content,and leaf C:N were affected by both temperature and water.Soil Fe and Zn were both significantly correlated with 10 soil elements,which reflected the importance of Fe and Zn in the soil of the study area.Soil C,N and Ca content,soil C:P and N:P increased firstly and then decreased with altitude,soil Mg,Na and Cu were negatively correlated with altitude.Soil P,Mg,Fe,Cu and Zn content,soil C:P and N:P were influenced by temperature;soil Ca content was mainly affected by water;soil Na and Cu content were affected by both temperature and water.Leaf Mn and Cu were positively correlated with soil Mn and Cu,soil elements had little effects on leaf elements.In addition to being affected by environmental factors directly,leaf and soil elements also adapted to environmental changes through the synergy between different elements.(3)Leaf ?13C was mainly affected by leaf Mn and Cu content,soil C and P content,soil C:N and N:P.Perhaps leaf elements content affected leaf photosynthesis,and had the indirect effect on leaf ?13C,soil elements content affected leaf elements content,and affected leaf photosynthesis and water use efficiency indirectly,and changed leaf ?13C ultimately.Soil ?13C was mainly affected by leaf Na content,leaf C:N,soil C,N,P and Cu content,and soil N:P.These elements may affect soil ?13C by the influence on soil microbial activities.