Effects Of Soil Moisture Gradient Changes On The Morphology And Composition Of Typical Grassland Herbs In Inner Mongolia

Since human beings entered the industrial revolution in the 1760s,human activities have intensified global changes,leading to a series of reactions:global temperature rise,atmospheric destruction,atmospheric CO2 concentration increase,polar ice melting,and so on.These changes have had a huge impact on the home we rely on for survival.Grassland area accounts for 24%of the total land area of the world,which is not only of great ecological value,but also of important food value.Drought has been one of the major natural disasters faced by human beings since ancient times.The changes of grassland ecosystem caused by drought have attracted widespread attention.Plant functional traits affected by environment change,the change is the comprehensive performance of plants to adapt to changes in the external environment,and to explore the changes of the relationship between plant and its environment,therefore,based on changes in plant functional traits of plant response to external environment change and adaptation mechanism has become the focus in the community ecology.The changes of leaf related traits(leaf length,leaf width,leaf area,etc.)can reflect the nutrient utilization strategy of plants adapted to the changes of soil factors,and the growth strategy and resource utilization ability of plants can be studied through the leaf traits of plants.Plant stomata is a channel regulating the gain and loss and balance of water and gas among photosynthesis,respiration and transpiration,which determines the efficiency and method of plant resource utilization,and plays an important role in the process of plant adaptation to environmental changes.Therefore,it is of great significance to study the response of plant functional traits and stomata to soil water changes.Hulun Lake is the largest lake in Inner Mongolia and the fourth largest fresh water lake in China,which nourish the vast Hulun Buir Grassland and is known as the"kidney of the grassland".In this study,the southern shore of Hulun Lake was selected as the study area to study the changes of functional traits of herbaceous plants,aiming to explore the response mechanism of plant leaves to soil moisture changes,and to predict the response of plants in the grassland ecosystem of Inner Mongolia to drought characteristics caused by global warming,to provide basic data for Hulun Lake National Nature Reserve and grassland ecosystem to respond to global climate change.The main research results are as follows:1.Achnatherum splendens(Trin.)Nevski,Allium polyrhizum Turcz.Ex Regel,Cleistogenes squarrosa(Trin.)Keng and Stipa krylovii Roshev are the main herbaceous plants in the south bank of Hulun Lake.The results showed that the four plants adapted to the decrease of soil water by reducing leaf length,leaf area and leaf dry matter mass.2.The contents of C and N in the leaves of the four plants were reduced by different change strategies:the contents of C in the leaves of A.splendens and S.krylovii increased,but the contents of N decreased.The content of N element in A.polyrhizum Turcz leaves increased.3.The most important characteristic of A.splendens affected by soil moisture is leaf area;the leaf dry matter weight and leaf C and leaf N content were the most important characters of A.polyrhizum Turcz;the leaf area and leaf C content were the most important characters of C.squarrosa;and the leaf dry matter weight and leaf specific leaf area were the most important characters of S.krylovii.3.Stomatal changes of the leaves of the four plants:A.splendens and S.krylovii increased the stomatal density,and A.polyrhizum Turcz reduced the stomatal density to cope with the decrease of soil moisture.When soil moisture decreased,the stomatal length of A.polyrhizum Turcz and C.squarrosa,the stomatal width of S.krylovii Roshev increased in different degrees.The results showed that different herbaceous plant groups in the same area adopted different strategies under the same environment of reduced soil water,which reflected the adaptation characteristics of biodiversity,taking the functional traits of plant leaves as the research index.