Representative Plant Communiy Functional Traits And Their Adaption In Loess Plateau Plant Restoration Region

In this study,we choose representative plant communities in the Loess Plateau,which include Lespedeza davurica,Artemisia sacrorum,Robinia pseudoacacia and Armeniaca sibirica.On the basis of various leaf functional traits,speices diversity and functional diversity of representative plant communities,as well as the relationships between the traits and environment,the adaptation strategy of community in relation to soil conditions was analyzed.The main conclusions are as follows: 1.The relationships between the traits and environment of representative plant communities in different site conditions.Leaf area,specific leaf area and leaf water content in of the plants in the loess hilly region showed that the shady slope was higher than that of the sunny slope,and the middle and lower slope sites were higher than the upliftv.Leaf thickness,leaf tissue density,leaf total phosphorus content,leaf total nitrogen content and leaf organic carbon content showed that the sunny slope was higher than that of the shady slope,and the upliftv were higher than the middle and lower slope sites.The changes of soil total phosphorus content,soil total nitrogen content and soil organic carbon content were as follows: the shady slope was larger than the sunny slope,and the middle and lower slope was larger than the uphill.The aspect,slope gradient and other site conditions through the impact of soil nutrient content caused by changes in plant leaf functional traits.The main influencing factors of plant leaf functional traits in different site conditions were soil total phosphorus content,followed by soil total nitrogen content.2.Anaysis of leaf functional traits and anatomical structure in different-aged representative plant communities.Specific leaf area,leaf area,leaf total nitrogen content and leaf organic carbon content of Robinia pseudoacacia and Armeniaca sibirica first increased and then decreased,by increasing stand age.The peak values of specific leaf area,leaf area,leaf total nitrogen content and leaf organic carbon content were obtained at 30 a.Along with the increased stand age,leaf total phosphorus content,leaf thickness and stomata density increased,while stomata length and stomata width decreased.Leaf area,specific leaf area,leaf total phosphorus content,leaf water content,leaf thickness and stomata density were the main indexes for Robinia pseudoacacia leaf functional traits responding to the increased stand age.leaf total phosphorus,leaf organic carbon content,specific leaf area,leaf thickness and stomata density were the main indexes for Armeniaca sibirica leaf functional traits responding to the increased stand age.The adaptability of Robinia pseudoacacia to arid environment in loess hilly region is stronger than that of Armeniaca sibirica.3.The relationships among the traits,anatomical structure and soil nutrients in different-aged representative plant communitiesAs plantatation age increased,soil total phosphorus content,soil total nitrogen content first increased and then decreased,while soil organic carbon content decreased.Soil total nitrogen content and soil organic carbon content were the main soil factors affecting the functional traits of Robinia pseudoacacia leaves at different forest ages.Soil organic carbon content was the main soil factor affecting the functional traits of almond leaves in different age groups.Soil nutrients in Robinia pseudoacacia and Armeniaca sibirica communities were improved along with the increased stand age,while the soil nutrient content of the higher aged plant community was significantly decreased.Therefore,we can intervene the higher aged plant community to make their soil nutrient content maintaining at a good level,so as to better adapt to the arid and barren soil environment in the loess hilly region.4.The relationships among speices diversity,functional diversity and environmental variables in different-aged representative plant communities.The Margalef richness index,Shannon-winner index,Pielous evenness index,Rao secondary entropy index,function richness index and functional evenness index of Robinia pseudoacacia and Armeniaca sibirica community first increased and then decreased.Species diversity was significantly positively correlated with functional diversity index.The total nitrogen content of soil was the main influencing factor of species diversity and functional diversity of different-aged Robinia pseudoacacia and Armeniaca sibirica community,followed by age.the age was the main influencing factor of the species diversity of Robinia pseudoacacia and Armeniaca sibirica community in the loess hilly region,and the soil total nitrogen content was the main environmental factor of the functional diversity of Robinia pseudoacacia and Armeniaca sibirica community in the loess hilly region.In conclusion,the plant functional traits,species diversity and functional diversity of loess hilly region in northern Shaanxi were significantly affected by topographic factors such as slope position and age.In the process of vegetation restoration in the hilly area of the Loess Plateau,the plant communities such as Robinia pseudoacacia and Armeniaca sibirica can be properly intervened(such as fertilization,pruning canopy branches,etc.)to maintain their soil nutrient content at a better level,then adapt to the arid and barren soil environment in the Loess Plateau.Lespedeza davurica and Artemisia sacrorum are better on the shady slope,which indicated that they are more suitable for planting on shady slope.The adaptability of Robinia pseudoacacia to the arid and barren environment in the loess hilly region is stronger than Armeniaca sibirica in the loess hilly region,indicating that it is more suitable to plant the Robinia pseudoacacia community in this area.