Variation Characteristics Of Plant Leaf Functional Traits And Their Relationship With Environmental Factors In Different Succession Stages Of Alpine Meadow In Gannan,Gansu Province

Functional traits of plant leaves could reflect the adaptation of vegetation to habitats.Different leaf traits of different species restricted the competitive advantage of the species in the community,resulted in changes in community structure and function and thus community succession.In recent years,leaf traits of species began to be used to predict changes in communities on succession gradients.In this paper,the typical communities of five succession stages in the enclosure of Gannan Alpine meadow were studied.According to the succession sequence of vegetation,and selected the dominant plants of different succession stages:Cirsium setosum,Elymus nutans,Medicago sativa,Artemisia desertorum and Potentilla fruticosa.Leaf functional traits were measured:Net photosynthetic rate?Pn?,Transpiration rate?Tr?,Stomatal conductance?Gs?,Leaf water content?LWC?,Specific leaf area?SLA?,Leaf organic carbon?LCC?,Leaf total nitrogen?LNC?,Leaf total phosphorus?LPC?,Photosynthetic nitrogen use efficiency?PUNE?,Photosynthetic phosphorus use efficiency?PUPE?,etc,and environmental factors such as Light intensity?LI?,Soil temperature?ST?,Soil water content?SWC?,Soil organic carbon?SOC?,Soil total nitrogen?STN?,Soil total phosphorus?STP?were also determined.The leaf functional characteristics,environmental factors and their relationships in different succession stages were analyzed.The main results were as follows:1.This enclosure roughly experienced herbage,semi-shrub and shrub.The vegetation coverage of the community from early stage to late stage were 95.50%,94.43%,94.75%,95.52%and 96.50%.There was no obvious rising or decreasing trend community with succession.Margalef richness index increased significantly with succession and reached the highest level?16.67?in the later stage of succession,while Shannon-Wiener diversity index increased first and then decreased with succession,showing an inverted“V”trend,ranging from 3.41⁴.34,with the maximum value appeared in the middle of succession.2.The leaf functional traits of dominant species showed regular changes with succession,which reflected the balance between species succession and resource acquisition,utilization and conservation.The dominant species in the early succession stage had higher Pn,Tr,SLA,LPC,PUNE,PUPE,the ranges of variation were4.53¹5.12?molCO₂·m^-2·s^-1,3.65⁵.77 molH₂O·m^-2·s^-1,148.47²34.74 cm²·g^-1,1.49².50 g·kg^-1,58.01²69.32?mol·g^-1·s^-1and 1185.77⁵040.04?mol·g^-1·s^-1.These traits made early species grow at a high rate and had the ability to acquire resources to better cope with harsh,barren environments.The dominant species in the late succession stage had higher Gs,LWC,LCC,and LNC,the change ranges were0.08⁰.16 mol·m^-2·s^-1,2.75³.90%,415.29⁵24.72 g·kg^-11 and 16.25²2.49 g·kg^-1,respectively.These characteristics indicated that in order to occupy a dominant position in the community at the later stage of succession,plants increased their own nutrient storage to improve their competitiveness.3.The environmental factors were significantly different in different succession stages.The SWC,SOC and STN showed a significant increase with the succession?P<0.05?,they all reached the maximum at the later stage(0.39%;37.61 g·kg^-1;3.57mg·kg^-1).LI and ST showed a significant decrease with the succession?P<0.05?,and reached the minimum at the later stage?66.43 lx;19.50??.STP decreased first and then increased with succession,the minimum value was 0.56 mg·kg^-11 in 15 years,and the maximum value was 0.79 mg·kg^-11 in 30 years of succession.4.The effects of environmental factors on leaf functional traits were analyzed by RDA constraint ordering.We found that the functional traits of plant leaves at the early stage of succession were mainly affected by LI and STN,and LI played a stronger role.The functional traits of plant leaves in the middle and late stages of succession were mainly affected by STP and SWC,and STP played a stronger role.Therefore,we could add nutrients to plants at different succession stages to ensure better growth of plants.The results of this study deepened the understanding of vegetation succession and the response of soil nutrients to vegetation restoration in Huang-alpine meadow area of Gannan Province.Further revealed the environmental adaptability of plant population at different succession stages,and provided theoretical guidance for setting the optimum enclosure period of alpine meadow artificial grassland and grassland management and ecological restoration.