Responses Of Plant Leaf Traits To Soil Phosphorus Concentrations And Its Functional Measurements To Soil And Water Conservation Function Of Typicai Communities In Mid-Yunnan

Understanding the influence of environmental factors on plant, and measuring accurately the function of constructed communities played a key role in vegetation restoration. Plant traits combined environmental factors with community features and functions together, could illustrate the responses to their affections and then gave an effect in return. However, it’s still inconclusive that how the plant traits respond to different soil phosphorus concentrations, and how much they affect the functions of communities. To answer this question, we analyzed plants leaf traits, components and constructions of typical communities in two small watersheds named Samachang and Chaihe locating in central Yunnan province, southwest of China. Main conclusions showed as follows:(1)There were similarities on clamite or environment conditions, while a big difference in soil nutrents and species diversity of typical communities from Samachang poor phosphorus area and Chaihe rich phosphorus zone. The most remarkable difference was total soil phodphorus concentration, numbered less than 0.2g/kg in Samachang and more than 2.0g/kg in Chaihe. The results of CCA (a kind of indirect gradient ranking analysis) showed that soil total and available phosphorus profoundly shaped the components and distributions of communities both in poor and rich phosphoru zone.(2)12 leaf traits indexes of 55 species from 10 kinds of typical communities in two zones were compared, results howed that leaf traits, including LDMC, LT etc., on species or canopy levels, had a significant difference between two zones. Response characters of plant leaf traits to soil phosphorus were identified and its optimal subsets were absorbed by recursive algorithm named YNCASC. The optimal trait subsets to soil phosphorus of plant leaf traits in Samachang was "LWC-LT-Pmass-N/P-P/K", while in the phosphorus-rich zone of Chaihe, "LT-Nmass-Pmass-Kmass" was the optimality set. The leaf thickness and P-mass were the remarkable single responsing traits in both zones.(3)The soil phosphorus concentration distinguished the adaption stratages, also plants traits efficiently responsed across the two different zones with a limitation in lower soil phosphorus area vs a tolerance in higher one. Then, a higher soil phosphorus condition made a higher LA, LT, SLA, LWC, N-mass, K-mass but a lower LMA and LDWC, suggested a more productivity, more consuming and faster recycling strategy was adapted in rich soil phosphorus zone.(4) There was a close corelationship between leaf traits diversities and soil and water conservational functions. The conopy traits played a significant regulator on soil and water conservation functions of communities. Surface runoff, soil erosion and loss of nitrogen and phosphorus were negative with FDiv of communities, and an increasing functional evenness of canopy was advantageous to the increase of soil erosion resistance.(5) Regression analyses were taken between the leaf trait diversity and runoff of the community, soil erosion, loss of N,P, indicating a close relationship of leaf diversity and the community’s function of soil and water conservation, two zones respectively. The diversity of phosphorus response characters may explain 60% up community function richness and divergence, but it can’t explain the community function evenness effectively since there’s some redundancies in the process of plant leaf adapting to the soil phosphorus. Moreover, Thick, Pmass, Nmass and N/P may be four significant indicators which imply the soil phosphorus’s change and the community’s ability of soil and water conservation.Gathering the results of how plant traits indicate the adaptive strategy of species and communities, how leaf traits vary from species level to community level in both two zones, along with how they respond to soil phosphorus and community functions, it seems reasonable to reach some conclusions:affected by the soil phosphorus, the communities in phosphorus-lean zone and the phosphorus-rich zone vary from the plant species, the community features, the function diversity and the ability of soil and water conservation. This implies that plants and communities have different adaptive strategy in these two zones. Meanwhile, plants in Rich phosphorus area tend to have a shorter lifespan and lower dry matter production leaf, with faster nutrient turnover rate and relatively inefficient runoff control ability, the present communities lead to more nitrogen and phosphorus nutrients loss with the runoff, suggesting that relatively lower metabolic species, like Keteleeria evelyniana, and soil and water erosion resistance species, like Alnus nepalensis, should be selected for communities construction pattern of artificial assistance restoration in rich soil phosphorus zone.