Plant Functional Trait Mediates Alpine Meadows Community Functional Feature And Physical And Chemical Proprieties Of Soil Relationships In Northwest Of Yunnan,China

Northwest Yunnan is one of the 25 biodiversity conservation hotspots in the world.It is one of the three unique species differentiation centers in China.The northwestern alpine meadow is the core of the entire Hengduan Mountain alpine meadow.In recent years,the human disturbance caused by the rise of tourism in Northwest Yunnan and the retreat of the snow caused by rising global temperatures are gradually changing the functional characteristics of alpine meadow communities.Therefore,the study of the relationship between the environment,plant functional traits and community functional feature of alpine meadows in northwest Yunnan has become the focus of ecological conservation.In order to explore the ecological process that plant functional trait mediates soil and plant community functional feature through selection effect and complementary effect,we selected alpine meadows in Shangri-La and Deqin County that were not disturbed or interfered with by humans as study area.For the study,a field survey was conducted in August 2017 to obtain vegetation and soil data,and a quantitative ecological method was used to determine the community type of alpine meadows in Northwestern Yunnan.The research mainly selected nine functional traits,including Height,SLA,LDMC,RL,LLWR,LF,GF,RM and Fruit.In terms of moisture,nutrients and decomposition,five soil indicators were selected for pH,SBD,Moisture,STN and C:N.Key soil factors and response-sensitive plant functional traits were obtained.On this basis,combined with selection effect and complementary effect on plant functional traits,the effects of soil on.meadow plant community functional feature were determined and key functional species were identified.The main findings are as follows:The alpine meadows in the study area can be divided into four types of meadow communities:hydric meadow,mesic meadow,xeric meadow and forest marginal meadow.With the increase of water,the soil bulk density is reduced,the soil nutrient is more,and the decomposition rate of organic matter is faster.As a special meadow in the transition zone,forest marginal meadow has the characteristics of high pH,and the characteristics of other soil factors are similar to those of mesic meadow.The four types of meadows are all living form with underground buds.The plants in hydric meadow are the tallest,mostly long and narrow leaves;the root length of the xeric meadow is the longest;plants of hydric meadow and mesic meadow are densely clustered,plants of forest marginal meadow are scattered;plants of mesic meadow tend to having single seeds that is superior in quality,the other tend to be multi-quantitative.There is a significant negative correlation between SLA and LDMC,and the poorer soil resource conditions,higher SLA and LDMC.The key soil factors are different in all meadows:in mesic meadow-pH,STN and Moisture;xeric meadow-pH,STN,SBD and Moisture.There are also differences in functional traits corresponding to response sensitivity,namely SLA and LF of mesic meadow,LLWR,GF,LF and RM of xeric meadow.In different habitats,assembly mechanisms of meadow communities are far different than the complex and obvious functional traits of plants is different.It may also be that one mechanism works or two mechanisms work at the same time,but it does not necessarily affect ultimate performance of community functional feature.Key soil factors affect community functional feature by selection effect and complementary effect of plant functional traits.On this basis,functional species that are sensitive to environmental responses in mesic and xeric meadows were identified.One is the native species indicating habitat characteristics:Poa chalarantha,Cyananthus incanus var.parvus,C.macrocalyx and Pedicularis longiflora in mesic meadow;Kobresia duthiei,K.royleana,Artemisia edgeworthii var.diffusa,Pterocephalus hookeri,Heracleum millefolium,Leontopodium franchetii,P.nevskii in xeric meadow.The other is an alternative functional species that indicates habitat changes:Potentilla delavayi,Taraxacum dissectum,T.leucanthum in mesic meadow;T.tibetanum,Stellera chamaejasme,Spenceria ramalan,P.fulgens,P.delavayi,Euphorbia nematocypha in xeric meadow.