Effects Of Karst Habitat Heterogeneity On Plant Leaf Functional Traits And Soil Nutrients

The shallow soil layer,discontinuous soil cover and fragile ecological environment in karst area of Southwest China seriously restrict the development of regional economy and threaten the security of ecosystem.Karst area has high habitat heterogeneity,different Mico-habitats are interlaced,which makes the karst landforms present certain complexity.Plant functional traits are the adaptive properties of internal physiology and external structure formed gradually in the long evolutionary process of plants to environmental changes.The leaf functional traits reflect the survival strategies of plants to adapt to the environment,and are closely related to plant biomass,resource acquisition and utilization and utilization efficiency.Therefore,Studying the variation,correlation and response to environmental factors among plant leaf functional traits is helpful to understand the survival strategies of plants in heterogeneous environment.However,it is unclear how plant functional traits change and how different growth form plants adapt in different heterogeneous habitats at present.In this paper,we sampled and measured the leaf area(LA),specific leaf area(SLA),leaf thickness(LT),leaf dry matter content(LDMC),leaf length width ratio(L/W)and leaf tissue density(LTD)of main tree species in karst area of Pingba District,Anshun City,exploring the variation characteristics and the correlation of leaf functional traits of main tree species in karst forest,as well as the effects of heterogeneous habitats on plant functional traits and soil nutrient characteristics.In order to understand the adaptation strategies of leaf functional traits of karst forest plants to the environment,and providing the reference for forest vegetation restoration in degraded karst area.The results are follows:(1)The degree of interspecific variation of main tree species is different in karst area.The variation range of woody plants'LA is between 4.244-63.984 cm~2,the variation coefficient is 51.867%,and the variation range of tree'LA is between10.094-185.623 cm~2,and the variation coefficient is 67.290%,both of which reached the high level of variation;The SLA,LTD and LT of the woody,tree and thrub plants also reached the level of medium variation;LDMC had the lowest variation level and is a relatively stable trait in plants.(2)The leaf functional traits are correlated among interspecific.SLA of woody plants,tree layer and shrub layer plants were significantly negatively correlated with LTD and LDMC;there were significant correlation between LTD with LT and LDMC;there was a significant negative correlation between LA and LTD in woody plants and shrub plants;However,LA was negatively correlated with L/W in tree layer.(3)The functional traits of main tree species showed different trends with the change of heterogeneous habitats in karst area.In general,LA decreased with the increase of habitat heterogeneity;SLA increased first and then decreased with the increase of habitat heterogeneity;LDMC increased with the increase of habitat heterogeneity;with the enhancement of habitat heterogeneity,the trend of LTD increased first,then decreased and then increased.Compared with non karst woody plants in the same latitude,the LA and SLA of this study are smaller,while the LT and LDMC are larger.It is beneficial for plants to reduce transpiration and store nutrients,to adapt to the drought and barren karst environment.(4)Soil nutrients showed different trends with the increase of habitat heterogeneity.Soil p H decreased with the increase of habitat heterogeneity;other nutrient indexes had no significant change trend with the increase of heterogeneity;soil stoichiometry increased first and then decreased with the increase of habitat heterogeneity;The relative soil nutrient content decreased with the increase of habitat heterogeneity,The relative stone nutrient content increased and then decreased with the increase of habitat heterogeneity.Compared with the national soil nutrient content,the soil N and P content in the study area were lower,but the SOC content was higher.(5)C/N ratio is the soil factor affecting the plant functional traits of the main tree species in karst area,while the environmental factors affecting the leaf functional traits of the main tree species are stone hole,stone groove and stone chink.In general,the degree of variation of each leaf functional trait was different among woody plants,among which LA had the largest variation and LDMC had the smallest variation;there were different degrees of correlation among the leaf functional traits.With the enhancement of habitat heterogeneity,SLA first increased and then decreased;LTD showed a trend of increasing first,then decreasing,and then increasing,while other traits had different trends in different growth types.Soil stoichiometry and relative stone soil nutrients increased first and then decreased with the increase of habitat heterogeneity,while relative soil nutrients decreased.C/N ratio,stone hole,stone chink and stone groove were the soil factors that affected the leaf functional properties of main tree species in karst area.