Changes Of Disanthus Cercidifolius Var.Longipe With Altitude Gradient And Developmental Stage In Leaf Functional Traits And Allometric Relationships

The trade-offs of different combinations of plant functional traits determine the life history strategy of plants,which in turn affects the coexistence mechanism of species.The allometric relationships of plants and their changes help to understand the adaptive response of plants.Disanthus cercidifolius var.longipes,a rare and endangered species,is distributed only in the southeast area of China.In this paper,we investigated D.cercidifolius var.longipes communities distributed along altitude gradient in Jiangxi province.Leaf functional traits and allometric relationships among the lamina mass,lamina area,lamina volume and lamina water content of D.cercidifolius var.longipes plants at different developmental stages were analyzed.Moreover,we revealed the changes of leaf functional traits and allometric relationship with ontogenetic development and altitude gradient.The results showed:(1)There were significant differences in leaf functional traits of D.cercidifolius var.longipes with different developmental stages.With plant development,both LT and LA increased,whereas LWC,SLA,LNC,and LPC decreased.(2)With the continuous development of D.cercidifolius var.longipes,the trait syndromes changed toward increasing LT and LA,but decreasing LWC,SLA,LNC,and LPC.(3)Allometric relationships among plants at different developmental stages were significant different.The increasing rate of lamina area was below or equal to that of lamina mass in adult trees,while the growth rate of lamina area was lower than that of lamina mass in saplings and seedlings;The lamina volume and lamina mass of adult trees grew at the same rate,but the lamina volume of saplings and seedlings grew faster than the lamina mass of them;The growth rate of lamina water content was slower than that of lamina mass in adult trees,meanwhile the growth rate of both characters grew at the same rate in saplings and seedlings.(4)The altitude gradient also influenced the allometric relationship among leaf traits.The allometric relationships between the lamina volume,lamina water content and lamina mass differed significantly among altitude gradients.At low elevation,the lamina volume and lamina mass grew at the same rate,meanwhile lamina water content grew slower than lamina mass.At high altitude,the lamina volume grew slower than lamina mass,and the lamina water content and lamina mass grew at the same rate.The results above indicated that the economic strategy of D.cercidifolius var.longipes changed from fast-profit to slow-profit pattern with developmental stage,and the investment strategy of leaf resources of D.cercidifolius var.longipes also responded to the changes of ontogenetic development and altitude gradient.The adult trees of D.cercidifolius var.longipes invested more lamina biomass in the development of light-harvesting area and assimilation structure,while the saplings and seedlings mainly invested lamina biomass in the development of vascular tissue.D.cercidifolius var.longipes plants tended to increase the lamina volume to capture more resources at middle and lower altitudes,while strengthen the construction of machinery and vascular tissue to resist external interference at high altitude areas.