The Functional Specialization Of Alternanthera Philoxeroides Under Heterogeneous Habitat With Different Light Level And Nutrients Level

Resource distribution is uneven in natural space. They might be dramatic change even on very small scales.Plants can achieve the resource access and use through plasticity on heterogeneous habitat. Under the rule of "Pursue good fortune and avoid disaster", the ramets with potential independence of clonal plant, which and have greater breadth of survival and ecological adaptation than non-clonal plants, can settle down, and develop their own by the ecological adaption strategies. Accordingly that, we propose the following hypothesis:In the resource heterogeneous habitat patches, the ramets of clonal plant absorb the most profitable resource of the habitat patches, then share resources and clonal integration by the connected stem. In order to absorb more nutrients efficiently and utilize maximum abundant resource of local place, the ramets of clonal adjust the biomass investment patterns and change the morphological characters and physiological characters, namely functional specialization, then clonal division occurred.Alternanthera philoxeroides is a typical invasive clonal plant. Take Alternanthera philoxeroides as object of study, simulating the heterogeneous habitats by setting different light levels and nutrients levels, this article research its feature of clonal division through three aspects (biomass distribution, morphological plasticity, physiological plasticity). The results of experiment showed that Alternanthera philoxeroides allocated more biomass to aboveground part in the heterogeneous habitat patches of high-light and low-nutrients. In adverse that it allocated more biomass to underground part in the habitat of low-light and high-nutrients. In habitat patches with heterogeneous resource, the proximal part experienced low-light and high-nutrients connected the distal part experienced high-light and low-nutrients, compared with the one whose connected pairs of ramets experienced homogeneous habitats of high-light and low nutrients, the Chlorophyll content (Ch1 a, and Ch1 b), and stomatal conductance, and transpiration rate, and net light photosynthetic rate and photosynthetic nitrogen utilization efficiency of the distal part are significantly improved by6.65%,91.43%,43.94%,91.46%,110.3% respectively. The proximal part experienced low-light and high-nutrients connected the distal part experienced high-light and low-nutrients, compared with the one whose connected pairs of ramets experienced homogeneous habitats of low-light and high nutrients, the distal part’s fraction of leaf nitrogen allocated to bioenergetics is significantly increased by 71.17%and fraction of leaf nitrogen allocated to light-harvesting components is significantly decreased by 61.45%. But fraction of leaf nitrogen allocated to all components of photosynthetic machinery of the distal one did not significantly different. Studies said that in the habitat heterogeneity, alternanthera phioxelroides photosynthetic respond to the change of light by changing the way of specific leaf area and total leaf nitrogen content is not very significant. And it would rather enhace photosynthetic nitrogen utilization efficiency (Pmax/NA) and change photosynthetic nitrogen distribution system to improve the photosynthetic capacity. The photosynthetic assimilation or photosynthetic product can be bidirectional transfer, but the main direction of transfer is from proximal ramets to distal ones. And the nutrients only can be transfer from the proximal ones to distal ones, namely "transfer to the top". The heterogeneous habitat stimulate the remets of clonal occur the functional specialization based on nitrogen. It’s based on clonal integration, improve their productivity through change the patterns of biomass allocation, morphological or physiological characteristics, and ultimately increased biomass of genets. The research found that in heterogeneous habitat, Aternanthera philoxeroides have distinct characteristics of clonal division which is associated with is its strong invasive ability or not, there need more comparative study about native clonal plants and invasive clonal plants.