Phenotypic Plasticity And Nitrogen Use Strategy Of A Clonal Plant Potentilla Anserine L. With Different Ages Under Heterogeneous Habitats

Age is one of the key features of understanding the life history, dynamics, adaptability and evolution of plant populations. Clonal plants in different age classes responded to heterogeneity with different growth and reproduction as well as different utilization strategies in soil nitrogen. However, the current understanding of the processes and mechanisms of these responses is very limited. Here, a pot experiment was conducted in an orthogonal design in greenhouse, and Potentilla anserine, a stoloniferous clonal plant, was selected. Heterogeneity was established with nitrogen and water in three different levels, respectively, and there were totally nine treatments with each repeated five times. Through the observations of two consecutive growth seasons in 2013 and 2014, this study attempted to explore the effects of heterogeneous water and nitrogen conditions on the phenotypic characteristics, clonal growth and nitrogen utilization strategy of P. anserine with different ages. The scientific questions were as follows:(1) How the biomass allocation patterns of P. anserine with different ages varied under heterogeneous water and nitrogen conditions?(2) How water and nitrogen heterogeneity affected the phenotypic plasticity and clonal growth of P. anserine with different ages?(3) How P. anserine responded to water and nitrogen heterogeneity on nitrogen utilization strategy?The main results and conclusions were as follows:(1) P. anserine under heterogeneous nitrogen and water conditions showed more significant responses to water treatments. The effect of different nitrogen treatments would be weakened when water had become the limiting factor. Water treatments had significant effects on the biomass allocation patterns of P. anserine, and the plant tended to produce more ramets with the increase of water.(2) With the increase of age classes, all the values of the phenotypic and growth characteristics parameters of the plant were significantly increased. P. anserine with larger age enhanced the clonal growth ability, reproduced more ramets, and consequently improved its adaptive capacity and reduced the risk in resource competition and utilization.(3) In low nitrogen level, P. anserine improved nitrogen conservation which indicated a longer nitrogen mean residence time; while in high nitrogen level, plant preferred tomaximize the increase of nitrogen productivity and speeded the turnover of the inner nitrogen. The nitrogen use efficiency of the plant was significantly improved with the increase of water. In summary, the interaction of water and nitrogen had a significant impact on the nitrogen utilization strategy of P. anserine.