漓江水陆交错带植物叶性状对水淹胁迫的响应及经济谱分析

以漓江水陆交错带为研究区,分两个条带分别量测了适生植物的5个叶性状指标:最大净光合速率(A_(max))、比叶重(LMA)、单位质量叶片全氮含量(N_(mass))、单位质量叶片全磷含量(P_(mass))、单位质量叶片全钾含量(K_(mass))。研究重度淹没带与微度淹没带不同功能型植物叶性状间的差异,分析并讨论重度淹没带叶性状间的关系与全球尺度是否存在差异,探究重度淹没带植物对水淹生境的生理响应机制。结果如下:(1)重度淹没带植物叶片的A_(mass)、N_(mass)、P_(mass)显著高于微度淹没带。(2)乔木、灌木叶片的LMA均显著高于草本植物,而A_(mass)、PPUE均显著低于草本植物。(3)重度淹没带草本叶性状指标的N_(mass)、P_(mass)、PNUE均显著高于微度微度淹没带,而乔木、灌木的叶性状在两个条带的差异则不显著。(4)重度淹没带植物叶性状关系与全球尺度基本一致,其植物叶片具有低LMA,高A_(mass)、Nmas s、P_(mass)。分析可知,重度淹没带植物在出露期提高叶片光合效率及相关营养水平可能是其适应水淹胁迫特殊生境的关键策略之一;不同功能型植物对同一环境的适应能力存在一定的差异,草本对于水淹环境的响应更为积极,适应能力更好;重度淹没带也存在叶经济谱,其植物在经济谱中属于"快速投资-收益"型物种。

Responses of leaf traits to submergence stress and analysis of the economic spectrum of plant species in an aquatic-terrestrial ecotone, the Li River

Five leaf traits were analyzed in different plant species in an aquatic-terrestrial ecotone, Li River, to investigate differences in these traits between different types of functional plants in severe and mild inundation zones, and to explore the physiological responses of plants suffering from long-term submergence stress. By analyzing the relationships between leaf traits in plants subjected to severe inundation, differences between the results of this study and those on the global scale are also discussed. The five leaf traits analyzed were:leaf mass per area (LMA), leaf maximum net photosynthesis rate (A_max), leaf nitrogen content per mass (N_mass), leaf phosphorus content per mass (P_mass), and leaf potassium content per mass (K_mass). The results were as follows:(1) The values of A_mass, N_mass, and P_mass under severe submergence were significantly higher than those under mild submergence. (2) The LMA value for grasses was relatively lower than that for trees and shrubs, whereas A_max and PNUE (photosynthetic nitrogen use efficiency) were higher for grasses. (3) The N_mass, P_mass, and PNUE values for grasses in the severe inundation zone were significantly higher than those in the mild inundation zone, while there were no significant differences in leaf traits for trees and shrubs between the two zones. (4) The relationships between leaf traits in the severe inundation zone were similar to those on the global scale, and the species in the severe inundation zone had lower LMA, higher A_mass, N_mass, and P_mass. These results suggest that improving photosynthetic capacity and increasing the levels of relevant leaf nutrients may be involved in the adaptation of plants to aquatic-terrestrial ecotone conditions. Compared with trees and shrubs, grasses showed stronger adaptability to submergence, which illustrates the differences in adaptability between different types of functional plants. The results of this study indicate that a spectrum of leaf economics also exists in plant species in the severe inundation zone, and that these represent species with a fast investment-return on the leaf economic spectrum.