湿地植物对泥沙淤积的适应

Adaptation of wetland plants to sedimentation stress:A review

泥沙淤积是湿地常见自然现象,常造成土壤容重、水含量和金属元素含量增加,而使土壤有机质、通气性及温度降低等,深刻影响着湿地植物生存、生长及植被演化。在长期适应进化过程中,适应者演化出一套有效的适应策略,克服了泥沙淤积的负面影响甚至依赖泥沙淤积完成生命周期,而不适应者则被驱离出湿地环境。主要适应策略包括:1)生活史对策,如产生大质量种子、休眠或无性繁殖增强等;2)形态学对策,如叶、茎或间隔子伸长、分枝角度缩小、分蘖增加、根冠比减少或产生气生根等;3)生理对策,如光合速率、CO2交换速率或植物激素含量升高等。在今后的研究中,泥沙淤积对种子休眠和植物生长促进的机理及植物生理变化特点等还有待进一步研究,同时应加强解剖学上的研究。

Sedimentation is a common phenomenon in wetlands. It generally increases soil bulk density, moisture content, and metal elements content, while decreases soil organic matter content, aeration condition, and temperature, giving effects on plant survival, growth, and vegetation succession. During the process of long-term adaptive evolution, wetland plants have evolved a series of efficient strategies to acclimate to sedimentation. Some plants have become so specialized that they actually require regular sand burial to maintain high vigor, while the others that don＇ t have effective strategies are disappeared. The main strategies include ： 1 ） life history strategy, e. g. , producing high-quality seed, seed dormancy, or enhanced elonal reproduction, 2） morphological responses, e.g., elongation of stem, leaf, or spacer, decreasing branching angle and root shoot ration, increasing tillers, and producing aerial roots, etc. , and 3 ） physiological responses, e. g. , enhanced photosynthetic rate, carbon dioxide exchange rate, and plant hormone level. Future research should focus on the mechanisms accounting for seed dormancy, plant performance, and physiological responses of plants to sedimentation. Meantime, anatomical study should be strengthened.