影响植物竞争的因子

华南农业大学林学院,广东广州 510642

综述;植物;竞争;资源;密度;环境

A review on factors affecting plant competition
XUE Li,FU Jing-dan

College of Forestry, South China Agricultural University, Guangzhou 510642, Guangdong, China

review; plant;competition;resource;density;environment

备注

竞争就是两个或两个以上的个体为争夺资源而发生的相互关系 ,它是植物种群和群落的关键过程。为了了解生态系统对环境变化的反应,综合了解植物竞争是必要的。与竞争有关的内部因素有植物密度、生物因子和生物量,影响竞争的环境因子包括光照、土壤水分、土壤养分、海拔。高密度通过抑制植物生长而对竞争产生影响。化感物质对周围植物产生影响。在树木和杂草草本根系重叠的土层,二者为获取资源而竞争。食草性动物选择取食一些植物种类而影响其竞争能力。植物能在形态上发生变化和通过改变地上和地下部分间的竞争能力来应对环境变化。当混交林中缺乏耐荫植物时,喜光植物长期成为优势种,而混交林中存在耐荫植物时,耐荫植物可以逐渐取代喜光植物而成为优势树种。在干旱条件下,矮小的植物需求的水分少,根系发达的植物种类能够减少单位长度根系表面的蒸发,所以能够生存更长的时间。在缺乏养分的土壤,植物竞争养分的能力受到其有效吸收养分能力的控制 ,在养分丰富的土壤上,具有最大生长率的植物是竞争的优胜者。植物间的光照竞争随海拔增加而下降。大尺度、长时期和多种群竞争的研究,多学科的综合研究,竞争机理与经验模型结合,植物竞争模型复杂化和根系竞争的研究,植物的形态可朔性和生理可朔性对竞争的影响是未来的研究热点。

The competition refers to the interactions of two or more individuals which compete for resources,and is a key process of plant populations and communities. A comprehensive and mechanistic understanding of plant competition is necessary to predict the responses of ecological systems to environmental changes. The inside factors affecting competition include plant density, biological factors and the biomass. The environmental factors related to competition include light, soil moisture, soil nutrient and altitude. High-density affects plant competition by controlling plant growth. Allelochemicals produced by plants directly affect their neighbors. Trees and grasses may compete for resources where their root systems overlap. Herbivorous animals chose to eat some plants,resulting in reduction of competition ability of the plants. Plants make morphological shifts and alter the competitive ability between above-ground and below-ground parts in response to the environmental changes. When shade-tolerant species are absent in mixed forest, less shade-tolerant species could maintain their dominance for a long period. In contrast, mixed forest with tolerant species would reduce the dominance of less-tolerant species, maintain and probably increase the dominance through the decline of less-tolerant species. Smaller plants should have longer survival time due to their smaller total water requirements when water is scarce, and the longer survival of plants with higher root allocation could be due to a relative reduction in transpiring surface per unit root length. In nutrient-deficient soils, plants are stressed directly by the lack of adequate nutrients and competitive interactions may be controlled by a plant’s ability to efficiently take up available nutrients. In nutrient-sufficient soils, plants with the highest maximum growth rates may well be the superior competitors. Intensity of light competition declines with altitude. The future research about competition will focus on large scale, long term and multi-population research, the multi-disciplinary cooperation, combining competition mechanisms with empirical models, complicated competition model and the root system competition, effects of morphological and physiological plasticity of plants on plant competition.