农林复合系统植物竞争研究进展

Research advances in plant competition in agroforestry systems

植物竞争是农林复合系统成功和可持续性的主要决定因素。使资源竞争最小化,资源利用最大化,是农林复合系统提高产量和总生产力的核心。本文对农林复合系统中林木-作物间对光、水分和养分的竞争作用、化感作用及与竞争相关的植物特性进行了综述。一般认为,在湿润地区,农林复合系统地上部分对光的竞争可能是系统生产力的主要决定因素;而在温带地区和半干旱热带地区,地下部分对水分的竞争可能限制着系统的生产力。在农林复合系统中,植物对光的竞争能力由叶面积、冠层结构等决定,对土壤水分和养分的竞争能力则取决于植物根系所占据的土壤空间、根系的形态和生理塑性、植物根系在土壤中的时空分布格局等。今后应加强不同区域农林复合系统中不同组分间的竞争作用的比较、竞争过程及生理机理、化感作用、菌根影响植物竞争的作用和机理、地上部分竞争和地下部分竞争的相互作用、全球变化与植物竞争等方面的研究。

Plant competition plays an important role in the success and sustainability of agroforestry systems. Minimizing competition and maximizing resource utilization increase crop yield and overall productivity of agroforestry systems. This paper introduces the concept and theory of plant competition, reviews competition for light, water and nutrient among trees and crops, and summarizes allelopathy and competition related plant traits in agroforestry systems. Aboveground competition for light among trees and crops is a major constraint under humid climate conditions, while belowground competition for water predominates in semi-arid tropics and temperate agroforestry systems. In agroforestry systems, plant competitive ability for light is decided by leaf area, canopy structure, et al. Root traits related to belowground competitive ability include occupied soil space, morphological and physical elasticity and spatial and temporal soil partitions. It is suggested that future research on agroforestry systems focus on comparisons among different components in different climatic conditions, competition processes and physiological mechanisms, plant allelopathy and the role and mechanism of mycorrhizae in plant competition, interactions between above- and below-ground competition and the effect of global climate change on plant competition of the agroforestry systems.