农田防护林生态系统结构研究进展

农田防护林生态系统结构决定着生态功能，其时空结构是该领域研究的核心，旨在探讨形成结构的完整性、稳定性、持久性的组件间的相互关系，将其分为树体结构、林带结构、林网结构、景观结构4个层次，针对各层次中结构研究的原理、方法及成果进行了综述，通过树木个体的形态、质态结构研究，应用分形图形学的手段可实现动态结构的可视化，以研究林带树体结构的生成机理；精确界定林带结构的分维疏透度。探讨农田防护林带最佳结构理论，以构建防护林带最佳结构计算机生成模型；确立多物种、多层次的窄林带小网格的林网优化模式；评价农田防护林景观的合理性、稳定性、持续性，是今后的重要研究方向。

Advances in studies on the structure of farmland shelterbelt ecosystem

The ecological function of farmland shelterbelt system is determined by its structure. The spatio-temporal structure is a key aspect in related researches, which is very necessary to study the integrity, stability and durability of shelterbelt modules. In this article, the researches on the structure of farmland shelterbelt ecosystem were reviewed from the four scales of tree structure, shelterbelt structure, shelterbelts network and landscape structure. The principles, methods and productions of each scale were summarized, and the prospects were also discussed. Dynamic simulation of tree growth process in shelterbelts could be conducted by the theory of form and quality structure of tree and by fractal graphics, which were helpful to study the mechanism of individual trees and belts based on photosynthetic and transpiration mechanism of individual trees.The mechanism model of shelterbelt porosity should be conducted,so that,the sustainable yield model of shelterbelt management could be established, and the optimized model of shelterbelt networks with multi-special and multi-hierarchical structure could also be formed. Evaluating the reasonability, stability and durability of shelterbelt landscape based on the theories and methods of landscape ecology was an important task in the future studies.