[Optimization of spatial arrangements and patterns for shelterbelts or windbreaks]

Spatial arrangements and patterns of shelterbelts or windbreaks are the key factors influencing the shelterbelt structures, shelter benefits, and shelterbelt sustainability. In order to keep the shelter benefits and achieve the sustainability of shelterbelts, it is necessary to keep the reasonable arrangements and patterns in spatiality and the continuation in time. Based on the investigations on the shelterbelts, which were established in 1992 as the models in Shuangjingzi Township, Changtu County, Liaoning Province, and combined with the experiences and practices of shelterbelt management, the authors studied and summarized the arrangements and patterns of shelterbelts, which included the direction of a single shelterbelt and shelterbelt-networks, the arrangement of tree composition in a shelterbelt, and the mixture of tree species for shelterbelts. Additionally, the spacing intervals between shelterbelt and the spatial patterns for regional shelterbelts were also discussed. The results indicated that the direction of both single shelterbelt and shelterbelt-networks should be perpendicular to the disaster winds. It is better for the structure of a shelterbelt to arrange the trees in triangle form in a shelterbelt. According to the edge effect, the tree species which grow slowly should be arranged in the edge lines, but the tree species which grow fast should be arranged in the inner lines of the mixed shelterbelts. Optimal spacing intervals between windbreaks could be predicted from the indices of a given windbreak structure (porosity), percentage of desired wind speed reduction, and tree growth model (model for determining initial protective maturity age). The patterns of shelterbelts in large scale should be evaluated and arranged according to the principles of landscape ecology. The results mentioned above would provide the evidences for shelterbelt sustainable management.