我国单季稻种植区的气候适宜性

从国家层次和年尺度阐明影响我国单季稻种植区分布的主导气候因子, 揭示我国单季稻种植区的潜在分布及其气候适宜性,可为我国优化单季稻生产布局、改进种植制度和引种提供科学依据.本文从国家层次和年尺度选取影响我国单季稻分布的潜在气候因子, 利用其地理分布信息,结合最大熵模型和ArcGIS的空间分析功能, 阐明影响我国单季稻分布的主导气候因子并构建我国单季稻分布与气候的关系模型. 结果表明: 影响我国单季稻潜在种植区分布的主导气候因子是年降水量、湿润指数和稳定通过18 ℃日数, 它们对单季稻分布的累积贡献率达到了潜在气候因子的94.5%; 基于主导气候因子和单季稻种植点分布的地理信息, 结合最大熵模型构建的我国单季稻种植区分布与气候的关系模型能够很好地模拟我国单季稻种植区的潜在分布. 根据待预测区单季稻的存在概率, 明确了我国单季稻种植区潜在分布的气候低、中、高适宜区和气候不适宜区, 并分析了各气候适宜区的气候特征.

Greenway network design of Great West River Pilot Area in Changsha City, Hunan Province of South-central China based on suitability analysis and GIS

Greenway construction plays very important roles in improving urban form and protecting its ecological environment, being one of the hot points in ecological research. However, for most places in China, the present greenway’s planning methods cannot be popularized due to the defect of excessive subjectivity and the shortage of scientificity and rationality. In this paper, suitability analysis was adopted to study the urban greenway network design, taking the Great West River Pilot Area in Changsha City as the object and under the support of GIS. The suitability analysis includes five steps, i.e., 1) selection of evaluation factors and determination of evaluation criteria, 2) calculation of the factors weights, 3) assessment of site suitability, 4) assessment of accessibility, and 5) delineation of greenway networks. The Pilot Area is located in the west side of Changsha City, as a "Two-Oriented Society" (resource-conserving and environment-friendly society) demonstration area of the Changsha-Zhuzhou-Xiangtan Urban Agglomeration. The results showed that the greenway network design with the combination of GIS and suitability analysis could be used as a design method for greenway network construction in the future, due to its less demand on related data, simplified operation, scientific evaluation process, and well-defined results. Three greenway networks with integrated functions and their own characteristics in the Pilot Area were designed, which could improve the urban form of the Area and its environmental quality, and provide a reference for the greenway project design in similar regions of China in the future.