Ecological suitability evaluation for torreya crop in Hangzhou city based on a GIS-based fuzzy model

Chinese torreya (T. grandis `Merrillii´), an evergreen coniferous tree mostly distributed in the mountainous areas of southern China, has a distinct economic potential. However, the planting distribution of torreya crop is not optimal and the torreya production and cultivation are restricted by regional environment conditions. In this study, a GIS-based fuzzy model combined with the principal of hierarchy analysis was applied to assess ecological suitability for torreya. The evaluation factor system of ecological suitability of Hangzhou torreya planting regions was established by choosing seven evaluation factors from climate, topography, and soil factors with Delphi method based on the ecological characteristics of torreya crop. Furthermore, the membership functions were set up according to the effect of each ecology factor on the growth and quality of torreya suitability. And the analytical hierarchy process (AHP) was used to determine the weight of factors. The results demonstrated that the highly, moderately, and non-suitable regions for the cultivation of torreya crop in Hangzhou were 5380.98, 6206.53, and 3735.50 km², and accounted for 35.12, 40.50 and 24.38% of the total evaluation area, respectively. The fuzzy membership function combined with AHP could be useful in quickly and accurately evaluating the ecological suitability of torreya crop. The results of this study can be used for further research on the possibilities for a large-scale commercialization of the crop with favourable ecological conditions and provide a scientific basis for land policy makers and land use planners.