Abstract:

To precisely characterize the spatial distribution of climate suitability for pasture cultivation in the Chongqing section of the Three Gorges reservoir area (TGRA), a comprehensive assessment was conducted. Daily meteorological data from 1058 observation stations from 2011 to 2020, a 30−meter digital elevation model (DEM), and climatic suitability indicators for five commonly cultivated pasture species were integrated. Eight factors, including mean annual temperature, accumulated temperature above 0℃, extreme temperature, mean annual precipitation, sunshine duration, frost−free period, mean relative humidity and elevation, were selected as zoning indicators. These indicators were spatialized using interpolation methods, and a new Pasture climate suitability index (PCSI) was constructed based on fuzzy mathematics and a weighted comprehensive evaluation method. Natural breaks (Jenks optimization) were used to classify climate suitability into three levels: suitable, sub−suitable and unsuitable, while areas categorized as other refer to water bodies and built−up land excluded from the suitability evaluation. The results showed that the PCSI values across the TGRA ranged from 0.47 to 0.76, with suitable areas (0.72−0.76) and sub−suitable areas (0.66−0.72) accounting for 65.0% and 32.2% of the total area, respectively, indicating favorable climatic conditions for pasture growth in most of the region. All five pasture species exhibited a relatively high level of climatic adaptability. In terms of overall suitability, the ranking from highest to lowest was: alfalfa > hybrid giant napier > sweet sorghum > annual ryegrass > napier grass. Although the spatial suitability patterns of the five species were generally consistent, there were regional differences in the proportions of suitability classes. Suitable and sub−suitable zones were widely distributed, while unsuitable areas were mainly located in the northern, eastern, southwestern and some southern high−altitude regions of the TGRA. The largest Suitable area proportion was observed for alfalfa (57.9%), while the highest proportion of unsuitable areas occurred for annual ryegrass (18.0%) and the lowest for alfalfa (6.7%). 

Key words: Three Gorges reservoir area (Chongqing section), Climate suitability for pasture grasses, Agro?climatic zoning, GIS