Assessing climatic suitability of Pinus radiata (D. Don) for summer rainfall environment of southwest China

Originating from a very restricted natural distribution Pinus radiata has become one of the most widely planted exotic pine species in the world, particularly in winter and uniform rainfall environments of the Southern Hemisphere. This paper describes a new climatic profile for the species that identifies summer rainfall areas in southwest China where the species may be suitable for environmental planting on degraded lands to reduce soil erosion. The new climatic profile delineates the climatic requirements of P. radiata through six climatic factors. It includes the absolute minimum temperature as a measure of frost risk in the continental climatic environment and also has lower temperature and rainfall limits than profiles previously developed for commercial plantations. Digital elevation models are developed at both regional and national scales to provide a surrogate of the three-dimensional geographic space of the target area for the spatial interpolation of climatic data. Areas with climatic conditions that match the new climatic profile are mapped using ArcInfo GIS. A chi-square statistic is used to evaluate the influence of each climate variable in the profile in determining the spatial limit of the mapped area. At the national scale, a climatically suitable area of more than 266,000 km2 across three provinces in southwest China is identified. Mean maximum temperature of the hottest month and the length of dry season appear to be the major factors limiting the spatial extent of matched areas at this broad scale. The results of climate matching for the Minjiang dry valley area in particular correspond well with the growth performance of experimental plantings in the field. At this regional scale, mean annual precipitation and mean minimum temperature of the coldest month are the major factors constraining the spatial extent of climatically suitable areas. The mapped areas can help define the working limits and serve as indicative zones for environmental plantings of P. radiata aimed at reducing soil erosion in southwest China. They will also enhance our understanding of the fundamental climatic niche and the potential geographical range of P. radiata.