Refining climate regionalization of cotton in the Northern Slope Economic Zone of Tianshan Mountain

Exploring the effect of climate change on the regionalization of cotton in the Northern Slope Economic Zone of Tianshan Mountain is important for development planning of Xinjiang cotton industry. Thus this study analyzed meteorological data for 19612010 from 11 meteorological stations in the Northern Slope Economic Zone of Tianshan Mountain using linear regression, t-test, Mann-Kendall method and IDW interpolation method. The study elaborately zoned climate regions of cotton with cumulative temperature ≥10 ℃, average temperature in July and frost free period as meterological indicators. Furthermore, the study determined the risk region, sub-suitable and suitable regions of cotton planting during a given era using GIS platform. The results showed that in recent 50 years, average temperature in July, frost free period and ≥10 ℃ cumulative temperature increased respectively by 0.05 ℃10a^-1, 2.9 d10a1 and 64.6 ℃10a^-1. Due to climate warming, the area of risk region of cotton planting dropped and was largely limited to the southeast zone. While the sub-suitable region of cotton planting shrank down to the east zone, the suitable region of cotton planting widened towards east, west and south. In the 1960s, the risk region of cotton planting covered Shawan County, Manasi County and Hutubi County. Then in the 2000s, the risk region of cotton planting decreased down to Urumqi vicinity with area of 3.6×10² km² in 20012010, 98.4% less than that in 1960s. Also sub-suitable region of cotton planting contracted down to around Urumqi in 20012010, decreasing by 88.0% compared with that in 1960s. Then area of sub-suitable region of cotton planting in the study area decreased to 8.6×10³ km². During 19611970, sub-suitable region of cotton planting was limited to Hutubi County. Then during 19912000, it decreased to the region around Urumqi County. However, the area of suitable region of cotton planting expanded by 18.4 times to 9.2×10⁴ km². The proportion of the suitable region of cotton planting was 91.2% of total cultivated cotton area. The suitable region of cotton planting potentially continued to expand with climate change. The study showed that the suitable cotton planting region will be the main cultivated cotton region in the Northern Slope Economic Zone of Tianshan Mountain in the 21^st century. This change was conducive for rational distribution of local cotton industry. It had realistic significance for the promotion of steady development of cotton industry in the Northern Slope Economic Zone of Tianshan Mountain.