Abstract:
Xinjiang is a main producing area of cotton in China. This study investigated the effects of global warming and plastic mulching on cotton-planting zoning of different matures in Xinjiang. The climatic data were from 173 meteorological stations during 1960-2015 in temperate zone around Xinjiang within a range of 200 km. The digital elevation mode data were from the United States Geological Survey, which had the resolution about 900 m. We analyzed the spatio-temporal variation of accumulated temperature not less than 10 ℃, frost-free period and mean temperature in July with the aid of ANUSPLIN interpolation software. The cotton-growing area was classified based on these 3 parameters. In addition, the change of planting boundaries and area of different cotton matures were studied with climate change and the compensation effect of plastic mulching. The main results included: 1) the accumulated temperature not less than 10 ℃, frost-free period and mean temperature in July showed an increasing trend in 1960-2015. Regional differences on thermal resources were obvious in Xinjiang. The accumulated temperature not less than 10 ℃, frost-free period and mean temperature in July were closely related to the terrain elevation. The thermal resources was richer in the southern Xinjiang than those the northern Xinjiang and richer in plain areas than in mountain areas. 2) under global warming, the ratio of planting areas of middle mature and early-middle mature cotton all increased. The area of middle mature cotton region increased by 3.82×104 km2, and the main increase areas were located in the eastern part of tarim basin. The increased area of early-middle mature cotton was widely distributed in the eastern Junggar Basin, the southern Turpan Basin, the southern Hami Basin and the western Tarim Basin. But the proportion of planting area of early maturing cotton did not change significantly and exceptional early-mature and unsuitable areas decreased. 3) the accumulated temperature not less than 10 oC and mean temperature in July were the main limiting factors in unsuitable planting areas, besides the areas near Tianshan, Altai and Kunlun Mountains were also restricted by frost-free period. The main thermal limiting factors in early-middle mature cotton areas (Taha), early mature cotton areas and most regions of exceptional early-mature were limited by the accumulated temperature not less than 10 ℃. 4) cotton plastic mulching had no significant influence on the planting boundaries of middle mature, early mature and unsuitable planting areas. But it had a significant influence on the planting boundaries of cotton areas in the area of the Junggar basin. With plastic mulching, the planting boundary of early-middle mature cotton extended 65 km to the east approximately, and that of early mature cotton areas extended 0-300 km to the east. With the plastic mulching, the planting area of early-middle mature cotton (Yeta) increased by 5.47×104 km2, some of which was from the former Taha cotton area. In addition, the planting areas of early mature and exceptional early-mature cotton decreased by 1.4% and 1.6% respectively. This study provide an effective method for cotton-planting zoning of different matures in Xinjiang.