Influence of spatiotemporal change of temperature and rainfall on major grain yields in southern Jiangsu Province, China

Abstract

Spatiotemporal differences in temperature and rainfall play an important role in grain production and have wider implications for food security, an issue in China that has received worldwide attention. Jiangsu Province on China's east coast is a major contributor to grain production and therefore the region's climate has particular relevance to research on the nation's food security. This study explores the link between spatiotemporal climate patterns and grain production, which include rice output, summer grain output, and average grain output of those two seasons, using temperature and rainfall data from a study area in southern Jiangsu Province. Meteorological data covering about 40 years (1976–2013) were collected from 13 meteorological stations around the study region. Grain output was acquired from the same year's statistical report from the local government. Based on the thin plate spline method, meteorological data and grain output were interpolated to the same geographic grid. Several statistical methods-regression analysis, moving average, Mann-Kendall, moving t-test, and wavelet analysis—were used to estimate the changing trends of metrological factors and grain output. The result showed that annual mean temperature, mean maximum temperature, and mean minimum temperature fluctuated and increased, and those changes were more abrupt in the late 1980s and early 1990s, with obvious periodic variation in three time scales: 25–32 years, 15–25 years, and 10–15 years. For abnormal annual rainfall, rainfall showed significant inter-annual difference in the region from 1976 to 2013. The results indicated that abrupt changes occurred from 1979 to 1980 and again from 2006 to 2007. Annual and seasonal rainfall also showed obvious periodic variation at the three time scales. The growth variation of average grain output increased with some fluctuation and was different in different periods. It gradually decreased from southeast to northwest, and had a very different spatial pattern. The annual mean temperature played an important role in agricultural production, but the annual rainfall had little effect on agriculture for annual and seasonal fluctuation from 1976 to 2013. Temperature indexes in spring, summer, and autumn had a significant effect on average rice output. For autumn grain output, temperature indexes also played an important role in summer and autumn. Moreover, correlation coefficients and p-values for temperature indexes and grain output were weak in summer, but also passed a significance test at the 95% confidence interval. The study helps understand the effect of climate change on grain production, and also provides a scientific foundation and theoretical support for formulating policy and measures on climatic adaptability for agricultural production in eastern China. Keywords: Spatial interpolation, Climate change, Trend analysis, Wavelet analysis, Abrupt analysis