Variation in Cropping Intensity in Northern China from 1982 to 2012 Based on GIMMS-NDVI Data

Mingjun Ding,Qian Chen,Liangjie Xin,Geli Zhang,Xiangming Xiao,Lanhui Li

doi:10.3390/su8111123

Abstract

Cropping intensity is an important indicator of the intensity of cropland use and plays a very important role in food security. In this study, we reconstructed a normalized difference vegetation index (NDVI) time-series from 1982 to 2012 using the Savitzky-Golay (S-G) technique and used it to derive a multiple cropping index (MCI) combined with land use data. Spatial–temporal patterns of variation in the MCI of northern China were as follows: (1) The MCI in northern China increased gradually from north-west to south-east; from 1982 to 2012, the mean cropping index across grid-cells over the study area increased by 4.36% per 10 years (p < 0.001) with fluctuations throughout the study period; (2) The mean MCI across grid-cells over the whole of northern China increased from 107% to 115% with all provinces showing an increasing trend throughout the 1980s and 1990s. Aside from Tianjin, Hebei, Beijing, and Shandong, all provinces also displayed an increasing trend between the 1990s and 2000s. Arable slope played an important role in the variation of the MCI; regions with slope ≤3° and the regions with slope >3° were characterized by inverse temporal MCI trends; (3) Drivers of change in the MCI were diverse and varied across different spatial and temporal scales; the MCI was affected by the changing agricultural population, deployment of food policies, and methods introduced for maximizing farmer benefits. For the protection of national food security, measures are needed to improve the MCI. However, more attention should also be given to the negative impacts that these measures may have on agricultural sustainability, such as soil pollution by chemical fertilizers and pesticides.

Highlights

Due to rapid population growth and urbanization in recent years, global food security has increasingly become a major concern [1]
Most studies have focused on changes in cropland area [3,8,9] and have, to some degree, ignored changes in cropping intensity despite multiple cropping intensity playing an important role in food security of populous countries such as China and India [10,11,12,13]
multiple cropping index (MCI) values averaged over the entire study period increased gradually from north-west to south-east across the study area of northern China

Summary

Introduction

Due to rapid population growth and urbanization in recent years, global food security has increasingly become a major concern [1]. Over the past several decades, rapid urban sprawl and industrialization in China has converted a growing amount of cropland into housing or construction land [3,4,5,6]. These transformations have increased the pressure on maintaining cropland area and meeting the demands of food security in China [7]. Most studies have focused on changes in cropland area [3,8,9] and have, to some degree, ignored changes in cropping intensity despite multiple cropping intensity playing an important role in food security of populous countries such as China and India [10,11,12,13]. Given the significance of cropping intensity, studies on the country-wide spatiotemporal dynamics of cropping intensity are necessary for a better understanding of food security and agriculture-related decision-making in China

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Methods

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Conclusion