No abstract

Drought is one of the major agricultural and meteorological disasters in China that occurs at high frequency, affects wide areas, and causes considerable agricultural loss. Research on the long-term spatiotemporal variability of arid climate and drought area in the context of global climate change is important and practically significant to the intention to cope with drought. Standardized precipitation index (SPI) was calculated using long-term monthly data of surface precipitation with 0.5º × 0.5º resolution at 12-month timescales. The capacity of the SPI index to describe arid climate was verified using three drought cases that occurred in Southern China in the early 2000s. The spatiotemporal variability of China's arid climate and drought area from the perspective of meteorological drought was analyzed. All categories of drought (i.e., mild, moderate, severe, and extreme) exhibited slight downward trend in terms of drought area, but variation was observed from region to region. Over the past 50 years, Southwest and Northeast China experienced more arid, while Southeast and Northwest China experienced the opposite.

This research is innovative in such aspects as research content, method and so on. Authors took Northeast China as study area, with the help from "3S" technology and based on spatial and temporal land resource data, agricultural statistics data and considering the natural and socio-economic factors. And, this paper analyzed the impact of cultivated land change on the grain production capacity within this region in terms of cultivated land quantity, cultivated land quality, crop structure etc. The natural resources, cultural structure and social-economic conditions among different regions may have great difference, the natural and social-economic factors will have different influence on the grain-production in different regions, and this proves that it is important to manage cultivated land resources based on regionalization. In the last few years, the peasants have increased the input amount on the cultivated land, such as the fertilizer and the plastic film, this caused the different influence on the cultivated land quality in the Northeast China. Under the above-mentioned background, this paper analyzed the cultivated land quality information in the Northeast region. The method was to explore the natural quality grading and utilizing quality grading on cultivated land respectively through the natural quality grading indicators and utilizing quality grading indicators system. Then we divided the whole region into high-yield cultivated land, medium-yield cultivated land and low-yield cultivated land based on grain yield per unit, correlation was analyzed between natural quality grading of land and grain yield per unit area, also between utilizing quality grading of land and grain yield per unit area through GIS method. In a word, this paper can provide help to sustainable utilization and management of cultivated land resource in this area, and give the useful method for the similar research.