| Arable land is one of the most important resources for human survival and development. Regional land use change is one of the hot topics in the study of global change, the change of cultivated land as the core content of land use change, has also became an important part of the global change research. Especially in the 21st century, with global economic and population grow rapidly, in front of tremendous development pressure. The quality and use pattern of cultivated land is undergoing unprecedented change. Africa is one of the important research areas of food security in the world. The current study of cultivated Land Change is focused on economically developed areas and ecologically fragile areas in Africa and there is no study of cultivated land changes in the continent-wide scale currently. Research has been carried out mainly used remote sensing method and survey data to analysis the cultivated land use changes and spatial characteristics, the study of the relationship between cultivated land use change and the environmental back ground is not enough. What’s more, existing researches mostly used middle or low resolution remote sensing image with a spatial resolution of 250 m and 1000 m.Taking Africa as the study area, using a spatial resolution of 30 meters of remote sensing image as information sources, adopting the methods of remote sensing image interpretation and GIS spatial analysis, using the land use change rate, single land use dynamic two-way model and relative change rate of land use, we analyzed the characteristics of cultivated land use change quantitatively and revealed the temporal and spatial evolution law of African arable land and the relationship between the cultivated land use change with environmental factors. This paper provide decision-making basis for adjustment of land use structure and agriculture layout and sustainable utilization of cultivated land and ecological environment protection in research area, and also provides a typical regional basis for global food security research.The main work are:Data collection, establish the Environment Database which including temperature, precipitation, elevation, slope, aspect and ecological zoning; Download the remote sensing images which covering Africa, interpreting remote sensing images, establish the databases of Africa’s 2000 and 2010 arable land use; Analysis of changes in the amount of cultivated land and spatial based on the use of different latitude and longitude, regional, national. Reveals the change of the cultivated land in different research perspective; Analysis of arable land transfer and flow based on different perspective; The study of relationship between the Change of Cultivated Land and Ecological environmental factors, reveal the relationship between the cultivated land use change and environmental factors and so on.The main results:(1) The distribution of Cultivated land:There are 2.00×106 square kilometers and 2.23×106 square kilometers arable land in 2000 and 2010. Arable land appears near 34 °E and 12°N; Rank different regions in order of arable land size, the result is East Africa, West Africa, North Africa, South Africa, middle Africa; In the national perspective farmland mainly concentrated in few countries, Africa’s top fifteen countries in farmland accounted for about 75% of the total area.(2) Characteristics of cultivated land change:2000-2010 African arable land increased by 2.25×105 square kilometers. An increase in the cultivated area mainly between 4°E to 19°E and 31°E to 39°E; Focus on the latitude between 22°S to 1° S and 9°N to 14°N; In the region scale the increase of arable land are mainly in East and West Africa; At the national scale the increase of arable land are mainly in Nigeria, Tanzania, Sudan, Chad, Kenya, Mozambique, Angola and other countries.(3) Characteristics of cultivated land transfer:The reduction of arable land in Africa in 2000 turned into woodland and grassland mainly, in some areas turn into shrub and bare land. Farmland newly added in 2010 is mainly from woodland, grassland and shrub land.(4) Temperature and precipitation have significant affects on the distribution of farmland. Farmland are mainly concentrated in where temperatures is between 21-29℃ and rainfall is 300-1200mm. Grade has finality influence to Arable land, more than 90% of the arable land is distributed in where the slope is between 0 to 2°, but the aspect has little impact on the cultivated land distribution changes. Ecological zoning synthetically reflects the regional ecological environment, cultivated land is mainly distributed in well tropical and subtropical grasslands and scrub area which combined Moisture and heat well.In brief, this is the first time to use high resolution image data of 30 meters for the study of whole arable land use change in Africa, and analyzed the relationship between the distribution of arable land across Africa and ecological environmental factors, Provides the scientific basis for the study area of cultivated land readjustment, and this paper is an important part of global food security research. |
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