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Understanding of cropland dynamics in a large geographical extent is mostly based on observations of area change, while the changes in landscape pattern are hardly assessed. The total amount of cropland in China has remained relatively stable in recent years, which might suggest there was little change.
GLP member Dr. Qiangyi Yu and colleagues, combined the number of cropland patches (NP) with the total cropland area (TA) for a more comprehensive characterization of cropland change in China. They used GlobeLand30 – a global land cover dataset with a 30m resolution for the years 2000 and 2010 – and characterize changes in TA and NP for each county as increase, stable, or decrease. This characterization showed that 703 out of 2420 counties experienced both cropland loss and increased fragmentation. The predominant cropland loss in these areas, especially in the North China Plain, was converted to artificial land.
Figure Characterization of cropland change in China combining TA change rate and NP change rate.
Another 212 were characterized by the opposite developments: an increase in cropland and decreased fragmentation. These counties, were mainly characterized by a conversion of forest areas and grassland areas. It suggested that the cropland conservation policy in China effectively protected the total cropland area in overall, but the consequences in terms of fragmentation might be underestimated. Counties with no obvious change in both indicators, measuring 279 counties, were mainly located in the Southeast.
These results were further compared with local level case studies: the fair consistency indicated alternatives of applying GlobeLand30 for analyzing landscape changes across scales and for cross-site comparisons.
Yu, Q., Hu, Q., van Vliet, J., Verburg, P.H., Wu, W., 2018. GlobeLand30 shows little cropland area loss but greater fragmentation in China. International Journal of Applied Earth Observation and Geoinformation 66, 37-45.