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Understanding crop patterns and their changes on regional scale is a critical requirement for projecting agro-ecosystem dynamics. However, tools and methods for mapping the distribution of crop area and yield are still lacking. Based on the cross-entropy theory, a spatial production allocation model(SPAM) has been developed for presenting spatio-temporal dynamics of maize cropping system in Northeast China during 1980–2010. The simulated results indicated that(1) maize sown area expanded northwards to 48°N before 2000, after that the increased sown area mainly occurred in the central and southern parts of Northeast China. Meanwhile, maize also expanded eastwards to 127°E and lower elevation(less than 100 m) as well as higher elevation(mainly distributed between 200 m and 350 m);(2) maize yield has been greatly promoted for most planted area of Northeast China, especially in the planted zone between 42°N and 48°N, while the yield increase was relatively homogeneous without obvious longitudinal variations for whole region;(3) maize planting density increased gradually to a moderately high level over the investigated period, which reflected the trend of aggregation of maize cultivation driven by market demand.
Understanding crop patterns and their changes on regional scale is a critical requirement for projecting agro-ecosystem dynamics. However, tools and methods for mapping the distribution of crop area and yield are still lacking. model (SPAM) has been developed for presenting spatio-temporal dynamics of maize cropping system in Northeast China during 1980-2010. The simulated results indicated that (1) maize sown area expanded northwards to 48 ° N before 2000, after that the increased sown area mainly occurred in the central and southern parts of Northeast China. Meanwhile, maize also expanded eastwards to 127 ° E and lower elevation (less than 100 m) as well as higher elevation (mainly distributed between 200 m and 350 m); (2 ) maize yield has been greatly promoted for most planted area of Northeast China, especially in the planted zone between 42 ° N and 48 ° N, while the yield increase was relatively homogeneous without obvious longitudinal variations for whole region; (3) maize planting density increased gradually to a moderately high level over the investigation period, which reflected the trend of aggregation of maize cultivation driven by market demand.