Study On The Relationship Between Maize Cultivation Distribution In China And Climate

To provide scientific support for planning maize production and making countermeasuresagainst the effects of climate change on maize cultivation, quantitative contribution of thepotential climatic factors on national and annual scale selected from the literature to thegeographic distribution of maize (spring maize, summer maize) cultivation in China wasevaluated, and the major climatic factors affecting maize(spring maize, summer maize)cultivation distribution were determined, in terms of the maize cultivation geographicaldistribution data from the agricultural meteorological observation stations, ChinaMeteorological Administration (CMA) and daily climate data with10km×10km spatialresolution from1961to2010, together with the correlation analysis method, the maximumentropy (MaxEnt) model, and the ArcGIS spatial analysis technique; the suitability formaize(spring maize, summer maize) cultivation in China was given by the existenceprobability obtained from the relationship between maize cultivation distribution and climate;the decadal dynamics of the major climatic factors during the past50years in different suitableareas of maize cultivation were analyzed; and the influence of climate change on the potentialdistribution of maize(spring maize, summer maize) cultivation in China was discussed. Themain conclusions are listed as follows.(1) The MaxEnt model is suitable for revealing the relationship between maize cultivationdistribution in China and climate. The results indicated that the importance, ranks and numbersof main climate controls differ for different maize varieties. The key climatic factors affectingcultivation distribution are duration days of≥10°C,≥10°C accumulated temperature, annualaverage temperature, the warmest month average temperature, annual precipitation, andhumidity index for maize (spring maize, summer maize, intercropping maize);≥10°Caccumulated temperature, duration days of≥10°C, the warmest month average temperature,annual average temperature, annual precipitation, humidity index and annual temperature rangefor spring maize; and annual average temperature, duration days of≥10°C,≥10°C accumulatedtemperature, the coldest month average temperature, the warmest month average temperature,annual precipitation, and humidity index for summer maize. (2) The suitability class of maize (spring maize, summer maize) potential cultivationdistribution was given by the existence probability (p) obtained the relationship betweenpotential maize (spring maize, summer maize) cultivation distribution and climate factors:p<0.05(unsuitable area),0.05≤p<0.33(less suitable area),0.33≤p<0.66(suitable area), andp≥0.66(optimum area), and the north boundary of spring maize cultivation distribution (around52.6°N) is very close to the actual cultivation boundary at present.(3) The dominant climatic factors affecting maize (spring maize, summer maize) during1961-2010showed significant temporal-spatial variation: the thermal resources improvedwith different extents on the national level, the most prominent change occurred in thenortheast China around1990's; water conditions fluctuated, and the arid and semi-arid regionsexpanded and humid regions became drier during1971-1980and2001-2010.(4) The potential cultivation distrubution of maize(spring maize, summer maize) showedan increasing tendency in China during1961-2010. The optimum and suitable area of springmaize cultivation showed an increase trend, its suitable area reached about3.4×10~6km~2in thelast10years, the northern boundary of spring maize cultivation distribution experienced fromshift southward, through shift northward to steadiness from1970's, the maximum northwardshift reached about1.4degrees in latitude, implying that climatic change is helpful forenlarging spring maize cultivation, but it might be limited by moisture conditions in some areas;the optimum area of summer maize cultivation distribution moved eastward, and the suitablearea southward. The summer maize cultivation area was more than6.7×10~6km~2in the last10years, its suitable area shifted northward around1990's, and the maximum shift reached about110km. Thus, the expansion of maize (spring maize, summer maize) cultivation in China ispossible under climatic change.