Abstract: Studies on the degree of crop climate suitability are beneficial to coping with the impacts of climate change on crop production, rationally developing and utilizing agricultural climate resources, and ensuring security of food production. In this study, we established crop climate suitability degree model. Based on multisite meteorological and phenological observation data of the North China Plain, we calculated the climate suitability degrees of typical crops (winter wheat and summer maize) during 1981 to 2017, and analyzed their spatialtemporal variation. The sunshine, temperature, precipitation and synthetic climate suitability degrees of winter wheat in the North China Plain during the growing season were 0.69, 0.63, 0.50 and 0.58, respectively. The lack of precipitation during growing season was the limiting factor of winter wheat growth in the North China Plain, while the sunshine, temperature, precipitation and synthetic climate suitability degrees of summer maize during growing season were all higher than 0.60. The change trends of temperature, precipitation and synthetic climate suitability degrees of winter wheat in the whole growing season were not obvious, but the sunshine suitability degree decreased with a rate of 0.020 （10 a^-1). During the whole growing season of summer maize, only the sunshine suitability degree decreased significantly, and the temperature, precipitation and synthetic climate suitability degrees did not change. Spatially, the sunshine suitability degree of winter wheat during the whole growing season increased from southwest to northeast, and the temperature suitability was generally low in the north and high in the south, while the precipitation and synthetic climate suitability degrees gradually increased from north to south. During the whole growing season of summer maize, the sunshine suitability degree increased from southwest to northeast, while the temperature suitability degree decreased from east to west, the precipitation suitability increased from northwest to southeast, and the synthetic climate suitability showed a “stepped” spatial distribution increasing from west to east.

Key words: litter removal, microbial biomass, subtropical sandy coastal area., enzyme activity, root trenching, microbial community composition