Abstract:

Rice is the staple food in China and its production is impacted jointly by natural environment and human activities. In this process, terrain condition not only determines the spatial pattern of environmental factors, such as water, heat and radiation, but also affects the agricultural management measures. Although many studies focused on the impact of one or several specific factors on crop production, few studies investigated the direct influence of terrain condition on rice production. Therefore, we selected Hunan Province, one of major rice producing areas in China with complex terrain conditions, as the study area. Based on the remote sensing data and statistical data, we applied the spatial statistical analysis to explore the effects of terrain factors on the rice production from the following three aspects: spatial pattern of paddy field, rice production process and the final yield. We found that: (1) Terrain has a significant impact on the spatial distribution of paddy filed at both regional and county scales. Most paddy fields are located on the northern plain and central hills where the elevation is generally below 300 meters with the slope less than 9° and relief degree less than 140 meters. Also, the spatial pattern of paddy fields in Hunan is sensitive to surface roughness and slope position. (2) Terrain does determine the distribution of temperature, sunlight and soil, and these three environmental factors consequently have direct impact on rice growth. Additionally, several terrain factors (elevation, slope and surface roughness) are related with the phenological stage of double-cropping rice, especially for elevation, which is closely associated with the planting stage for early rice and harvesting stage for late rice. (3) However, compared with the pattern of paddy field and rice production process, the influences of terrain factors on the rice yield are not so evident except for elevation. (4) There is a spatial mismatch between spatial distribution of paddy field and production resources due to terrain factors: although paddy fields are widespread in the northern plain, the yield in this region is lower than that in the hilly area of central Hunan due to limited heat. Our results highly imply that the managers should guide farmers to choose suitable variety and planting system and allocate rice production resources in the northern plain so as to ensure food security.

Key words: rice production, terrain factors, spatial autocorrelation, spatial pattern, rice phenology