| Food is related to the national economy and people’s livelihood,and food security is an important foundation of national security.The Loess Plateau has a special geographical location,rich light and heat resources and a wide planting area of corn.It is very important to study the production potential of light and temperature and the suitability of planting area of corn in this area,so as to provide theoretical basis and scientific basis for agricultural production and food security in the Loess Plateau.Taking the Loess Plateau as the research area,using the stepwise correction method and generalized regression neural network(GRNN),combined with Arc GIS,this paper analyzes the temporal and spatial distribution characteristics and change trend of main climate factors in the Loess Plateau from 1961 to2017,calculates the light and temperature production potential in this area,analyzes the temporal and spatial distribution and change trend of light and temperature production potential,and determines the potential and suitability evaluation of corn planting suitable areas in the Loess Plateau.The main conclusions are as follows:(1)The annual average temperature of the Loess Plateau has an obvious warming trend,especially in winter and spring.The annual average temperature suddenly changed from relatively cold stage to relatively warm stage in 1996.The annual average temperature increases from north to South and from west to East in turn.The annual average temperature and altitude are consistent with the topographic distribution.The temperature rise in the north of the Loess Plateau is relatively large in Hetao area of Inner Mongolia,Northern Shaanxi,Wutai Mountain Area of Shanxi,northern Ningxia and Eastern Gansu,and the overall temperature rise in the south is small.The average annual sunshine hours fluctuate and show a decreasing trend as a whole,but the decreasing trend is not significant.The sunshine hours increase significantly in spring and decrease in other seasons.The average annual sunshine hours had a sudden change around 1983.The increasing part of sunshine hours is concentrated in the middle of the Loess Plateau,and the eastern part and Xining area of Qinghai show a decreasing trend.(2)The phenological periods of Maize in the Loess Plateau have changed significantly during the growing season,which is mainly reflected in the advance of the phenological period of maize.Specifically,the phenological period of Maize in the Loess Plateau is significantly advanced from sowing to jointing,and the date from tasseling to maturity is also advanced,but less than the former.Therefore,the total number of days in the whole growth period of Maize in the Loess Plateau has increased slightly,increasing by 0.8 days every 10 years.In terms of flowering in Zhongwei and Yulin,the flowering of maize was delayed in advance.In the growing season,the accumulated temperature increased significantly and the radiation decreased significantly.(3)The photosynthetic production potential of the Loess Plateau fluctuated between years and decreased significantly as a whole.The photosynthetic production potential presents the distribution of high in the northwest,low in the southeast and gradient decline.The high value area is concentrated in the northern part of Ningxia Hui Autonomous Region,and the low value is divided into Guanzhong plain area and southeast part of Hejin.The photosynthetic production potential in the West and east of the Loess Plateau shows a decreasing trend,and the increasing areas are Ordos City in Inner Mongolia,Ningnan region in Ningxia and Xi’an in Shaanxi.The distribution of light temperature production potential is similar to that of photosynthetic production potential,which is high in Northwest and low in Southeast.The climate production potential of Gannan,Ningnan,Ordos Yulin Yan’an area shows an upward trend,the climate tendency rate of Baoji Xi’an area,most of Shanxi Province and Xining Gansu Lanzhou area of Qinghai Province is negative,and the light and temperature production potential shows a downward trend.(4)The combination of GRNN and GIS is an effective method to analyze the suitability of planting area,with an accuracy of 80%.About 8.44% of the study area(16811km2)is very suitable for planting corn,mainly distributed in Guanzhong Plain and southern Shanxi with relatively flat terrain;69.69%(138846km2)is moderately suitable for planting corn,which is distributed around the highly suitable area,Zhongwei Yinchuan Shizuishan area,Hetao area of Inner Mongolia,most of Shaanxi and some basins of Shanxi;21.14%(42118km2)is not recommended to plant corn,0.73%(1447km2)of the land is permanently unsuitable for planting corn,and the unsuitable areas are distributed in Northwest Shanxi,part of Southern Ningxia and most of Qinghai.The suitable planting area determined by GRNN and GIS method is higher than the actual corn planting area,which is related to the policy of returning farmland to forest,the acceleration of urbanization,and the planting of miscellaneous grains and cash crops in the Loess Plateau... |
PDF Full Text Request