Spatiotemporal Pattern Of Winter Wheat In Beijing-Tianjin-Hebei Region

The role of spatial pattern has been appreciated in agricultural research.Research on the spatial pattern of crops is conducive to optimizing land use patterns and ensuring national food security.Winter wheat is one of the most important crops in my country,the planting area of winter wheat is about 20%of my country’s total grain planting area.The area of winter wheat in the Beijing-Tianjin-Hebei region ranks fourth in the country.the temporal and spatial distribution of winter wheat planting area in this region has changed significantly with natural and social development.Obtain the spatial and temporal distribution information of winter wheat in the region.Quickly obtain information on the temporal and spatial distribution of winter wheat in the region,and then,Research on the characteristics and driving forces of the temporal and spatial distribution of winter wheat in this region.Which is great significance to guide winter wheat planting and protect wheat yield.Remote sensing technology has the advantages of fast speed,wide coverage and visualization,and provides ideas for the study of regional winter wheat temporal and spatial distribution changes.Remote sensing technology has the advantages of fast speed,wide coverage and visualization.With the Landsat TM/OLI remote sensing images from 2010 to 2019,Extracted the spatial distribution information of winter wheat planting in Beijing-Tianjin-Hebei region on the basis of the best time and best method.Analyzed the spatiotemporal evolution characteristics of Winter wheat planting structure from the area characteristics and landscape pattern index.We further explored Combined with the data of precipitation and human factors,the driving factors of the temporal and spatial distribution of winter wheat were qualitatively analyzed.The main research contents and conclusions were as follows:1.Random Forest classification method as the optimal algorithm for extracting winter wheat spatial pattern information.Because of the high accuracy and fast calculation speed.From March 14 th to May23 th is the best time interval for winter wheat remote sensing recognition.Among them,the winter wheat remote sensing recognition accuracy is the best in the first ten days of May,which is the jointing period of winter wheat in Beijing-Tianjin-Hebei winter wheat region.2.It was feasible to use the medium and high resolution satellite image data of winter wheat to identify the best time phase as the data source,and it was feasible to use random forest classification method to realize the rapid identification and extraction of winter wheat at the provincial scale.Taking the remote sensing image of the best time interval for winter wheat identification as the data source,using the random forest classification method,the spatial distribution information of winter wheat in 2010,2014 and 2019 in Beijing-Tianjin-Hebei region had been obtained.The overall accuracy reached 91.69%,90.25%,and 93.22% respectively.3.The extraction results of winter wheat in Beijing-Tianjin-Hebei Region showed that,The planting area of winter wheat from 2010 to 2019 showed a downward trend.The specific characteristics of the change were: on the time scale,the winter wheat planting area has shrunk significantly before 2014,and the shrinking rate is relatively high;after 2014,the winter wheat planting area has further shrunk,but the shrinking rate has decreased significantly.On the spatial scale,the winter wheat planting area showed a significant characteristic: increasing in the south and decreasing in the north.Landscape pattern index was used to evaluate the temporal and spatial distribution of winter wheat,it was found that winter wheat planting in Beijing-Tianjin-Hebei had been developing towards a concentrated and contiguous trend.The shape regularity of the plots gradually increases.The influence of a single landscape type on the landscape in the region was reduced,and the ecological stability was enhanced.4.The changes in the spatial and temporal distribution of winter wheat in the Beijing-Tianjin-Hebei region were more affected by humanistic driving forces than natural driving forces.The specific performances were as follows: The winter wheat planting area in Beijing and Tianjin was less affected by precipitation and policies,but was greatly affected by urbanization.The winter wheat planting area in Hebei Province was less affected by urbanization,but was heavily affected by policies and precipitation.The spatial change of precipitation has less influence on the spatial change of winter wheat than the temporal change of precipitation on the change of winter wheat planting area.In the southwest and northeast of the Beijing-Tianjin-Hebei winter wheat planting area,the winter wheat planting area was significantly affected by the process of urbanization.Changes in the east,southeast and northwest of the winter wheat planting area was mainly affected by policies.