Dongting Lake is the largest lake in the middle reaches of the Yangtze River in China. For centuries, people inhabiting the Dongting Lake area have been reclaiming land and constructing dams for flood resistance, agricultural production, and rural settlement, forming geographical entities known as polders. In this study, the regional spatial distributions of polders in the Dongting Lake area in 1949, 1998, and 2013 were obtained using historical maps and modern remotely sensed data, revealing changes since the establishment of the People’s Republic of China. Nanxian County was then selected to demonstrate polder changes at the county level, because it has undergone the most dramatic changes in the area. Different polder change models for the Datonghu, Yule, and Renhe polders were analyzed for eight periods: 1644 (the early Qing Dynasty), 1911 (the late Qing Dynasty), 1930 (the Republic of China), 1949 (the People’s Republic of China), 1963, 1970, 1998, and 2013. Three resulting polder evolution models are: 1) reclaiming polders from lakes, 2) integrating polders by stream merging, and 3) abandoning polders for flood release. The polder evolution models demonstrate the wisdom of local people in using land resources according to the specific regional conditions. Throughout their long-term historical evolution, the spatial distribution of polders in the Dongting Lake area tended to be homogeneous, and the degree of human disturbance tended to be stable. However, a shift occurred, from pure polder area growth or removal to more comprehensive management and protection of the regional environment.

Tick-borne encephalitis (TBE) is one of natural foci diseases transmitted by ticks. Its distribution and transmission are closely related to geographic and environmental factors. Identification of environmental determinates of TBE is of great importance to understanding the general distribution of existing and potential TBE natural foci. Hulunbuir, one of the most severe endemic areas of the disease, is selected as the study area. Statistical analysis, global and local spatial autocorrelation analysis, and regression methods were applied to detect the spatiotemporal characteristics, compare the impact degree of associated factors, and model the risk distribution using the heterogeneity. The statistical analysis of gridded geographic and environmental factors and TBE incidence show that the TBE patients mainly occurred during spring and summer and that there is a significant positive spatial autocorrelation between the distribution of TBE cases and environmental characteristics. The impact degree of these factors on TBE risks has the following descending order: temperature, relative humidity, vegetation coverage, precipitation and topography. A high-risk area with a triangle shape was determined in the central part of Hulunbuir; the low-risk area is located in the two belts next to the outside edge of the central triangle. The TBE risk distribution revealed that the impact of the geographic factors changed depending on the heterogeneity.

Cultivated land resources are an important basis of regional sustainability; thus, it is important to determine the distribution of the cultivated land in the Northeast Asia trans-boundary area of China, Russia and Mongolia, which has a continuous geographic and ecological environment and an uneven population distribution. Extracting information about the cultivated land and determining the spatial and temporal distribution of its features in this large trans-boundary area is a challenge. In this study, we derived information about the cultivated land of the North-South Transect in Northeast Asia by Linear Spectral Mixing Model, using time series data with MODerate resolution Imaging Spectroradiometer (MODIS) in 2000 and 2010. The validation showed more than 98% pixels with a root mean square error less than 0.05. The overall accuracy and spatial consistency coefficients were 81.63% and 0.78 in 2000 and 72.81% and 0.75 in 2010, respectively. The transect analyses indicate the presence of a greater amount of cultivated land in the south and less in the north. China owns most of the cultivated land in the transect area, followed by Mongolia and then Russia. A gradient analysis revealed a decrease of 34.16% of the cultivated land between 2000 and 2010. The amount of cultivated land decreased 22.37%, 58.93%, and 64.73% in China, Russia, and Mongolia, respectively. An analysis shows that the amount of cultivated land is primarily influenced by the various land development and protection policies in the different counties in this trans-boundary area.