(1) Background: Human settlements are a basic requirement for human survival and development. The natural suitability of human settlements directly affects human health and their quality of life and, to some extent, also dictates the size of the regional population and economy, as well as the level of urbanization. (2) Methods: This study presents a kilometer grid-based comprehensive human settlement suitability (HSS) evaluation model (containing the relief degree of the land surface (RDLS), the temperature–humidity index (THI), the land surface water abundance index (LSWAI), and the land cover index (LCI)). (3) Results: Based on the correlations between the four factors (i.e., the normalized RDLS (NRDLS), normalized THI (NTHI), LSWAI, and LCI), the NRDLS and NTHI were determined to be the leading factors, and the LSWAI and LCI were considered to be the auxiliary factors. The auxiliary factors were used to enhance the comprehensive HSS model determined by the leading factors. Based on this logic, spatial and index models were established separately. The HSS index for the BRI regions ranged from 0.07 to 1.00. Six levels of HSS were determined—namely, unsuitable, critically unsuitable, critically suitable, generally suitable, moderately suitable, and highly suitable conditions. In particular, the human settlements suitability is dominated by critically suitable and suitable conditions that accounted for 63% of the BRI. (4) Conclusions: The evaluation results of human settlements showed that topographic and climatic conditions are important limiting factors for the suitability of human settlements. Due to the renewability and manmade adjustability of hydrological and land cover conditions, the comprehensive suitability of human settlements shows differences in different geographic spaces along the BRI. The results provide a decision-making basis for the research on the resource carrying capacity and reasonable distribution of populations in the BRI, so as to realize the sustainable development along the regions.

(1) Background: Fire affects global agricultural and/or forest ecosystems with high biomass accumulation. However, the delineation of fire-hazardous areas based on satellite-derived active fire intensity is not well-studied. Therefore, examining the characteristics of fire occurrence and development plays an important role in zoning fire-hazardous areas and promoting fire management. (2) Methods: A fire intensity (FI) index was developed with Visible Infrared Imaging Radiometer Suite (VIIRS) active fires and then applied to identify fire-hazardous areas in Northeast China. Combined with terrain, land cover and net primary productivity (NPP), the spatial and temporal characteristics of active fire occurrence were consistently analyzed. Next, a conceptual decision tree model was constructed for delineating fire-induced patterns impacted by varied factors in Northeast China. (3) Results: The accidental, frequent, prone and high-incidence areas of active fires defined by the FI index accounted for 31.62%, 30.97%, 26.23% and 11.18%, respectively. More than 90% of active fires occurred in areas with altitude <350 m above sea level (asl), slope <3° and NPP between 2500–5000 kg·C/m². Similarly, about 75% occurred in cropland and forest. Then, four fire-induced conceptual patterns driven by different factors were classified, including the agricultural and forest active fire-induced patterns (i.e., the Agri-pattern and FRST pattern) with NPP ranging 2500–5000 kg·C/m², and two others related to settlements and unused land with an altitude <350 m asl. The Agri-pattern dominates in Northeast China because of agricultural straw burning. (4) Conclusions: Despite the national bans of open burning of straws, active fires due to agricultural production have occurred frequently in Northeast China in the last decade, followed by small and sporadic forest fires. The approach for defining fire-hazardous areas and varied fire occurrence patterns is of significance for fire management and risk prediction at continental to global scales.

Climate is an important factor that affects the livability of a region. The climate suitability of a region's environment for human settlement profoundly affects the regional socio-economic development and the population distribution. Tibet is an area that is sensitive to climate change. Given the impact of global climate change, the climate suitability of Tibet has undergone significant changes. In this study, the temperature humidity index (THI) values for Tibet were calculated, and the relationships between the population distribution and the THI were analyzed quantitatively. In this way, the zoning standards for climate suitability in Tibet were determined such that the climate suitability could be evaluated. The results show that the average annual temperature in the southeast of Tibet, where the population was densely distributed, was relatively high. The mean annual relative humidity showed a trend of gradually decreasing from south to north. Regions with a suitable climate, including the high suitability areas (HSAs), the moderately suitable areas (MSAs) and the low suitability areas (LSAs), accounted for only 7.90% of the total area but accommodated over 40% of the total population. The critically suitable areas (CSAs) accounted for 37.81% of the land area and 48.24% of the total population. Non-suitable areas (NSAs) were widely distributed in Tibet and accounted for 54.29% of the total area and 11.33% of the total population. The results of this study may provide a reference for guiding the reasonable distribution of population and promoting the optimization of the spatial planning in Tibet.

The increase of agricultural land abandonment is one of the main changes in land use in China over the recent years. In China, the abandonment phenomenon has become one of the most serious problems in the last 20 years. Abandoned farmlands make the land in a vicious circle. Preventing the farmland from abandonment is an urgent issue for China. Thus, abandoned farmland survey is very important; it can provide scientific evidence for food security, land use planning and economic development of China. The conventional investigation approach of abandonment status is field survey. It cannot meet the demand of large area because of the lack of efficiency and timeliness. Remote sensing technology has advantages of large spatial observing area, high real-time, wide spectrum ranges and all weather imaging capability. It has worked successfully in many fields, but was rarely applied in terms of investigation and assessment of arable land abandonment. In this work, Xinyang City in Henan Province was selected as a study area. SPOT-5 images and MODIS NDVI data were used for surveying and extracting the abandoned farmland. This paper introduces the theories, processes and results of three methods for abstracting abandoned farmland on the basic of remote sensing, assesses the efficiency and accuracy of them, and compares the merits and demerits of them, sums up the workable technique for the study area.

Human settlements’ suitability in ecologically fragile regions is critical for sustainable development and ecological security. However, comprehensive assessments that integrate multiple natural environmental factors are insufficient. Here, we establish a human settlements suitability index (HSI) to assess human settlements’ suitability on the Qinghai–Tibet Plateau, including Relief Degree of Land Surface (RDLS), Temperature–Humidity Index (THI), Land Surface Water Abundance Index (LSWAI), and Land Cover Index (LCI). The results show that: (1) The RDLS of the Qinghai–Tibet Plateau was generally high, reflecting elevated terrain and steep topography, with strong regional variation. THI increases from the northwest arid region to the southeast, while high LSWAI and LCI were concentrated and show a zonal distribution. (2) The HSI ranged from 0.07 to 1, with seven suitability types. Low-suitability was distributed in the Kunlun, Gangdise, Himalayas, and the northern and southern parts of the Tibetan valleys. Mid-suitability appeared in the Sichuan–Tibet Alpine Canyon, while high-suitability was concentrated in the northeast (Qaidam Basin, Qilian, Hengduan Mountains), the west (Menyu), and the Qaidam Basin. (3) Low-suitability covered over 70% of the Qinghai–Tibet Plateau but hosts only 20% of the population. Mid-suitability occupied about 20% of the land, yet contained nearly 70% of the population. High-suitability (HSI > 0.7) areas were limited but concentrated populations in the Qaidam Basin, southern Tibetan valleys, and eastern Sichuan–Tibet Alpine Valleys. Future development should target these high-suitability regions to support sustainable population growth and reduce land pressure. These findings provide a scientific basis for regional planning, population distribution, and ecological security on the Qinghai–Tibet Plateau.