Global fires are expanding, and it is necessary to establish an active fire prevention and evaluation system. Among them, active fire risk assessment is a key part of fire prevention. Based on the Fire Sensitivity Index (FSI), this paper uses the data of active fire, population density, NPP, minimum temperature and altitude to evaluate the active fire risk under the coupling characteristics of the spatial distribution of different geographical elements and the location of active fire. At the same time, using the Fire Potential Index model (FPI), Based on temperature, relative humidity, and vegetation coverage, assess the potential risk of global active fires under the existing vegetation distribution. The results show that the regions in high value FSI are distributed in both temperate and tropical zones, and the occurrence regions are mainly at middle and low altitudes with relatively sparse population. The regions in low value of the FPI is transitioning to the middle value regions, that is, the probability of active fire occurrence in some regions increases, and the fire risk increases. Moreover, the regions in high value of the FPI has decreased, and it is also transitioning to the middle value regions. Even though the global fire risk assessment results based on the FPI show that the high-risk regions have decreased, the low-risk areas are gradually transitioning to the medium-risk regions. In this paper, the global large-scale research area is divided into several regular grids, and the spatial expression of the FSI of small-scale active fire occurrence is realized by optimizing the active fire occurrence risk assessment model. The results have important implications for active fire management decision-making.

The study of natural suitability of human settlements environment aims at objectively revealing the human settlements under the influence of natural geographic elements, which to quantitatively characterize the pattern of regional population distribution under natural limitations or suitability. Based on the kilometer grid, the study establishes the Human Settlements Index (HSI), which includes Relief Degree of Land Surface (RDLS), Temperature-Humidity Index (THI), Land Surface Water Abundance Index (LSWAI) and Land Cover Index (LCI). The main conclusions are as follows: (1) The RDLS of Qinghai-Tibet Plateau is dominated by high values (high elevation, sharp topographic undulation), with great regional differences. It is obviously different that the THI of the region, which shows an increasing trend from the northwest arid region to the southeast. However, both the high LSWAI and the LCI distribute on intensively and zonally. (2) Supposed that the auxiliary elements (hydrology, vegetation) enhance dominant elements (topography, climate), the conclusion shows that the HSI between 0.07~1 in the study area, averages 0.45. According to the grading judgment of the topographic and climatic suitability, with the restriction of physiological elements on human habitation, there defines the 7 types of human settlements environment suitability. (3) The unsuitable type account for 32.48% of the total area, and only 1.87% of the corresponding population, mainly distributed in the Kunlun mountains, the Gangdis mountains and the western side of the Himalayas. As an important basis, human settlements suitability provides scientific basis for resources and environment carrying capacity, moreover, it supports the regional planning and population distribution.