# How Will Rwandan Land Use/Land Cover Change under High Population Pressure and Changing Climate?
## 1 Introduction  
Over the years, sustainable development in Africa has been the focus of global attention. Although the population density of Sub-Saharan Africa is still relatively low (43 persons/km\({}^{2}\)) [1], the population distribution in East Africa is extremely uneven because of the differences in topography and climate brought about by the Great Rift Valley. The population density in some areas exceeds 300-500 persons/km\({}^{2}\)[2, 3]. The land resources in this area have been under long-term pressure from the ever-increasing population. The rapid population growth has given rise to numerous challenges, such as land degradation, loss of biodiversity, excessive deforestation, water shortages, and difficulty in ensuring food security. The emergence of these problems undoubtedly has a negative effect on sustainable development [4, 5]. The land resources, which are critical for human survival, are the carriers of these problems. Anthropogenic activities and the natural environment can both induce and restrict changes in LULC [6, 7]. The expansion of cities caused by rapid economic development and the expansion of arable land caused by the rapidly expanding population occur at the expense of forests, wetlands, and grasslands [8]. Rwanda has witnessed rapid population growth and economic development since the 1990s, which have brought about dramatic changes in the LULC pattern of the country [9]. Rwanda relies heavily on rain-fed agriculture, which makes agricultural production andfood security vulnerable to variations in rainfall. From 1990 to 2015, the cropland area increased substantially. The rapid expansion of cropland involves the conversion of natural ecosystems, water, and vegetation into cropland [9]. Large-scale destruction of forests will cause changes in the water conservation function of forests, which alters the groundwater cycle at the watershed or regional (the regional) scale [10]. In turn, this causes changes in the local microclimate, resulting in changes in conditions such as precipitation and temperature [11]. Precipitation and temperature are the two most important factors affecting food crops, and changes in these factors negatively impact food production, which eventually causes further expansion of cropland. Cropland is an important source of livelihood for Rwandans. As the population has increased, the arable area owned by each family has gradually decreased over time. To meet the demand of the growing population for food crops, the landscape pattern in this region has gradually become more fragmented and the number of patches has steadily increased [12]. Moreover, the production capacity of cropland and the self-sufficiency of food crops has gradually declined. This has led to a phenomenon in which increased cultivation increases poverty, and greater poverty necessitates increased cultivation. This vicious circle has severe negative impacts on sustainable development. Although researchers have studied LULC in Rwanda, they have primarily focused on the following three aspects, namely policy, soil properties, and land use transfer (land use/land cover change). In terms of policy, researchers believe that more smallholder land can improve grain output to some extent and enhance food security [13; 14; 15; 16]. [PERSON] [12] argued that smallholders play a dominant role in rural areas in Rwanda because they acquire their land mostly through borrowing. This approach to land acquisition can stimulate smallholders to invest more labor in their limited land and thus achieve higher yields. [PERSON] [17] found that when the farm area is below 1 ha, the yield can be increased, whereas the opposite is true when the farm area exceeds 1 ha. This type of research is helpful to the formulation of 'top-down' land use policies. In terms of soil properties, researchers believe that changes in LULC type reduce soil fertility to a certain extent, resulting in the loss of soil nutrients [18]. [PERSON] et al.