Currently, due to climate change, desertification, and the intensification of anthropogenic degradation of ecosystems, research on the conservation, restoration, and monitoring of populations of endemic, rare, and endangered plant species in arid regions has become particularly urgent. Endemism is one of the most important and widespread concepts in biogeography and serves as a key criterion for environmental protection. However, despite high biological diversity in many regions, knowledge about endemism remains limited [1] . This also applies to the Southwestern Kyzylkum, a region with high biological diversity, where there is insufficient information regarding the diversity and distribution of endemic species [2] .

In this study area, activities related to the exploration of mineral resources (oil, gas, gold), livestock farming, road construction, land development for agricultural use, urbanization, and climate change are factors that significantly contribute to the high risk of biodiversity loss. The extinction of a species or population under the influence of such factors negatively impacts biological diversity and leads to the loss of genetic information specific to the species. This process is most commonly observed in endemic species. Endemic plants are the most vulnerable component of flora because the extinction of even one of them leads to an irreversible loss of biodiversity [3] . The conservation of biological diversity in areas with a high concentration of endemic species and the identification of such areas is a priority task for environmental protection. The number of endemic species in the study area serves as preliminary information about the importance of preserving this region.

The Southwestern Kyzylkum is one of the most significant parts of the Central Asian deserts, rich in endemic species, and is one of the centers for the formation of local species [2] . At the same time, the region consists of various ecological landscapes, including riparian zones, sandy deserts, residual mountains, and anthropogenic environments. It can be stated that the strong manifestation of anthropogenic pressure in this area is negatively affecting the populations of endemic species.

Information about the rare and endemic plants of the Southwestern Kyzylkum has been provided in the works of I.I. Granitov [4] , F.O. Khasanov et al. [5] , H.K. Esanov [6] , O.S. Abduraimov [7] , K.Sh. Tojibaev et al. [8] , and H.F. Shomurodov [9] [10] .

I.I. Granitov [4] believed that subsequent research on the flora of the Kyzylkum would enrich the list of endemics. In his studies of the Kyzylkum region, he noted that there are 226 endemic species in Central Asia (25% of the total flora), of which 141 species (24%) belong to the Southwestern Kyzylkum flora. Later studies [5] indeed expanded the composition of Kyzylkum endemics, and our research results further support this finding. F.O. Khasanov et al. [5] reported 41 endemic species and 11 subendemics in the Kyzylkum region. H.K. Esanov [2] identified 143 species (18.01% of the region’s flora) from 23 families and 70 genera of Central Asian endemics in the Southwestern Kyzylkum region. Among these, representatives of the Calligonum L. genus play an important role.

The object of the research is the rare and endemic species of the Calligonum L. genus in the Southwestern Kyzylkum flora. Herbarium specimens collected during field studies were identified using the works Flora Uzbekistana [11] and Conspectus Florae Asiae Mediae [12] . To identify rare and endemic species, the Red Book of the Republic of Uzbekistan [13] and the International Red List (IUCN) [14] were used. To determine the distribution areas of the species, field studies and specimens stored in the Uzbekistan National Herbarium (TASH) at the Institute of Botany, Academy of Sciences of the Republic of Uzbekistan, were used. These species were studied using a route method in the areas surrounding Dengiz-kul, Karakul (Poykent), and Kuljuktau in the Southwestern Kyzylkum. The populations of these species consist of 20 to 500 individuals. The study utilized data from the WCRP coupled model intercomparison project (Phase 6) and simulations from CMIP6. The obtained data were based on the WGS1984 coordinate system. For modeling, climate scenarios SSP1-RCP2.6 for the period 2021-2040 were selected. A bio-climatic model was created using the MaxEnt 3.4.4 software, and a map was generated using the ArcGIS software.

The conducted research focused on the distribution of four species from the Calligonum L. genus listed in the Red Book of Uzbekistan and the International Union for Conservation of Nature (IUCN) Red List: C. paletzkianum Litv., C. molle Litv., Calligonum zakirovii (Khalk.) F.O. Khass., and C. matteianum Drobow. These species are considered rare and endemic in the region. Their distribution in Uzbekistan is most notably found around the Dengizkul area [15] - [17] . The ranges of these species are steadily shrinking due to anthropogenic impacts. This is particularly driven by livestock grazing, various geological exploration activities, land development, and other factors. Based on the research findings, current distribution areas and modern GIS maps were created ( Figures 1-4 ). Additionally, specimens from the National Herbarium were studied, and relevant data were collected.

In conclusion, the Kyzylkum Desert is one of the main centers of development for the species of the Calligonum genus. In Kyzylkum, Calligonum is considered a leading genus rich in endemic species. The increasing anthropogenic impacts in the region are negatively affecting the populations and distribution areas of these species. In particular, the growing use of species for firewood, climate change, a decrease in precipitation, and the increasing number of livestock (around 10,000) and their uncontrolled grazing are contributing to these negative effects. To prevent further damage, it is necessary to establish protected areas in regions where these rare and endemic species are distributed.