Geographical Issues

Methodology for determining the Spatial Distribution and Detection of Brandt's Vole Burrow Systems Utilizing Faster R-CNN model

2024-05-14T11:02:31+08:00

Most small rodent populations around the world exhibit fascinating population dynamics, capturing the attention of numerous scholars due to their multi-year cyclic fluctuations in population size and astonishing amplitude of these fluctuations. Hulunbuir steppe stands as a crucial global hub for livestock production, yet in recent decades, the area has faced recurring challenges from steppes rodent invasions, with Brandt's vole (Lasiopodomys brandtii, BV) being particularly rampant among them. They exhibit seasonal reproduction and strong social behavior, and are generally considered pests, especially during population outbreak years. Prior studies suggest that BV population outbreaks tend to happen across a wider geographic area, and a strong indicator for identifying rodent outbreaks is recognizing their burrow clusters (burrow systems). Hence, this paper conducts target object detection of BV burrow clusters in the typical steppes of Hulunbuir using two GF-2 satellite images (covering an area exceeding 1000 km²). from 2021 (the year of the BV outbreak). This task is accomplished by incorporating the Faster R-CNN model in combination with three detection approaches: object-based image classification (OBIC), based on vegetation indices classification (BVIC), and based on texture classification (BTC). The results indicate that OBIC demonstrated the highest robustness in BV burrow clusters detection, achieving an average AP of 63.80% and an F1 score of 0.722 across the two images. BTC exhibited the second-highest level of accuracy, achieving an average AP of 55.95% and an F1 score of 0.6660. In contrast, BVIC achieved the lowest level of accuracy among the three methods, with an average AP of merely 29.45% and an F1 score of 0.4370. Overall, this study demonstrates the crucial role of utilizing high-resolution satellite imagery combined with DL-based object detection techniques in effectively monitoring and managing the potential outbreaks of steppe rodent pests across larger spatial extents.

Changes in the biomass of pasture plants and some impacts in Mongolia

2024-08-03T12:53:27+08:00

The biomass of pasture plants varies depending on general conditions such as climate, soil type, ecological zone, and hydrological network. Drought is defined as a condition in which the plants wither and stop growing because there is insufficient rainfall during the growing season, soil moisture decreases due to extreme heat, and the hydrological balance of the soil is disturbed. The amount of pasture biomass varies greatly depending on the drought conditions. According to our analysis, the correlation between pasture biomass and average air temperature during plant growth was 0.30 – -0.77, precipitation was -0.04–0.73, and the proportion of drought and semi–drought was 0.05–0.85. This shows that in 11 regions and 8 regions of the belt, the proportion of drought and semi-drought areas had a high correlation with yield, while in 2 regions, the air temperature and in 1 region, the precipitation were highly correlated in Mongolia. In a year with normal summer precipitation, the biomass of pasture plants is 2.3 q/ha in the high mountains, 6.2 q/ha in the forest-steppe, 4.8 q/ha in the steppe, 2.4 q/ha in the semi-desert steppe, and 1.5 q/ha in the desert. is 2.3 q/ha in the mountains, 6.2 q/ha in the forest-steppe, 4.8 q/ha in the steppe, 2.4 q/ha in the semi-desert steppe, and 1.5 q/ha in the desert. On the other hand, the biomass in a semi–drought decreases by an average of 0.9 q/ha in the high mountains, 2.4 q/ha in forest steppes, 1.8 q/ha in steppes, 0.9 q/ha in semi-desert steppes, and 0.6 q/ha in deserts. But in drought, the biomass decreases by 1.7 q/ha in high mountains, 4.5 q/ha in forest steppes, 3.8 q/ha in steppes, 1.8 q/ha in semi-desert steppes, and 1.1 q/ha in deserts

The impact of faults on forming of the Chuluut Canyon, Central Mongolia

2024-09-28T21:48:08+08:00

Canyon formation is of significant interest in geomorphological studies of flowing waters, yet no studies have been conducted on this subject in Mongolia. Geomorphological methods were used to determine the shape and regularity of the Chuluut River Canyon, which is a major tourist destination. The development of the lava plateau forming the canyon was also assessed through morphological analysis. The study combined the analysis of morphometric and satellite images with field research data. The crust of the study area is ~45 km thick, with a lava plateau formed during the period from the late Miocene to the Pleistocene. The Chuluut River's orientation and the canyon formation were controlled by the main (Chuluut) fault, which extends from the southwest to the northeast, and orthogonal faults, intersecting it from the south to the north. The length of the Chuluut Canyon is about 32 km, the area is 9.3 km², the average width of the canyon is 230 meters, the depth is 58.4 meters, the volume of the canyon is 1.03 km³, and the average slope is 45°. As a result of fault activity, linear structures formed on the surface, folds developed on the mountain slopes, and faults appeared in the bedrock. These factors are the primary contributors to the canyon formation, influencing sharp bends in the river, with some stretches of the river flowing in a straight direction due to the fault. This fault had not previously been identified on geological or geomorphological maps or in other studies and it has been newly documented in this research.