Land-Use Change Related to Topography and Societal Drivers in High-Mountains – A Case Study in the Upper Watershed of the Tergi (Kazbegi Region), Greater Caucasus

Abstract

Abstract High mountain ecosystems, with strong topographic and climatic gradients, are fragile and particularly sensitive to changes in land use. The abandonment of historic cultural landscapes has often led to changes in the pattern of land cover and thus, to a shift in the functions of high mountain landscapes, like fresh water supply, productivity or erosion control. In order to understand the effects of land-use change on the land-cover pattern at the local and regional scale, we analyzed and classified the mountainous landscape structure in the Kazbegi region in Georgia, located in the Central Greater Caucasus. For 13 settlements, we determined the land cover as present in 1987 and 2015, and quantified the changes over time to detect land-cover development trends for each settlement. Using a cluster analysis, the study area was analyzed regarding to topography (altitude, aspect, slope) and distance to settlements at the regional scale to gain six groups with separating conditions. Furthermore, each settlement was classified according to topography and land-cover change to obtain site-specific, comparative development trends. Our results show that this Caucasian high-mountain landscape is characterized by open grassland (67%) used as pasture and hay meadow, and natural birch forests (7%) in patches in the upper half of the subalpine belt. Within the settlements but also in their surroundings, field vegetables are cultivated in home gardens (1%). Land-cover change during the observation period mainly affected the cultural grassland with hay meadow abandonment. Moreover, shrubbery and forest expanded considerably on abandoned pastures. We further detected a strong relationship to topography that considerably varied between settlements resulting in specific trends in land-use change. Hay-making and arable land cultivation are focused today on sun-exposed and gentle slopes near the settlements. Shrub encroachment and reforestations were localized on farther distances and mostly on north-exposed slopes. Besides providing basic information about the historic and current land-use and land-cover patterns, our results quantify the landscape change during almost 30 years. A spatio-temporal analysis revealed an understanding of how land-use decisions influence the landscape pattern. In the context of societal development, regional socioeconomic processes, like shifts in the agricultural structure and population outmigration, seem to be societal drivers of changes. Our findings reveal linkages and interrelationships between natural, human-induced environmental and socioeconomic processes within high-mountain socio-ecological systems. Moreover, we suggest that sustainable land-use strategies for spatial development on sub-regional level, especially in marginal high-mountain regions, should consider topography and its influence on land-use change.