Assessment of Long-term Vegetation Cover Change in Mountainous Areas of the Moroccan High-Atlas Using Close-Range Remote Sensing and Climatic Variables

Research on the impact of climate change on land-use change has focused on satellite imagery and/or aerial photography, particularly for extensive areas. However, although close-range remote sensing methods (terrestrial photos) are of great interest for spatiotemporal analysis of landscape change, they are rarely used. In the present study, historical close-range terrestrial photos taken in 1950 and contemporary digital imagery acquired in 2020 over the same areas are combined, processed and analyzed to quantify the extent of vegetation covers (forest and agriculture) during 70 years in the mountainous regions of the Moroccan High-Atlas. We also analyzed to what extent climatic factors (temperature, rainfall, and snowfall) have contributed to this extent. Results showed that climatic observations over the past 70 years, 1950 to 2020, have gradually decreased year by year for snowfall and rainfall (i.e., less or no snow and about 50% decrease of rainfall) due to global warming. However, forest cover site has increased by 16% during this period, while the bare soil class has decreased by the same percentage. Whereas, agricultural site shows a decrease of bare soil class by 29%, contrariwise, vegetation covers and constructions classes have increased by 27 and 2%, respectively. Nevertheless, although the climatic variables point to global warming, there has been significant growth and development of vegetation covers across the study areas. These results are probably due to the migration and expansion of the vegetation species towards mountainous regions at high altitudes, their adaptation to new climatic conditions, and the absence of snowpack. Likewise, we demonstrated how the combination of close-range remote sensing and climate variables could play a complementary role to other data such as satellite images and/or aerial photos to assess long-term land cover change in mountainous areas on a finer scale.