Exploring the potential of nature-based solutions in drylands: the Aral Sea case

The challenges of climate change and desertification pose significant threats to dryland ecosystems, which are among the most vulnerable environments on Earth. This thesis explores the potential of nature-based solutions (NbS) in addressing these challenges and enhancing the resilience and sustainability of dryland ecosystems.

The research identifies and compiles evidence of existing and viable NbS from global drylands, with a particular focus on the effectiveness of afforestation in the degraded landscape of the South Aral Sea (Uzbekistan), where severe desiccation has transformed much of the Seabed into an arid, desert-like environment. The study examines how NbS can mitigate ecological degradation while contributing to environmental sustainability and socio-economic resilience, employing an interdisciplinary approach that integrates earth observation, field ecological monitoring, and social surveys.

Further, the research evaluates different land use and land cover (LULC) mapping and classification methods, recommending the most accurate approach for drylands based on ground truth data and the latest field observations. It also assesses LULC changes over the past decade, specifically between 2013 and 2023, to understand ecosystem trajectories and evaluate the effectiveness of afforestation efforts during this period. Special emphasis is placed on applying the Modified Soil Adjusted Vegetation Index (MSAVI) to monitor vegetation status in drylands, correlating spectral indices with vegetation productivity dynamics and biomass. Additionally, the research evaluates the climate change adaptation and mitigation potential of afforested areas in the study region by estimating the carbon pool, providing albedo change estimates influenced by the desiccation of the largest local water body, and offering insights into the vulnerability of afforested areas to the ongoing consequences of climate change.

Key findings indicate that afforestation efforts have resulted in measurable improvements in vegetation cover and productivity in parts of the South Aral Sea, thereby enhancing ecosystem services and contributing to both climate change adaptation and mitigation. However, the study also underscores the importance of adaptive management and continuous monitoring to ensure the long-term success of afforested areas, as well as the need to consider trade-offs between the benefits and drawbacks of such measures in global drylands.