Review of Organic Carbon Dynamics and Its Interrelationships with Soil Properties in Combating Desertification and Preventing Ecosystem Degradation

Background and Objectives: Desertification is a global process with extensive consequences, reducing agricultural productivity, threatening food security, and posing challenges to rural livelihoods in arid and semi-arid regions. It is exacerbated through feedback loops involving vegetation degradation, soil fertility decline, and water scarcity, with human activities such as overgrazing, deforestation, climate change, and unsustainable land management playing pivotal roles. Soil organic carbon (SOC) dynamics serve as a key factor in maintaining soil health, ecosystem resilience, and controlling environmental processes. This review examines the mechanisms of SOC influence on erosive factors and its interrelationships with soil properties to propose sustainable management strategies for combating desertification and preventing ecosystem degradation.
Materials and Methods: This study was conducted as a review based on the collection and analysis of international and domestic scientific articles. Focus was placed on extracting and integrating findings related to SOC impacts on soil stability, water retention, hydraulic behavior, nutrient cycling and fertility, plant species diversity, and microbial population and diversity. The role of land use changes (deforestation and intensive agriculture) in SOC dynamics and desertification intensification was evaluated.
Results: SOC acts as a foundational element for soil hydrophysical behaviors and a source of active chemical reactions, shaping the interaction patterns of desertification-limiting factors. Increased SOC enhances aggregate stability through particle binding and concentration in coarse aggregates, improves water holding capacity at saturation and field capacity, facilitates gas exchange, and renders soil resistant to wind and water erosion. In nutrient cycling, SOC elevates cation exchange capacity, regulates element availability, reduces leaching, stimulates root growth. At the ecosystem scale, SOC boosts plant biodiversity (e.g., Shannon index), particularly in arid areas based on organic matter quality. SOC alters bacteria-to-fungi ratios in the rhizosphere, increases microbial genetic diversity, and strengthens copiotrophic populations, with long-term changes exerting deeper impacts than short-term ones. Deforestation reduces organic inputs, accelerates decomposition and erosion, while intensive agriculture with heavy tillage and monoculture significantly depletes SOC. In Iran, where over 75% of areas are prone to desertification, SOC differences between critical and vulnerable zones are evident; forest and rangeland uses maintain higher SOC levels, whereas intensive agriculture markedly reduces it. Significant correlations exist between SOC decline, and desertification indices. Climate change reduces precipitation quantity and diversity while increasing temperature, negatively affecting SOC inputs and preservation. Management of plant residues, conservation tillage, and revegetation with resistant species in drylands boost SOC potential and performance.
Conclusion: SOC serves as the cornerstone of soil hydrophysical behavior and substrate, driving active chemical reactions crucial for controlling desertification. Augmenting coarse soil grain abundance, fostering new soil grain formation, enhancing water retention at saturation and field capacity, improving hydraulic behavior and gas exchange, boosting root growth and capillary root numbers, increasing exchangeable element concentrations, prolonging nutrient availability while curbing leaching, altering bacteria-to-fungi ratios in the rhizosphere, and enriching microbial population abundance and diversity are all effects of heightened SOC levels. These factors should inform land use decisions, advocating for reduced deforestation and intensive agriculture practices. National carbon sequestration schemes and participatory projects (e.g., contour furrowing and shrub planting) with socio-ecological approaches demonstrate greater success in reversing degradation.