Exploring soil health and sustainability in the Northwestern Himalayas: assessing indicators amidst changing land use

Soil quality and health are fundamental to ecosystem sustainability, particularly in the Northwestern Himalayas, where steep slopes, high erosion rates, and land use changes accelerate soil degradation. Unlike stable lowland ecosystems, Himalayan soils are highly vulnerable to nutrient loss, organic matter depletion, and microbial instability due to extreme climatic variations and dynamic land use patterns. This review consolidates research on soil health indicators, emphasizing microbial biomass carbon (MBC), enzyme activity, and organic carbon content as essential metrics for assessing soil quality. These indicators reflect biological, chemical, and physical processes influencing nutrient cycling, microbial diversity, and soil functionality. However, their predictive power varies with land use shifts, seasonal changes, and the inherent variability of Himalayan soils, necessitating region-specific calibration for improved accuracy. Organic matter decomposition is a key indicator of soil health, yet its assessment in rugged terrains is challenging. The Normalized Difference Vegetation Index (NDVI) provides a remote sensing solution, helping identify degraded soil zones and guiding targeted restoration efforts. NDVI alone cannot fully assess soil health, as vegetation cover may not always correspond to soil quality. This review evaluates NDVI’s effectiveness across various land use systems for distinguishing vegetated from non-vegetated areas, facilitating reforestation and land use monitoring. Given the region’s ecological sensitivity, a single indicator approach is insufficient. We advocate for a composite soil health assessment framework incorporating biochemical indicators such as enzyme activity, phospholipid fatty acid (PLFA) profiles, DNA profiling, carbon pools, and nitrogen levels. A gradient-based soil sampling strategy, rather than random sampling, is recommended to capture altitude and slope effects on microbial dynamics and soil function. While these approaches are tailored for the Northwestern Himalayas, similar challenges exist in mountain ecosystems worldwide. Integrating remote sensing with biochemical assessments can enhance soil management strategies, ensuring long-term sustainability and ecological resilience in both the Himalayas and other vulnerable mountain regions.