Effect of Himalayan cedar forest longevity on soil properties in the Kumaun Himalaya, Uttarakhand, India

The Himalayan cedar forests in the temperate regions of the Himalaya are crucial for providing ecosystem services such as carbon storage and nutrient maintenance, playing a vital role in combating climate change. This study employs a Dendrochronological approach to examine the impact of Himalayan cedar forest stands on soil properties across five distinct sites in the Kumaun Himalaya. Soil samples were collected from a depth of 0–15 cm and analyzed for total nitrogen (TN), total phosphorus (TP), soil organic carbon (SOC), pH, and C:N ratios. Tree-ring samples were also collected taken from the same sites. Our analysis revealed a positive correlation between tree age and SOC content. Notably, the oldest forests at Jageshwar Dham (480 years) and Hatkalika (413 years) exhibited the highest levels of SOC, TP, and TN, while the youngest forests at Naudunga (135 years) and Patal Bhuwaneshwar (134 years) showed the lowest values. Significant differences in all soil parameters were confirmed through a Tukey post hoc test. Additionally, the relationship between climate and tree growth was analyzed using tree-ring chronologies and meteorological records, indicating that cool and moist spring conditions (February-May) enhance tree growth by increasing soil microbial activity. Our findings emphasize that conserving older natural forests, particularly mature Himalayan cedar forests, is crucial for maintaining soil characteristics, including carbon storage and nutrient levels, to support sustainable soil health and climate change mitigation.