Invasive Acacia tortilis and Soil Organic Carbon Dynamics in Jorbeer Conservation Reserve, Bikaner, Rajasthan, India

Abstract

Soil organic carbon (SOC) is widely recognized as a critical indicator of soil health, productivity, and climate change mitigation potential, particularly in fragile arid ecosystems where organic matter is naturally low. The present study examines the effect of Acacia tortilis, a hardy leguminous tree species with invasive tendencies in the Thar Desert, on SOC levels within the Jorbeer Conservation Reserve, Bikaner, Rajasthan. Soil samples were systematically collected from three distinct land-use categories—dumping site, grassland, and adjacent non-vegetated open areas (controls)—under A. tortilis canopy and across four seasonal periods (summer, rainy, winter, and spring). SOC content was quantified at two soil depths (0–15 cm and 15–30 cm) using standardized methodologies. Results revealed that soils under A. tortilis exhibited significantly higher SOC concentrations than open control sites, with the most pronounced enhancement recorded during the winter season. This increase can be attributed to increased litter deposition, moderated soil temperature fluctuations, and improved microclimatic conditions that are conducive to organic matter accumulation and microbial activity beneath the tree canopy. Among all land-use categories, the dumping zone recorded the highest SOC levels, followed by grassland and open land. The findings highlight the ecological role of A. tortilis in enhancing SOC and improving soil quality in arid ecosystems, while simultaneously raising concerns about its invasive spread and impact on native grassland biodiversity. The study underscores the importance of balancing carbon sequestration benefits with biodiversity conservation when evaluating the role of exotic leguminous trees in arid land management and ecological restoration.