The soil response in experimental Leucaena leucocephala plots under manipulated rainfall regimes

Abstract

Leucaena leucocephala, a prominent invasive woody plant in India, is constantly recognised for its capacity to invade in various ecosystems. The chances of invasion by L. leucocephala are increasing due to rainfall variability, to which the plant has already adapted. However, the understanding of L. leucocephala, particularly its response to soil attributes and alterations in nutrient cycling processes under varying rainfall conditions, is currently inadequate. In response to the perceived threat of rainfall shift and invasion impacting native plant species through soil modification, the study was designed to investigate the interplay between L. leucocephala invasion and simulated rainfall conditions. The experimental setup included three rainout shelter plots receiving different precipitation levels (low, normal, and high) and subplots within each plot dedicated to pure stands of L. leucocephala. The study findings reveal significant variations in soil inorganic nitrogen and N-mineralization based on precipitation levels and seasons, with the highest values observed in the high rainfall plot and during the rainy season. In contrast, microbial biomass (carbon and nitrogen) peaked in the low rainfall plot and during the summer season, indicating a contrasting trend. The implications of the study suggest that, in addition to variable rainfall, L. leucocephala may play a significant role in altering nutrient cycling, particularly nitrogen cycling. The plant enhances soil properties related to nitrogen availability, creating opportunities for multiple invasions and potentially leading to a chance of “Invasion Meltdown,” with a significant threat to native biodiversity. Overall, the research is emphasizing the need for a comprehensive understanding of these dynamics to formulate effective management strategies for preserving native ecosystems. © International Society for Tropical Ecology 2025.