Understanding competition between two invasive woody plants of India under an altered rainfall regime

Abstract

Prosopis juliflora and Leucaena leucocephala are notable examples of invasive woody plants that can spread throughout similar habitats in India. However, little is known about how these two species may interact with one another if future rainfall pattern shifts, which is particularly concerning. Recognizing the pivotal role of eco-physiological parameters in deciphering the dynamics of interspecific competition, a study was devised to elucidate the interplay between L. leucocephala and P. juliflora under simulated rainfall conditions. At Botanical Garden, Banaras Hindu University, Varanasi, UP, India, three fixed rainout shelter plots were established, each receiving distinct precipitation levels: low rainfall (LR), normal rainfall (NR), and high rainfall (HR). Within each plot, three replicate subplots were dedicated to pure stands of L. leucocephala (L), pure stands of P. juliflora (P), and mixed stands of the two species (LP). The findings of the study underscore significant variations in soil Inorganic N, N-mineralization, based on precipitation levels, with maximum values observed in HR plot and L. Similarly, biomass, photosynthetic rate, and transpiration rate exhibited significant variability in response to precipitation treatment, reaching their highest values in HR plot and L. Conversely, root length, root-shoot ratio, and water use efficiency peaked in LR plot and P, presenting a contrasting trend. This study suggests that L. leucocephala may facilitate the growth of P. juliflora by improving the soil's nitrogen availability and, consequently, the eco-physiological characteristics of the plant in mixed plant stands. Furthermore, L. leucocephala is providing P. juliflora with favourable conditions for robust growth under water stress—a scenario indicative of Facilitative approach. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.