Ecological status and spatial extent of non-native shrubs Lantana camara L. and Ageratina adenophora Sprengel in the forest communities of western Himalaya

Abstract

This research elucidates the ecological status and spatial extent of two non-native invasive species, Lantana camara L. and Ageratina adenophorum Sprengel, within dominant forest communities across an altitude gradient in the western Himalayan region. The study, conducted from 2017 to 2019 in the Nainital district of Kumaun Himalaya, focused on four forest communities; Sal, Chir-pine, Banj-oak, and Mixed-oak, spanning an altitudinal range from 300 to 2250 meters. Environmental predictors encompassing topographic, physiographic, and climatic factors, along with species occurrence records, were employed to determine spatial extent. The MaxEnt statistical model, a machine learning algorithm, facilitated the assessment of the spatial distribution of invasives. Results indicate that L. camara has invaded Sal, Chir-pine, and Banj oak forests but has not established in high-elevation mixed-oak stands. Conversely, A. adenophora has invaded Chir-pine, Banj-oak, and Mixed-oak stands but has not been observed in low-altitude Sal forests. No significant variation in species number, diversity, or distribution pattern along the elevation gradient was observed for either species. Spatial assessment using MaxEnt revealed an estimated area of 380 km² for A. adenophora and 285 km² for L. camara. The study highlights the mid-altitude zone as the most vulnerable to species invasion. This scientific inquiry contributes valuable insights for the conservation of non-native shrubs, offering guidance for effective, species-specific conservation and management strategies in the Himalayan region.