Grass fires and road structure influence plant invasions in a critical wildlife habitat in north-eastern India

Abstract

Summary One of the multiple threats to protected areas worldwide, invasive plant species have the potential to decrease biodiversity and ecosystem function. We studied changes in infestation by two widespread invasive plant species – Chromolaena odorata and Mikania micrantha – in India’s Manas National Park, a critical conservation site for threatened flora and fauna. Based on field surveys in 2011 and 2019, we found that C. odorata and M. micrantha were present in most of the sampled plots and had newly invaded over 20% of the plots. However, the abundance of M. micrantha decreased in 45% of the plots while C. odorata increased in >50% of the plots. We used a decision tree-based regression with environmental variables as predictors to generate the distribution, abundance and invasion risk maps of the two species. Among environmental variables, road proximity and fire frequency had the strongest influences, respectively, on C. odorata and M. micrantha. Invaded quadrats exhibited lower native-plant diversity than non-invaded quadrats, and C. odorata specifically had a strong negative association with native-plant community structure. These invasive species have increased their range and abundance, and our predicted invasion risk maps indicate the areas where management intervention is urgently needed.

Ecological insights and environmental threats of invasive alien plantChromolaena odorata: Prospects for sustainable management

“…The harmful effects of C. odorata can be further synergized with the presence of another potential plant invader. In this context, C. odorata infestation in conjunction with M. micrantha showed the potential to outcompete the entire grasslands of this park (Banerjee et al, 2023). In this respect, field survey revealed that the abundance of C. odorata increased in >50% of the plots of Manas National Park (Banerjee et al, 2023).…”

“…In this context, C. odorata infestation in conjunction with M. micrantha showed the potential to outcompete the entire grasslands of this park (Banerjee et al, 2023). In this respect, field survey revealed that the abundance of C. odorata increased in >50% of the plots of Manas National Park (Banerjee et al, 2023). Heavy infestation of these plant invaders from Asteraceae (i.e., C. odorata and M. micrantha ) can lead to shrinkage in the wildlife habitat of Asiatic wild buffalo ( Bulbulus arnee ), introduced One‐horned rhino ( Rhinoceros unicornis ), Swamp deer ( Rucervus duvaucelii ) and Hog deer ( Axis pornicus ) (Nath et al, 2019).…”

“…Herein, the dispersion dynamics and high invasive potential of C. odorata under the effect of climate change and multiple anthropogenic stressors can facilitate its abrupt range expansion in introduced global landscapes (Kishore et al, 2024). In an ecological study of Manas National park, North East India, Banerjee et al (2023) with invasion risk map showed C. odorata to be even more aggressive invader compared to Mikania micrantha Kunth. In this respect, C. odorata specifically exhibited a strong negative association with native‐plant community structure when compared with M. micrantha .…”