S. Aravind1,2, Subhrajit Goswami1,3, Ankila J. Hiremath1 and Bharath Sundaram1
1Ashoka Trust for Research in Ecology and the Environment (ATREE), Bengaluru, India
2Pondicherry University, India
3Doon University, Dehradun, India
The invasion of Lantana camara L. (hereafter, lantana) is considered as one of the primary threats to plant communities in the Western Ghats biodiversity hotspot in India. The bulk of the research on the impacts of invasive plants lacks a temporal context, with more than half of all studies lasting less than 1 year and less than 8% of studies extending over 4 years or more (Stricker et al. 2015). We examined the pattern of spread and impacts of lantana invasion on native vegetation across different forest types in a heterogeneous landscape from 1997 to 2018. This is probably the only long term study tracking invasive species and its impacts in India. We extend the study on lantana inventory done by Murali & Shetty (2001) in 1997 across a study area of 540 km2, which was re-censused by Sundaram & Hiremath (2012) in 2008. In 2018, we revisited the plots and evaluated the impact caused by lantana at the landscape level and at the level of individual forest types. Over two decades, there was a tremendous increase in the presence and abundance of lantana, accompanied by a decline of native species. The mean density of lantana increased tenfold over two decades, while native species density declined by nearly half. Lantana invasions were accompanied by reductions in species richness and diversity, and an increase in evenness both at the landscape level and at the level of forest types. The highly heterogeneous landscape has become more homogeneous over the 20 year period. Lantana became the dominant species by 2008 (Sundaram & Hiremath 2012), and seems to have accelerated its dominance by 2018. Species composition and demographic structure in different forest types also showed a significant shift. Overall, our long-term monitoring of lantana invasion enables prediction of possible future trajectories of invasives and impacts on native species, and therefore can aid in remedial management.
Murali K. S. & Setty R. S. (2001) Effect of weeds Lantana camara and Chromelina odorata growth on the species diversity, regeneration and stem density of tree and shrub layer in BRT sanctuary. Curr. Sci. 80: 675–678.
Stricker K. B., Hagan D. & Flory S. L. (2015) Improving methods to evaluate the impacts of plant invasions: lessons from 40 years of research. AoB Plants 7: plv028
Sundaram B. & Hiremath A. J. (2012) Lantana camara invasion in a heterogeneous landscape: patterns of spread and correlation with changes in native vegetation. Biol. Invas. 14: 1127–1141.