The interaction between invasive species had a higher negative impact on native flora, fauna, and the livelihood of indigenous communities across the world. However, there are limited studies to talk about the interaction between invasive species themselves and on native species. Our objectives were to examine the impact of Senna spectabilis (Senna) and its interaction with Lantana camara (Lantana). On native plant species. Furthermore, to understand the community perspective and their Traditional Ecological Knowledge towards Senna's impact on native species and also on Lantana. The study has been conducted in three ranges MM Hills, Palar, and Ramapura of Malai Mahadeshwara Hills Wildlife Sanctuary, covering an area of 906.2 km². For the vegetation survey, 10 X 10 meter plots were laid at random in areas that had been visually identified and classified by the presence of Senna, Lantana, and both species. The density of all stems ≥ 1 cm DBH, shrubs and climbers, herbs, and grass percentage. To understand the influence of Senna and Lantana on community variables data was analysed on species abundance, species richness, Shannon diversity index, and evenness.

The mean density of Senna ≥ 1 cm DBH is higher than all native species ≥ 1 cm DBH in all types of forest including moist deciduous, dry deciduous, and scrub. Community variables declined significantly in moist deciduous forest, but Lantana still dominates in other forest types. Native species abundance and species richness were high in the plots infested with Lantana and recorded low in plots infested with Senna compared to Lantana. There was also a tremendous change in the population structure of native tree species with the reduction in the density of saplings and seedlings because of competition with Senna and Lantana. Amongst other plant species, species richness of herbs was significantly affected in the presence of Senna than Lantana. Idemonstrated the insidious effect of Senna on native vegetation in our study area.

The communities in the study site had a compendium view regarding the spread of Senna, they collectively indicated that Senna is a menace to native biodiversity and it has more impact than Lantana. Interestingly, they indicate that Senna swiftly overshadows Lantana establishing its dominance in the landscape. They strongly suggest that Senna has to be removed or controlled, if not it will directly affect their livelihood by reducing the Non-Timber Forest Products and Wild Food Plants and creating fodder scarcity for their livestock in the forest.