Invasion and distribution of exotic plants in the tropical forests of Western Ghats, India

Invasion of exotics in the tropical forests of Western Ghats is a serious concern for forest managers and conservationists. Present study aims to evaluate the diversity of exotics and native understory species occupying different forest types in relation to tree density in an area typical to the region. Stratified random sampling was used to analyze the diversity of both tree and understory flora of different vegetation types (different tropical forest types including subtypes like grasslands and savannahs and also teak plantations). One-way ANOVA and Spearman correlation was used to test the relationship between exotics, native understory species and trees. Results showed that diversity of exotic species is negatively correlated with the density of trees. Also, occurrence and distribution of exotics varied with proximity to human habitations. Rarefaction curve of understory flora (include both exotics and native understory species) in different vegetation types showed that floristic diversity was higher in disturbed and tree-scarce vegetation types as compared to undisturbed and tree-dense vegetation types.