Effect of invasive species on forest composition in tropical dry forest: a case study of invasion by Gliricidia sepium

Ecological concerns caused by biological invasion have been considered an inevitable threat to global sustainability. The superior competitive ability of invasive plant species (IPS) has an impact on vegetation composition and loss of native flora. Recognising IPS at an early stage would significantly contribute to controlling invasive plants, protecting biodiversity and formulating appropriate strategies. Most of the studies available on invasive plants are descriptive and largely confined to non-woody species. The present study focused on the alien Gliricidia sepium, a tree species, to determine the invasive potential of its distribution in tropical dry deciduous forests of Central India. Forty square plots (25 x 25 m) were laid out at each uninvaded and invaded forest to enumerate phytosociological attributes to determine the impact of G. sepium on vegetation composition and community structure. Higher density (37.2 individuals ha(-1)), basal area (6.32 m(2) ha(-1)) and importance value index (95.8) contributed by G. sepium clearly showed the suppression of seedlings, saplings and trees of native forest species at the invaded sites in terms of species richness, cover and other attributes as compared to at the uninvaded sites. Further, other invasive attributes such as higher seed production, dieback phenomenon, higher coppicing power and higher growth rate as observed during the study clearly affirmed the early speculation that the species might be invasive. The species has a strong potential to spread vigorously and may gradually become invasive throughout the country as already reported from various parts of India. In the present study area, G. sepium was introduced due to restoration and plantation programmes and our findings indicate its negative impact on the native vegetation. Thus, we strongly recommend the avoidance of this species for both plantation and restoration programmes, especially for Indian forests. The study helps in early recognition and rapid monitoring of G. sepium to control its spread throughout the country.