Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Seed biology and early seedling developmental traits of Clidemia hirta, an invasive species of Sri Lankan rainforests compared to two native species sharing the same habitat.

Abstract

Comparative studies on invasive species with native species sharing the same habitats are valuable in controlling invasive plants. This study compared seed biology and seedling development traits of two native species, Melastoma malabathricum L and Plectranthus kanneliyensis Willemse, and the invasive species Clidemia hirta (L.) D. Don, which share a tropical rainforest habitat in Sri Lanka. In particular, the adaptability of these species to their habitat was assessed. Seed moisture content, dormancy status and desiccation sensitivity were also tested. Seedling growth and survival was observed through greenhouse experiments. Seeds of all the study species germinated > 50% in light/dark conditions, but none germinated in complete darkness or under green light. Time taken to reach 50% germination (T50) and final germination percentage suggested that C. hirta and P. kanneliyensis seeds are non-dormant while M. malabathricum seeds are dormant. All study species produced desiccation tolerant seeds. Under all light conditions, seeds of C. hirta recorded the highest seed germination and seedling survival percentage, while P. kanneliyensis had the highest growth rate. Interspecies difference in photosynthesis efficiency was not observed. These experiments demonstrated that the study species have different strategies to adapt to their shared habitat. Furthermore, higher germination percentage and higher survival may be the key factors that determines the invading ability of C. hirta, enabling them to outcompete M. malabathricum and P. kanneliyensis. Hence, immediate actions must be taken to prevent further invasion of C. hirta into disturbed sites in tropical rainforest regions.