The invasive weed Gorse (Ulex europaeus L.) in Sri Lanka: Implications of Naturalization over a Century

Prishanthini Muthulingam and Buddhi Marambe

Keywords:

Gorse, Ulex europaeus, naturalization, invasive alien plant species (IAPS), climate change

Abstract:

Gorse (Ulex europaeus L.) has invaded about 50 countries outside its native range (the Iberian peninsular and Western Europe), extending its range from the high-elevation tropics to the subAntarctic islands. Its habit, adaptability, and ability to colonize disturbed ground make it one of the world's most invasive weeds. Gorse has a long history in Sri Lanka, after its initial introduction in 1988 as an ornamental plant at the Royal Botanical Gardens, at Peradeniya. However, it is only about three decades since Sri Lanka first initiated research and assessments on gorse and similar Invasive Alien Plant Species (IAPS). Gorse eradication has been widely attempted in the Central Highlands of Sri Lanka, where gorse populations are localized. These control attempts have had limited success thus far. We reviewed ~60 country-specific and worldwide articles on gorse to gather information on its biology, impacts on biodiversity, and gorse management. We identified some significant gaps in research data and inadequate information, specifically on ecology, invasive behaviour, and management actions in reducing the weed’s spread. The IAPS project in Sri Lanka, initiated with the support of the Global Environment Facility (GEF) in 2011, was an eye-opener for more research on the ecology and behaviour of invasive plants, as well as their biodiversity values. Our studies, conducted exclusively on gorse-infested areas in Sri Lanka are still preliminary and limited. However, it was evident that gorse negatively affected the biodiversity of specially protected sites and natural forest areas, while playing a beneficial ecological role by providing habitat for specific endemic fauna. There is a possibility of gorse expanding its range and distribution into neighbouring zones with climate change occurring in the near future. Management actions taken against gorse in Sri Lanka are primarily mechanical removal, which is only marginally successful. Long-term, more effective and sustainable approaches are required to manage gorse in Sri Lanka. These will have to incorporate competition from fastgrowing indigenous vegetation, herbicides, biological control agents, and possibly, controlled grazing and controlled burning. In implementing such integrated management, particular attention needs to be paid to the identified research gaps, especially the impacts on native and endemic fauna and flora in sensitive habitats.