Plant diversity assessment of karst limestone, a case study of Malaysia’s Batu Caves

Abstract

Batu Caves hill is typical of karst hills in Peninsular Malaysia due to its small size and high biodiversity. It harbours 366 vascular plant species that represent about 25% of the Peninsula’s limestone flora. Five species are endemic to Batu Caves and 23 are threatened species. This high biodiversity is the result of many microhabitats, each with their own assemblages of species. Threats are especially severe as the area of Batu Caves is surrounded by urbanisation that encroaches to the foot of cliffs, is vulnerable to fire, habitat disturbance and, formerly, by quarrying. Assigning a Conservation Importance Score (CIS) to all species is quantitative and accurate, can be implemented rapidly and produces reproducible results. Species with highest CIS are native species of primary vegetation, restricted to limestone substrates, endangered conservation status and, in this case, endemic to Batu Caves. It allows not only species, but microhabitats, sites within a hill and different hills to be compared. By identifying and surveying all microhabitats and focusing on locating endemic and threatened species, maximum biodiversity can be captured. Of the 16 microhabitats identified, the most threatened were the buffer zone, lower levels of steep earth-covered slopes and cave entrances. Application of this method provides a scientific basis for balancing the need to protect microhabitats and sites with the highest CIS, with their multiple uses by various stakeholders, which, at Batu Caves, include the activities of cave temples and eco-recreation. It also provides a scientific quantitative method to compare hills to ensure that those hills with highest CIS are not released for mining.