Limestone Forests and Caves
Limestone has supplied us with many benefits, yet we remain indiscriminate in our quarrying and clearing activities. They form part of the natural world that is so critical to this planet's life support system, yet they receive so little protection and conservation.
Caves within the hills support bat populations vital for pollination and pest control. Some have underground river systems that help regulate the flow of water into the main rivers. These underground river systems become refugia for freshwater fauna during the dry season when streams above ground disappear completely whilst pools of water may still be present in the caves.
Limestone hills take a long time to form, but once gone, they are irreplaceable, and with them the entire ecosystem.
Apart from quarrying, limestone hills are also vulnerable to other threats. Among them are unsustainable agriculture practices such as burning and indiscriminate land clearing; mining for gold and antimony in limestone sites such as in Bau, Sarawak; building of temples, especially at ground-level caves in Pahang, Perak and Selangor; tourism development such as in Langkawi and Sarawak; and flooding related to hydroelectric dam construction as in Kelantan, Pahang and Terengganu.
Granting these limestone hills state park status would be ideal as most of them are on state land. Unless limestone hills are located in inaccessible and remote areas or lie within protected national parks, there are few laws to protect them.
In Peninsular Malaysia, limestone forest areas are estimated at 26,000ha, mostly concentrated in the northern states, and 50,000ha in Sabah and Sarawak. There are more than 300 scattered limestone outcrops in the peninsula. A number of these consist of limestone islands in the Langkawi archipelago, with major outcrops in Kelantan, Perlis, Kedah, Perak and northern Pahang. Many more are scattered in the lowlands of eastern Sabah and in southwest and northeast Sarawak.
Limestone forest areas are home to about 14% of the region's plant species, and of these, about 130 species are known to grow only in limestone areas and nowhere else. Many orchid species are ideally adapted to the harsh environment of limestone hills. However, some species, such as the white slipper orchid (Paphiopedilum niveum), are already in danger of extinction due to over-collection by horticulture enthusiasts.
Other than wild orchids, limestone areas with caves are also important to bats. These insect-eating bats consume tonnes of mosquitoes and moths, and this benefits us and our crops. The fruit bats also do us a great favour by pollinating trees, especially fruit trees, as well as providing their guano as an invaluable fertiliser.
Some reptiles and amphibians are also well adapted to living in caves. The cave racer, a cave-dwelling snake, is commonly encountered and feeds on bats. Freshwater turtles, such as the Asian leaf turtle, are a common resident in streams flowing through caves. Additionally, several invertebrates such as the cave cricket may only be found in caves.
What would help is having a long-term strategy for the use of limestone hills. These hills can be assessed for their biodiversity, cultural and recreational values. Those that rank highly could be protected while others that rank low in these aspects can be assigned to quarrying. It would be less damaging for certain hills to be written off completely for quarrying, than for indiscriminate quarrying activities here and there as is common in Perak.
If limestone formations and their ecosystems are to survive, there needs to be more awareness about their importance among the public and state authorities to support their conservation.