to biodiversity worldwide after habitat destruction and species exploitation (WEF, 2020). Increasing globalization, together with environmental changes including climate change, favour the introduction and establishment of IAS. International trade is a key route for IAS, through trade in new plant species and animals. Transportation and shipping and trade in agricultural commodities, can also lead to unintentional introduction of IAS. As IAS transcend national borders, it is important to have coordinated action at the ASEAN rather than just at the national level. Combining information on invasion and establishment of IAS can strengthen early-warning and eradication strategies especially, since most countries have limited capacity to act. A legislative framework should be in place to manage and mitigate the impact. The importance of mitigating the spread and impact of IAS is recognised under the Convention on Biological Diversity (CBD). Article 8(h) of the CBD states that Each Contracting Party shall, as far as possible and as appropriate, prevent the introduction of control or eradication of those alien species which threaten ecosystems, habitats or species. In Southeast Asia, invasive plants have clogged up waterways, and invasive fish have displaced native species thus transforming aquatic ecosystems (Yong et al., 2014). One of the most destructive invasive weeds threatening ASEAN and global natural ecosystems is the giant salivinia (Salvinia molesta). It is found in different waterbodies including water catchment areas, irrigated rice fields, ponds and slow-moving rivers. It has infested naturally occurring oxbow lakes in Kinabatangan, Sabah in Malaysia. Mechanical and physical control have been ineffective and uneconomical. However, biological control using the weevil Cyrtobagous salviniae has proven to be highly effective in Peninsular Malaysia and has recently been distributed in Sabah also so as to establish populations in areas infested with S. molesta.
Image 5.3: Clidemia hirta
Source: Wikimedia, photo by Forest & Kim Starr
The IAS, Clidemia hirta from tropical America suppresses the native canopy tree species that are dependent on gaps for successful regeneration. It was postulated to have the potential to modify the forest ecosystem at Pasoh Forest, a near pristine primary forest in Peninsular Malaysia by changing the composition of the plant communities in the treefall gaps thus altering forest regeneration (Peters, 2001). It thus suppresses the native canopy tree species that are dependent on gaps for successful regeneration.
As Southeast Asia is mainly an agricultural region, early monitoring and rapid action at the operational level are extremely important for mitigating IAS, especially those that may destroy crops. Malaysia adopted the National Action Plan on Invasive Alien Species (NAP IAS) in 2014−2018 which was subsequently renewed 69
