Impacts in Asia
The availability of plants used daily by many poorer communities in Asia depends on the biodiversity of the areas in which they live. In Indonesia, more than 40 million people make use of about 6,000 plant species, while more than 80% of the Philippines’ rural population uses herbal remedies. Colonisation by invasive species diminishes the supply of essential native plants – for instance, by smothering trees and affecting regeneration – and greatly increases the time it takes people to collect what they need.
The overwhelming majority of the world’s smallholder family farms – 500 million (87%) – are in Asia. They are feeling the impact as invasive species destroy crop yields, and increase the cost of cultivation and farm management due to the pesticides, herbicides and labour required to keep them at bay.
Rice is the most important crop in Asia, grown on over 197 million hectares, and providing food and income for 474 million people. Invasive pests including the common rice black bug (Scotinophara coarctata) constrain production in a number of countries – attacking rice plants at all growth stages and causing losses of up to 35%, equivalent to US$55m.
Cassava is planted as a famine reserve crop due to its ability to thrive in poor soils and resist drought. Asia produces 28% of the world’s cassava, but the crop’s potential to alleviate poverty and support rural development is being limited by pests and diseases, particularly the cassava mosaic virus.
Invasive plants and shrubs also reduce the productivity of pasturelands and displace indigenous forage and grass species that livestock graze on, driving pastoralists into smaller, less optimal areas, or forcing them to travel a great deal further to find viable grazing lands.
Fishing and water transport are important in many wetland areas of Asia, such as Cambodia, Vietnam and the Philippines, and invasive aquatic weeds are widespread. Water hyacinth, for example, forms dense mats on the surface, blocking out sunlight and outcompeting native floating plants and other aquatic organisms for nutrients. Weeds also impede river traffic and contribute to flooding by clogging waterways.