Ambassador - Diann Black Layne

IAS Headquarters

Escalating international trade is moving increasing numbers of organisms more rapidly around the world, thereby increasing the threat of harmful impacts by these species on native ecosystems and human economic interests. The government’s effort to prevent unwanted invasions is being overwhelmed. It must be noted that the acceleration of climate change has in turn also increased the incidence of the invasive alien species negative impacts on biodiversity and ecosystem services, threatening human health and life quality.

They have become one of the main threats to the world at both national and international levels as these species have spread and multiplied rapidly due to the lack of natural predators, diseases, and preference for more polluted environments.

Human impacts on the ecosystems of our planet continue to grow. Our increasing population and expanding levels of consumption mean that an increased amount of people are consuming more of nature’s goods and services, pushing against the limits of sustainability. Greatly expanding global trade is feeding this consumption, with large containers of goods moving quickly from one part of the world to another by plane, ship, train and truck. One critical element in this economic globalization is the movement of organisms from one part of the world to another through trade, transport, travel and tourism.

Many of these movements of organisms into new ecosystems where they are alien (also called non-native, non-indigenous or exotic) are generally beneficial to people. Others have very mixed impacts, benefiting some individuals or interest groups while disadvantaging others. And in few cases, especially disease organisms and pests of forests or agricultural crops, the alien species is detrimental to almost all.


This resource guide addresses the latter groups. Invasive Alien Species (IAS), that subset of alien species whose establishment and spread threatens ecosystems, habitats, or species with economic or ecological harm. Farmers have been fighting pests since the very beginnings of agriculture, and disease organisms have been a major focus of scientists for well over a hundred years.

However, the general global problem of invasive alien species has been brought to the world’s attention only relatively recently by ecologists who were concerned that native species and ecosystems were being disrupted. Much of the work to date on IAS has focused on their biological and ecological characteristics, the vulnerability of ecosystems to invasions, and the use of various means of control against invasives.
However, the problem of IAS is above all an anthropogenic one, for the following reasons:

◌ Many invasive alien species are intentionally introduced for economic reasons (a major human endeavour), implying that those earning economic benefits should also be responsible for economic costs should the alien become invasive.

◌ The populace is principally responsible for moving eggs, seeds, spores, vegetative parts, and whole organisms from one place to another, especially through modern global transport and travel.

◌ While some species are capable of invading well-protected, “intact” ecosystems, IAS more often seem to invade habitats altered by humans, such as agricultural fields, human settlements, and roadways.

◌ The magnitude of the problem of invasive alien species is defined by people, and the response is also designed and implemented by people, with different degrees of impact on different groups of people.

Substantial evidence indicates a rapid recent growth in the impact and number of IAS. Trade and more generally economic development, leads to more IAS. Countries that are more effectively tied into the global trading system tend to have more IAS, being positively linked to the development of terrestrial transport networks, migration rates, number of tourists visiting the country, and trade in commodities.

The general global picture shows tremendous mixing of species, with unpredictable long-term results but a clear trend toward homogenization. The future is certain to bring considerable additional species shuffling as people continue to influence ecosystems in various ways, not least through both purposeful and accidental introduction of species as an inevitable consequence of growing global trade.

This shuffling will yield species that become more abundant and many others that will decline in numbers (or even become extinct), but the overall effect will likely be a global loss of biodiversity at species and genetic levels.