"Urge governments and donor agencies to increase funding to facilitate the development of prevention, management and monitoring programmes, essential research, and economic analysis on invasive alien plants" (Declaration of Méze, 2005).

Invasive alien species are animals, plants or other organisms introduced by man into places out of their natural range of distribution, where they become established and disperse, generating a negative impact on the local ecosystem and species.

They represent the second most significant cause of species extinction worldwide after habitat destruction, and in islands, they are undisputedly first. The impacts of alien invasive species are immense, insidious, and usually irreversible. They are causing significant damage to ecological, economic and health levels. As a matter of fact, they can compete with native species, act as pests or pathogens for cultivated or domesticated species, or even disseminate allergic or infectious agents.

The spread of invasive species is facilitated by increasing trade, travel, and the transporting of goods, as these organisms may “hitchhike” on ships, containers, cars, soils, etc. This is therefore a global problem that requires international cooperation and action.

https://cmsdata.iucn.org/img/invasi

Collectively, invasive plants are estimated to spread as fast as 200 acres per hour on federal lands in the western U. S. Invasive weeds have invaded approximately 17 million acres of public lands and have quadrupled their range from 1985 to 1995. This value does not include the rate of spread on non-federal lands, so the rate of spread and its impact is actually much greater. The negative economic and ecologic impacts of invasive plants are many and include:

• Agricultural losses for both ranchers and farmers
• Damaged habitat of threatened and endangered species (flora and fauna)
• Displaced native vegetation and lowering of biodiversity
• Human health problems (allergies, irritants, infections, etc.)
• Increased requirements for land management and lower property values
• Increased soil erosion, damaged watersheds, water quantity and quality problems, and damaged fisheries
• Reduced opportunities for land use and recreational activities (hunting, birding, hiking, camping)