It’s often better to eradicate, but can we eradicate better?

Invasive species eradications have achieved important conservation gains the world over. Growing numbers of eradication take place, however, in complex and highly altered ecosystems with high risks of unexpected ecological effects. Ecosystems that contain multiple invaders, have lost one or more native species along with their functional roles, or have undergone long-term change to soil and other site conditions can respond to eradication with mixed results. The most common secondary outcome of a single-species eradication is the ecological release of a second (plant or prey) exotic species previously controlled by the removed species (herbivore or predator) through top-down regulation. Examples of a variety of other undesirable secondary outcomes also exist, challenging invasive species managers to develop tools for predicting and averting these “surprises”. Most unexpected outcomes can be understood and anticipated through knowledge about species interactions and the general ecological rules that they follow. Several tools that already exist, including thorough pre- and post-eradication monitoring and restoration measures such as reseeding, simply need to be applied more routinely in eradication projects. Other areas deserve to be carefully explored, such as formal but qualitative approaches to ecological assessment during the planning stages of an eradication project. As eradication moves from narrow invasive species management to actively pursuing and practicing restoration, it will be able to achieve clear conservation results in increasingly challenging settings without accidental, adverse effects.

Author Zavaleta, E. S.
Year 2002
Secondary title International Conference on Eradication of Island Invasives
Publisher IUCN Invasive Species Specialist Group
Pages 393-403