Introduced plants rarely ‘outcompete’ native plants. When we overgraze with livestock, kill predators, burn and clear, fewer plant species may survive. Those that do well have special adaptations to high disturbance regimes. High grazing pressure may facilitate communities dominated by less palatable plants, some of which are introduced.
Plant diversity forms a ‘biotic resistance’ that limits competitive dominance by any one species. Even in systems in which introduced plants are competitively superior, coexistence can develop through the complexity of interactions that form ecosystems. Large predators can help restore a more diverse plant community in which monocultures are less likely to form.
Weeding does not help promote native plants, but weeds do. There are many examples of native plants and animals forming dependencies on introduced plants. For instance, across its introduced range the lantana shrub (Lantana camara) provides a broad variety of benefits by promoting the regeneration of some native plant species, improving soil retention, and providing habitat for native animals, along with a range of medical uses and opportunities for local economies.
What have the weeds ever done for us?
Apart from increasing primary productivity… sequestering carbon… feeding livestock… feeding wild herbivores… sheltering small animals… sheltering large animals… providing food, medicine and employment to humans… stabilising, aerating and improving soil… promoting native plants… and improving overall biodiversity…..?
By Arian Wallach