Firn J., MacDougall A.S., Schmidt S.M. & Buckley Y.M. (2010).
Early emergence and resource availability can competitively favour natives over a functionally-similar invader.
Oecologia. 163: 775-784
Competition is an interaction between living organisms for resources, space or other prizes where ultimately there is a winner and loser(s). As a society we love competition, it forms an enate part of our character, with some even saying humans thrive on it. Some people might prefer team competitions, e.g. cricket, ice hockey (GO CANADA GO!), baseball; some people might prefer one on one competitions, e.g. boxing, singles tennis, ultimate fighting; then others might (particularly plant ecologists like me) prefer competitive interactions between plant species! In this study, we take an invasive plant species that is often described as competitive and set-up competitive interactions between this species and two native grasses. All three of these species are functionally similar— C4 perennial, tussock grasses capable of growing under similar climatic and edaphic conditions. Once Lovegrass dominates, these species tend not to co-exist in the same community together. The limiting similarity hypothesis suggests that these three species should compete for resources and because of the recent dominance of the invader it should be the strongest competitor. In this study, we found that the invader is not always competitively superior; instead, its competitive ability depends on the abiotic and biotic conditions. Under pulsed water/low nutrients or continuous watering, the ability of the invader to suppress the growth of the natives was reduced; while the natives were able to suppress the growth of the invader when they had a 3 week head-start. These findings provide insight for restoration, as the competitive effect of a functionally similar invader may be reduced by altering abiotic and biotic conditions in favour of natives.