Interplay of limiting factors explains context dependence in plant invasions

Context dependence impedes accurate prediction in ecology, including the extent and impact of invasion. Using a grassland experiment, we show that the interplay of limiting factors can explain why invasion trends vary with circumstance. By manipulating invader seed dose and physical disturbance and tracking cover of groups of fast and slow invaders in three communities over three years, we examined how seed-, resource- and growth rate-limitation affected the abundance and diversity impacts of invading plants. Evidence indicated that seeds primarily limited cover of resource-acquisitive fast invaders in early and mid successional communities, growth rate limited resource conservative slow invaders in early and mid succession, and resources limited invasion of both groups in late succession. Resident community diversity declined as invader cover increased, consistent with effects of resource limitation. A greater focus on limiting factors in invasion ecology will provide us with a structure for predicting invasion outcomes in different situations.