Magnitude and timing of resource pulses interact to affect plant invasion

Human activities can cause resource fluctuations through reducing uptake by the resident vegetation (e.g., disturbance) or through changing external resource supply (e.g., fertilization). Resource fluctuations often occur as pulses which are low frequency, large magnitude and short duration, and now are recognized as an important driver of plant invasions. However, resource pulses often vary dramatically in a number of attributes, yet how these attributes mediate the impacts of resource pulses on plant invasions remains unclear. Erigeron canadensis is a serious invader of disturbed habitats and agricultural fields in China. Thus, it experiences nutrient pulses with different magnitudes and timings. Here, we grew E. canadensis and six co-occurring native plant species with three different magnitudes of nutrient enrichment (low, medium or high). For each magnitude, we added equivalent amounts of nutrients with a constant supply as a control or one of three pulses with different timings (e...