Disturbance is the key to plant invasions in cold environments

LEMBRECHTS J. J., PAUCHARD, A., LENOIR, J., NUÑEZ, M. A., GERON, C., VEN, A., BRAVO-MONASTERIO, P., TENEB, E., NIJS, I. & MILBAU, A.

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA

NATL ACAD SCIENCES

Lugar: Washington DC, USA; Año: 2016

0027-8424

Until now, nonnative plant species were rarely found at high elevationsand latitudes. However, partly because of climate warming, biologicalinvasions are now on the rise in these extremely cold environments.These plant invasions make it timely to undertake a thoroughexperimental assessment of what has previously been holding themback. This knowledge is key to developing efficient management of theincreasing risks of cold-climate invasions. Here, we integrate humaninterventions (i.e., disturbance, nutrient addition, and propagule input)and climatic factors (i.e., temperature) into one seed-addition experimentacross two continents: the subantarctic Andes and subarcticScandinavian mountains (Scandes), to disentangle their roles in limitingor favoring plant invasions. Disturbance was found as the maindeterminant of plant invader success (i.e., establishment, growth, andflowering) along the entire cold-climate gradient, explaining 40?60% ofthe total variance in our models, with no indication of any facilitativeeffect from the native vegetation. Higher nutrient levels additionallystimulated biomass production and flowering. Establishment and floweringdisplayed a hump-shaped response with increasing elevation,suggesting that competition is the main limit on invader success atlow elevations, as opposed to low-growing-season temperatures athigh elevations. Our experiment showed, however, that nonnativeplants can establish, grow, and flower well above their current elevationallimits in high-latitude mountains. We thus argue that cold-climateecosystems are likely to see rapid increases in plant invasions inthe near future as a result of a synergistic interaction between increasinghuman-mediated disturbances and climate warming