Recovery dynamics and invasibility of herbaceous plant communities after exposure to experimental climate extremes
Faculty of Sciences. Biology
Basic and applied ecology / Gesellschaft für Ökologie [Göttingen] - Göttingen
, p. 583-591
University of Antwerp
Do climatic extremes increase the invasibility of plant communities, for example through the creation of gaps and the associated local surplus of available resources? To address this question, small experimental communities consisting of three forb species were first subjected to extreme drought and/or heat treatments in different seasons and species mortality and end-of-season biomass were examined. Then, the establishment of new species and their effects on the productivity of the community were recorded in two subsequent years without additional treatments. The immediate response to the experimentally induced extremes was similar in all three originally planted species, with drought treatments in summer and autumn, especially when combined with heat, inducing the greatest plant mortality. Recovery in terms of end-of-season aboveground biomass was species-specific however. The dominant species, the N-fixer Trifolium repens, recovered poorly from the drought and drought+heat treatments. Differences in community biomass between treatments and to the controls were no longer significant in the next year. Graminoid species, especially, successfully invaded the communities, possibly because of functional dissimilarity with the species already present. Invasibility in the year following the extreme events was increased in communities that had been exposed to both a heat wave and a drought, but the number of newly established species did not increase community productivity. The identities of invading species varied distinctly, but had no clear relation with the extreme events the communities had been exposed too. The induced climate extremes greatly affected the survival and productivity of the species and influenced the invasibility of the plant communities. However, none of the community properties seemed to be affected in the longer run, as the induced responses faded out after one or two years.