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- Title
Competitive interactions between established grasses and woody plant seedlings under elevated CO levels are mediated by soil water availability.
- Authors
Manea, A.; Leishman, M.
- Abstract
The expansion of woody plants into grasslands has been observed worldwide and is likely to have widespread ecological consequences. One proposal is that woody plant expansion into grasslands is driven in part by the rise in atmospheric CO concentrations. We have examined the effect of CO concentration on the competitive interactions between established C grasses and woody plant seedlings in a model grassland system. Woody plant seedlings were grown in mesocosms together with established C grasses in three competition treatments (root competition, shoot competition and root + shoot competition) under ambient and elevated CO levels. We found that the growth of the woody plant seedlings was suppressed by competition from grasses, with root and shoot competition having similar competitive effects on growth. In contrast to expectations, woody plant seedling growth was reduced at elevated CO levels compared to that at the ambient CO level across all competition treatments, with the most plausible explanation being reduced light and soil water availability in the elevated CO mesocosms. Reduced light and soil water availability in the elevated CO mesocosms was associated with an increased leaf area index of the grasses which offset the reductions in stomatal conductance and increased rainfall interception. The woody plant seedlings also had reduced 'escapability' (stem biomass and stem height) under elevated compared to ambient CO levels. Our results suggest that the expansion of woody plants into grasslands in the future will likely be context-dependent, with the establishment success of woody plant seedlings being strongly coupled to the CO response of competing grasses and to soil water availability.
- Subjects
COMPETITION (Biology); WOODY plants; PLANT ecology; SOIL moisture; CARBON monoxide &; the environment; GRASSES
- Publication
Oecologia, 2015, Vol 177, Issue 2, p499
- ISSN
0029-8549
- Publication type
Article
- DOI
10.1007/s00442-014-3143-z