Elevated CO2 does not offset greater water stress predicted under climate change for native and exotic riparian plants

New Phytologist
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Abstract

  • In semiarid western North American riparian ecosystems, increased drought and lower streamflows under climate change may reduce plant growth and recruitment, and favor drought‐tolerant exotic species over mesic native species. We tested whether elevated atmospheric CO2 might ameliorate these effects by improving plant water‐use efficiency.
  • We examined the effects of CO2 and water availability on seedlings of two native (Populus deltoides spp. monilifera, Salix exigua) and three exotic (Elaeagnus angustifolia, Tamarix spp., Ulmus pumila) western North American riparian species in a CO2‐controlled glasshouse, using 1‐m‐deep pots with different water‐table decline rates.
  • Low water availability reduced seedling biomass by 70–97%, and hindered the native species more than the exotics. Elevated CO2 increased biomass by 15%, with similar effects on natives and exotics. Elevated CO2 increased intrinsic water‐use efficiency (Δ13Cleaf), but did not increase biomass more in drier treatments than wetter treatments.
  • The moderate positive effects of elevated CO2 on riparian seedlings are unlikely to counteract the large negative effects of increased aridity projected under climate change. Our results suggest that increased aridity will reduce riparian seedling growth despite elevated CO2, and will reduce growth more for native Salix and Populus than for drought‐tolerant exotic species.
Publication type Article
Publication Subtype Journal Article
Title Elevated CO2 does not offset greater water stress predicted under climate change for native and exotic riparian plants
Series title New Phytologist
DOI 10.1111/nph.12030
Volume 197
Issue 2
Year Published 2013
Language English
Publisher Wiley
Publisher location Hoboken, NJ
Contributing office(s) Fort Collins Science Center
Description 12 p.
First page 532
Last page 543
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