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Elevated CO 2 does not offset greater water stress predicted under climate change for native and exotic riparian plants
Author(s) -
Perry Laura G.,
Shafroth Patrick B.,
Blumenthal Dana M.,
Morgan Jack A.,
LeCain Daniel R.
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12030
Subject(s) - riparian zone , seedling , biomass (ecology) , water use efficiency , arid , introduced species , native plant , biology , invasive species , ecosystem , climate change , agronomy , environmental science , botany , ecology , habitat , irrigation
Summary 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 CO 2 might ameliorate these effects by improving plant water‐use efficiency. We examined the effects of CO 2 and water availability on seedlings of two native ( P opulus deltoides spp. monilifera , S alix exigua ) and three exotic ( E laeagnus angustifolia , T amarix spp., U lmus pumila ) western North American riparian species in a CO 2 ‐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 CO 2 increased biomass by 15%, with similar effects on natives and exotics. Elevated CO 2 increased intrinsic water‐use efficiency (Δ 13 C leaf ), but did not increase biomass more in drier treatments than wetter treatments. The moderate positive effects of elevated CO 2 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 CO 2 , and will reduce growth more for native Salix and Populus than for drought‐tolerant exotic species.