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Greater impact of extreme drought on photosynthesis of grasslands exposed to a warmer climate in spite of acclimation
Author(s) -
Zavalloni Costanza,
Gielen Birgit,
De Boeck Hans J.,
Lemmens Catherine M.H.M.,
Ceulemans Reinhart,
Nijs Ivan
Publication year - 2009
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2009.01214.x
Subject(s) - stomatal conductance , acclimatization , transpiration , photosynthesis , environmental science , air temperature , precipitation , carbon dioxide , climate change , water use efficiency , biology , agronomy , botany , horticulture , ecology , atmospheric sciences , geography , meteorology , geology
In view of the projected increase in the frequency of extreme events during this century, we investigated the impact of a drought extreme on leaf ecophysiological parameters and carbon isotope composition (δ 13 C) of grassland communities with species richness (S) of one, three or nine species. The communities, grown for 3 years at either ambient air temperatures (ambient T air ) or ambient T air + 3°C (elevated T air ), were additionally subjected to an imposed drought by withholding water for 24 days. During the previous 3 years equal precipitation was applied in both temperature treatments, thus communities at elevated T air had experienced more frequent, mild droughts. However, it was unknown whether this resulted in a higher resistance for facing extreme droughts. At similar soil matric potentials stomatal conductance (g s ) and transpiration (Tr) were higher at elevated than ambient T air , indicating acclimation to lower soil water content. Despite the stomatal acclimation observed, plants in elevated T air showed a lower resistance to the drought extreme as indicated by their lower photosynthetic rate (A max ), g s and Tr during the entire duration of the drought extreme. Lower values for A max , Tr and g s were also recorded in species at S = 3 as compared with species at S = 1 for both temperature treatments, but no further differences with S = 9 suggesting that stress was not alleviated at higher S‐levels. The discrimination of 13 C was poorly correlated with measurements of instantaneous leaf water‐use efficiency (A max /Tr) and, with this time scale and sampling method, it was not possible to detect any potential change in plant water‐use efficiency using leaf δ 13 C.