IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
artículos
Título:
Water use efficiency of 25 co-existing Patagonian species growing under different soil water availability
Autor/es:
GOLLUSCIO, R.A.; OESTERHELD, M.
Revista:
OECOLOGIA
Editorial:
Springer
Referencias:
Año: 2007 vol. 154 p. 207 - 217
ISSN:
0029-8549
Resumen:
The variation of plant water use efficiency(WUE) with water availability has two interacting components:a plastic response, evident when individuals of thesame genotype are compared (e.g. wet versus dry years),and an interspecific response, evident when different speciesliving in habitats with different water availability arecompared. We analysed the WUE of 25 Patagonian speciesthat belong to four life forms (grasses, shrubs, annual herbsand perennial herbs) in relation to the climatic conditionsof 2 years and the mean historic water availability experiencedby each species. To estimate water availability, wecalculated the effective soil water potential (EWP) of eachspecies, based on available information about soil waterdynamics, phenology and root system structure. To estimateWUE, we used isotopic discrimination of leaf C(D13C) and mean annual water vapour difference betweenleaves and atmosphere (De) measured in situ. For theplastic response, for every species and life form, WUEincreased from the dry to the wet year. We hypothesize thatphotosynthesis was less nutrient limited in the wet than inthe dry year, facilitating higher net photosynthesis rates perunit of stomatal conductance in the wet year. For theinterspecific response, WUE was lower in species native todrier habitats than in species native to wetter habitats. Thisresponse was mostly accounted for by a decrease in Dewith EWP. Annual herbs, which avoid drought in time(they have the earliest growth cycle), and shrubs, whichavoid drought in space (they have the deepest roots),showed the highest EWP and WUE. We conclude that theconventional wisdom which states that the highest WUEoccurs within a species during the driest years, and amongspecies in the driest habitats, does not always hold true, andthat co-existing life forms drastically differ in wateravailability and water economy.