Abstract

CHICAHUALA, Martín S; STEINAKER, Diego F  and  DEMARIA, Manuel R. Phenological responses of C₃ and C₄ grasses to annual changes in precipitation and temperature. Ecol. austral [online]. 2018, vol.28, n.2, pp.455-466. ISSN 1667-782X.

Temperature and precipitation are key factors in plant phenology and productivity. Modifications on growth and reproductive cycles may affect the relative fitness of the species, altering their interactions and ecosystem functions. In native grasslands of San Luis province, Argentina, C₃ (cold-season) and C₄ (warm-season) grasses coexist, which makes these grasslands particularly interesting. In this study, we evaluated how phenology of four native grasses (two C₃ and two C₄) is related to changes in temperature and rainfall. We compared phenological data collected in situ during two periods: from 1976 to 1986 and from 2008 to 2010. We found that warmer summers were related with a delay on the reproductive offset and the length of the reproductive cycle in all four species. In contrast, warmer springs were related with earlier flowering of C₄, but later flowering of C₃ grasses. Years with rainy winters were related with earlier flowering onsets in C₃ species, while rainy summers were related with later and longer reproductive cycles in C₄ grasses. These results provide valuable information about vegetation responses to climate and may be used for range management purposes.

Keywords : Winter grasses; Summer grasses; Poa ligularis; Piptochaetium napostaense; Eustachys retusa; Schizachyrium condensatum; Climate change; Functional groups; Climatic correlations; Reproductive phenology.

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