IDASZKIN Yanina Lorena
Does low temperature prevent Spartina alterniflora from expanding toward the austral-most salt marshes?
IDASZKIN, YANINA LORENA; BORTOLUS, A
Año: 2011 vol. 212 p. 553 - 561
Along the Atlantic coast of South America, the northern salt marshes (42º S or lower) are dominated by Spartina species while the southern salt marshes (43º S or grater) are dominated by Sarcocornia perennis. The most abundant Spartina species are Spartina densiflora, which is present in most coastal marshes, and Spartina alterniflora, that was never recorded above the ~ 42º S. It is not clear why S. alterniflora has not succeeded in the southern marshes, in which the low marsh zone remains as an extensive bared mud flat. We address the hypothesis that the absence of S. alterniflora in the south is driven by the cold temperatures inversely related with increasing latitudes along the East coast of Patagonia. To evaluate this hypothesis we carried out an experiment in which we manipulated the temperature in combination with frost formation and photoperiod. We found that cold temperature produced a negative effect on S. alterniflora, and this effect seems accentuated by the frost but not by the reduction in the photoperiod. Our results suggest that the absence of S. alterniflora in the southernmost salt marshes of Patagonia is a consequence of the frost as an outcome of the co-occurrence of low temperature and high humidity. The importance of our results is discussed in the context of the global warming and how Spartina species enlarge their distributional range toward higher latitudes.