Abstract

DEZZOTTI, Alejandro; MEDINA, Andrea  and  MORTORO, Ariel. Climate and life forms of plants in the andean - extra-andean transition of northern Patagonia from argentina. Bol. Soc. Argent. Bot. [online]. 2021, vol.56, n.3, pp.347-369. ISSN 1851-2372.  http://dx.doi.org/10.31055/1851.2372.v56.n3.32588.

Background and aims: Restricted self-locomotion exposes plants to stress which promotes adaptation. In the Andean - Extra-Andean ecotone of Argentinean Patagonia, adaptation has been mainly associated to aridity. In this research, the adaptation of plants to coldness was evaluated based on the analysis of life forms which represent a survival strategy during the unfavourable season.

M&M: In Aguas Frías (38° 46' S, 70° 54' W) and Litrán (38° 54' S, 71° 01' W), the climate was characterized through meteorological information and the vegetation types through a physiognomic - floristic approach. Plants were classified according to species, origin, growth form, and life form, and the abundance of each category was estimated through incidence data.

Results: The climate is cold temperate humid to semiarid, and the vegetation belongs to the Patagonian and Subantarctic phytogeographic provinces. The vegetation units comprised forests, steppes and grasslands. Total richness was 148; 139 species were natives and perennials, 122 herbaceous, 143 rare, and 64 belonged to a single unit. The similarity between units was low, and hemicryptophytes dominated the floristic (68%) and the vegetational (56%) biological spectra.

Conclusions: The intense environmental gradient shaped the strong compositional and structural variability of the vegetation, and coldness would have been a key factor judging by the dominance of a life form adapted to low temperatures. A better understanding of this relationships is essential for a sound management of Patagonian ecosystems.

Keywords : Cold stress; forest - steppe ecotone; species frequency; species richness.

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