Anales del Jardín Botánico de Madrid, Vol 62, No 2 (2005)

Polen y vegetación en la Patagonia extraandina argentina a 45º S


https://doi.org/10.3989/ajbm.2005.v62.i2.15

Lidia S. Burry
Departamento de Biología, Universidad Nacional de Mar del Plata, Argentina

Héctor L. D’Antoni
Ames Research Center, NASA, United States

Jorge L. Frangi
Laboratorio Investigación de Sistemas Ecológicos y Ambientales, Universidad Nacional de La Plata, Argentina

Abstract


Modern pollen dispersal and deposition in relation to vegetation and environmental variables at 45° S was studied in Argentinian Patagonia east of the Andes to build a modern pollen model. This model will serve to identify modern pollen assemblages that are analog of past pollen assemblages. A west-to-east gradient of decreasing precipitation and increasing temperature determines four vegetation units: (1) grass steppe, (2) grass-bush steppe, (3) bush steppe and (4) bush-brush steppe. Pollen samples were analyzed by classification and ordination methods, and correlated to environmental variables. The steppes (a) dominated by the functional type grass, (1) grass steppe, and (2) grass-bush steppe located in the more humid and cooler west end of the region were separated from the (b) bush-dominated steppes (3) bush steppe and (4) bush-brush steppe occurring in the central and eastern parts of the region, where conditions are drier and warmer. Azonal communities were identified as halophytic bush steppes within different vegetation units along the west-east gradient. Environmental variables related to vegetation distribution are temperature and interannual precipitation variability associated with the precipitation gradient from the cordillera to the coast, and soil salinity in the case of azonal communities.

Keywords


community; functional types; modern analog; modern pollen; numerical methods

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