Asociaciones polínicas de sedimentos superficiales del norte de la región chaqueña argentina.

PEREIRA ELIZABETH; TORRES GONZALO ROMÁN

REVISTA DE BIOLOGíA TROPICAL

REVISTA DE BIOLOGIA TROPICAL

Lugar: Turrialba; Año: 2018

0034-7744

The composition and distribution of pollen assemblages of surface sediments along an environmental in the north of Argentine Chaco region (23°-27°S, 59°-63°W) was analyzed, in order to recognize the spatial changes of vegetation and distinguish indicators of natural (floods, droughts) and/or anthropogenic disturbances (fires, weeds of crops and grazing). Thirty-five samples were taken into an environmental gradient comprising 600 km length in SE-NW direction. The analyses was performed by multivariate methods and the importance value index (IVI). Zonation showed a gradual replacement of biotypes and taxa. In the eastern zone, the pollen of palms (Copernica alba), herbs (Poaceae) and high trees (Schinopsis balansae) were dominant. Towards the middle zone, the pollen of low trees (Schinus, Prosopis ruscifolia, Pisonia zapallo), shrubs (Celtis, Castela) and herbs (Amaranthaceae/Chenopodiaceae, Poaceae) were dominant. The western zone recorded the highest content of pollen of high trees (Schinopsis balansae, Schinopsis lorentzii, Astronium). Pollen types were detected that allowed to discern environmental contingencies, such as floods (Copernicia alba, Juncaginaceae, Cyperaceae) and anthropic activities, such as fires (Trithrinax, Shinus, Aspidosperma quebracho-blanco), weeds of crops (Amaranthaceae/Chenopodiaceae, Gomphrena, Urticaceae, Ambrosia) and grazing (Prosopis ruscifolia, Prosopis kuntzei, Capparicordis, Cerciduim praecox). The most important pollen types were: Schinopsis balansae (9%), Celtis (8.4%), Poaceae (7.5%), Schinus (6.9%), Copernicia alba (3.7%), among others. Three pollen assemblages were differentiated which represent the follow communities: 1) palms and savannas, 2) low forests and scrublands and 3) high forests, that are distributed in precipitation thresholds corresponding to, 1 100 - 1 000 mm, 1 000 - 850 mm and 850 - 700 mm respectively. Results expand the knowledge about the pollen assemblages of the Argentine Chaco region, offering a good perspective to interpret the dynamic of the landscape during the Holocene in the region.