Vegetation response to different forcings during the Holocene in the Rio de la Plata grasslands and southern Patagonia.

A.R. PRIETO, M.V. MANCINI, S. STUTZ, I. VILANOVA, M.S. TONELLO

Bariloche, Argentina

Congreso; VI Southern Connection Congress; 2010

<!-- /* Font Definitions */ @font-face {font-family:DejaVuSans-Bold; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:0; mso-generic-font-family:auto; mso-font-format:other; mso-font-pitch:auto; mso-font-signature:3 0 0 0 1 0;} @font-face {font-family:DejaVuSans; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:0; mso-generic-font-family:auto; mso-font-format:other; mso-font-pitch:auto; mso-font-signature:3 0 0 0 1 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} h1 {mso-style-next:Normal; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; page-break-after:avoid; mso-outline-level:1; mso-layout-grid-align:none; text-autospace:none; font-size:10.0pt; font-family:DejaVuSans-Bold; mso-font-kerning:0pt;} p.MsoBodyText, li.MsoBodyText, div.MsoBodyText {margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; mso-layout-grid-align:none; text-autospace:none; font-size:10.0pt; font-family:DejaVuSans; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman"; font-style:italic;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> This project is being carried out to improve the understanding of the Río de la Plata grasslands (RPG) and southwestern Patagonia (SWP) paleoclimate based on new palynological records from different environments with different temporal resolution since the Last Glacial. Both areas were selected considering their vulnerability to the present climate change. The aims are to obtain a better insight into paleoclimatic interpretations, to distinguish natural (climate change, sea-level fluctuations, volcanic eruptions) from anthropic forcing implied in vegetation changes, to analyze if the same forcings were at work in both areas for different time-windows, and to identify fire frequencies related to different climatic conditions and human impact. Holocene quantitative climatic estimations from the RPG and SWP pointed out that the variability of Pann associated to changes in the atmospheric circulation was a major forcing in both areas. However, temperature change did also induce vegetation changes in the northern Santa Cruz forest and in the semi-arid steppes. In southern Patagonia fire regimes could be closely related to the Pann trends but whether these have a direct effect on vegetation or not need further analysis. During the mid-Holocene RPG coastal vegetation was strong ly influenced by sea-level fluctuations and volcanic ash fall influenced the semi-arid Patagonian communities. Anthropogenic forcings has been a major cause of vegetation change since the European settlement