Fire history of Nothofagus pumilio forests along a precipitation gradient in southern Patagonian Andes of Argentina

BIANCHI, LUCAS O.; RADINS, MARCOS; MUNDO, IGNACIO A.; BONADA, ANABELA; VILLALBA, RICARDO

Mendoza

Congreso; Ameridendro 2016 - Third American Dendrochronology Conference; 2016

IANIGLA - Tree Ring Society

p { margin-bottom: 0.25cm; direction: ltr; color: rgb(0, 0, 0); line-height: 120%; }p.western { font-family: "Liberation Serif","Times New Roman",serif; font-size: 12pt; }p.cjk { font-family: "Droid Sans Fallback"; font-size: 12pt; }p.ctl { font-family: "FreeSans","Arial",sans-serif; font-size: 12pt; }Fire is a frequent disturbance in theNothofagus pumilioforests across the southern Patagonian Andes. However, historicalrecords of fire occurrence in the region are scarce. Most firehistories in the Patagonian Andes have been derived from fire scarsin conifers; broadleaf species have rarely been used. Recent studieshave shown the potential of the deciduous N.pumilio, the dominant tree in thesouthern Andes, for developing tree-ring based records of firehistory in the region. In this study, we reconstructed the firehistory in N. pumilio forestsalong a precipitation gradient from the dry forest-steppe ecotonearound Lago Viedma (49º 29'S) to the humid forests in the vicinityof Laguna del Desierto (49º 05'S). We analyzed a total of 153fire-scarred partial cross-sectionsfrom 8 sites along this precipitation gradient. Although severalfires were dendrochronologically dated across the region, two majorevents were recorded for the years 1924 and 1935 in the dry and wetsectors, respectively. The total area burned during the fires isrelated to the fire location along the steep rainfall gradient: firesin the eastern dry sites cover larger areas (more than 500 ha) thanthose recorded in the western and more humid sites (less than 5 ha),reflecting the large influence of moisture in modulating fire size.To determine the influences of climatic variation on fire occurrence,we compare the scarce climatic records in the region with our firehistory. Although fire occurrence is closely related to humanactivities, we found fire years associated with warm and dry summers.