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

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

Mendoza

Conferencia; AMERIDENDRO 2016; 2016

Laboratorio de Dendrocronología - IANIGLA - CCT CONICET Mendoza

p { margin-bottom: 0.25cm; line-height: 120%; }Fire is a frequentdisturbance in the Nothofagus pumilio forests across the southernPatagonian Andes. However, historical records of fire occurrence inthe region are scarce. Most fire histories in the Patagonian Andeshave been derived from fire scars in conifers; broadleaf species haverarely been used. Recent studies have shown the potential of thedeciduous N. pumilio, the dominant tree in the southern Andes, fordeveloping tree- ring based records of fire history in the region. Inthis study, we reconstructed the fire history in N. pumilio forestsalong a precipitation gradient from the dry forest-steppe ecotonearound Lago Viedma (49°29'S) to the humid forests in the vicinity ofLaguna del Desierto (49°05'S). We analyzed a total of 153 fire-scarred partial cross-sections from 8 sites along this precipitationgradient. Although several fires were dendrochronologically datedacross the region, two major events were recorded for the years 1924and 1935 in the dry and wet sectors, respectively. The total areaburned during the fires is related to the fire location along thesteep rainfall gradient: fires in the eastern dry sites cover largerareas (more than 500 ha) than those recorded in the western and morehumid sites (less than 5 ha) reflecting the large influence ofmoisture in modulating fire size. To determine the influences ofclimatic variation on fire occurrence, we compare the scarce climaticrecords in the region with our fire history. Although fire occurrenceis closely related to human activities, we found fire yearsassociated with warm and dry summers.