Changes in height growth patterns in the upper tree-line forests of Tierra del Fuego in relation to climate change.

IVANCICH HORACIO; MARTÍNEZ PASTUR GUILLERMO; ROIG FIDEL; BARRERA MARCELO; PULIDO FERNANDO

Concepción

Conferencia; IUFRO Landscape Ecology Conference; 2012

IUFRO

Nothofagus pumilio forests occupy the mountain slopes reaching to altitudinal limit forest. At this extreme stressful environment, we found the optimum conditions to study changes in growth pattern due to climate variations. The aim was to analyze recent changes in stem height growth in forests located in the altitudinal tree-line along Tierra del Fuego (Argentina), and establish possible linkages to changes observed in surface temperature during the last decades. Nine sites were sampled, and four plots were measured in each site. Forest structure and stem analyses were conducted to assess height growth patterns. ANOVAs and classification analyses were conducted using site and years as main variables. Tree-growth height increased along the time, e.g. 1.0 cm.year-1 during 1870-1959, 2.7 cm.year-1 during 1960-1979 and 5.0 cm.year-1 during 1980-2010. These differences were significant between periods and sites, explained by geographic location. Increments in stem height growth seems to be related with positive trends in the worldwide average surface temperature during the second half of the twentieth century. A decline in the stem height growth registered during the last two decades, also can be explained by regional lowering of the average air temperature.