%0 Journal Article %T Changes in height growth patterns in the upper tree-line forests of Tierra del Fuego in relation to climate change Cambios en los patrones de crecimiento de los bosques del l¨ªmite superior altitudinal de Tierra del Fuego en relaci¨®n al cambio clim¨¢tico %A Horacio S Ivancich %A Guillermo J Mart¨ªnez Pastur %A Fidel A Roig %A Marcelo D Barrera %J Bosque (Valdivia) %D 2012 %I Universidad Austral de Chile %X Nothofagus pumilio occupy the mountain slopes reaching to the upper altitudinal limit of the forests. This extremely stressful environment represents the optimum conditions to study changes in growth patterns due to climate variations. Our goal was to analyze recent changes in stem height growth in forests located in the upper altitudinal tree-line along Tierra del Fuego (Argentina), and establish possible linkages to changes observed in surface temperature during the last decades. Nine locations were sampled, and four plots were measured in each location. Forest structure was characterized, and stem analyses were performed to assess height growth patterns. ANOVAs and classification analyses were conducted using location and time as main variables. Tree-growth height increased with 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 locations, and can be related to its geographical situation. Increment in stem height growth seems to be related with the worldwide surface air temperature. A decline in stem height growth registered during the last two decades can also be related with the regional decrease in the mean air temperature. The analysis of stem height growth is a useful tool to evaluate the incidence of climate change over trees growing under extreme environmental conditions. Los bosques de Nothofagus pumilio ocupan las laderas de monta a hasta alcanzar el limite altitudinal del bosque. Estos ambientes extremos, donde los bosques est¨¢n bajo condiciones de estr¨¦s ambiental, son ¨®ptimos para estudiar patrones de cambio debidos a variaciones clim¨¢ticas. El objetivo fue analizar cambios recientes en el crecimiento en altura en bosques localizados en el tree-line altitudinal en Tierra del Fuego (Argentina) y establecer posibles vinculaciones con cambios en la temperatura observados durante las ¨²ltimas d¨¦cadas. Se muestrearon nueve sitios, y se midieron cuatro parcelas en cada sitio. Se determin¨® la estructura forestal y se realizaron an¨¢lisis fustales para evaluar los patrones de crecimiento en altura. Se realizaron ANOVA y an¨¢lisis de clasificaci¨®n usando como factores principales al sitio y al tiempo. El crecimiento en altura aument¨® a lo largo del tiempo, e.g. 1,0 cm a o-1 durante 1870-1959, 2,7 cm a o-1 durante 1960-1979 y 5,0 cm a o-1 durante 1980-2010. Esas diferencias fueron significativas entre per¨ªodos de tiempo y sitios, pudiendo estar relacionadas con la localizaci¨®n geogr¨¢fica. El incremento en el crecimiento en altura observad %K bosque altitudinal %K Nothofagus %K crecimiento en altura %K cambio clim¨¢tico %K estructura forestal %K tree-line %K Nothofagus %K height growth %K climate change %K forest structure %U http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-92002012000300006