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Background:Climatic variables determining the most suitable sites for the woodlands of Tierra del Fuego are not yet as well understood as those related to their geographical range. Aim:The aim of this paper is to provide some insights into the relationships between climatic niche and current distribution of threeNothofagusspecies in Tierra del Fuego. Methods:We have identified the climatic variables responsible for the most suitable sites for three sub-AntarcticNothofaguswoodland types within their climatic ranges by calculating suitability indices, using the CLIMPAIR niche-based phytoclimatic model. Results:The distribution range of the majorNothofaguswoodlands is mainly driven by variables related to water stress, whereas phytoclimatic suitability is mainly driven by thermal variables related to warm summer temperatures forNothofagus betuloidesandN. pumilioand to winter cold forN. antarcticathat are also mainly responsible for the peculiarity of the Fueguian climate. Conclusions:These findings introduce a new perspective in the study of theNothofagusecology, based on the climatic traits responsible for the high-suitability locations instead of the traditional focus on the overall geographical distribution. [ABSTRACT FROM PUBLISHER]

Seedling browsing by livestock has been indicated as major threat for forest sustainability use. Nothofagus pumilio forests are part of the livestock raising system in Patagonia, but because of the sparse understory cover, livestock graze mainly on flood meadows within the forest matrix. The complexity of the environment under study (forests and flood meadows) means that an adaptive predictor is needed to evaluate the intensity of resource use by livestock in order to assess its effect on the forest. Distance to flood meadows was evaluated as a predictor of the use intensity of the forest by livestock and its effect on the understory. The study was conducted at three sites in Chubut Province, Patagonia-Argentina. We established transects in the forest 320 m long, starting at the edge flood meadow-forest. In these transects, the livestock presence indicators (soil compaction, density of feces and trails) and composition of the understory were evaluated. Generalized Linear Model for repeated measures for longitudinal data were used. The indicators showed that distance is efficient for estimating forest use intensity by livestock. The understory varied with distance, the cover of exotic herbaceous was higher near the flood meadow. Far from the flood meadow, the cover was entirely composited of native species. The results support the use of distance to flood meadows as a tool for decision making in livestock and forest management in N. pumilio forests, and for further research on livestock effect on the forest. [ABSTRACT FROM AUTHOR]

In the northwest of Chubut poplars are established as lines for wind break in grazing land protection or where they are grown non-irrigated hay. Populus nigra 'Italica' is the most widespread clone in linear plantations, located in different site qualities. There is no background on height growth and Site Index in the area. Eight sites were selected for sampling where 24 dominant trees were felled for stem analysis. With the database of age-height resulting from stem analysis of sample trees, we adjusted the Chapman-Richard's model, using nonlinear regression techniques. We built a family of height growth curves using the guide curve methodology. Site Index curves, based on height and age, were constructed by mathematical deduction of height growth unction, taking as reference age 25 years at breast height. We defined five site qualities, with a range of 4 meters, with Site Index from 19 to 35 m. [ABSTRACT FROM AUTHOR]