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Background: Polyphenol-enriched tea is an interesting product for food industries under the current consumer demands. This study aimed at evaluating the Nothofagus antarctica (NA) species as a valuable source of bioactive compounds as well as obtaining an optimized organic green tea (OGT)-NA blend. NA leaves of different developmental stages and several mixture proportions were analyzed. HPLC–DAD–ESI/MSn was used to identify and quantify the polyphenol compounds. Antioxidant capacity and the type of interaction occurring between constituents were assessed. Results: NA infusions exhibited high polyphenol diversity and some differences in the individual concentration were found between NA leaves. NA polyphenol profile showed great complementarity to the one present in green tea. Besides, NA impacted positively the antioxidant strength in the mixtures. Finally, the 67% OGT-33% NA blend exhibited an optimized performance in relative and total polyphenol contents and antioxidant properties, and thus, it could be recommended as a novel beverage. Conclusions: N. antarctica is a valuable source of polyphenol compounds and its combination with green tea, in a blend, could represent an interesting food product. In addition, this new non-wood product constitutes a novel productive strategy for adding value to the silvopastoral systems with positive socio-economic impact. Estación Experimental Agropecuaria Bariloche Fil: Mattera, María Gabriela. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Bariloche. Area Forestal; Argentina Fil: Mattera, Maria Gabriela. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Langenheim, Mariana Elsa. Universidad Nacional del Comahue. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Reiner, Gabriela. Universidad Nacional del Comahue. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Peri, Pablo Luis. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Santa Cruz; Argentina Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Moreno, Diego A. Universidad de Murcia. Centro de Edafología y Biología Aplicada del Segura; España

Ecologically sustainable forest management aims to preserve ecosystem integrity by providing wood and nonwood values. For this, it is necessary to determine the losses produced by the different management practices in natural forest resilience. The aim was to determine changes in forest structure values along the natural cycle and human impacts generated by rural timber, pastoral and silvopastoral uses in managed, unmanaged, and transformed Nothofagus antarctica forests of Tierra del Fuego (Argentina), as well as in some associated environments (grasslands). We sampled 145 sites to determine landscape characterization, microclimate, soil properties, debris, forest structure and regeneration under different conditions: (i) six phases of natural forest dynamic (even-and uneven-aged), (ii) four types of management and conversion alternatives with and without natural regeneration, and (iii) forest edges and grasslands. Main results showed that stand characteristics (abiotic, soil, forest structure, and regeneration) did not significantly change along the different natural forest phases in even- and uneven-aged structures. However, many studied variables strongly varied depending on harvesting intensities and fire occurrence. The magnitude of these changes was directly related to the impact degree. Multivariate analyses showed a close relationship among the different natural forest phases, and how stands with harvesting or different conversion intensity differ from the control stands, or how much they become similar to openlands. Through different indexes, we related the modifications of the stand characteristics with the magnitude and direction of the changes. Then, these could be used to propose sustainable forest management strategies in the framework of silvopastoral systems., Facultad de Ciencias Agrarias y Forestales

Usually, stands with aging trees are considered forests with higher conservation values, regardless their structural diversity and other functional attributes. Natural stands present a wide range of age structures, from even-aged stands growing at different development growth phases (e.g. CO = stands at initial or final optimum development growth phase, MD = stands at mature or decaying development growth phases) to uneven-aged stands with mixed development growth phases (e.g. UOG = stands combining mature or decaying development growth phases with initial or final optimum development growth phases, UMD = stands combining only mature and decaying development growth phases). The aim of this work was to compare richness and cover of understory vascular plants of even- and uneven-aged stands of Nothofagus antarctica (nire) forests in Tierra del Fuego (Argentina), and relate these characteristics with abiotic, soil and forest structure variables. A total of 75 stands were sampled across the natural range distribution of the forests, where understory (point intercept method), forest structure (angle count sampling and eye-fish photos) and environmental (soil) variables were measured. 17 one-way ANOVAs were conducted using Tukey test at p UOG > MD > CO (17–28 total, and 13–24 native species, respectively). Neither exotic species richness (4–5 species) nor understory cover significantly changed among treatments (total, dicots, ferns and bryophytes). However, monocots cover significantly differed among treatments (F = 3.9, p = 0.012), where UMD > MD > UOG > CO. Finally, indicator species cover for environmental degradation did not present significant differences (F = 2.1, p = 0.106), but they were positive related to forests growing in mature stages. We concluded that uneven-aged stands presented significantly higher conservation values compared to even-aged stands, where mature/decay stands have better conservation values than optimum growth development phases. These findings can be used for better silviculture practices that combine silvopastoral use and conservation strategies., Facultad de Ciencias Agrarias y Forestales, Consejo Nacional de Investigaciones Científicas y Técnicas

Fil: Goldenberg, Matías G. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; Argentina. Fil: Nacif, Marcos E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; Argentina. Fil: Oddi, Facundo J. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; Argentina. Fil: Garibaldi, Lucas Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; Argentina. Fil: Goldenberg, Matías G. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Fil: Nacif, Marcos E. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Fil: Oddi, Facundo J. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Fil: Garibaldi, Lucas Alejandro. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Nothofagus antarctica (G. Forst.) Oerst. stands of northern Patagonia (Argentina) have great potential to provide multiple ecosystem services. Nonetheless, the lack of basic information limits the application of silvicultural treatments to this forest type. This study reports the early response to three systematic strip thinning treatments (30%, 50%, and 70%) carried out during 2013 in a 30-year-old N. antarctica stand, where control plots (i.e., no thinning) were also established. Subplots were located within each plot. Basal diameters (BD) of all retained stems were measured in the non-vegetative season (winter) of 2016, 2017, and 2018 to calculate basal diameter annual increment (BDI) and stand volume growth. BDI ranged from 1.9 mm year-1 in the control plots to 2.7 mm year-1 at 70% thinning. Relative BDI also responded positively to thinning intensity. Stand volume growth decreased non-linearly with thinning intensity from 3.36 m3 ha-1 year-1 in the control plots to 0.71 m3 ha-1 year-1 when thinning was 70%. Smaller differences were observed between control plots, 30% thinning, and 50% thinning. Our results show that N. antarctica forests, in the stem exclusion stage, respond to strip thinning. Thus, silviculture based on this management system could favor the development of retained trees without losing productivity if it remains under 50% intensity. This outcome represents an important incremental contribution to the design of silvicultural interventions in northern Patagonia.

Nutrient resorption is crucial for mineral element conservation and efficiency of forest species, but knowledge on its significance and the mechanisms involved is still limited for most species and habitats. Focusing on the harsh conditions for plant growth and survival of southern Patagonia, a field study for comparing the rate of foliar resorption of macro-, micro-nutrients, and trace elements in coexisting Nothofagus pumilio and Nothofagus antarctica forests was performed. Forests located in three contrasting productivity sites (with different soil and climatic conditions) were selected, and mature, functional versus senescent leaves of both species were collected at two different dates of the growing season. Macro- (N, P, Ca, K, S, and Mg), micronutrients (B, Cu, Fe, Mn, Zn, and Ni), and trace elements (Al, Li, Pb, Rb, Sr, Ti, and Tl) were determined in foliar tissues. The mineral element concentrations of mature and senescent leaves were used for calculating the nutrient resorption efficiency (NuR). In general, and making an average of all sites and species, macro-nutrient resorption showed a decreasing trend for N > S = K > P > Mg, being Ca the only macro-nutrient with negative values (i.e., no resorption). Resorption of the majority of the elements did not vary between species in any of the evaluated sites. Variation across sites in nutrient resorption efficiency for most macronutrients, some micronutrients, and trace elements was observed for N. antarctica, whereas N. pumilio had a similar NuR for all experimental sites. On the other hand, regardless of the site or the species, some elements were not resorbed (e.g., B, Cu, Fe, Mn, Al, and Ti). It is concluded that both Nothofagus species performed similarly concerning their nutrient conservation strategy, when coexisting in the same mixed forest. However, no evidence was gained for an increased rate of foliar NuR in association with the sites subjected to more limiting soil and climatic conditions for plant growth. EEA Santa Cruz Fil: Bahamonde, Héctor Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Universidad Nacional de la Patagonia Austral; Argentina Fil: Fernández, Victoria. Universidad Tecnológica de Madrid. School of Forest Engineering. Forest Genetics and Ecophysiology Research Group; España Fil: Gyenge, Javier. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Agencia de Extensión Rural Tandil; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mattenet, Francisco Javier. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The role of understory plants in native forests is critical for ecosystem function,wildlife protection and ecosystem productivity. The interest to estimate biodiversity increased during the last decades at landscape level. The objective was to elaborate a map of potential biodiversity (MPB) of understory species of Nothofagus forest using potential habitat suitability maps (PHS) of 15 plants in Santa Cruz province, Argentina. Additionally, we asked the following questions: (i) Were plant species differentially distributed according to the forest types?, (ii) do forest types represent different plant species assemblagewith specific ecological niche requirements?, and (iii) is it possibleto detect hotspots in the MBP according to the forest types?We used 721 plots database of vascular plants, fromwhere 15 indicator specieswere identified. The assemblage species for different forests (Nothofagus antarctica, N. pumilio and evergreen mixed) were analysed using a detrended correspondence analysis. Also, we explored 41 potential explanatory variables to develop PHS, and combined these maps to obtain one MPB (1?100%). Finally, we analysed the outputs into a GIS through different landscapes alternatives to detect hotspot areas. Marginality and specialization values allowed identifying species assemblage that presented similar variability in the habitat requirements. MPB varied across the landscape, with higher values in the south and lower values near glaciers. MPB had the highest values in N. antarctica forest with N50% cover at landscape level. N. antarctica present more hotspots than N. pumilio forests, mainly in the south, compared to mixed evergreen forests which present few hotspots near glaciers. These results can be used as a tool to design newmanagement and conservation strategies at landscape level. Fil: Rosas, Yamina Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

The use of biomass as an energy resource is key to the subsistence and development of diverse rural populations throughout the world. Particularly, the study of seasonal variation in firewood consumption contributes knowledge that can be used in detailed community management of this resource. In a rural community of the Patagonian steppe, seasonal variation in domestic consumption of fuel plants was studied. Possible socioeconomic conditioning factors (i.e., size of family unit, infrastructure of dwellings, number of combustion appliances used) were analysed, and seasonal variation in the richness of plant species used was determined. Average biomass consumption was found to be 12000 kg/year/home and 1479kg/year/per capita, with significantly higher values during winter (63 kg/day/home), than in summer (18.5 kg/day/home). The richness of fuel species used varied significantly during the year, and in line with biomass estimates, the highest use consensus for species was recorded during winter and autumn, with exotic species predominating. The maximum difference in species was registered in autumn, due to an increase in the stockpiling of wood bought for winter, when the preference is for high caloric value and accessible commercial price. During the year the main species used were Salix spp. and Nothofagus antarctica (G. Forst.) Oerst. The differential needs as seen from a local perspective, and their use strategies, require an integrated, multifaceted proposal, such as the progressive incorporation of high efficiency stoves and the implementation of local wooded areas for firewood. Fil: Morales, Daniela Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Centro de Investigación Esquel de Montaña y Estepa Patagónica; Argentina Fil: Molares, Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Centro de Investigación Esquel de Montaña y Estepa Patagónica; Argentina Fil: Ladio, Ana Haydee. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina

Key message: Soil texture and temperature-related variables were the variables that most contributed toNothofagus antarcticaforest height in southern Patagonia. This information may be useful for improving forest management, for instance related to the establishment of silvopastoral systems or selection of suitable sites for forest reforestation in southern Patagonia. Context: Changes in forest productivity result from a combination of climate, topography, and soil properties. Aims: The relative importance of edaphic and climatic variables as drivers of productivity in Nothofagus antarctica forests of southern Patagonia, Argentina, was evaluated. Methods: A total of 48 mature stands of N. antarctica were selected. For each study site, we measured the height of three mature dominant trees, as an indicator of productivity. Seven soil, five spatial, and 19 climatic features were determined and related to forest productivity. Through partial least squares regression analyses, we obtained a model that was an effective predictor of height of mature dominant trees in the regional data set presented here. Results: The four variables that most contributed to the predictive power of the model were altitude, temperature annual range, soil texture, and temperature seasonality. Conclusion: The information gathered in this study suggested that the incidence of the soil and temperature-related variables on the height of dominant trees, at the regionally evaluated scale, was higher than the effect of water-related variables. Fil: Bahamonde, Héctor Alejandro. Universidad Nacional de la Patagonia Austral; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Martínez Pastur, Guillermo José. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Soler Esteban, Rosina Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Rosas, Yamina Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Ladd, Brenton. Universidad Cientifica del Sur; Perú. University of New South Wales; Australia Fil: Guardia, Sandra Duarte. Universidad Cientifica del Sur; Perú Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

This study evaluated the seed production and quality and the subsequent regeneration establishment in five pure Nothofagus antarctica forests growing at different site qualities and crown cover during 10 years, in Southern Patagonia (Argentina). Four traps of 1 m2 were installed in each stand and sampled monthly (between February and May) each year. The incorporation and survival of seedlings were evaluated using four permanent plots of 1 m2 in each stand. The site quality of the studied forests did not influence seed production and regeneration. The amount of seed production and seed quality were proved to have a decisive influence on the N. antarctica seedling establishment in the subsequent years. At the same time, our results suggest that independently of the site class, the canopy openness for silvopastoral use improved the conditions for seedling establishment. However, the success of seedling survival over time would be conditioned for the influence of other factors such as understory competition. Fil: Bahamonde, Héctor Alejandro. Universidad Nacional de la Patagonia Austral; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Monelos, Lucas Humberto. Universidad Nacional de la Patagonia Austral; Argentina Fil: Soler Esteban, Rosina Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Aim of the study: To analyse the effectiveness of thinning on tree growth, forest structure and microclimatic variables along seven years after cuttings in a secondary Nothofagus antarctica forest in Southern Patagonia. Area of study: Five hectares of homogeneous stand of secondary forests (54º15’46” SL, 66º59’41” WL) in Tierra del Fuego, Argentina. Material and methods: One control and two thinning levels were established, and forest structure, growth, crown dynamic and microclimate variables in long-term permanent plots were evaluated. Main comparisons were made using multiple ANOVAs. Main results: Intensive thinning in secondary forests allowed to increase tree individual growth rates by doubling the radiation levels at the understory level that enhances the silvopastoral management. These forests showed a desirable resilience to the forest interventions and natural disturbances (e.g. heavy defoliator attack), with a rapid reaction in the canopy cover growth. Research highlights: Monitoring of thinning for silvopastoral management must include easy and cheap measuring variables, e.g. diameter growth as a proxy for timber production objectives and hemispherical photos (crown cover and radiation) as a proxy for pasture production. Long-term monitoring allowed to identify reliable indicators that assist new sustainable management alternatives., Laboratorio de Investigación de Sistemas Ecológicos y Ambientales

The anthracological study of Paredón Lanfré (Patagonia, Argentina) highlights the presence of radial cracks with a marked difference between the percentage of affected coniferous charcoal (Fitzroya cupressoides and Austrocedrus chilensis) compared to the angiosperms (e.g., Nothofagus antarctica and Nothofagus dombeyi). The aim of this work was to obtain experimental comparison data from two Patagonian conifers to understand the prehistoric combustion behavior of the region. These results showed a discrepancy between the average of shrinkage cracks made with green wood fires and those with dry wood fires. The study of the caliber of charcoal recovered from Paredón Lanfré showed significant differences between the samples of F. cupressoides and A. chilensis. The calculation of correlation between size and shrinkage cracks suggests for both species that the size is not related to the number of registered shrinkage cracks in charcoal studied. Therefore, the gauge would not be a variable which could influence the presence of shrinkage cracks in the charcoal. Consequently, the difference of average shrinkage cracks between the two specimens may result from another variable that remains to be identified. Fil: Caruso, Laura Lihue. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; Argentina. Istituto per la Valorizzazione del Legno e delle Specie Arboree; Italia Fil: Théry Parisot, I.. Centre National de la Recherche Scientifique; Francia Fil: Carré, A.. Centre National de la Recherche Scientifique; Francia Fil: Fernández, Pablo Marcelo. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentina

Nothofagus antarctica, is the most important species of the silvopastoral systems of southern Patagonia. However, there is limited information on the ecophysiological response mechanisms of seedlings for survival under different resource availability regimes, and whether such processes may differ between provenances. In this study, we evaluated the functional response to water shortage of seedlings of four N. antarctica provenances grown under controlled conditions. After an initial full irrigation period, seedlings were subjected to a water shortage cycle. Measurements of the diameter at the base of the stem, net photosynthesis (An), stomatal conductance to water vapour (gs), predawn water potential (Ψpd), osmotic potential at maximum and zero turgor (Π₁₀₀; Π₀), relative water content at zero turgor (RWC₀) and maximum modulus of elasticity (Emax) were carried out during the experimental period. Differences between provenances concerning An and gs rates were recorded under full irrigation conditions, but were not detected in association with drought stress. All provenances had similar osmotic potential values (Π₁₀₀ and Π₀) at full irrigation, but water shortage led to significant osmotic potential differences between provenances. During the whole experimental period, no significant differences on RWC₀ and Emax values were recorded among provenances. Under full irrigation conditions, all N. antarctica provenances had a similar physiological performance which suggests that environmental conditions may be the main driver for phenotypic differences in this species. From the osmotic adjustment results gathered, it is derived that a major osmoregulation capacity in response to water shortage is a common feature of all the N. antarctica provenances evaluated., Facultad de Ciencias Agrarias y Forestales, Laboratorio de Investigación de Sistemas Ecológicos y Ambientales

Nothofagus antarctica es una especie de los bosques Andino-Patagónicos, con una amplia distribución que se extiende desde el norte de Neuquén hasta Tierra del Fuego. Si bien los bosques de N. antartica son de gran importancia económica para la región, en la actualidad son muy afectados por actividades humanas como el pastoreo, la extracción de leña, la conversión en pastos y el reemplazo por plantaciones de coníferas. Estas actividades alteran la estructura original del bosque de N. antartica, lo cual afecta el funcionamiento de los ecosistemas en su conjunto y determina la pérdida de biodiversidad. Desde julio de 2008 a mayo de 2010, en el noroeste de Chubut, Patagonia, analizamos el efecto de las perturbaciones asociadas con distintas estrategias de manejo sobre la composición de especies y la estructura de los bosques de N. antartica. Los disturbios de los bosques de N. antartica considerados en este estudio se derivan de la extracción de leña por manchones y parquizado, la conversión de bosques en pasturas, los incendios ocurridos hace 15 y 25 años y, a modo de control, también se consideraron los bosques prístinos. La estructura, composición y diversidad de especies se diferenciaron entre bosques afectados por diversos disturbios. La mayor cobertura de los estratos arbóreos y arbustivos se observó en los sitios prístinos (PR), mientras que la mayor cobertura del estrato herbáceo se observó en los sitios convertidos en pasturas. El diámetro a la altura del pecho (DAP) y el área basal (BA) de los individuos de N. antarctica fue mayor en los sitios afectados por la extracción de leña por parquizado (FWL) que por parche (FWP), mientras que la densidad (número de individuos) fue mayor en los sitios quemados hace 25 años (B25). La cobertura del dosel fue mayor en PR y FWL, en comparación con los restantes sitios de muestreo. Aunque se encontraron diferencias en riqueza entre los sitios de muestreo (fue mayor en los sitios sometidos a extracción de leña pormanchones y parquizado [FWP y FWL]), no se encontraron diferencias de diversidad y dominancia entre sitios de muestreo. Nuestros resultados son comparados con los obtenidos en estudios previos en la Patagonia y resultan de importancia en la mejora en la gestión de los bosques de N. antarctica y su conservación. Nothofagus antarctica is a species of the Andean-Patagonian forest with a wide distribution from the north of Neuquén to Tierra del Fuego. Although the N. antarctica forests are of great economic importance for the region, they are intensely affected nowadays by human activities such as grazing, firewood extraction, conversion into pastures and the replacement by coniferous plantations. These activities produce changes in the N. antarctica forest, mainly by the alteration of its original structure affecting the performance of the ecosystem as a whole, resulting in the loss of biodiversity. Since July 2008 up to May 2010 in the northwest of Chubut, Patagonia, we analyzed the effect of disturbances associated with different management strategies on species composition and structure of N. antarctica forest. The disturbances on N. antarctica forest considered in this study are derived from extraction of firewood by patches and landscapes, conversion of forests into pastures, forest fires occurred 15 and 25 years ago. Pristine forest was considered a control. The structure, composition and species diversity differ between forests affected by different disturbances. The higher arboreal and shrub stratum cover was observed in pristine sites (PR) while the largest herbaceous cover was observed in sites converted into pasture. The diameter at breast height (DAP) and the basal area (BA) of individuals of N. antarctica was larger than in those sites affected by firewood extraction at the landscape scale (FWL) than at the patch scale (FWP), while the density (number of individuals) was higher in the sites burned 25 years ago (B25). The canopy cover was higher in PR and FWL compared with those in the remaining sampling sites. Although some differences were found in the richness among the sampling sites, being higher in firewood extraction by patches and landscaped sites (FWP and FWL), there were no differences of diversity and dominance among sampling sites. Our results are compared with those obtained in previous studies in Patagonia and are of importance in the improvement of the management of N. antarctica forest and its conservation.

Nothofagus trees host Misodendrum, an endemic mistletoe of the subantarctic forests of Chile and Argentina. Differences in the infection intensity on a given host and patches of infected trees are observed within the forest. We used allozymes to test for genetic differences between uninfected and infected Nothofagus trees (Nothofagus antarctica (G. Forst.) Oerst.) by two species of Misodendrum (Misodendrum linearifolium DC. and Misodendrum punctulatum DC.) at three sites. Non-metric multidimensional scaling ordination was performed using the presence of each of 26 total alleles in 166 trees of N. antarctica (89 uninfected and 77 infected). Sites with higher degrees of infection by M. punctulatum can be distinguished in the ordination. The number of infections per tree has a significant correlation with the ordination axis. ANOSIM analysis showed significant differences between infected and uninfected trees when they were infected by M. punctulatum but not by M. linearifolium. Differences between sites were also found, but the two sites with higher degrees of infection by M. punctulatum did not differ from each other. The intrapopulation genetic structure of N. antarctica could be maintained by the mistletoe Misodendrum through host selection. Fil: Vidal Russell, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina Fil: Premoli Il'grande, Andrea Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina

Myrtaceae, the gum tree family, is a large angiosperm clade of 5671 species mostly distributed in tropical and subtropical regions of the world. In the southernmost tip of South America (Santa Cruz province) where the fossils analysed in this study come from (Rı´o Turbio Formation), this family is virtually absent and the extant vegetation is largely dominated by deciduous Nothofagus pumilio and Nothofagus antarctica. During the early Paleogene, however, the Myrtaceae were an important element in southern Patagonian floras. Here, we report and describe ten taxa related to the extant genera Eugenia, Myrcia, Psidium, Myrcianthes and possible Eucalyptus and Campomanesia. The presence of a high diversity of Myrtaceae during the Eocene in one of the southernmost regions of the world could be thought as unusual. However, during this period of time (45 Ma), a number of other tropical lineages also reached these high latitudes probably as a consequence a warming climatic trend. In fact, through the Paleocene–Early Eocene interval, climatic conditions were the warmest of the Cenozoic. After this period of time, a progressive decline in temperature forced the migration of megathermal elements towards lower latitudes and, at the same time, led to the expansion of forest dominated by Nothofagus which predominate the region today. Fil: Panti, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina

Fil: Bianchi, Lucas O. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Fil: Bianchi, Lucas O. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Fil: Bianchi, Lucas O. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Defossé, Guillermo E. Universidad Nacional de la Patagonia "san Juan Bosco". Facultad de Ingenieria - Sede Esquel. Departamento de Ingenieria Forestal; Argentina. Fil: Defossé, Guillermo E. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Fil: Defossé, Guillermo E. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Aim of study: The Canadian Forest Fire Weather Index (FWI) is being implemented all over the world. This index is being adapted to the Argentinean ecosystems since the year 2000. With the objective of calibrating the Fine Fuel Moisture Code (FFMC) of the FWI system to Patagonian forests, we studied the relationship between ignition probability and fine dead surface fuel moisture content (MC) as an indicator of potential fire ignition. Area of study: The study area is located in northwestern Patagonia, Argentina, and comprised two main forest types (cypress and ñire) grown under a Mediterranean climate, with a dry summer and precipitations during winter and autumn (~500-800 mm per year). Material and Methods: We conducted lab ignition tests fires to determine the threshold of fine dead fuel ignition at different MC levels. Moisture content of dead fine surface fuels in the field was measured every 10-15 days from November to March for three seasons. We calculated the FFMC during these seasons and correlated it with the measured MC by applying a logistic regression model. We combined the results of the ignition tests and of the regressions to suggest FFMC categories for estimating fire danger in Patagonian forests. Main results: The ignition threshold occurred at MC values of 21.5 and 25.0% for cypress and ñire sites, respectively. The MC measured varied from 7.3 to 129.6%, and the calculated FFMC varied between 13.4 and 92.6. Highly significant regressions resulted when FFMC was related to MC. The ignition threshold corresponded to a FFMC=85. We proposed to divide the FFMC scale in three fire danger categories: Low (FFMC89). Research highlights: Our results provide a useful tool for predicting fire danger in these ecosystems, and are a contribution to the development of the Argentinean Fire Danger Rating and a reference for similar studies in other countries where the FWI is being implemented.

In most temperate forest, nitrogen (N) is considered a limiting factor. This becomes important in extreme environments, as Nothofagus antarctica forests, where the antecedents are scarce. Thinning practices in N. antarctica forests for silvopastoral uses may modify the soil N dynamics. Therefore, the objective of this work was to evaluate the temporal variation of soil N in these ecosystems. The mineral extractable soil N, net nitrification and net N mineralization were evaluated under different crown cover and two site quality stands. The mineral N extractable (NH4 ??N ? NO3 -?N) was measured periodically. Net nitrification and net N mineralization were estimated through the technique of incubation of intact samples with tubes. The total mineral extractable N concentration varied between crown cover and dates, with no differences among site classes. The lowest and highest values were found in the minimal and intermediate crown cover, respectively. In the higher site quality stand, the annual net N mineralization was lower in the minimal crown cover reaching 11 kg N ha-1 year-1, and higher in the maximal crown cover (54 kg N ha-1 year-1). In the lower site quality stand there was no differences among crown cover. The same pattern was found for net nitrification. Thinning practices for silvopastoral use of these forests, keeping intermediate crown cover values, did not affect both N mineralization and nitrification. However, the results suggest that total trees removal from the ecosystem may decrease N mineralization and nitrification. Fil: Bahamonde, Hector Alejandro. Universidad Nacional de la Patagonia Austral; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Alvarez, Roberto. Universidad de Buenos Aires. Facultad de Agronomia; Argentina Fil: Barneix, Atilio Jose. Universidad de Buenos Aires. Facultad de Agronomia; Argentina Fil: Moretto, Alicia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Above- and below-ground C pools were measured in pure even-aged stands of Nothofagusantarctica (Forster f.) Oersted at different ages (5–220 years), crown and site classes in the Patagonian region. Mean tissue C concentration varied from 46.3% in medium sized roots of dominant trees to 56.1% in rotten wood for trees grown in low quality sites. Total C concentration was in the order of: heartwood > rotten wood > sapwood > bark > small branches > coarse roots > leaves > medium roots > fine roots. Sigmoid functions were fitted for total C accumulation and C root/shoot ratio of individual trees against age. Total C accumulated by mature dominant trees was six times greater than suppressed trees in the same stands, and total C accumulated by mature dominant trees grown on the best site quality was doubled that of those on the lowest site quality. Crown classes and site quality also affected the moment of maximum C accumulation, e.g. dominant trees growing on the worse site quality sequestered 0.73 kg C tree−1 year−1 at 139 years compared to the best site where 1.44 kg C tree−1 year−1 at 116 years was sequestered. C root/shoot ratio decreased over time from a maximum value of 1.3–2.2 at 5 years to a steady-state asymptote of 0.3–0.7 beyond 60 years of age depending on site quality. Thus, root C accumulation was greater during the regeneration phase and for trees growing on the poorest sites. The equations developed for individual trees have been used to estimate stand C accumulation from forest inventory data. Total stand C content ranged from 128.0 to 350.9 Mg C ha−1, where the soil C pool represented 52–73% of total ecosystem C depending on age and site quality. Proposed equations can be used for practical purposes such as estimating the impact of silvicultural practices (e.g. thinning or silvopastoral systems) on forest C storage or evaluating the development of both above- and below-ground C over the forest life cycle for different site qualities for accurate quantification of C pools at regional scale. Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Gargaglione, Verónica. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

The success ofthe reproductive process in trees depends on abiotic and biotic factors that determine the final outcome of natural regeneration. Silviculture alters biotic and abiotic factors and results in secondary forest structures. To effectively manage these forests, it is necessary to understand the bottlenecks in reproductive stages using a whole-cycle approach study. The aim ofthis study was to analyse flowering and seeding patterns in primary, secondary and silvopastoral managed Nothofagus antarctica forests, including investigating the pre-dispersion foraging of insects and birds, as well as abscised biomass production. A high percentage of female flowers produced fruits (95 96%) in which the main loss factor before seeding was the abscission ofimmature fruits (11 14%). Seeding was greater in secondary forests (11.4 million ha1), but managed stands presented a higher percentage offlowers resulting in seeds (82%). However, secondary forests had a better seed quality (17% viable seeds), where the main loss factor was empty seeds in all treatments (39 50%). Biotic factors (foraging by insects and birds) were higher in disturbed than primary forests. Nothofagus antarctica produce large quantities of seeds, but abscised immature fruits and empty seeds due to self-incompatibility mechanisms appeared as the major loss factors. EEA INTA Santa Cruz Fil: Soler Esteban, Rosina Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Centro Austral de Investigaciones Científicas (CADIC). Ushuaia, Tierra del Fuego; Argentina. Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Centro Austral de Investigaciones Científicas (CADIC). Ushuaia, Tierra del Fuego; Argentina. Fil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Centro Austral de Investigaciones Científicas (CADIC). Ushuaia, Tierra del Fuego; Argentina. Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral (UNPA). Santa Cruz; Argentina. Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.

Data on tree biomass are essential for understanding the forest carbon cycle and plant adaptations to the environment. We determined biomass accumulation and allometric relationships in the partitioning of biomass between aboveground woody biomass, leaves and roots in Nothofagus antarctica. We measured above- and belowground biomass of N. antarctica trees across different ages (5-220 years) and crown classes (dominant, codominant, intermediate and suppressed) in three site qualities. The biomass allocation patterns were studied by fitting allometric functions in biomass partitioning between leaves (ML), stem and branches (MS) and roots (MR). These patterns were tested for all pooled data and according to site quality and crown classes. Biomass accumulation varied with crown class and site quality. The root component represented 26-72% of the total biomass depending on age and site. N. antarctica scaling exponents for the relationships ML vs. MS, MA vs. MR, and MS vs. MR were close to those predicted by the allometric biomass partitioning model. However, when biomass allocation was analyzed by site quality the scaling exponents varied following the optimal partitioning theory which states that plants should allocate more biomass to the part of the plant that acquires the most limiting resource. In contrast, the crown class effect on biomass partitioning was almost negligible. In conclusion, to obtain accurate estimations of biomass in N. antarctica trees the allometric approach appears as an useful tool but the site quality should be taken into consideration. Fil: Gargaglione, Veronica Beatriz. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral; Argentina Fil: Rubio, Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; Argentina

N. antarctica occurs in the widest range of habitat types among all South American Notho–fagus. The aim of this study is to investigate adaptive responses by variation in morphological (tree form and leaf characters), and environmental traits (soils) of the polymorphic N. ant–arctica. Also we analyze the effect of genetic drift and limited gene flow in such predominantly apomict by means of neutral variation (isozymes). We studied four potentially different morphological variants each associated with a separate habitat 1) an arboreal variant growing in optimal environments; 2) a sparsely branched variant of temporarily flooded basins or flats; 3) a dwarf variant growing at high elevation, and 4) a shrub-like variant inhabiting matorral environments. The study was restricted latitudinally to Nahuel Huapi National Park, Argentina. For each habitat type we investigated two sites. Nothofagus antarctica shows locally occurring phenotypes. The forest and the high elevation variants were morphologically distinct from the matorral and the basin types. The latter were undistinguishable except for more profuse branching in the matorral type as a result of sprouting due to recent fires. Isozyme evidence indicates a great deal of within-population genetic diversity which is maintained by outcrossing and significant among-site divergence (F = 18%) that reflects limited gene flow.The apparent high phenotypic and genetic variability in N. antarctica is due to both plasticity and genotypic effects as a result of stable population structure and long periods of isolation which may be reinforced by selection at diverse biotopes.ST

Pinus species, which have formed the foundation of commercial forestry industry in many countries, are known to be invasive in natural ecosystems, especially in the Southern Hemisphere. Pinus contorta is considered one of the most aggressively invasive plantation species. In this paper we aim to: (a) determine patterns of P. contorta invasion in relation to its size and age structure and spatial distribution and (b) determine the effect of vegetation cover on its regeneration. For this purpose, we have chosen the Malalcahuello National Reserve in south-central Chile, which is dominated by Araucaria araucana forests. In the three P. contorta trial plots, attributes were measured in order to describe its current structure. We selected one of the three P. contorta trial plots and set eight 50 m wide and 125 m centrifugal transects starting at the North Azimuth (08) orientation and then one each 458. In each transect 25 circular plots of 2.5 m radius were established every 25 m. In each plot, we measured collar diameter (CD) for each P. contorta individual and adjusted a diameter–age function. We recorded the presence of cones for each individual P. contorta within the plots and the total number of P. contorta individuals. In each plot, we measured percent vegetation cover (grass, understory and canopy). The selected parent stand showed a decrease in density from the original plantation spacing, from 2500 to 150 plants ha � 1 . Of all sampled individuals, only a 38% had cones. We found reproductive structures in trees as young as 5-year-old. Regeneration was found in all transects. Mean density for the area was 1600 plants ha � 1 , and the greater plant number was found in the West transect, reaching an average of 6600 plants ha � 1 . Through the interpolation performed with the kriging method, a map of the area with the spatial gradient of plant density was obtained. Naturally regenerated individuals of P. contorta occupied an area of 78 ha where the most distant individual is located in the southeast direction at an average distance of 1200 m from the three study plots. We determined that a positive association exists between P. contorta and the species A. araucana and Nothofagus antarctica. The capacity for early and consistent reproduction and the establishment of individuals dispersed at great distances from the original plots allow us to conclude that P. contorta has great potential as an invasive species in forests of this area of the Andes of southern South America. Invasion of P. contorta has many important implications for the conservation of native forests in our region including diminished regeneration of A. araucana.

• Background and Aims: Trees with a partial leaf-shedding pattern and other morphological features a priori considered intermediate between those of the deciduous Nothofagus antarctica (G. Forster) Oersted and the evergreen N. dombeyi (Mirb.) Oersted (Nothofagaceae) were found in natural stands. The hybridization between a deciduous and an evergreen species of Nothofagus has not been reported so far in natural communities. • Methods: The putative hybrids and the two presumed parental species were compared using 14 enzyme systems as well as shoot, leaf and reproductive morphology. • Key Results: Six enzyme systems showed good resolution (MDH-B, IDH, SKDH, 6-PGDH, GOT and PGI) and in four of them (PGI, MDH-B, SKDH and 6-PGDH) the putative hybrids showed intermediate zymogram patterns between N. antarctica and N. dombeyi. Both principal coordinates analysis on isozyme data and principal components analysis (PCA) on quantitative morphological traits of shoots and leaves separated both parental species and located the putative hybrids closer to N. antarctica than to N. dombeyi. In the PCA, the number of basal cataphylls and the length:width ratio of leaves were the variables most discriminating among shoots of the three entities. The putative hybrids were intermediate between both species regarding leaf vernation, outline and venation, variation in leaf shape (length/width) with position on the parent shoot and in staminate inflorescence and cupule morphology. For other morphological traits, the putative hybrids resembled one of the parental species or differed from both species (e.g. valve morphology). • Conclusions: Isoenzymatic and morphological data sets support the idea of the hybrid nature (probably F 1 generation) of the semi-deciduous trees found. Nothofagus antarctica and N. dombeyi are probably more closely related than previously assumed. The relevance of pollen type in revealing evolutionary relationships between Nothofagus species is supported, and that of leaf-shedding pattern is rejected. © 2004 Annals of Botany Company. Fil:Picca, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

The size (length and diameter) and number of leaf primordia of winter buds of #Nothofagus antarctica# (G. Forster) Oerst. shrubs were compared with the size and number of leaves of shoots derived from buds in equivalent positions. Buds developed in two successive years were compared in terms of size and number of leaf primordia. Bud size and the number of leaf primordia per bud were greater for distal than for proximally positioned buds. Shoots that developed in the five positions closest to the distal end of their parent shoots had significantly more leaves than more proximally positioned shoots of the same parent shoots. The positive relationship between the size of a shoot and that of its parent shoot was stronger for proximal than for distal positions on the parent shoots. For each bud position on the parent shoots there were differences in the number of leaf primordia per bud between consecutive years. The correlations between the number of leaf primordia per bud and bud size, bud position and parent shoot size varied between years. Only shoots produced close to the distal end of a parent shoot developed neoformed leaves; more proximal sibling shoots consisted entirely of preformed leaves. Leaf neoformation, a process usually linked with high shoot vigour in woody plants, seems to be widespread among the relatively small shoots developed in #N. antarctica# shrubs, which may relate to the species' opportunistic response to disturbance.