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Berry production is a non-wood product worldwide recognized by its nutritional value and taste, but the most studied species are non-native commercial plants in productive areas, leaving aside native berries. We propose that native berries (Berberis microphylla G.Forst) naturally growing in degradation forests areas could diversify livestock establishment production and complement traditional uses (e.g., livestock). The aims of this work were to 1) environmentally characterize (e.g., soil nutrient content and physical conditions, air conditions and photosynthetically active radiation) in three degraded Nothofagus antarctica Oerst. forest (due to past fires and livestock use) of Tierra del Fuego; and 2) evaluate berries production of B. microphylla in terms of quality production (e.g., fruit number and weigh per shrub) and in terms of quality (individual fruit weight, fruit pulp percentage, and soluble solids content) to assess provisioning ecosystem service of this native shrub in different degraded areas. Studied sites were defined as: 1) Severe soil degradation condition (SEV) (high frequency of horses, bulls and some native guanacos year round, severe soil erosion, and shorter herbaceous layer), 2) Moderate soil degradation condition (MOD) (cattle and guanaco year round, intermediate level of soil erosion and intermediate height of herbaceous layer), and 3) Slight soil degradation condition (SLI) (livestock only during winter, but high frequency of native guanacos, lower soil erosion and taller herbaceous layer). (SEV) had the highest air and soil temperature, least soils nutrients content, highest bulk density, the least soil water content and the poorest fruit production. (MOD) had the highest soil water content and nutrient-rich soils, while (SLI) had the highest relative air humidity and PAR. B. microphylla shrubs grow with similar morphology on the different soil degraded condition. The highest fruit production were at (SLI), however the (SEV) had the highest soluble solids. We conclude that calafate shrubs in degraded Nothofagus forests offer a provisioning ecosystem service through their excellent fruits quality. Livestock farms could diversify their production through native fruits taking advantage of the altered areas occupied by B. microphylla. However, we recommend avoiding intensive livestock use in burned forests since it could lead to an irreversible soil erosion. Proper livestock management in Nothofagus burned forest could keep over the time not only the recognized ecosystem provision services (fruits, meat, wood), but also those of regulation and support that calafate shrubs offer and that make the functionality of the ecosystem., Food Science; Agriculture; Calafate; Degraded Forests; Fruit Production; Native Berries; Patagonia

Los bosques de ñire (Nothofagus antarctica) en el sur de Patagonia se ubican mayoritariamente limitando con la estepa. De esta manera, han sido utilizados como sistemas silvopastoriles con ganadería ovina y/o bovina desde fines de 1800. Esta actividad que combina tres componentes principales (árboles, sotobosque y animales) en una misma unidad de suelo conlleva una serie de interacciones ecológicas entre dichos factores. En esta revisión se presentan los principales hallazgos respecto de las sinergias y antagonismos que se generan en estos sistemas silvopastoriles en el extremo sur de Patagonia continental y su incidencia a nivel paisaje. Destacan en estos sistemas el efecto de las interacciones entre coberturas de copa y calidad de sitio de los rodales sobre: el microclima, la productividad primaria y calidad nutritiva del sotobosque, la instalación de regeneración arbórea, el ciclado denutrientes y el comportamiento animal. En general, los estudios presentados indican que en estos sistemas prevalecen las interacciones positivas, sin embargo hay otros aspectos que a escala paisaje deben ser tenidos en cuenta para no comprometer la conservación de estos bosques australes. Ñire (Nothofagus antarctica) forests in southern Patagonia are mostly located in the limit with the steppe. Thus, these forests have been used as silvopastoral systems with sheep and / or cattle livestock since the late 1800s. This activity combines three main components (trees, understory and cattle) in a same surface, which implies several ecological interactions between those factors. In this review the main research about synergies and antagonisms generated in these systems in southern continental Patagonia are presented. The effects of interactions between crown cover and site quality over: microclimate, primary productivity and nutritive value of forage, installation of tree regeneration; nutrient cycling and livestock behaviour; are highlighted. In general, the studied publications indicate that in these systems the positive interactions are dominant. However, there are other issues at landscape scale which require special attention to guarantee the conservation of these southern forests. 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: Gargaglione, Veronica Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Universidad Nacional de la Patagonia Austral; Argentina Fil: Ormaechea, Sebastián Gabriel. 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 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

Silvopastoral systems in Nothofagus antarctica (ñire) forest have become an economical, ecological and productive alternative in Patagonia. Southern Patagonia’s experience over the past 12 years with silvopastoral systems is reviewed. The productivity and nutritive value (crude protein content and dry matter digestibility) of the understorey grassland were dependent on the interaction of environmental (mainly soil water availability and light intensity) and management factors under the trees and in turn determined animal performance. A method developed for carrying capacity estimation at the paddock level was based on the potential aboveground net primary production, and values ranged from 85 to 2200 kg DM ha−1 year−1. Planned thinning in secondary forest stands provides wood production and also improves the undestorey DM production by increasing incoming radiation. Within a management plan, a stand’s water stress conditions as well as the use of Reineke’s stand density index are proposed to assist in determining thinning intensities. Livestock production is the main annual income of silvopastoral systems where cattle and mixed livestock production (cattle + sheep) is the main activity. Animal performance at the whole farm scale is presented by comparing traditional extensive grazing management with an adaptive silvopastoral management that included strategic separation in homogeneous areas (grass steppe, forest and riparian meadows), stocking rate adjustment to grassland net primary production and the protection of regeneration from herbivores browsing. Data from litter decomposition, nutrient cycling and carbon storage studies also are presented. Finally, aspects related to the criteria and indicators to assess ñire forest’s sustainability under silvopastoral use along with biodiversity conservation issues are presented. Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Sur; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Bahamonde, Héctor Alejandro. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Sur; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina Fil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Gargaglione, Veronica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Sur; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina Fil: Soler Esteban, Rosina Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Ormaechea, Sebastián Gabriel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Sur; Argentina Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Bioindicators could act as early warning indicators of environmental changes, ecosystem stress or taxonomic diversity. Pseudoscorpions have rarely been used as bioindicators, due to lack of information about their ecology, habitat selection, niche preferences and requirements, especially in southern Nothofagus forests. We studied the distribution and abundance of a pseudoscorpion species, Neochelanops michaelseni (Simon 1902), in different vegetation types (Nothofagus antarctica and N. pumilio forests, grasslands and peatlands) and examined how this species responded to different forest uses (harvesting and silvopastoral management), to explore its utility as a bioindicator. The study was conducted on long-term plots located at two ranches in Tierra del Fuego, using pit-fall traps during one summer. Neochelanops michaelseni abundance was higher in Nothofagus forests than in open ecosystems, which could be attributed to their affinity for litter and coarse woody debris. In N. pumilio forests, the pseudoscorpions were sensitive to harvesting, with similar abundances in harvested forests (aggregated and dispersed retentions) and grasslands. In N. antarctica forests, differences were not detected among unmanaged and silvopastoral managed forests, probably due to higher understory plant growth, and lesser diminishing of litter and debris by thinning than by harvesting. We conclude that the pseudoscorpion, N. Michaelseni, can be a good bioindicator for ecosystem conservation and for evaluating recovery rate in the ecological conditions of impacted Nothofagus forests, and that management practice intensities should be regulated to create more suitable habitats for pseudoscorpion diversity conservation. Fil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Kreps, Gaston. 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: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Porta, Andrés Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Ramirez, Martin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Litter input is one of the key components that define nutrient cycling in forests and the majority of studies only consider the tree components of litterfall. However, epiphytic species can play a crucial role in litter input throughout the growing season. This work evaluates changes in litter production by mistletoe (Misodendrum sp.) and epiphytic lichen (Usnea sp.), related to crown cover in mature unmanaged, second-growth and managed (thinned for silvopastoral use) forests in Tierra del Fuego (Argentina). We used plastic traps to collect litterfall biomass from trees, lichens and mistletoes on a monthly basis over three consecutive years. Tree litter was considerable during autumn (March to May), which is typical of Nothofagus deciduous species in the Southern hemisphere. In contrast, peak litterfall from mistletoes and lichens occurred during spring and summer seasons. Tree litter (1954e3398 kg dry matter ha 1 year 1) was correlated with crown cover gradient being highest in second-growth forests and lowest in thinned sites. While litter input from mistletoes did not vary among forest types (307 e333 kg dry matter ha 1 year 1), lichen litter (11e40 kg dry matter ha 1 year 1) was higher in unmanaged and thinned mature forests despite differences in tree crown cover. Contrary to what we expected, the management practices investigated here did not affect the biomass of canopy communities compared to unmanaged mature forests. Mistletoes and lichens significantly increased the spatial (forest type) and temporal complexity (extended period of falling) of litterfall in Nothofagus antarctica forests. This study provides a starting point to understand the ecological relevance of canopy communities in the Patagonian forests of southern Argentina. Fil: Soler Esteban, Rosina Matilde. 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: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina 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

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

Studies in South America have reported increments of invasivity of Pinus spp. after fire events. These increments are due to morphological and physiological adaptations to wildfires that some species of this specific genus presents. Pinus contorta is an invasive species in temperate ecosystems, affecting Araucaria araucana and Nothofagus antarctica forests in Malalcahuello National Reserve, Chile. In order to comprehend the regeneration response to post-fire, it is necessary to know the response and tolerance of the seeds to high temperatures. Seeds of P. contorta, A. araucana and N. antarctica were sown in pots with sand and subsequently heated at 80, 100 and 120 °C for five minutes. Germination and seedling survival tests were carried out in a greenhouse. Germination in N. antarctica was null. Heat treatments did not have a negative effect on the germination of P. contorta, but they did on A. araucana inhibiting the germination at temperatures over 100 °C. These results suggest that when undergoing a fire of high intensity, P. contorta has a competitive advantage over A. araucana and N. antarctica; the seed bank would have more possibilities to survive the effects of a wildfire., Estudios en Sudamérica han reportado aumentos en la invasividad de Pinus spp. después de eventos de fuego. Esto se debe a adaptaciones morfológicas y fisiológicas a incendios que presentan algunas especies de este género. Pinus contorta es uno de los pinos más invasores en ecosistemas templados y se encuentra invadiendo los bosques de Araucaria araucana y Nothofagus antarctica en la Reserva Nacional Malalcahuello, Chile. Para comprender la respuesta potencial de la regeneración post-incendios en árboles, es necesario conocer la respuesta y tolerancia de la semilla a altas temperaturas. Semillas de P. contorta, A. araucana y N. antarctica fueron sembradas en bandejas con arena y sometidas a 80, 100 y 120 °C por cinco minutos, después fueron llevadas al invernadero para evaluar la germinación y supervivencia de las plántulas. La germinación para N. antarctica fue nula incluso en el control. Las altas temperaturas no presentaron efectos negativos en la germinación de P. contorta, pero sí en A. araucana inhibiendo la germinación a temperaturas mayores a 100 °C. Estos resultados sugieren que, en incendios de alta intensidad, las semillas de P. contorta tiene una ventaja competitiva sobre A. araucana y N. antarctica, ya que el banco de semillas tendrá mayores posibilidades de sobrevivir ante un incendio forestal.

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

Desarrollamos un modelo de estados y transiciones (MEyT) para el bosque de ñire (Nothofagus antarctica) en el norte de la Patagonia, con el fin de sintetizar el conocimiento disperso sobre las repuestas de este sistema al manejo silvopastoril. En base a una recopilación bibliográfica, a un taller de expertos seguido por sesiones de consulta y a relevamientos de campo propusimos los estados alternativos e identificamos los disturbios naturales y las prácticas de manejo más comunes que disparan cambios entre estados. Definimos siete estados, 13 transiciones de degradación y cuatro de restauración. Los bosques más íntegros están dominados por ñire y caña (Chusquea culeou) y el estado más degradado lo componen estepas sub-arbustivas de cadillo (Acaena splendens). Los estados intermedios serían los más aptos para el uso silvopastoril (bosque abierto de ñire con caña y pastizal, y bosque de ñire con pastizal), pero tienen una alta inestabilidad con las prácticas de manejo actuales, ya que, a causa de dicho manejo, con el paso del tiempo perderían el componente arbóreo y la cobertura de caña. El pastoreo, la extracción forestal, los incendios y las especies invasoras son los principales factores que disparan las transiciones de degradación. Estos efectos están agravados por la competencia del componente herbáceo con la vegetación arbórea, la mortandad de árboles y de caña, y por la erosión del suelo. La reversión de las transiciones de degradación no se produce de forma natural en el horizonte productivo del predio (~40 años) y requiere del uso de tecnologías como plantación, protección de los plantines de árboles y desarbustado. La identificación de las fases de riesgo en cada estado permite contar con alertas tempranas de deterioro, visualizar los efectos del manejo y orientar las prácticas para mantener la composición y estructura del bosque dentro de los límites que contemplan los aspectos productivo y ambiental. We built a state-and-transition model (S&TM) for the ñire forest system under silvopastoral use in north-western Patagonia, with the aim to identify management effects on the vegetation. The model can help design practices that maintain the system within ‘desired' conditions in the long term. Based on a review of published and unpublished literature, an expert workshop and consultation, and field surveys we proposed alternative states and their response to natural disturbances and current management practices. We defined seven states, 13 degradation and four restoration transitions, and the factors and levels that trigger the transitions (i.e., grazing, frewood extraction, fire and/or dispersal of invasive plants). The best-conserved forest is dominated by ñire (Nothofagus antarctica) and cane (Chusquea couleou), while the most degraded state corresponds to sub-shrubby steppes dominated by Acaena splendens (cadillo). The intermediate states are likely to be the most suitable for silvopastoral use (open ñire and cane forest, and ñire forest with grassland) but are highly unstable. Therefore, with the common current practices, the tree component and cane cover are lost with time. Invasion of exotic species, competition with the herbaceous vegetation, mortality of trees and cane, and soil erosion are the processes that trigger transitions. Most degradation transitions are difficult to revert because they require high-cost practices and/or have a long recovery time. Building the S & TM brought together scattered information about long-term changes in the vegetation. The identification of risk phases enables early warning of degradation. Fil: Rusch, Verónica. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; Argentina Fil: López, Dardo Rubén. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Manfredi. Estación Forestal Villa Dolores; Argentina Fil: Cavallero, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina Fil: Rusch, Graciela M.. Norwegian Institute for Nature Research; Noruega Fil: Garibaldi, Lucas Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional de Rio Negro. Sede Andina; Argentina Fil: Grosfeld, Javier Edgardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santa Cruz. Universidad Tecnológica Nacional. Facultad Regional Santa Cruz. Centro de Investigaciones y Transferencia de Santa Cruz. Universidad Nacional de la Patagonia Austral. Centro de Investigaciones y Transferencia de Santa Cruz; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad Nacional de la Patagonia Austral; Argentina

Question Could disturbance by fire and ungulate herbivory alter fire regimes by increasing flammability in shrublands and early-successional forests? Location Nahuel Huapi National Park, northwest Patagonia, Argentina. Methods We compared four characteristics that influence fuel flammability – fine fuel load, plant bulk density, percentage fine fuel, and percentage dead fine fuel – and the vertical distribution of live and dead fine fuel at recently burned ( 50 yr) sites, both in the presence and absence of cattle, for six resprouting species: non-palatable Lomatia hirsuta and Diostea juncea, moderately palatable Nothofagus antarctica and Schinus patagonicus, and highly palatable Maytenus boaria and Ribes magellanicum. Results Changes in flammability in response to recent fire, and to a lesser extent cattle browsing, were strongly dependent on species identity. Non-palatable L. hirsuta tended to increase in flammability following fire, whereas cattle did not affect its fuel properties. Nothofagus antarctica showed ambiguous responses: plants had reduced plant bulk density at recently burned sites, implying reduced flammability, but changes in percentage fine and dead fine fuel point to increasing flammability at burned sites with cattle. Diostea juncea and S. patagonicus showed increased plant bulk density at sites with cattle and increased percentage fine fuel in response to fire. Cattle browsing was the main driver of variability in flammability for highly palatable species, showing increased plant bulk density and percentage fine fuel in response to cattle. Fire had a strong effect on the vertical distribution of live and dead fine fuel, showing an increase of burnable biomass in response to recent fire. The reduction of vertical fuel continuity was extreme on highly palatable species. In contrast, moderately and non-palatable species, which are abundant under herbivore pressure, were characterized by vertically well-distributed fine fuel biomass in the presence of cattle. Conclusions Responses of flammability traits to fire and cattle depended on species identity, but the majority of the species studied showed higher fuel flammability at recently burned sites affected by cattle. Domestic livestock, by increasing the flammability of post-fire vegetation, may be key agents in altering fire regimes in forest–shrubland mosaics.

Nothofagus antarctica forests in south Patagonia are usually used as silvopastoral systems but how grasses and trees compete for specific resources, such as nitrogen in these systems is unknown. To understand interactions between grasses and N. antarctica trees for N, an experiment with 15N labeled fertilizer was carried out comparing N absorption by grasses growing under trees (silvopastoral system) with an open site. Labeled 15NH415NO3 fertilizer at 10 % atom excess was added in spring at both sites and 15N was measured in herbage, soil and trees every 30 days during the growing season. Soil was the component that containing the greatest amount of N and greatest 15N recovery. Grasses growing in the silvopastoral system absorbed almost double of the fertilizer applied than grasses in the open site (32.4 kg N ha−1derived from fertilizer based on 15N recovery). Roots were also an important fate for N absorbed, representing 50 and 63 % of total 15N recovered in grass roots of open and silvopastoral sites, respectively. Trees absorbed 69 % less applied N than grasses in the silvopastoral system; being mainly allocated in small branches, sapwood and fine roots. Overall, 15N recovery was 65 % higher in the silvopastoral system (tree + grasses) than in the open site (grasses). Silvopastoral system made more efficient use of the 15N added. These results indicated that N. antarctica trees in the silvopastoral system may “facilitate” fertilizer N absorption of grasses by improving environmental conditions like water availability or by reducing competition for inorganic N between soil microorganisms and plants. Fil: Gargaglione, Veronica Beatriz. Universidad Nacional de la Patagonia Austral; Argentina. Instituto Nacional de Tecnología Agropecuaria. Estación Experimental Santa Cruz; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina. Instituto Nacional de Tecnología Agropecuaria. Estación Experimental Santa Cruz; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rubio, Gerardo. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The effect of a pine invasion on the fuel characteristics was studied to predict fire behaviour and hypothesize potential changes on fire regime. Subalpine Andean forests, fire-prone environments, in the Malalcahuello Reserve in south-central Chile were invaded by the non-native Pinus contorta affecting the native endangered trees Araucaria araucana and Nothofagus antarctica communities. Several fuel components were evaluated by studying different variables, such as fuel load, vertical and horizontal continuity, and flammability of native and invasive tree species. The survey was conducted in five stand conditions: A. araucana and N. antarctica stands, each with and without invasion of P. contorta, and stands with only P. contorta (invasion source). The invasion of P. contorta increased the vertical fuel continuity in the Araucaria forest. The flammability analysis showed that P. contorta is a species highly flammable in comparison to the native trees. The invasion of P. contorta in the Malalcahuello Reserve is under progression and if the process of invasion continues the effects on fuel characteristics will increase. These results suggest that wildfires will be more intense and severe, and that the type of fires of the Malalcahuello Reserve will change from a mixed fire regime to a crown fire regime. These changes will affect plant regeneration, and a positive feedback that favours the P. contorta invasion could emerge. Long-term studies to understand the effect of invasive woody plants on the fire regime are essential for the control of these invasions, especially for the conservation of biodiversity and ecosystem processes in the Araucaria–Nothofagus ecosystems is the Chilean and Argentinean Patagonia.

SUMMARY In northwestern Chubut province extensive cattle rearing is the main economic activity developed under nire canopy (Nothofagus antarctica) in silvopastoral systems with a wide range of livestock stocking rates. Cattle’s browsing causes damages on nire saplings, compromises tree regeneration and consequently woodland sustainability. In the present study, we aimed at evaluating the effects of cattle browsing on nire tree regeneration along time, as related to stocking rate and plant height. Our study was conducted in three livestock rearing settlements in Chubut province, Argentina. Our results revealed that cattle management under low stocking rates along summer range ( 0.8 UG ha -1 ), for an extended period, determines suppressed tree regeneration with a shrubby architecture and lower growing rates. Under such conditions livestock exclusions are needed for at least 20 years to allow regeneration recover. It is possible to make compatible livestock production with woodland persistence by managing low cattle stocking rates and monitoring saplings height.

Resumen Se describe una nueva especie de Idiostolus, Idiostolus schaeferi n.sp. del sur de Chile. Esta especie se encuentra asociada a Nothofagus antarctica (Nothofagaceae) y Pilgerodendron uviferum (Cupressaceae), siendo este último el primer registro de una cupresácea como hospedero de la familia Idiostolidae.

A pronounced environmental gradient dictates the dominance of Nothofagus in the foothills on the eastern side of the Andes Mountains in Patagonia, Argentina. Below 50° southern latitude, open forests of Nothofagus antarctica (ñire) dominate the landscape towards the Patagonian steppe where annual rainfall is low. With increasing rates of annual rainfall, corresponding with an increase in elevation, closed forests of N. pumilio (lenga) replace those of ñire. During a short-term study we assessed differences in stand structure and examined environmental, structural and functional traits related to tree water use of ñire and lenga. Sap velocity reached similar maximum rates (95–100 L m−2 sapwood h−1), but whole-tree water use (Q) was significantly lower in ñire (8–13 L day−1 tree−1) compared to lenga (20–90 L day−1 tree−1) resulting in lower stand transpiration (ñire: 0.51 mm day−1; lenga: 3.42 mm day−1) despite similar tree densities. Related to this, wind speed had a particularly significant impact on Q of ñire, but not lenga. The ratio of leaf area to sapwood area (AL/AS) clearly identified ñire to be more structurally proficient at conserving water. While stem diameter (DBH) and crown area (AC) were well related in both species, only lenga exhibited relationships between variables related to tree allometry and physiology (AC/Q, DBH/Q). Our results provide the first ecophysiological characterization of the two Nothofagus species that define important and widespread ecosystems in southern Patagonia (not only below 50°S), and provide useful data to scale water use of both species from tree to stand. Fil: Pfautsch, Sebastian. University of Sydney; Australia. University of Western Sydney; Australia Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Macfarlane, Craig. CSIRO Ecosystem Sciences; Australia Fil: Ogtrop, Floris van. University of Sydney; Australia Fil: Adams, Mark A.. University of Sydney; Australia

Montane forests provide the natural framework to test for various ecological settings at distinct elevations as they may affect population demography, which in turn will affect the spatial genetic structure (SGS). We analyzed the fine-scale SGS of Nothofagus pumilio, which dominates mountain areas of Patagonia, in three pairs of sites at contrasting elevations (low- vs. high-elevation). Within a total area of 1 ha fresh leaf tissue from 90 individuals was collected at each of the six studied stands following a spatially explicit sampling design. Population genetic diversity parameters were analyzed for all sampled individuals using five polymorphic isozyme loci, and a subset of 50 individuals per stand were also screened for five microsatellite loci. The SGS was assessed on 50 individuals / stand, using the combined datasets of isozymes and microsatellites. Most low-elevation stands consisted of older individuals with complex age structures and genetically diverse plots. In contrast, high-elevation stands and one post-fire low-elevation population yielded even-aged structures with evidence of growth suppression, and were genetically homogeneous. All stands yielded significant SGS. Similarly to mature stands of the non-sprouter congener N. dombeyi, multi-age low-altitude N. pumilio yielded significant SGS weakened by competing species of the understory and the formation of seedling banks. Alike the sprouter N. antarctica, high-altitude stands produced significant SGS as a consequence of occasional seedling establishment reinforced by vegetative spread. Fil: Mathiasen, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; 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

El ñirre en su distribución natural convive con una ganadería extensiva, la que provoca una fuerte presión sobre la regeneración natural y la perpetuidad del bosque, así los ñirrantales exhiben fragmentación y envejecimiento. El principal agente perturbador del medio natural es el hombre, que ha intensificado el uso del suelo para lograr un desarrollo económico. Lograr buscar el equilibrio entre producción y sustentabilidad es el desafío de la investigación forestal y en este sentido el presente trabajo busca iniciar un camino para compatibilizar el uso forestal y ganadero en el marco del manejo silvopastoral sustentable de bosques de ñirre en la Región de Aysén. Nothofagus antarctica (G. Forster) Oerst. (ñirre o ñire) es una especie del bosque nativo que no está ajena a estas perturbaciones, crece en las zonas cordilleranas de Chile y Argentina y es una de las especies forestales con mayor plasticidad ecológica; presenta tres tipos de expresión fenotípica dependiendo del sitio donde se desarrolla. Se distinguen los morfotipos arborescente, achaparrado y camefítico Ramírez et al., 1985). El subtipo forestal ñirre representa regionalmente una superficie de 131.593,4 ha, con presencia en la mayoría de las comunas a excepción de Las Guaitecas. Las mayores poblaciones de ñirre se presentan en las Provincias de Coyhaique y Capitán Prat con 61.630,6 ha y 37.241,3 ha, respectivamente. En el área de distribución natural de los ñirrantales, la actividad forestal convive con la ganadera, con importantes áreas de resguardo de ganado en épocas invernales y bajo alta presión para la obtención de leña. Un porcentaje importante de los cerca de 500.000 m3 de leña que se consume anualmente en la región proviene de los bosques de ñirre. La leña de esta especie es preferida por su alto poder calórico en comparación con la a lenga (2.850 kcal/dm3 vs 2.400 kcal/dm3). Estas presiones generan preocupación por los ecosistemas de ñirre, que solo con técnicas de manejo apropiadas podrán continuar otorgando múltiples bienes y servicios a perpetuidad. En la actual legislación no está regulado el manejo de bosque nativo bajo un enfoque integrado silvo pastoral. La escasa información respecto del tema motivó al Instituto Forestal a iniciar el proyecto Pautas de Manejo Silvopastoral para Bosques de Nothofagus antarctica (ñirre) en la Región de Aysén, que ha buscado desarrollar investigación para hacer viable la producción silvopastoral sustentable en bosques pertenecientes a pequeños productores forestales de la región y cuyos principales resultados son presentados en el presente documento. EEA Santa Cruz Fil: Salinas Sanhueza, Jaime. Instituto Forestal (INFOR), sede Patagonia; Chile. 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; Argentina. Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fil: Hepp, Christian. Instituto de Investigaciones Agropecuarias (INIA). Centro Tamel Aike; Chile. Fil: Acuña, Bernardo. Instituto Forestal (INFOR), sede Patagonia; Chile.

Tesis presentada para optar al Grado de Doctor en Ciencias Naturales Fil: Szulkin Dolhatz, Daniel E.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina

Desde inicios del siglo XX, junto a los primeros vestigios de colonización del territorio aysenino, los bosques nativos fueron objeto de fuertes disturbios antrópicos. Enormes extensiones de terrenos fueron afectadas por los más grandes incendios de bosques registrados en Chile, iniciados con el fin de habilitar suelos para la agricultura y la ganadería. Nothofagus antarctica (G. Forster) Oerst. (ñirre o ñire) es una especie del bosque nativo que no está ajena a estas perturbaciones, crece en las zonas cordilleranas de Chile y Argentina y es una de las especies forestales con mayor plasticidad ecológica. En la actual legislación no está regulado el manejo de bosque nativo bajo un enfoque integrado silvopastoral. La escasa información respecto del tema motivó al Instituto Forestal a iniciar el proyecto Pautas de Manejo Silvopastoral para Bosques de Nothofagus antarctica (ñirre) en la Región de Aysén, que ha buscado desarrollar investigación para hacer viable la producción silvopastoral sustentable en bosques pertenecientes a pequeños productores forestales de la región y cuyos principales resultados son presentados en el presente documento. Fil: Salinas, Jaime. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional.patagonia Sur. Estacion Experimental Agropecuaria Santa Cruz.; Argentina Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Hepp, Christian. Instituto de Investigaciones Agropecuarias.; Chile Fil: Acuña, Bernardo. No especifíca

En este contexto, el objetivo del presente trabajo fue evaluar otras formas de dispersión del ñire a largas distancias. En primavera del 2012, se efectuó un relevamiento por los cursos de agua del Río Turbio y Río Gallegos través de la navegación con kayaks. El inicio del mismo fue desde la localidad de 28 de Noviembre (51°36'21" S, 72°11'54" W) ubicado en las cercanías de las masas boscosas continuas y puras de ñire, hasta la localidad de Río Gallegos (51°37'20" S, 69°13'01" W) a lo largo de aproximadamente 300 km de navegación. Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Cientificas; Argentina Fil: Monelos, Lucas H. Universidad Nacional de la Patagonia Austral; Argentina Fil: Beroiz, Mario. Consejo Agrario Provincial (Santa Cruz); Argentina

The importance of grasses and graminoids for sheep nutrition in Argentinean Patagonia is widely recognized. Focusing on sheep nutrition, we assessed the concentration of mineral elements in grasses growing in three ecological areas of southern Patagonia, representing a vegetation and climate gradient. With the aim of establishing potential relationships, tissue concentrations of several essential and non-essential elements for plants were determined, analyzing also soil properties. Soil and plant tissue mineral element concentrations varied between ecological areas and also depending on the particular element. The results obtained provide novel information about the nutritional characteristics of the main feeding source for sheep in southern Patagonia, but further trials will be required for improving our understanding of mineral element nutrition in relation to sheep production. 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 Politécnica de Madrid. Escuela Técnica Superior de Ingeniería de Montes, Forestal y del Medio Natural. Departamento de Sistemas y Recursos Naturales; España 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 southern fringes of the South American landmass provide a rare opportunity to examine the development of moorland vegetation with sparse tree cover in a wet, cool temperate climate of the Southern Hemisphere. We present a record of changes in vegetation over the past 17,000 years, from a lake in extreme southern Chile (Isla Santa Inés, Magallanes region, 53°38.97S; 72°25.24W), where human influence on vegetation is negligible. The western archipelago of Tierra del Fuego remained treeless for most of the Lateglacial period; Lycopodium magellanicum, Gunnera magellanica and heath species dominated the vegetation. Nothofagus may have survived the last glacial maximum at the eastern edge of the Magellan glaciers from where it spread southwestwards and established in the region at around 10,500 cal. yr BP. Nothofagus antarctica was likely the earlier colonizing tree in the western islands, followed shortly after by Nothofagus betuloides . At 9000 cal. yr BP moorland communities expanded at the expense of Nothofagus woodland. Simultaneously, Nothofagus species shifted to dominance of the evergreen Nothofagus betuloides and the Magellanic rain forest established in the region. Rapid and drastic vegetation changes occurred at 5200 cal. yr BP, after the Mt Burney MB2 eruption, including the expansion and establishment of Pilgerodendron uviferum and the development of mixed Nothofagus-Pilgerodendron-Drimys woodland. Scattered populations of Nothofagus , as they occur today in westernmost Tierra del Fuego may be a good analogue for Nothofagus populations during the Lateglacial in eastern sites. peerReviewed

Question: In northwest Patagonia burning of fire-resistant forests creates a community-level positive feedback towards increased fire occurrence because of successional replacement by fire-prone shrublands. We hypothesize that variability in plant traits related to time since last fire and to herbivory by cattle may affect foliar flammability, thus providing a flammability-promoting mechanism operating at the level of individual plants. We examine how plant foliar traits affecting flammability vary across species and at sites recovering from recent fires ( 50 yr, both in the presence and absence of cattle. Location: Nahuel Huapi National Park, northwest Patagonia, Argentina. Methods: We measured four foliar traits expected to affect flammability: leaf moisture, leaf size, specific leaf area and leaf strength, and conducted tests of ignitability (time to ignition and duration of combustion) on leaves of six common tall shrub and small tree species: non-palatable Lomatia hirsuta and Diostea juncea, moderately palatable Nothofagus antarctica and Schinus patagonicus and highly palatable Maytenus boaria and Ribes magellanicum. We used ANOVA and PCA to examine potential relationships among species flammability traits, time since fire and presence or absence of cattle. Results: At plant level, variability in flammability-related foliar properties is strongly and consistently related to time since last fire, whereas effects of cattle are more variable across species and treatments. In comparison with unburned forests, the dominant woody species at shrubland sites showed reduced leaf moisture, leaf size and specific leaf area. Under pressure from cattle, N. antarctica, one of the most important woody species in these shrublands, showed changes in some foliar traits expected to enhance flammability (e.g. shorter time to ignition) but overall the influence of cattle on flammability was not consistent. Conclusions: The current study demonstrates that plant foliar traits vary between recently burned and unburned sites, and that these variations may enhance foliar flammability in shrubland communities. We hypothesize that variability in plant traits related to time since last fire and to herbivory by cattle may affect foliar flammability, thus providing a flammability-promoting mechanism operating at the level of individual plants. In northwestern Patagonia, Argentina, plant foliar traits vary between recently burned and unburned sites, and these variations may enhance foliar flammability in shrubland communities. Fil: Blackhall, Melisa. 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 Fil: Raffaele, Estela. 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 Fil: Veblen, Thomas. State University of Colorado at Boulder; Estados Unidos

In a Mapuche community situated in the sub-antarctic forest of the northwest of Argentine Patagonia, analysis was carried out on forest environmental perception and its relation to the resilience of the body of traditional botanical knowledge regarding medicinal plants. Data was obtained on the ethno-classification and differential use of the forest gathering environment with respect to its practical and cultural value. Semi-structured interviews were carried out with 30 randomly chosen inhabitants, and the data were analysed using qualitative methods and non-parametric statistics. Most citations (64.5%) were of species gathered in Nothofagus antarctica forest, 26.2% were of species from N. pumilio forest, and 20.3% referred to species from a mixed forest, with N. dombeyi. The forests studied have low values for similarity in terms of medicinal species richness, indicating a unique offer of therapeutic resources in each one. The use of the different forest types seems to be associated with the search for therapeutic resources for specific ailments. However, the redundancy of functions of species in each forest type can offer alternative remedies, which provides plant conservation, security and the possibility of reorganisation of their traditional medicinal knowledge. This case study showed the importance of considering folk systems and the role that this knowledge has played in plant resource management and forest protection. Different forests are used and valued differentially, not only with regard to usefulness but also in symbolic-religious terms, and together they fulfil a cushioning function, protecting holistically traditional botanical knowledge, people’s health and forests. It is of great importance, therefore, that conservation policies favouring environmental heterogeneity are implemented, and that local inhabitants participate in the development of management plans.

The role of environmental variables on litter decomposition and its nutrient release in Nothofagus antarctica forest in Patagonia is poorly understood. Moreover, in these forests under silvopastoral use there are few antecedents. Litter decomposition and nutrient release of grasses and tree leaves were evaluated under different crown cover and two site quality stands during 480 days. Organic matter decomposition varied with crown cover for both types of litter, achieving mean values of 23 and 34% for maximal and minimal crown cover, respectively. Total transmitted radiation was the main environmental factor explaining 61 and 49% of the variation of grass and tree leaves decay rates, respectively. N, P, and Ca were mineralized during first 60 days in decomposing tree leaves and then immobilized without differences between crown cover. The K was immobilized during the evaluated period. In decomposing grass leaves the results varied according to site quality and time. There was a tendency of nutrient mineralization at the first 120 days and then immobilization. The removal of trees for silvopastoral use of N. antarctica may increase litter decomposition by changing the microclimate, but nutrients release or immobilization was mainly affected for their concentration in decomposing material. Fil: Bahamonde, Héctor Alejandro. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; Argentina. Universidad Nacional de la Patagonia Austral; Argentina Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; Argentina Fil: Alvarez, Roberto. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Barneix, Atilio José. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; 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

In phylogenetically related plant species, hybridization can influence their current genetic structure. Long-lasting hybridization may be related to persistence in shared glacial refugia, where the differential abilities of each species to survive could have provided adaptations to changing environmental conditions. In temperate South American forests at the Patagonia region, the pattern of Quaternary glaciations offered several opportunities for refuge. At mid-latitudes (42° to 44° S), particular topographic characteristics determined different glaciation patterns, defining the existence of a transitional zone. We studied two widespread Nothofagus species (Nothofagus pumilio, Nothofagus antarctica) characterized by contrasting plasticity. We screened 40 coupled populations with three cpDNA markers and found 14 different haplotypes. Both species presented significant phylogeographic structure (N ST ≥ G ST, p > 0.001), with two geographically segregated lineages (north–south). A latitudinal cline in the distribution of genetic diversity was determined, with most variable populations in the north (35°–41° S). Population diversity diminished to southern latitudes, but a particular situation occurs between 42°S and 44°S. The transition zone, a putative refuge area, presented unique haplotypes. The more plastic species, N. antarctica, probably persisted in more refuge areas, which could be reflected in its higher levels of diversity. In these species, sympatric distribution explains introgression (IG > IG e), but the differential levels of haplotype sharing between N. pumilio and N. antarctica at population level are relevant to the understanding of phylogeographic patterns. Hybridization may have facilitated recruitment in the onset of postglacial colonization by middle to long-distance pollen dispersal. In the current scenario of climate change, the presence of hybrids with different plastic responses is of remarkable importance.

n-Alkane distributions are frequently used as palaeoclimate proxies in ombrotrophic peat deposits. Although n-alkane distributions differ strongly between plant species, n-alkanes are not species-specific molecules. For a proper interpretation, it is important to understand the different abundances of n-alkanes in various plant species as well as the changes that occur when plant litter is transformed to peat. In particular because molecular markers are especially valuable in highly decomposed peat where plant remains are no longer recognizable, it is important to understand the effects of decomposition on n-alkane distributions. The organic matter (OM) of a high-resolution sampled, 9 m thick, ombrotrophic peat deposit from Tierra del Fuego was analysed with pyrolysis-gas chromatography/mass spectrometry (pyrolysis-GC/MS). The same samples were analysed for carbon (C) and nitrogen (N) content. Depth profiles of C:N ratio, the summed lignin and summed polysaccharide pyrolysis products, and markers specific for Sphagnum spp., Empetrum rubrum and Nothofagus antarctica, enabled a reconstruction of changes in vegetation composition to be made. This reconstruction was used to examine the validity of the n-C23 alkane to indicate Sphagnum and the summed long chain n-alkanes (C29 and C31) to reflect leaf input of the woody species E. rubrum and N. antarctica. Our results show that even in Sphagnum-dominated peat, the n-alkane distribution is not determined by Sphagnum but by leaf input of E. rubrum and N. antarctica. However, good correlations between the n-C23 alkane and the Sphagnum marker 4-isopropenylphenol, and between the summed n-C29 and n-C31 alkanes and the marker of N. antarctica support that their relative change with depth can be used to indicate the abundance of these species in Sphagnum-dominated peat. In peat with relatively low contributions of Sphagnum, both n-alkane proxies (C23 and C29 + C31) reflect the degree of decomposition. We evaluated the influence of Sphagnum dominance, decomposition, and pyrolysis on the n-alkane distributions in peat OM.

Stable isotope natural abundance measurements integrate across several biogeochemical processes in ecosystem N and C dynamics. Here, we report trends in natural isotope abundance (δ13C and δ15N in plant and soil) along a climosequence of 33 Nothofagus forest stands located within Patagonia, Southern Argentina. We measured 28 different abiotic variables (both climatic variables and soil properties) to characterize environmental conditions at each of the 33 sites. Foliar δ13C values ranged from −35.4‰ to −27.7‰, and correlated positively with foliar δ15N values, ranging from −3.7‰ to 5.2‰. Soil δ13C and δ15N values reflected the isotopic trends of the foliar tissues and ranged from −29.8‰ to −25.3‰, and −4.8‰ to 6.4‰, respectively, with no significant differences between Nothofagus species (Nothofagus pumilio, Nothofagus antarctica, Nothofagus betuloides). Principal component analysis and multiple regressions suggested that mainly water availability variables (mean annual precipitation), but not soil properties, explained between 42% and 79% of the variations in foliar and soil δ13C and δ15N natural abundance, which declined with increased moisture supply. We conclude that a decline in water use efficiency at wetter sites promotes both the depletion of heavy C and N isotopes in soil and plant biomass. Soil δ13C values were higher than those of the plant tissues and this difference increased as annual precipitation increased. No such differences were apparent when δ15N values in soil and plant were compared, which indicates that climatic differences contributed more to the overall C balance than to the overall N balance in these forest ecosystems.

Nothofagus antarctica is the most representative species of the native mixed forest occupying ecotone areas between forests and steppe in NW Patagonia, South-America. In this type of environment, vulnerability to climate change is particularly enhanced. Predictions of future climatic conditions for this region indicate an increment of atmospheric temperature and also, a high variability of rain events, threatening forest persistence and productivity. In this framework, management strategies are crucial to guarantee sustainability of native vegetation systems. The objective of this study was to study the effect of tree density on the ecophysiological limitations of water use of N. antarctica, as a proxy to its productivity, during a drought period. Compared with the unthinned forest, the thinned forest showed higher soil water availability, higher sapflow density (Js) and canopy conductance (Gc) values, similar aerodynamic conductance (Ga) and a low degree of coupling to vapor pressure deficit. Ecophysiological results demonstrated a high limitation over gas exchange of individual N. antarctica trees imposed by the resistance in the hydraulic soil-to-leaf pathway in the unthinned-natural condition. Surprisingly, our results suggest structural limitations in the unthinned stand which reduce the ability of N. antarctica trees to take advantage of wet seasons, at least in the short term. Thinning could decrease the susceptibility of N. antarctica-based systems to drought stress, by increasing resource availability to the remaining trees, thus contributing to enhance the persistence of this species under climate change conditions.

In NW Patagonia, South America, natural shrublands and mixed forests of short Nothofagus antarctica (G. Forst.) Oerst. trees are currently being replaced by plantations with Pseudotsuga menziesii (Mirb) Franco. This land use change is controversial because the region is prone to drought, and replacement of native vegetation by planted forests may increase vegetation water use. The goal of this study was to examine the physiological differences, especially the response of water flux and canopy conductance to microclimate, that lead to greater water use by exotic trees compared to native trees. Meteorological variables and sapflow density of P. menziesii and four native woody species were measured in the growing season 2005–2006. Canopy conductance (gc) was estimated for both the exotic (monoculture) and native (multi-species) systems, including the individual contributions of each species of the native forest. Sapflow density, stand-level transpiration and gc were related to leaf-to-air vapor pressure difference (VPD). All native species had different magnitudes and diurnal patterns of sapflow density compared to P. menziesii, which could be explained by the different gc responses to VPD. Stomatal sensitivity to VPD suggested that all native species have a stronger stomatal control of leaf water potential and transpiration due to hydraulic limitations compared to P. menziesii. In conclusion, differences in water use between a P. menziesii plantation and a contiguous native mixed forest of similar basal area could be explained by different gc responses to VPD between species (higher sensitivity in the native species), in addition to particular characteristics of the native forest structure.

The resource use efficiency, the relationship between productivity and the amount of used resources, have been proposed to increase as forests increase their productivity and rate of resource use (Binkley, D., Stape, J.L., Ryan, M.G., 2004. Thinking about efficiency of resource use in forests. For. Ecol. Manage. 1–2, 5–16). To test the generality of this hypothesis, we estimated annual productivity and water use efficiency (WUE) of an exotic Douglas-fir ( Pseudotsuga menziesii (Mirb) Franco) plantation and a multi-species native forest in N.W. Patagonia, both growing on the same site. We hypothetized that, within a site, the more productive system ( a priori the Douglas-fir plantation) has a higher WUE than the less productive system (the native forest), and that within the native forest, the more productive species have higher WUE than the less productive ones. Five taxa were the most conspicuous woody species in the native forest, which was codominated by Nothofagus antarctica and Lomatia hirsuta . Both studied systems had reached their maximum leaf area index (approximately, 5 and 11 for the native and exotic forests, respectively). Annual productivity was 2.3 times higher in the Douglas-fir plantation than in the native forest, however two native species showed similar values of biomass productivity than the exotic species. The amount of water used by the native system was lower than that used by the Douglas-fir plantation, but not as low as the observed differences in productivity, thus resulting in a higher WUE in the Douglas-fir plantation than in the native forest (1.8 times higher). In addition, WUE was also different among the native species. The lower WUE at the stand level in the case of the native forest probably is due to the presence of retamos and lauras. We concluded that: (1) the more productive system (the Douglas-fir plantation) had a higher WUE than the less productive system (the native mixed forest); (2) within the native mixed forest, the most productive species ( L. hirsuta and N. antarctica ) had the highest WUE of all native species. Future research is needed to explain the physiological causes (daily patterns of transpiration and carbon fixation and allocation) of the observed differences in WUE between species and whole systems.

The above- and belowground biomass and nutrient content (N, P, K, Ca, S and Mg) of pure deciduous Nothofagus antarctica (Forster f.) Oersted stands grown in a marginal site and aged from 8 to 180 years were measured in Southern Patagonia. The total biomass accumulated ranged from 60.8 to 70.8 Mg ha −1 for regeneration and final growth stand, respectively. The proportions of belowground components were 51.6, 47.2, 43.9 and 46.7% for regeneration, initial growth, final growth and mature stand, respectively. Also, crown classes affected the biomass accumulation where dominant trees had 38.4 Mg ha −1 and suppressed trees 2.6 Mg ha −1 to the stand biomass in mature stand. Nutrient concentrations varied according to tree component, crown class and stand age. Total nutrient concentration graded in the fallowing order: leaves > bark > middle roots > small branches > fine roots > sapwood > coarse roots > heartwood. While N and K concentrations increased with age in leaves and fine roots, concentration of Ca increased with stand age in all components. Dominant trees had higher N, K and Ca concentrations in leaves, and higher P, K and S concentrations in roots, compared with suppressed trees. Although the stands had similar biomass at different ages, there were important differences in nutrient accumulation per hectare from 979.8 kg ha −1 at the initial growth phase to 665.5 kg ha −1 at mature stands. Nutrient storage for mature and final growth stands was in the order Ca > N > K > P > Mg > S, and for regeneration stand was Ca > N > K > Mg > P > S. Belowground biomass represented an important budget of all nutrients. At early ages, N, K, S, Ca and Mg were about 50% in the belowground components. However, P was 60% in belowground biomass and then increased to 70% in mature stands. These data can assist to quantify the impact of different silviculture practices which should aim to leave material (mainly leaves, small branches and bark) on the site to ameliorate nutrient removal and to avoid a decline of long-term yields.

Conservation strategies of forested landscapes must consider biodiversity of the included site types, i.e. timber-quality forests and associated non-timber-quality stands. The objectives were to characterize forest overstory structure in timber-quality versus associated non-timber-quality stands; and to compare their understory communities. Six forest types were sampled in Nothofagus forests of Tierra del Fuego (Argentina): two timber-quality N. pumilio forests, and four associated non-timber-quality stands (edge, N. antarctica, wetlands and streamside forests). Overstory structure and understory vegetation (species richness, frequencies, cover and biomass) were characterized during spring and summer seasons. Analysis of variance and multivariates were carried out. Overstory structure differed across the site types, with higher tree size, canopy closure and tree volume in timber-quality stands. Fifty-one understory plant species were observed, but understory variables varied with site types, especially wetlands (highest native and exotic richness, cover and biomass, and 25% of exclusive species). Site types were grouped in three: N. antarctica stands, streamside stands and the other N. pumilio forests according to multivariate analysis. Forty three percent of plants were distributed in all site types, and all timber-quality forest understory species were present in some associated non-timber-quality stands. Timber-quality N. pumilio forests have a marginal value for understory conservation compared to associated non-timber-quality stands, because these last include all the plants observed in timber-quality forests and also possess many exclusive species. Therefore, protection of associated non-timber-quality stands during forest management planning could increase understory conservation at landscape level, and these could be better reserves of understory diversity than retentions of timber-quality stands. 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: Rivero, Paola. Universidad Nacional del Litoral; Argentina Fil: Busso, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina

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

El bosque nativo Andino- Patagónico se caracteriza por la presencia de diversas especies de Nothofagus (Fagales: Nothofagaceae). Estas especies leñosas no sólo representan una pieza del patrimonio natural, sino que además se presentan como una alternativa productiva de cultivo. Estudiar la ecología del comportamiento de los insectos fitófagos nativos del bosque Andino-Patagónico permite estudiar los mecanismos de elección, la biología del insecto y brindan información sobre el mantenimiento del estado sanitario del bosque como así también para el Manejo Integrado de Plagas (MIP). El objetivo general de mi tesis fue estudiar las elecciones que realizan algunas especies de insectos fitófagos asociados a N.antarctica, N. dombeyi, N. obliqua, N. nervosa y N. pumilio durante su comportamiento de búsqueda de recursos de hábitat y/o alimenticios. Como así también determinar qué variables explican dichos comportamientos. Para ello, desarrollé una metodología experimental y un protocolo de análisis de datos innovador para pruebas de preferencia pareadas y llevé a cabo tres casos de estudio. En el primer caso, mi objetivo fue estudiar el comportamiento de búsqueda de hábitat de pupación y la relación con las propiedades físico-químicas del sustrato para el minador de hojas Notofenusa surosa (Hymenoptera: Tenthredinidae). Seleccioné diferentes tipos de sustratos y evalué en cuál sustrato formaba la pupa. Mediante la generación de varios modelos determiné que estas larvas son capaces de elegir su sustrato y el porcentaje de materia orgánica fue el parámetro que mejor explicó sus elecciones. En el segundo caso de estudio, mi objetivo fue evaluar la conducta de selección de la planta hospedadora en el insecto succionador Sinopla perpunctatus (Hemiptera: Acanthosomatidae) y determinar si parámetros como la edad y la ceniza volcánica influyen en el comportamiento del insecto durante este proceso. Evalué las preferencias con ramas de N. antarctica, N. nervosa, N. obliqua y de una planta de plástico (control). La variable respuesta fue la elección de planta en forma diaria para cada individuo durante una semana. Las plantas preferidas para S.perpunctatus fueron N. antarctica y N. obliqua, mientras que N. nervosa ocupó el segundo lugar. Las defensas físicas y/o químicas de las hojas entre las especies explicarían esta escala de preferencias. A partir del modelo seleccionado pude analizar que el comportamiento del insecto no resulta afectado por las cenizas o el transcurso del tiempo, sino que está determinado por el efecto hogar, es decir una vez que el insecto elige su planta hospedadora decide establecerse y no cambiar. En este aspecto la falta de motivación podría ser explicada por la “Teoría de forrajeo óptimo”. Para el tercer caso de estudio, el objetivo fue evaluar las preferencias de una planta hospedadora para tres especies de insectos masticadores Polydrusus nothofagii, P. roseaus (Coleoptera: Curculionidae) y Perzelia arda (Lepidoptera: Oecophoridae), y determinar la relación entre sus preferencias y las propiedades nutricionales de las hojas. Seleccioné 22 árboles diferentes del género Nothofagus y dos plantas no hospedadoras a modo de control (Populus nigra y Salix nigra). Recolecté muestras de hojas de las plantas hospedadoras y medí sus propiedades nutricionales. Simultáneamente coloqué un insecto dentro de un contenedor con hojas de dos tipos de árboles diferentes (estímulos). Luego observé en cuál de los dos estímulos se habían alimentado. A partir de los resultados establecí una escala de preferencias de cada árbol para cada insecto. Las tres especies de insectos se alimentaron de los Nothofagus ofrecidos y presentaron escalas de preferencia diferentes. A partir de los modelos generados con las propiedades de las hojas, pude comprobar que la celulosa es la propiedad que mejor explica las elecciones realizadas por los insectos. Sin embargo, las especies de Polydrusus prefieren hojas con menor contenido de celulosa, mientras que P. arda es opuesta. Por lo tanto, la celulosa puede actuar como una defensa anti-herbivoría para los Curculionidae. Los estudios del comportamiento realizados mediante este tipo de pruebas de preferencia brindan conocimientos biológicos sobre los insectos del bosque y establecen un punto de partida hacia la comprensión de las implicancias que poseen estos insectos estudiados en los planes de manejo silvícola y en el mantenimiento del estado sanitario del bosque. Fil: Pietrantuono, Ana Laura. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentina.

Nothofagus antarctica (Forster f.) Oersted is a deciduous tree species, which naturally grows on poorly drained or drier eastern sites in the Andes Mountain near Patagonian steppe. Above- and below-ground biomass and nutrients pools were measured in pure even-aged stands at different ages (5–220 years) and crown classes. Functions were fitted for total biomass and nutrients accumulation, and root/shoot ratio of individual trees against age. Total biomass accumulated for mature dominant trees was eight times greater than mature suppressed trees. Biomass root/shoot ratio decreased with age from 1.8 to a steady-state of 0.5. All nutrients concentration (except Ca) decreased with age and varied according to the degree of crown suppression classes. Nutrient concentrations varied between biomass pool components following the order leaves > bark > small branches > fine roots > medium roots > rooten wood > coarse roots > sapwood > heartwood. Total nutrient accumulation followed the order dominant > codominant > intermediate > suppressed trees and its accumulation rate varied over time, e.g. P accumulation rate of dominant trees increased from 0.17 g tree−1 year−1 during regeneration to 1.39 g tree−1 year−1 in mature trees. Nutrients uptake reached a peak during the period of maximum biomass production, and root/shoot ratio of nutrients decreased from its maximum value at 5 years of age (0.6, 4.0, 0.9, 1.5, 1.0 and 2.6 for N, P, K, Ca, S and Mg, respectively) to a steady-state asymptote beyond 50 years of age. Thus, accumulation of nutrients in roots was greater during the regeneration phase of stand development, and nutrient accumulation increased in above-ground over time. Also, nutrient use efficiency increased in mature trees (111–220 years) and decreased in suppressed crown classes. The equations developed for individual trees have been used to estimate stand biomass and nutrient accumulation from forest inventories data. Total stand biomass varied from 62.5 to 133.4 t ha−1 and total nutrients accumulation ranged from 3 kg Mg ha−1 to 1235 kg Ca ha−1. Proposed equations can be used for practical purposes such as to estimate pasture nutrients requirement in a silvopastoral system based on nutrients supply from leaf litter returns, or to determine amelioration practices like debarking stems before harvesting.

North American beavers ( Castor canadensis ) were introduced into southern South America in 1946. Since that time, their populations have greatly expanded. In their native range, beavers shape riparian ecosystems by selectively feeding on particular plant species, increasing herbaceous richness and creating a distinct plant community. To test their effects as exotic engineers on sub-Antarctic vegetation, we quantified beaver impacts on tree canopy cover and seedling abundance and composition, as well as their impacts on herbaceous species richness, abundance and composition on Navarino Island, Cape Horn County, Chile (55°S). Beavers significantly reduced forest canopy up to 30 m away from streams, essentially eliminating riparian forests. The tree seedling bank was greatly reduced and seedling species composition was changed by suppressing Nothofagus betuloides and Nothofagus pumilio , but allowing Nothofagus antarctica . Herbaceous richness and abundance almost doubled in meadows. However, unlike beaver effects on North American herbaceous plant communities, much of this richness was due to invasion by exotic plants, and beaver modifications of the meadow vegetation assemblage did not result in a significantly different community, compared to forests. Overall, 42% of plant species were shared between both habitat types. Our results indicate that, as predicted from North American studies, beaver-engineering increased local herbaceous richness. Unlike in their native range, though, they did not create a unique plant community in sub-Antarctic landscapes. Plus, the elimination of Nothofagus forests and their seedling bank and the creation of invasion pathways for exotic plants together threaten one of the world’s most pristine temperate forest ecosystems.

Although positive interactions among plants are believed to be common in primary succession, they have rarely been demonstrated on glacial moraines. In Patagonia, the prostrate shrub Empetrum rubrum is dominant in early succession in recently deglaciated valleys, eventually being replaced by the small tree Nothofagus antarctica. This study experimentally evaluates the effects of E. rubrum shrubs on density, biomass, growth and survival of N. antarctica seedlings. The initial density of the seedlings was significantly higher under the canopy of Empetrum than in open areas. A removal experiment was performed to evaluate the influence of Empetrum on survival and growth of seedlings that germinated naturally beneath the canopy of this species. The shrub cover was removed from half of a sample of randomly selected seedlings, and left intact above the remainder. One year later, seedlings with an intact cover of E. rubrum showed significantly higher survival, growth and leaf number than seedlings which had been exposed. The results suggest that the presence of E. rubrum facilitates the establishment of N. antarctica in post-glacial succession, mainly as a result of more favourable microclimatic conditions under the shrub canopy.

Summary • Tierra del Fuego is subject to increases in solar UV-B radiation in the austral spring and summer due to ozone depletion. • Plastic films were used to filter solar UV-B radiation over peatland plots through six field seasons, resulting in near-ambient (c. 90%) and reduced (c. 17%) solar UV-B treatments. • As in the first three field seasons of treatments, near-ambient UV-B caused reduced height growth but had no effect on biomass production of the moss Sphagnum magellanicum. It reduced leaf and rhizome growth of Tetroncium magellanicum. Height growth and morphology of Empetrum rubrum and Nothofagus antarctica were only affected by solar UV-B during the fourth to sixth field seasons. There was also a decrease in Tetroncium leaf nitrogen under near-ambient UV-B. • Growth of Sphagnum was less affected than that of most emergent vascular plants. This enabled the Sphagnum mat to engulf more Nothofagus, and limit the escape of Empetrum under near-ambient UV-B. Yet, differences in the response of species to solar UV-B were not expressed as changes in plant community composition.

The objectives of this study were to test potential effects of solar ultraviolet-B (UV-B) radiation on (i) foliage nutritional quality and foliage decomposition rates of six plant species of this fen ecosystem (Nothofagus antarctica, Carex curta, C. decidua and C. magellanica; Acaena magellanica and Gunnera magellanica) and (ii) feeding preferences for these plant species of the slug Deroceras reticulatum prevalent in this ecosystem. In a mixed-diet selection slugs were offered leaves of the six species that had been grown for three years in experimental field plots under either near-ambient or reduced solar ultraviolet-B (UV-B) radiation. The chosen characteristics of leaf quality (nitrogen concentration, carbon:nitrogen ratio, specific leaf area) and leaf decomposition rates of the six species varied significantly among species but were not affected by the UV-B treatments. However, there were UV-B treatment effects on slug feeding preference for two plant species. For the tree species, Nothofagus, slugs had consumed only one-third as much foliage grown under near-ambient UV-B radiation as of foliage grown under reduced UV-B by the end of the feeding experiment. In contrast, leaves of the sedge C. decidua that had been grown under near-ambient UV-B were consumed twice as much as leaves grown under reduced UV-B radiation. Consumption of foliage for the other four species was similar for the two UV-B treatments. Additionally, diet selection of the slugs was also significantly affected by prior UV-B conditions under which foliage had been grown. Nothofagus leaves were consumed proportionately less and C. decidua proportionately more if the foliage had been grown under near-ambient UV-B radiation.

Estudios en Sudamérica han reportado aumentos en la invasividad de Pinus spp. después de eventos de fuego. Esto se debe a adaptaciones morfológicas y fisiológicas a incendios que presentan algunas especies de este género. Pinus contorta es uno de los pinos más invasores en ecosistemas templados y se encuentra invadiendo los bosques de Araucaria araucana y Nothofagus antarctica en la Reserva Nacional Malalcahuello, Chile. Para comprender la respuesta potencial de la regeneración post-incendios en árboles, es necesario conocer la respuesta y tolerancia de la semilla a altas temperaturas. Semillas de P. contorta, A. araucana y N. antarctica fueron sembradas en bandejas con arena y sometidas a 80, 100 y 120 °C por cinco minutos, después fueron llevadas al invernadero para evaluar la germinación y supervivencia de las plántulas. La germinación para N. antarctica fue nula incluso en el control. Las altas temperaturas no presentaron efectos negativos en la germinación de P. contorta, pero sí en A. araucana inhibiendo la germinación a temperaturas mayores a 100 °C. Estos resultados sugieren que, en incendios de alta intensidad, las semillas de P. contorta tiene una ventaja competitiva sobre A. araucana y N. antarctica, ya que el banco de semillas tendrá mayores posibilidades de sobrevivir ante un incendio forestal. Studies in South America have reported increments of invasivity of Pinus spp. after fire events. These increments are due to morphological and physiological adaptations to wildfires that some species of this specific genus presents. Pinus contorta is an invasive species in temperate ecosystems, affecting Araucaria araucana and Nothofagus antarctica forests in Malalcahuello National Reserve, Chile. In order to comprehend the regeneration response to post-fire, it is necessary to know the response and tolerance of the seeds to high temperatures. Seeds of P. contorta, A. araucana and N. antarctica were sown in pots with sand and subsequently heated at 80, 100 and 120 °C for five minutes. Germination and seedling survival tests were carried out in a greenhouse. Germination in N. antarctica was null. Heat treatments did not have a negative effect on the germination of P. contorta, but they did on A. araucana inhibiting the germination at temperatures over 100 °C. These results suggest that when undergoing a fire of high intensity, P. contorta has a competitive advantage over A. araucana and N. antarctica; the seed bank would have more possibilities to survive the effects of a wildfire.

We evaluated the annual litterfall and nutrients return in primary forests of Nothofagus antarctica growing at three different site classes (SC) (III, IV and V) and compared two of these forests with adjacent stands under silvopastoral use (thinned 40 years ago), in Patagonia, Argentina. Traps were installed in each stand and sampled monthly during the litterfall over 10 years. Sample from the five stands was ground for further analyses of nutrients (N, P, K, Ca, Mg and S). The litterfall varied significantly between SC, but not between years, from 1,306 to 1,972 kg ha−1 in the best site. The nutrients return from litterfall did not change neither between site classes and years in most nutrients. Comparing primary forests with silvopastoral stands, in SCIV, significant differences among uses occurred for litterfall production and nutrients return, being higher in primary forest. While, in SCV, the litterfall and nutrients return practically did not change among uses. The results showed the incidence of site quality and forest use on the litterfall and nutrients return in N. antarctica forests. Fil: Bahamonde, Nora. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad Nacional de la Patagonia Austral; 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: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Monelos, L.. Universidad Nacional de la Patagonia Austral; Argentina

1. Plant growth and pigmentation of the moss Sphagnum magellanicum and the vascular plants Empetrum rubrum, Nothofagus antarctica and Tetroncium magellanicum were measured under near-ambient (90% of ambient) and reduced (20%) ultraviolet-B (UV-B) radiation for three growing seasons in a Sphagnum peatland in Tierra del Fuego, Argentina (55°S). 2. Reduction of solar UV-B increased height growth but decreased volumetric density in S. magellanicum so that biomass production was not influenced during the 3 years. The morphology of vascular plants tended not to respond to UV-B reduction. 3. A 10-20% decrease in UV-B-absorbing compounds occurred in T. magellanicum under solar UV-B reduction. No effects were seen on chlorophyll or carotenoids in S. magellanicum, although, for UV-B-absorbing compounds, a significant interaction between UV-B and year suggests some response to solar UV-B reduction. 4. The climate-related growth of the dwarf shrub E. rubrum was assessed retrospectively by correlating an 8-year record of annual stem elongation with macroclimatic factors including solar UV-B and visible radiation, precipitation and temperature. 5. No significant negative correlations were found between annual E. rubrum stem elongation and ambient solar UV-B, the ratio of UV-B: visible radiation, or the 305-nm: 340-nm irradiance ratio for an 8-year record (1990-91 to 1997-98), nor was stem elongation affected by solar UV-B reduction in our experimental field plots after 3 years. 6. The role of solar UV-B radiation on plant growth in Sphagnum peatlands in Tierra del Fuego, Argentina, is likely to depend on the severity of stratospheric ozone depletion over the next several decades. The increases in ambient solar UV-B associated with ozone depletion over the last 20 years are less than the difference between our radiation treatments. Therefore, providing that the ozone layer substantially recovers by the middle of this century, only modest effects of increased solar UV-B on plant growth may be expected. Fil: Searles, Peter Stoughton. State University of Utah; Estados Unidos Fil: Flint, Stephan D.. State University of Utah; Estados Unidos Fil: Diaz, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Rousseaux, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Ballare, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Caldwell, Martyn M.. State University of Utah; Estados Unidos

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