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Foliar anatomy and morphology are strongly related to physiological performance; therefore, phenotypic plasticity in leaves to variations in environmental conditions, such as irradiance and soil moisture availability, can be related to growth rate and survivorship, mainly during critical growth phases, such as establishment. The aim of this work was to analyze changes in the foliar internal anatomy (tissue proportions and cell dimensions) and external morphology (leaf length, width and area) of Nothofagus pumilio (Poepp. et Endl.) Krasser seedlings growing in a greenhouse under controlled irradiance (three levels) and soil moisture (two levels) during one growing season (measured three times), and to relate them to physiological traits. Three irradiance levels (4, 26 and 64% of the natural incident light) and two soil moisture levels (40 and 80% soil capacity) were evaluated during November, January and March. Internal foliar anatomy of seedlings was analyzed using digital photographs of histological cuttings, while leaf gross morphology was measured using digital calipers and image analysis software. Most internal anatomical variables presented significant differences under different irradiance levels during the growing season, but differences were not detected between soil moisture levels. Palisade parenchyma was the tissue most sensitive to irradiance levels, and high irradiance levels (64% natural incident light) produced greater values in most of the internal anatomical variables than lower irradiance levels (4–24% natural incident light). Complementarily, larger leaves were observed in medium and low irradiance levels, as well as under low soil moisture levels (40% soil capacity). The relationship of main results with some eco-physiological traits was discussed. Foliar internal anatomical and external morphological plasticity allows quick acclimation of seedlings to environmental changes (e.g., during harvesting). These results can be used to propose new forest practices that consider soil moisture and light availability changes to maintain high physiological performance of seedlings. [ABSTRACT FROM PUBLISHER]

Silvopastoral systems are one of the strategies proposed to manage natural forests in southern Patagonia for livestock and timber purposes. In the context of climate change, it is necessary to design new management proposals to improve forest carbon sequestration. The objective was to quantify the innate carbon stocking (t C ha−1) variation in Nothofagus antarctica forests under natural dynamics in even- and uneven-aged structures, and in harvested and transformed stands. Carbon stocks were sampled in 145 forest stands, identifying 14 different components in above- and belowground strata. Results showed that the carbon content of the stands varied significantly with age (e.g., C contribution of different tree components), ranging from 289 to 386 t C ha−1. Deadwood was the variable that varied most among the successional stages. In harvested stands, carbon content changed significantly with increasing harvesting intensity (from 84.6% to 55.7%) and was lower than in non-harvested stands. These changes were reflected in reduced carbon accumulation in trees, deadwood, and soil layer and increased accumulation in understory plants. Silvopastoral system management can achieve a balance between productive objectives and maintenance of carbon stocks in managed forests, resulting in higher resilience and lower carbon losses, thus promoting sustainable forest management. [ABSTRACT FROM AUTHOR]

New silvicultural proposals based on long-term trials are needed to develop forest management strategies. Radial growth response was the preferred proxy for managers to define thinning levels and best years for intervention. We analyzed long-term thinning strategies in secondary Nothofagus pumilio forests (55 years old) in Tierra del Fuego (Argentina) to determine and quantify the effect on radial growth. Samplings were conducted in a trial area established in 1965 where three interventions (17, 33 and 44 years after harvesting) with different thinning strategies were applied. We employed dendrochronological techniques to measure and co-date ring widths, comparing 19 different thinning strategies (n = 100 slices x 2 reading sections). Average ring width (RW), basal area increment (BAI), and periodic annual increment every five years (PAI5) were calculated and compared through univariate comparisons. Radial growth responses were directly related to thinning intensity; however, a differential response was found according to thinning strategy (e.g. selective and systematic cuttings) and always significantly higher than the control (3 vs. 1 mm year-1). The maximum growth occurred between 2 and 4 years after thinning (YAT), and progressively decreased until reaching pre-cutting levels (5 to 8 YAT). The analyses of the thinning strategies showed that initial systematic thinning followed by at least light thinning when growth rates recover their pre-intervention values is the most convenient combination of intermediate treatments for Nothofagus pumilio forests. These results can contribute to better silvicultural decision-making in secondary forests and provide information to analyze the feasibility of their implementation. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) content supports several ecosystem services. Quantifying SOC requires: (i) accurate C estimates of forest components, and (ii) soil estimates. However, SOC is difficult to measure, so predictive models are needed. Our objective was to model SOC stocks within 30 cm depth in Patagonian forests based on climatic, topographic and vegetation productivity measures from satellite images, including Dynamic Habitat Indices and Land Surface Temperature derived from Landsat-8. We used data from 1320 stands of different forest types in Patagonia, and random forest regression to map SOC. The model captured SOC variability well (R² = 0.60, RMSE = 22.1%), considering the huge latitudinal extension (36.4° to 55.1° SL) and the great diversity of forest types. Mean SOC was 134.4 ton C ha−1 ± 25.2, totaling 404.2 million ton C across Patagonia. Overall, SOC values were highest in valleys of the Andes mountains and in southern Tierra del Fuego, ranging from 53.5 to 277.8 ton C ha−1 for the whole Patagonia region. Soil organic carbon is a metric relevant to many applications, connecting major issues such as forest management, conservation, and livestock production, and having spatially explicit estimates of SOC enables managers to fulfil the international agreements that Argentina has joined. [ABSTRACT FROM AUTHOR]

Most of the native forests in Argentina are used for livestock production with little sustainable silvopastoral management. Our objective here is to discuss different management strategies where natural and human capital are combined to co-produce ecosystem services (ES) provided by silvopastoral systems in native forests, interacting with different ecosystem functions and biodiversity. Also, we provide perspectives that should be analyzed in a context of socio-ecological approaches in agro-forestry landscapes. Four types of theoretical strategies are proposed (win-win, win-lose, lose-win and lose-lose), which define the social-ecological and economic thresholds that determine the provision of ES and biodiversity in the long term. The evidence of the win-lose strategy occurs when the silvopastoral systems are managed mainly to increase economic profitability through increments in forage biomass aimed to increase livestock production in the medium and long term. Deferred deforestation was presented as a typical example of lose-lose strategy in the Chaco region based on short-term management strategies by only obtaining commodities (crops or livestock products) without considering the negative interactions with other ES and loss of biodiversity. The information provided in this work should assist stakeholders and researchers to identify thresholds of economic profitability and ecological resilience in ecosystems under management. The proposed approaches provide a utilitarian vision of ecosystem services and key aspects of social-ecological resilience. [ABSTRACT FROM AUTHOR]

Browsing damage by native ungulates is often to be considered one of the reasons of regeneration failure in Nothofagus pumilio silvicultural systems. Fencing and hunting in forests at regeneration phase have been proposed to mitigate browsing effects. This study aims to determine effectiveness of these control methods in harvested forests, evaluating browsing damage over regeneration, as well as climate-related constraints (freezing or desiccation). Forest structure and regeneration plots were established in two exclosures against native ungulates ( Lama guanicoe ) by wire fences in the Chilean portion of Tierra del Fuego island, where tree regeneration density, growth, abiotic damage and quality (multi-stems and base/stem deformation) were assessed. Exclosures did not influence regeneration density (at the initial stage with < 1.3 m high, and at the advanced stage with >1.3 m high). However, sapling height at 10-years old was significantly lower outside (40–50 cm high) than inside exclosures (80–100 cm), and also increased their annual height growth, probably as a hunting effect. Likewise, quality was better inside exclosures. Alongside browsing, abiotic conditions negatively influenced sapling quality in the regeneration phase (20%–28% of all seedlings), but greatly to taller plants (as those from inside exclosure). This highlights the importance of considering climatic factors when analysing browsing effects. For best results, control of guanaco in recently harvested areas by fencing should be applied in combination with a reduction of guanaco density through continuous hunting. The benefits of mitigation actions (fencing and hunting) on regeneration growth may shorten the regeneration phase period in shelterwood cutting forests (30–50% less time), but incremental costs must be analysed in the framework of management planning by means of long-term studies. [ABSTRACT FROM AUTHOR]

Vespula germanica is an invasive worldwide species that has been detected in continental Patagonia of Argentina and Chile. In this work, we extend the range of this invasive wasp in Patagonia to include the Tierra del Fuego Archipelago. We indicate the location, year and habitat of each sighting and/or collection. The expansion pattern of this species indicates that it is well established in natural and anthropogenic areas and that it has most probably depended on human transport to arrive from the continent. This short communication also provides information to take practical measures for its mitigation and control, including basic information for the citizens of the island to become aware of its presence and help it not arrive to new areas. Finally, more research is recommended for management and control of this new invasive species in Tierra del Fuego. [ABSTRACT FROM AUTHOR]