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Modern forestry systems rely on typologies of forest types (FTs). In Argentina, several proposals have been developed, but they lack unified criteria. The objective was to compare different approaches, specifically focusing on (i) phenoclusters (functional forests based on vegetation phenology variations and climate variables) and (ii) forest canopy cover composition by tree species. We conducted comparative uni-variate analyses using data from national forest inventories, forest models (biodiversity, carbon, structure), and regional climate. We assessed the performance of phenoclusters in differentiating the variability of native forests (proxy: forest structure), biodiversity (proxy: indicator species), and environmental factors (proxies: soil carbon stock, elevation, climate). Additionally, we proposed a simple FT classification methodology based on species composition, considering the basal area of tree species. Finally, we compared the performance of both proposals. Our findings showed that classifications based on forest canopy cover composition are feasible to implement in regions dominated by mono-specific forests. However, phenoclusters allowed for the increased complexity of categories at the landscape level. Conversely, in regions where multi-specific stands prevailed, classifications based on forest canopy cover composition proved ineffective; however, phenoclusters facilitated a reduction in complexity at the landscape level. These results offer a pathway to harmonize national FT classifications by employing criteria and indicators to achieve sustainable forest management and conservation initiatives. [ABSTRACT FROM AUTHOR]

The development of long-term scenarios to outline pathways for achieving carbon neutrality by 2050 has become a standard practice in climate change policy planning. In Argentina, a modelling process was initiated in 2019 in the agriculture, forestry and other land use (AFOLU) sector utilizing three tools: FABLE calculator, Dinamica EGO and Nature Map. In order to generate technical inputs for the modelling exercise a stakeholder dialogue was launched. A 2050 Carbon Neutrality scenario was developed, alongside several intermediate scenarios based on stakeholders´ visions of the future. The modelling results demonstrated the biophysical feasibility of achieving carbon neutrality in the Argentinean AFOLU sector by 2050. However, alignment with current sectoral priorities was identified as a challenge, leading stakeholders to propose less ambitious scenarios as more attainable targets. This experience underscored the significance of constructing multiple policy scenarios, facilitating the evaluation of diverse potential future trajectories for policymaking. These different pathways provided contrasting perspectives between political objectives, such as achieving carbon neutrality, and the practical feasibility of local implementation. Moreover, the process highlighted the vital role of integrating the private sector and environmental non-governmental organizations (NGOs) in long-term climate planning, emphasizing the need for inclusive collaboration to address climate challenges effectively. Stakeholder-based modelling approaches serve as valuable discussion tools to initiate and accompany political discussions concerning the efforts required to achieve carbon neutrality. Modelling outputs provide quantitative demonstrations of the challenges involved, while stakeholder dialogues facilitate the identification of barriers and enabling conditions required to promote a successful transition. It is necessary to enhance institutionalized public-private dialogue spaces that extend beyond specific projects and government changes, given their importance in facilitating participatory long-term thinking. Nevertheless, collective scenario construction alone seems insufficient to drive the profound changes that are required. [ABSTRACT FROM AUTHOR]

Background: The nationally determined contribution (NDC) presented by Argentina within the framework of the Paris Agreement is aligned with the decisions made in the context of the United Nations Framework Convention on Climate Change (UNFCCC) on the reduction of emissions derived from deforestation and forest degradation, as well as forest carbon conservation (REDD+). In addition, climate change constitutes one of the greatest threats to forest biodiversity and ecosystem services. However, the soil organic carbon (SOC) stocks of native forests have not been incorporated into the Forest Reference Emission Levels calculations and for conservation planning under climate variability due to a lack of information. The objectives of this study were: (i) to model SOC stocks to 30 cm of native forests at a national scale using climatic, topographic and vegetation as predictor variables, and (ii) to relate SOC stocks with spatial–temporal remotely sensed indices to determine biodiversity conservation concerns due to threats from high inter-annual climate variability. Methods: We used 1040 forest soil samples (0–30 cm) to generate spatially explicit estimates of SOC native forests in Argentina at a spatial resolution of approximately 200 m. We selected 52 potential predictive environmental covariates, which represent key factors for the spatial distribution of SOC. All covariate maps were uploaded to the Google Earth Engine cloud-based computing platform for subsequent modelling. To determine the biodiversity threats from high inter-annual climate variability, we employed the spatial–temporal satellite-derived indices based on Enhanced Vegetation Index (EVI) and land surface temperature (LST) images from Landsat imagery. Results: SOC model (0–30 cm depth) prediction accounted for 69% of the variation of this soil property across the whole native forest coverage in Argentina. Total mean SOC stock reached 2.81 Pg C (2.71–2.84 Pg C with a probability of 90%) for a total area of 460,790 km2, where Chaco forests represented 58.4% of total SOC stored, followed by Andean Patagonian forests (16.7%) and Espinal forests (10.0%). SOC stock model was fitted as a function of regional climate, which greatly influenced forest ecosystems, including precipitation (annual mean precipitation and precipitation of warmest quarter) and temperature (day land surface temperature, seasonality, maximum temperature of warmest month, month of maximum temperature, night land surface temperature, and monthly minimum temperature). Biodiversity was influenced by the SOC levels and the forest regions. Conclusions: In the framework of the Kyoto Protocol and REDD+, information derived in the present work from the estimate of SOC in native forests can be incorporated into the annual National Inventory Report of Argentina to assist forest management proposals. It also gives insight into how native forests can be more resilient to reduce the impact of biodiversity loss. [ABSTRACT FROM AUTHOR]

Background and Aims The vulnerability and responsiveness of forests to drought are immensely variable across biomes. Intraspecific tree responses to drought in species with wide niche breadths that grow across contrasting climatically environments might provide key information regarding forest resistance and changes in species distribution under climate change. Using a species with an exceptionally wide niche breath, we tested the hypothesis that tree populations thriving in dry environments are more resistant to drought than those growing in moist locations. Methods We determined temporal trends in tree radial growth of 12 tree populations of Nothofagus antarctica (Nothofagaceae) located across a sharp precipitation gradient (annual precipitation of 500–2000 mm) in Chile and Argentina. Using dendrochronological methods, we fitted generalized additive mixed-effect models to predict the annual basal area increment as a function of year and dryness (De Martonne aridity index). We also measured carbon and oxygen isotope signals (and estimated intrinsic water-use efficiency) to provide potential physiological causes for tree growth responses to drought. Key Results We found unexpected improvements in growth during 1980–1998 in moist sites, while growth responses in dry sites were mixed. All populations, independent of site moisture, showed an increase in their intrinsic water-use efficiency in recent decades, a tendency that seemed to be explained by an increase in the photosynthetic rate instead of drought-induced stomatal closure, given that δ18O did not change with time. Conclusions The absence of drought-induced negative effects on tree growth in a tree species with a wide niche breadth is promising because it might relate to the causal mechanisms tree species possess to face ongoing drought events. We suggest that the drought resistance of N. antarctica might be attributable to its low stature and relatively low growth rate. [ABSTRACT FROM AUTHOR]

In Argentina, current food and land-use systems are drivers of greenhouse gas emissions, biodiversity loss, nutrient outflows, chemical pollution and water stress, while they fail to produce sustainable livelihoods for farmers and herders. Argentina must transition toward more sustainable food and land-use systems to achieve the sustainable development goals (SDGs) and the objectives of the Paris Agreement. Here, we present mid-century food and land-use system pathways to achieve biodiversity, freshwater use, food production and greenhouse gas emission targets, co-developed with the government, research and civil society stakeholders. We used a multi-model approach, integrating outputs from a food system and land-use accounting tool (FABLE calculator), a land-use allocation model (Dinamica EGO) and a spatially explicit conservation prioritization approach (NatureMap) to construct a carbon neutral, actionable food system and land-use scenario that could also lead to the achievement of biodiversity, freshwater use, food production and carbon storage targets by 2050. Such integrated approaches are rare, despite their high value for helping cross-sectoral experts and policymakers cut through complexity to find pathways to achieve multiple sustainability objectives in tandem. This paper presents a nationally designed transferable methodology to: (1) construct a carbon neutral pathway toward 2050, (2) create spatially explicit land-use projections, (3) detect and assess trade-offs between sustainability goals, (4) modify this pathway to foster co-benefits and (5) work toward concurrent attainment of multiple SDGs. Preliminary results suggest Argentina is well suited to meet multiple SDGs, provided businesses, civil society and government agree to several key commitments, including completely halting deforestation, promoting afforestation and reforestation, and increasing agricultural productivity to spare natural lands. [ABSTRACT FROM AUTHOR]

Droughts are projected to increase in magnitude, frequency and duration in the near future. In rangelands, the provision of valuable ecosystem services such as forage supply for livestock productivity is intimately linked to rainfall patterns, which makes it particularly vulnerable to droughts. Nonetheless, rangelands can differ in their sensitivity to droughts as shown by strong differences in the impacts of inter‐annual precipitation changes on vegetation productivity in different sites. The aim of this study was to assess the sensitivity to droughts of nine rangelands located across a broad aridity gradient in Argentina, South America.We experimentally imposed comparable droughts under field conditions by reducing a fixed proportion of each incoming precipitation event within‐year during three consecutive years and tracked changes in total aboveground and forage productivity.We found that arid and semi‐arid rangelands were more severely impaired in their forage provision by drought than mesic rangelands, that is that sensitivity to drought declined as aridity decreased. Forage productivity decreased on average by c. 50%, in arid and semi‐arid rangelands, whereas mesic sites did not exhibit significant changes between drought and control treatments. The negative impact in forage productivity of arid and semi‐arid rangelands was mainly driven by the productivity reduction of few key plant species at each site. In seven of the nine rangelands, we found detrimental effects of drought on forage productivity during the first experimental‐drought year, and in five of them the impact was further accentuated until the end of the experiment, which indicates how serious can these events be.Synthesis and applications. Our main findings indicate that the drought‐induced impacts on forage provision are higher as aridity increases. This pattern highlights the urgent need to implement strategies to mitigate the detrimental consequences of drought, particularly in arid and semiarid rangelands, where forage provision is strongly associated with human well‐being. Management approaches focused on key forage species, such as reducing the grazing pressure during drought periods according to these species' productivity dynamics can attenuate impacts on vulnerable ecosystems, preserving the rangelands' integrity while maintaining high long‐term productivity levels. [ABSTRACT FROM AUTHOR]

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• Baseline soil organic carbon (SOC) and soil texture were the most important explanatory variables to describe geographical variation of SOC in forest plantations of Argentina. • On average, baseline SOC stock was higher than in the paired forest plantations (65.7 and 61.8 Mg ha−1, respectively). • Eucalyptus plantations induce a decrease in soil carbon in places with >49 Mg ha−1 of original SOC. • 98% of forest plantations showed soil carbon saturation deficit estimated from soil texture. Forest plantations (through afforestation or reforestation) have been proposed as a valuable option to mitigate carbon (C) emissions. However, high spatiotemporal variation has been observed in soil organic carbon (SOC) pools associated to these systems. It has been proposed that SOC stock (Mg/ha) changes under forest plantations (ΔSOC) are related to the SOCstock in the natural system being replaced with positive ΔSOC in the sites with lowest initial SOCstock and negative ΔSOC in sites with initially high SOCstock. Although there is some debate related with statistical artifacts, the slope of this relationship may depend on environmental, biological and anthropic variables. In this context, we took advantage of a recent effort to quantify soil organic C stocks in forest plantations and contiguous land uses along 136 sites across a wide climatic and edaphic gradient in Argentina, South-America, to explore the patterns and drivers of SOC change due to this land-use change. We also added 183 data from a systematic bibliographic survey. Average ΔSOC of all the studied paired sites was low (average of −3.85 ± 29.97 Mg ha−1), with 57 % of the paired sites showing a negative change. After applying a diagnosis method to detect statistical regression-to-the-mean bias and considering the pooled data and the different forest plantation groups (Pinus spp., Eucalyptus spp., Salicaceae spp, and native species), only Eucalyptus plantations showed a negative relationship between ΔSOC and SOCstock in the control situation (i.e. a significant and negative impact on SOC in high-C soils). In general, most of the sites where forest plantations were introduced in Argentina have a relatively low baseline SOC (SOCstock < 200 Mg ha−1), and 98 % of the studied sites showed SOC deficit (Csat-def) estimated as the difference between the observed vs. the theoretical maximal C storage potential based on silt and clay content. SOCstock and the Csat-def variation in forest plantations across regions were explained mainly by the SOCstock of the natural situation where the plantation was installed, followed by edaphic and some climatic variables. Within the silvicultural variables evaluated, only the forest species cultivated had a significant effect at the scale evaluated and within the range of stand densities (medium to high) and ages (close to rotation period in each region) considered. Our results indicate that -along a broad range of environmental situations but within a limited set of silvicultural conditions- in average forests plantations decrease soil carbon stock. However, there are situations -that could be coarsely predicted with a model with multiple variables and their interactions- where the change is positive bringing opportunities to increase the C sequestration service of planted forests. [ABSTRACT FROM AUTHOR]

The sustainable use of ñire forests requires knowledge of its dynamics and management to maintain long-term main forest ecosystem services. The aim of this work was to develop a structural–functional state and transition model for ñire forests in southern Patagonia. For this, provincial inventory information was analyzed together with information from permanent PEBANPA plots (plots of Ecology and Biodiversity, natural environments in Southern Patagonia) and studies of ecology and eco-physiology in ñire forests. This allowed the description of plant communities on these ecological sites and the history of natural disturbances. Seven states and 10 negative transitions were described, as well the factors that trigger transitions (levels of grazing, fire and intense logging). Mature forests with low grazing, no extractive activity and complete canopy cover (>70%) correspond to the reference state or condition of greater integrity, and grassland or murtillar (dominance ofEmpetrum rubrum) with forest loss is considered the most degraded state. Negative transitions determine the threshold crossings associated with the reduction or loss of resilience to the previous or original state. The development of state and transition models allows for early warnings of deterioration and is a tool to achieve more productive and environmental value. [ABSTRACT FROM AUTHOR]

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 year. 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. [ABSTRACT FROM AUTHOR]

The Mesozoic Botucatú paleoerg at the southwestern margin of Gondwana includes a succession of eolian dunes cross-strata which are presently exposed in Otumpa Hills (Central Northern Argentina). Here, the architectural facies, petrology, and provenance of those rocks were studied in order to investigate depositional environments and paleoclimates. The stratigraphic sequence included basal eolian two-dimensional crescentic dunes (Slp) overlain by three-dimensional crescentic dunes of smaller scale (Smt). These were correlated with the Upper Member Rivera of the Tacuarembó Formation (Uruguay), or its equivalent in Brazil, the Botucatú Formation. These outcrops partially mark the southwestern margin of the Botucatú paleoerg along the Chaco–Paraná Basin boundary. The paleocurrents from the W, NW, and SW and the U–Pb ages of detrital zircons indicate a main Pampean cratonic and secondary Andean magmatic arc (180 Ma) source. A detrital zircon of 180 Ma by U–Pb limits a maximum depositional age at 180 Ma (Toarcian) for facies Slp. Upwards, the phreatic silcrete and calcrete indicate semiarid conditions during the Paleocene, which are correlated with the Queguay Formation of Uruguay. A saprolite paleoweathering profile, recording wet tropical–hyper-tropical climate at the Early Eocene and representing the Gondwana landscape and climate conditions, crowns the sequence. This study represents the first provenance and surface texture analysis of minerals from the Botucatú paleoerg and was instrumental to unravel past environmental and sedimentary conditions. [ABSTRACT FROM AUTHOR]

• The spatial distribution of Gonopterodendron sarmientoi , an endangered tree species of the Dry Chaco, was determined. • G. sarmientoi 's habitat was mainly influenced by precipitation. • The current distribution map of G. sarmientoi provides a tool for effective management and conservation strategies. • The map assist decision-makers to adjust the Territorial Planning of the Native Forests in Chaco region. For management and conservation strategies in the long term is necessary to know the species distribution and main biophysical aspects that determine the structure and dynamics of the forest. The aim of this work was to determine the potential and current spatial distribution of Gonopterodendron sarmientoi , an emblematic and endangered tree species of the Dry Chaco. A further aim was to superimpose the distribution of G. sarmientoi , with the zonation in the current Territorial Planning of Native Forests (OTBN, its acronym in Spanish) to provide basic information for conservation and management of the species. For this, a Maxent model was developed to quantify the relationship between G. sarmientoi occurrence and key environmental variables (including water, topography, and climate as a variables). G. sarmientoi 's habitat was mainly influenced by precipitation variables, and secondarily by temperature variables. Considering the OTBN defined by the local forest authority, of the current area of G. sarmientoi (2,477,009 ha), the majority (57.9%) corresponded to the yellow category (forest areas with medium conservation value) and only 10.6% to the red category (high conservation value). It is important to note that around 600,686 ha (24.3%) of native forest with G. sarmientoi is in the green category (low conservation value) subject to change in land use, and 178,107 ha was uncategorized forest (7.2%). For effective management and conservation strategies, the current habitat distribution map of G. sarmientoi provides decision-makers an opportunity to review and adjust the native forests zoning at a provincial scale within the framework of the OTBN, mainly the green category (legal deforestation) with the occurrence of the endangered G. sarmientoi. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Stable isotope natural abundance measurements integrate across several biogeochemical processes in ecosystem N and C dynamics. Here, we report trends in natural isotope abundance (δ13 C and δ15 N in plant and soil) along a climosequence of 33 N othofagus 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 δ13 C values ranged from −35.4‰ to −27.7‰, and correlated positively with foliar δ15 N values, ranging from −3.7‰ to 5.2‰. Soil δ13 C and δ15 N 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 N othofagus species ( N othofagus pumilio, N othofagus antarctica, N othofagus 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 δ13 C and δ15 N 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 δ13 C values were higher than those of the plant tissues and this difference increased as annual precipitation increased. No such differences were apparent when δ15 N 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. [ABSTRACT FROM AUTHOR]

Shade cloth is commonly used in agroforestry research. It produces a continuous, uniform reduced light environment. Shade cloth and a slatted structure were compared in relation to the inability to represent the light regime and plant responses of an agroforestry system. The split-split-plot randomised block experiment had main plots as covering status (with or without radiata pine trees), subplots as artificial shade (none, shade cloth or wooden slats) and sub-subplots as growth rotation, over sown alfalfa, in three replicates. The quantity of light transmittance was 49% under trees, 41% under cloth and 44% under slats. Temporal changes and spectral composition under trees were more accurately reproduced under the slats than shade cloth. The red to far red ratio was 0.64 under tree shade and 0.74 during the shaded period under slats. This compared with 1.31 in open pasture, 1.28 under shade cloth in open and 1.26 under slats during sunny periods. To compensate for low light quantity and quality, alfalfa had elongated stems and internodes. In open pasture and under cloth in the open, it produced short stems. The mean dry matter yield under trees was 68% of the 30.3 t ha in open pasture, 56% under cloth and 57% under slats. The slats induced similar morphological responses in alfalfa to those in the agroforestry system. The magnitude of changes had little effect on growth and yield responses. The artificial slatted structure approximated the intermittent light environment and consequent plant responses observed in an agroforestry system. [ABSTRACT FROM AUTHOR]

Abstract: Above- and below-ground C pools were measured in pure even-aged stands of Nothofagus antarctica (Forster f.) Oersted at different ages (5–220 years), crown and site classes in the Patagonian region. Mean tissue C concentration varied from 46.3% in medium sized roots of dominant trees to 56.1% in rotten wood for trees grown in low quality sites. Total C concentration was in the order of: heartwood>rotten wood>sapwood>bark>small branches>coarse roots>leaves>medium roots>fine roots. Sigmoid functions were fitted for total C accumulation and C root/shoot ratio of individual trees against age. Total C accumulated by mature dominant trees was six times greater than suppressed trees in the same stands, and total C accumulated by mature dominant trees grown on the best site quality was doubled that of those on the lowest site quality. Crown classes and site quality also affected the moment of maximum C accumulation, e.g. dominant trees growing on the worse site quality sequestered 0.73kgCtree−1 year−1 at 139 years compared to the best site where 1.44kgCtree−1 year−1 at 116 years was sequestered. C root/shoot ratio decreased over time from a maximum value of 1.3–2.2 at 5 years to a steady-state asymptote of 0.3–0.7 beyond 60 years of age depending on site quality. Thus, root C accumulation was greater during the regeneration phase and for trees growing on the poorest sites. The equations developed for individual trees have been used to estimate stand C accumulation from forest inventory data. Total stand C content ranged from 128.0 to 350.9MgCha−1, where the soil C pool represented 52–73% of total ecosystem C depending on age and site quality. Proposed equations can be used for practical purposes such as estimating the impact of silvicultural practices (e.g. thinning or silvopastoral systems) on forest C storage or evaluating the development of both above- and below-ground C over the forest life cycle for different site qualities for accurate quantification of C pools at regional scale. [Copyright &y& Elsevier]

Abstract: We hypothesized that different dominant grasses species display contrasting nutrient accumulation, allocation and conservation strategies. Also, we expect a distinctive pattern of carbon and biomass partitioning according to plant sizes. The aim was to quantify the amount of biomass, carbon and nutrients in both above- and belowground components for four dominant grasses in grasslands steppe. We analyzed biomass, carbon and nutrients (N, P, K, Ca, Mg and S) of each dominant grass species corresponding to different sizes and separated in components (green and senesced leaves, pseudostem, and fine and coarse roots). Total biomass accumulation for individual grass plants was affected by plant size and species and ranged from 15.4 to 684g dry matter plant−1. The biomass root/shoot ratio ranged from 0.28 to 3.40. Total nutrient concentration generally graded in all species the following order: green leaves>fine roots>pseudostem>coarse roots>senesced leaves. Storage of any particular nutrient varied depending mainly on species. Mean nutrient resorption efficiency varied according to the growing season and specie being maximum for K and minimum for Mg. The equations developed for individual grass plants could be used to assist quantitative predictions of biomass, carbon and nutrient accumulation per hectare. [Copyright &y& Elsevier]

Most of the industrial, urban and sewage discharges are released into the La Plata River, Argentina without any previous treatment. However, few works have investigated the extent of metal contamination. The aim of this study was to assess the levels of cadmium, copper, lead and zinc in liver and gills of adults Prochilodus lineatus collected from three sampling stations along the coast of the La Plata River: Berazategui, Berisso and Atalaya (from north to south). Samplings were performed during 2002 and 2004. Berazategui and Berisso were located nearby the main ducts that discharge the urban and domestic waste disposal from the cities of Buenos Aires and La Plata, respectively. The third station, Atalaya, was free of sewage discharges. Levels of cadmium and copper in liver were always higher than those found in gills. Instead, for lead and zinc, high levels were observed either in liver or gills, depending on the sampling station and the sampling period. In both tissues, the concentrations of metals did not differ significantly between male and female fish. In liver samples, the concentrations of cadmium, copper and zinc tended to increase from north to south. Instead, the levels of lead followed an opposite pattern. No clear tendencies were observed in gill samples. The data may be useful as reference levels of metal contaminants in P. lineatus, the most important fish species in the La Plata River system. [ABSTRACT FROM AUTHOR]

Abstract: Forestry practices integrating ecological and social criteria have been replacing those based only on economic values. Traditional silviculture, such as shelterwood cuts (SC), transforms uneven-aged original stands to an even-aged managed forest. Recently, other methods have proposed to conserve some of the original heterogeneity of the old-growth forests. One proposal leaves 30% of the timber quality forest area as aggregated retention and 20% basal area as dispersed retention. The aim of this study was to analyze the feasibility of timber management with aggregated and dispersed retention in Nothofagus pumilio old-growth forests by analyzing timber and harvesting yield potential compared with traditional regeneration systems. Also, remnant tree stability of aggregated retention was analyzed. Timber yield potential of old-growth forests varied from 136 to 479m3 ha−1 across a site quality gradient. High grading cutting improved yield index (timber volume and harvested basal area (HBA) ratio of 7.9m3 m−2). In contrast, this index decreased in clear-cuts (4.7m3 m−2) and shelterwood cuts (4.9m3 m−2). The index also decreased in the aggregated and dispersed retention treatment (5.1m3 m−2), but with higher timber harvested volumes. Windthrow of remaining trees in aggregated retention was related to time, being significantly higher during the first year after harvesting. Windthrow was affected by crown class and position into the aggregates of the remnant trees as well as site quality of the stand. Regeneration methods with aggregated retention were feasible across the entire site quality gradient, and economic losses were not significant when compared to shelterwood cuts. The method also resulted in stability of the remnant overstory, which maintained the ecological conditions to ensure biodiversity conservation and continuity of harvested stands. [Copyright &y& Elsevier]

Evaluates the existence and the productive potential of wood for the Argentinian sawmill industry in a shelterwood seed cut of Nothofagus pumilio forests along the range of site classes. Variation in total stand volumes, volume yield and number of timber logs.

Soil microorganisms communities regulate key functions in terrestrial ecosystems and contributes to the formation of stable organic matter and hence climate change mitigation. The structure, diversity and activity of soil microbial communities are influenced by the quantity and quality of organic compounds entering soils through the contribution of their root exudates and plant litter, which the microorganisms use as a substrate for biosynthesis and energy source. However, grazing effect on the soil microorganisms showed variable results dependent on the ecosystem under study. One of the main challenges of this millennium is the sustainability of agricultural production, especially in fragile soils such as those present in Patagonia. Therefore, our objective was to evaluate the responses of microbial biomass carbon (MBC), soil basal respiration (SBR), the derived coefficients and the abundance of fungi and bacteria under contrasting long-term grazing intensities in an environmental gradient. The study was established in three ecological areas Mata Negra Thicket (MNT), Dry Magellanic Steppe (DMS) and Humid Magellanic Steppe (HMS) with two grazing intensities. Soil samples were taken over two years in different seasons (autumn, winter, spring and summer). Results showed that biotic and abiotic factors (temperature and precipitation), plant communities and soil characteristics modulated the microbial structure and function in ecological area. On the other hand, high grazing intensity decreased the MBC and microbial coefficient (qM). There was a seasonal and interannual dynamic in the MBC and the bacteria and fungal communities, attributed mainly to temperature and precipitation. The results indicated that the effect of grazing intensity in soil microbial communities depends largely on intrinsic characteristics of each ecological area defined by the environmental gradient. • Soil microbial properties in an environmental gradient the Southern Patagonia. • Positive relationship between soil organic carbon (SOC), microbial biomass carbon (MBC) and soil basal respiration (SBR). • High grazing intensity decreased the microbial biomass carbon and microbial coefficient. • Seasonal and interannual dynamic in the MBC and the in bacteria and fungi communities. [ABSTRACT FROM AUTHOR]

Applications of mineral fertilizer to grasslands have become more frequent in recent decades to increase forage production. However, the impacts of mineral fertilizer on the soil microbiome is poorly understood in cold semiarid grassland ecosystems of Southern Patagonia, Argentina. Therefore, our objective was to analyze experimentally the influence of mineral nutrient fertilization (N, P, K, and NPK in combination) on soil microbial community attributes, such as microbial biomass carbon (MBC) and nitrogen (MBN), soil basal respiration (SBR), microbial metabolic coefficients, the colonization of endophytic fungi such as arbuscular mycorrhizal (AM) fungi, and dark septate endophytes (DSE), and aboveground plant productivity. Mineral fertilization with macronutrients (N, P, K, and NPK) decreased the SBR, qCO 2 , AM fungi and DSE fungi, but did not generate changes in MBC and MBN. The magnitude of these responses depends on years after fertilization. We found that soil microbiome was strongly dependent on a range of biotic and abiotic factors, such as growing season precipitation, aboveground plant biomass the relationship between the microbial biomass and microbial respiration, and between endophytic fungi and plants. This work improved our understanding of the soil microorganisms' response to mineral fertilizer application and provides new insights into soil nutrient dynamics and ecosystem functioning. • Mineral fertilization did not modify the soil microbial biomass. • Soil microbial activity was reduced by applications of mineral fertilizer. • Mineral fertilization decreased the symbiotic fungi, such as AM and DSE. • Responses of microbial variables depended on years after fertilization. [ABSTRACT FROM AUTHOR]

Abstract: Despite its reduced penetration depth, audiomagnetotelluric (AMT) studies can be used to determine a broad range of features related to little studied geothermal fields. This technique requires a stepwise interpretation of results taking into consideration diverse information (e.g. topographic, hydrological, geological and/or structural data) to constrain the characteristics of the study area. In this work, an AMT study was performed at the hot springs in the northern segment of the La Candelaria Range in order to characterize the area at depth. Geometric aspects of the shallow subsurface were determined based on the dimensional and distortion analysis of the impedance tensors. Also, the correlation between structural features and regional strikes allowed us to define two geoelectric domains, useful to determine the controls on fluid circulation. The subsurface resistivity distribution was determined through 1D and 2D models. The patterns of the 1D models were compared with the morpho-structure of the range. Shallow and deep conductive zones were defined and a possible shallow geothermal system scheme proposed. A strong correlation was found between the AMT results and the geological framework of the region, showing the relevance of using AMT in geothermal areas during the early stages of subsurface prospecting. [Copyright &y& Elsevier]

Populus nigra cv Italica (Alamo criollo) is the main species planted for windbreaks in Santa Cruz Province (Argentina). Alamo has been a traditional source of poles for rural constructions in southern Patagonia. The objective of this work was to evaluate the natural and CCA-treated durability of P. nigra cv Italica cultivated in different sites of Santa Cruz. Laboratory decay tests were carried out using the modified ASTM Standards D-1413 (1976) and the Lo´pez and Deschamps (1978) technique, with two fungal species: white rot Trametes versicolor and brown rot Lentinus lepideus. Lenga (Nothofagus pumilio) heartwood, a widely used native timber in the region, was also included in the study as a control. Physical and anatomical analyses were carried out.Although important differences were found in anatomical and physical properties of Alamo timbers between sites of, no significant differences were found in relative weight loss over 50 and 150 days, for either fungal species. Natural Alamo timber had the greatest weight loss over 150 days (66.8% for T. versicolor and 29.8% for L. lepideus). CCA treatment improved the Alamo wood durability compared with Lenga heartwood (1.1% versus 29.2% weight loss with T. versicolor and 2.5% versus 13.6% for L. lepideus, respectively). [Copyright &y& Elsevier]

Over the past three decades, studies have provided important information on the current volcanic activity and the associated thermal anomalies spread over the southern Puna in Argentina, as in the Cerro Blanco Volcanic Complex case. The volcanic-hosted geothermal systems have received critical attention since they are low-carbon energy sources and are frequently linked to geothermal lithium deposits. A key issue in developing productive projects is quantifying the thermal resource because this value determines investor interest. Our research aims to estimate the power capacity of the Cerro Blanco geothermal system in terms of MWe. Two methods were employed: a conductive cooling of the magmatic chamber and the classical volumetric method, coupled with Montecarlo simulations. After a rigorous analysis of recently published data, a 3D structural mapping supported by a series of analogue models, combined with a deep fluid compositional reconstruction, was employed to estimate the reservoir temperature and to support the resource assessment. Our experimental calderas show that the collapse onset is controlled by a combination of internal reverse faults and peripheral ring faults; concentric inner faults propagate outward from the caldera structure's central part. The 3D structural mapping highlights that the main structures of the Cerro Blanco geothermal system constrain the reservoir area. The estimation obtained by the magmatic heat transfer method indicates that Cerro Blanco might produce 6 MWe per km2 at 50% confidence and that it hosts a total power capacity of 127 MWe. Also, it was calculated that there are >18 km2 above 200 °C at 2 km depth. By the volumetric method, a power capacity of 6 MWe and 32 MWe at 90% and 50% confidence were estimated, respectively. These results should be interpreted cautiously considering that, for example, 1% of the unknown recovery factor correlates with 4.1 MWe in the power capacity. These estimations do not confirm the existence of the geothermal resource but raise encouraging results. Moreover, they become relevant because the Cerro Blanco geothermal system has few thermal manifestations and might be considered a blind geothermal system. • Cerro Blanco might produce 6 MWe per km2. • It has a power capacity of 32 MWe at 50% confidence. • Might be > 18 km2 above 200 °C at 2 km depth. • It could be considered a blind geothermal system. [ABSTRACT FROM AUTHOR]

Abstract: The climate of Patagonia is semi-arid and characterised by frequent strong winds. Wind erosion is potentially a serious soil degradation process that impacts long-term sustainability of local agricultural systems, but the conditions and the rates of wind erosion in this region have not been studied extensively. The aim of this study was to quantify windblown mass transport on a sandy soil in Central Patagonia. Aeolian mass fluxes were measured in the valley of Sarmiento (Chubut province, Argentina) using two saltiphones and 24 Modified Wilson and Cooke (MWAC) sediment catchers. The latter were installed along three transects: (1) a control on a bare strip of land cleared of its natural vegetation, to measure the maximum wind erosion; (2) a similar transect protected by an artificial windbreak with an optical porosity of 50%; and (3) a transect in a cherry orchard protected with the same type of windbreak. Nine windstorms were recorded throughout the experimental period. Storms with wind speed peaks of 20m s−1 caused a total soil loss of 248Mg ha−1 in the control strip and heavily depleted the soil of its erodible fraction. The artificial windbreak reduced the soil loss by 51.0% on average, while no erosion was recorded in the cherry orchard. Measured maximum mass transport values were used to fit five sediment transport equations in order to select the best equation to integrate into a GIS-based wind erosion prediction system. The Kawamura (1964) equation showed the highest model efficiency and was considered to be the best sediment transport equation for the Patagonia conditions. It expresses total mass transport as a function of two empirical constants: the threshold friction velocity (u *t), and an erodibility coefficient C Ka. It is concluded that wind erosion in Central Patagonia poses a serious risk of soil degradation once the natural vegetation is removed due to overgrazing or other anthropogenic activities. [Copyright &y& Elsevier]

• Soil aggregates were formed in the new top soil 5.5 yr. after the volcanic eruption. • Smaller size fractions of water-stable aggregates dominate the top soil with lower C and N content. • Larger size fractions of water-stable aggregates were lower but with higher C and N content. • Good grassland conditions (biological legacy) improved the soil aggregates quality compared to poor ones. • Meadows showed a fast soil C recovery and thus a potential to mitigate volcanic CO 2. Although volcanism may be perceived by the society as a phenomenon with mostly negative consequences, this is not always the case especially for natural systems. There is a limited knowledge on how the deposited pristine ash becomes immobilized and stabilized in the soil after the volcanic event. Here, we studied processes of soil aggregates formation in the buried ash layer in an early stage of the succession as well as the influence of the biological legacy (previous land management history) on these processes after the 2011 volcanic event of the Puyehue–Cordón Caulle Volcanic Complex. 5.5 years after the eruption we collected soil cores to a 10 cm depth in wet and mesic meadows with good and poor grassland conditions induced by light and heavy grazing intensity, respectively, in the East semiarid region of North Patagonia, Argentina. The ash layer was observed down to 5 cm from the soil surface, clearly differentiating a newly developed soil layer formed after the volcanic event. Accordingly, the top 5 cm were examined for the distribution of different size fractions of water-stable soil aggregates and their associated organic carbon (C) and total nitrogen (N) contents. We detected signs of physical and physicochemical changes in respect to the pristine ash collected at these sites in 2011. Soil neoformation processes were detected through the presence of large (4%) and small (21%) macroaggregates, although microaggregates (~45%) and silt + clay fractions (~29%) dominated the soil mass (ash-soil matrix: 0–5 cm depth). C and N contents decreased in a sequence: large macroaggregates ≥ small macroaggregates > microaggregates ≥ silt + clay, highlighting the importance of soil organic matter in the formation of larger-size aggregates and their quality (C and N contents). Biological legacy influenced soil aggregate formation and their quality, as reflected by a higher mass of small macroaggregates and a lower mass of microaggregates (only in mesic meadows) and by higher C and N contents under good grassland conditions. The seasonal hydrological conditions of meadow soils (i.e., soil water content, wetting and drying cycles) via effects on biological and physical processes likely resulted in a reduced aggregation in wet meadows. We noticed an incipient but present soil aggregation processes in these semiarid wetlands translated in the immobilization and stabilization of the buried ashes in the soil. The total C content in the new 0–5 cm soil layer increased at a rate of 1.0 Mg C ha−1 yr−1, on average. This indicates a functional recovery of the ecosystem along with a substantial CO 2 mitigation potential in the ashes stabilized with soil organic matter, which might partially counterbalance CO 2 emitted during the eruption. [ABSTRACT FROM AUTHOR]

Group A rotaviruses (RVA) are the most frequent etiological agents causing severe diarrhea in infants and surveillance of genotype, and genetic characteristics of circulating strains are necessary in order to evaluate vaccine programs. The objectives of this work were to describe G and P genotype from 2012 through 2014 in Buenos Aires, Argentina completing an overview of 19 years of genotype surveillance in our region and to characterize an emerging G1P[8] strain associated with severe cases and five fatalities in 2014. We performed genotyping by RT-PCR. The sequencing of several genes, phylogenetic analyses, and comparative epidemiological data were used to know the origin and phylogenetic relationships of the emerging G1P[8] strain. Along with this report, 19 years of continuous RVA genotype surveillance in Argentina in the pre-vaccine era was covered. During the last year of this surveillance, 2014, a significantly increased incidence of RVA associated gastroenteritis was related to the reemergence of G1P[8] strains, being these ones detected in low frequency in the last nine years. Interestingly, the patients affected were significantly older when compared with those from the last six seasons. Additionally, phylogenetic analysis of several genes infer that these G1P[8] strains were closely related to Asian strains circulating during 2012 and 2013. In addition to this, the suggested extra continental origin for the 2014 G1P[8] strains and the very low circulation of G1 type during nine years probably explain the increased incidence and severity in the gastroenteritis cases and the particular epidemiologic characteristics. In conclusion, this work gives us a whole panorama of the pre-vaccine era of the RVA molecular epidemiology in the most populated region of Argentina. In this way, this work inspires us to continue with this type of studies in the post-vaccination era. • RVA genotype fluctuation along 19 years in the pre-vaccine era was reviewed • Increased incidence of severe RVA associated diarrhoeas during 2014 in Buenos Aires • The reemergence of G1P[8] strains detected in 2014 was associated with severe cases • 2014 RVA associated gastroenteritis patients were older than those from last years • Phylogenetic analyses suggest an extra continental introduction of G1 strains [ABSTRACT FROM AUTHOR]