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Mast seeding is characteristic of many long-lived tree species and widely proposed as a mechanism to reduce seed predation. However, whether the efficiency of this reproductive response may vary depending on type of seed predator (e.g., invertebrates vs. vertebrates) or depending on local characteristics, remains seldom explored. We evaluated for 8 yrs the patterns of seed production in antarctic beech ( Nothofagus antarctica ) forests related to management and its influence on insect and bird pre-dispersal seed predation. Along the study, mature seed production was highly variable across years (the population-level coefficient of variation, CVp: 0.98–1.14) and spatially synchronized (Pearson correlation coefficient: 0.83–0.86). Forest type (primary unmanaged, secondary-growth and managed stands) did not influence the amount of seed production nor masting patterns. Mean yearly seed predation by insects was higher than by birds, and their relationship with seeding patterns differed: i.e., while the proportion of seeds predated by insects increased during non-mast years maximum bird predation occurred in mast years. Therefore, predation by insects and birds showed a strong negative relationship. Our results suggest that effectiveness of masting to escape seed predators may be highly depend on the type of predator. We address whether this effect may be due to differences in life history traits among the seed predators involved (i.e., degree of host specificity, dispersal ability or the duration of the life-cycle) and whether an “imperfect” control of avian seed predation may partially be advantageous for the dynamics of the masting species to enhance seed dispersal. [ABSTRACT FROM AUTHOR]

• Rainy growing seasons induce mast seeding events. • Greater evidence of synchrony seed production in pure forests. • Seed productivity increases with high NDVI-peak in N. pumilio forests. • Seed productivity increases with late growing season-end in N. betuloides. • Management must consider how seeding fluctuations produce recruitment delays. The ecological mechanisms that regulate seeding processes in temperate forests are poorly understood especially in the Southern Hemisphere. We studied the effect of different growing season metrics determined by the Normalized Difference Vegetation Index (NDVI) across eight annual periods between 2012 and 2020. We analyzed the seed production and biomass of two Nothofagus species in Tierra del Fuego (Argentina) to develop new tools for ecological forest management strategies. We focused on three forest types in coast and mountain landscapes: (i) pure deciduous N. pumilio , (ii) pure evergreen N. betuloides , and (iii) mixed forests with a similar proportion of both species. We performed generalized linear models for each species to analyze the influence of the growing season metrics and regional climate patterns (temperature and rainfall) considering forest types on coasts and mountains as main factors and analyzing seed production and biomass. Seed production and biomass annually varied with tree species growing at different landscape locations, with marked synchrony for each forest type, but not between different species or landscape locations (e.g. deciduous and evergreen species presented different synchrony among years). Seed production and biomass were higher when NDVI-peak was high in N. pumilio and when the growing season end was late in N. betuloides. For N. pumilio , the seed production and biomass were significantly leaded by growing season minimum temperature and growing season rainfall in coastal and mountain forests. For N. betuloides , the higher seed production and biomass were significantly influenced by non-growing season maximum temperature, growing season rainfall and non-growing season rainfall in coastal and mountain forests. These outputs highlight the importance of considering the fluctuation of the growing season in the modeling of seed production and biomass. Forest management guidelines should forecast rainy years that may benefit seedling recruitment after stand management or conservation efforts of target species (e.g. simulations of population dynamics at stand-level, decisions about passive vs active restoration in degraded forests for recover of the natural ecosystem functions). [ABSTRACT FROM AUTHOR]

Effects of forest harvesting on biodiversity can be varied and complex to understand. We provide a meta-analysis of 553 studies plants, insects and birds to identify the general responses to Variable Retention harvesting (VR) 1–8 years post-harvest in Nothofagus pumilio forests of southern Patagonia. The analysis is focused on: (i) richness and abundance, (ii) origin and habitat (native forest specialist species, native species of other habitats, alien species), and (iii) temporal trends after harvesting. Our objective was to evaluate why biodiversity increases after variable retention harvesting, by assessing the effects on (i) species richness and abundance in general, (ii) native forest specialists, native generalist species and alien species, and (iii) the recovery of biodiversity toward original conditions. Forests managed with VR supported higher overall richness and abundance of plants, insects and birds in aggregate and dispersed retention than unmanaged stands, but with similar values each other. However, origin and habitat of species affected responses to VR. Aggregates support higher native forest specialist plant and lower plants of habitats other than dispersed retention. However, both retention treatments increased alien plants, although its richness and abundance was higher in dispersed retention. Native forest specialist insects were reduced in comparison to unmanaged forest, while insects of other habitats showed a positive response to both aggregate and dispersed retention as well as did for bird species richness and abundance compared to unmanaged forests. We found evidence for recovery of original conditions for native forest specialist plants and insects, and plants of other habitats. In contrast, alien plants and native insects of other habitats increased continuously in the studies included through those representing 8 years post-harvest. Major differences among both retention patterns included significantly higher richness and abundance of alien plants and native insects of other habitats in dispersed retention. Our synthesis shows recovery toward original conditions for some taxa, but demonstrates long-term establishment of alien plants as well as insect species not associated with native N . pumilio forests. These have emerged as a main potential threat to conservation of forests under VR prescription, at least at the stand level. Retention forestry could play a fundamental role for conservation in productive temperate forests, but the influence of retention pattern and aggregate size are still unclear. [ABSTRACT FROM AUTHOR]

• Thinning affects species composition even 15–50 years after harvesting. • A specialist forest bird specie disappeared in thinned forests. • Location and canopy cover categories better describe bird community structure. • Forest structure and food availability better explain most bird functional traits. Low intensity silviculture has been used to decrease the impact of forest harvesting, for example, on bird species and structural diversity. The objective of this work was to analyse the long-term effect of thinning on bird communities of Nothofagus antarctica forests in Tierra del Fuego (Argentina), compared with unthinned forests at two different locations. Thinning was performed 15 and 50 years ago at each location (ranches), therefore we also evaluated other common forest habitat types to differentiate these effects (location and time). We sampled four habitat types associated to overstory canopy cover (CC) categories: thinned (35–65% CC), and three unthinned forests (open with <35% CC, closed with 65–85% CC, and very closed with >85% CC), totalling 32 sampling sites (2 ranches × 4 canopy cover × 4 replicates). Bird assemblages' structure and functional traits (e.g., richness, density, trophic groups, use of strata) were surveyed during two consecutive summers (2017–2020) at each site. We also characterized habitats by: (i) forest structure and ground cover (e.g., basal area, debris, and saplings); and (ii) food availability, considering understory plants consumed by birds (e.g., plant richness, grasses and dicots cover) and arthropods (e.g., total abundance). We evaluated the effect of CC, ranch, time, habitat and food availability by Generalised Linear Mixed Models and multivariate analyses (Multiple Response Permutation Procedure, Canonical Correspondence Analysis). In thinned forests, some bird structure and functional traits remained similar to closed forests; however, thinning increased bird species richness, being more similar to open forests. Effect of time could not be detected. CC and ranch were the factors that better described bird community structure, while forest structure, ground cover and food availability (e.g., dominant height, basal area, proportion of Hymenoptera) were the main drivers of most functional traits. The whole bird assemblage was better explained by 4–6 habitat structure and food availability variables depending on location (ranch). Results suggest thinning will benefit bird conservation if thinned forests maintain characteristics of mature forests (e.g., basal area > 40 m2/ha, shrub cover > 5%). [ABSTRACT FROM AUTHOR]

• Estimation of biomass, carbon and nutrients content in tree components are needed. • Nutrient and fibre contents varied across natural gradients (site quality and crown classes). • Nutrient contents and fibre composition varied across the component types. • High tree growth rate affected tissue density and fibre content by increasing C content. • The findings allow to define new modelling strategies for accurate forest estimations. Estimation of biomass and nutrient contents in tree components are essential for evaluating the impact of harvesting on carbon fixation capacity, bio-element recycling, and long-term effect on the balance that influence over net primary productivity. In many reports, fixed values were roughly considered at tree and stand level; however, the nutrient contents can vary across natural gradients (e.g. site quality and crown class) and according tree components (e.g. leaves, branches, bark, wood); and also, can be related to their fibre contents. The objective was to determine these changes in one tree species (Nothofagus pumilio) growing in Southern Patagonia (Argentina), comparing carbon (C), nitrogen (N) and fibre tissue contents of above-ground biomass across site quality and crown class gradients. We found that C, N and fibre (cellulose, hemicellulose, lignin) at different tree compartments varied with the site quality and crown class gradients (dominant, codominant, intermediate, suppressed). High tree growth rate (better site qualities and dominant trees) affected tissue density and fibre content by increasing C content (e.g. lignin generated higher carbon content). Also, we found the same trend for N content, which was more evidently related to some tissues (e.g. leaves). The use of fixed values in the modelling for tree or stand approaches in C or N estimations can generate significant biases in N. pumilio trees, being necessary consider specific values for the different natural gradients that influence over this tree growth species. Calculating accurately the stored and sequestered C or N contents can improve management strategies and modelling of the natural forest stands. The information provided in the present study suggests the need of incorporate the natural gradients into the tree models for C sequestration and N storage estimations. [ABSTRACT FROM AUTHOR]

Abstract: The current silvicultural prescriptions for Nothofagus are designed to stimulate natural regeneration by opening the canopy. One of these methods is variable retention, which can include either or both aggregated and dispersed retention. Different degrees of retention may modify microclimatic variables differently and consequently offer dissimilar microenvironmental conditions for regeneration. Retained canopy influences both biotic and abiotic factors. The objective was to evaluate Nothofagus pumilio regeneration along edge-related gradients within aggregated retention, and in the different microenvironments within the harvested areas. The remnant canopy cover after harvesting greatly influenced regeneration mainly by decreasing radiation transmittance and soil moisture availability. Aspect (direction to the azimuth) and distance from edge of aggregates influenced regeneration density, height and growth. In dispersed retention, microenvironments generated by different types of understory plant cover, debris, and proximity of remnant trees also influenced regeneration. High levels of understory cover (up 50%) and medium levels of harvesting debris cover (25–50%) had a positive impact, while close proximity to remnant trees had a negative impact on regeneration. These findings can be used to improve silvicultural and harvesting prescriptions to ensure successful establishment of regeneration and maximize potential growth. [ABSTRACT FROM AUTHOR]

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

• Vascular plants and spiders present different assemblages in Fuegian landscapes. • Variable retention harvesting influences spider and understory plant diversity. • Forest structure variables have negative correlations with spider and plant richness. • Aggregated and dispersed retentions contribute to conserve spiders and plants. • Potential bioindicators were identified for forests and associated environments. Variable retention mitigates negative effects of traditional harvesting on biodiversity, maintaining legacies in harvested forests as habitat for sensitive species, and generating other habitats for early-seral species. Their assessment, including drivers, has a high concern for society. Likewise, species association with ecosystems in the landscape (as different forest types, grasslands and peatlands) are unknown for some taxa and regions, and could explain species flow into harvested areas. Therefore, we evaluated the forest harvest impact on ground-dwelling spiders and vascular plants, their diversity and association to vegetation types in the landscape matrix, and richness and abundance correlations with forest structure. Six natural common habitats were studied in Tierra del Fuego (Argentina), where variable retention has been implemented: aggregated (AR) and dispersed (DR) retention in harvested Nothofagus pumilio forests, unharvested primary forests (NPF) as reference, grasslands (G), peatlands (P), and unharvested N. antarctica forests (NAF). We surveyed spiders (N = 432, by 6 habitats × 6 replicates × 6 collections × 2 years), and vascular plants (N = 36, by 6 habitats × 6 replicates), and characterized forest structure in wooded ecosystems. We determined for both taxa richness, relative abundance (total captures/ground cover) and Shannon-Wiener and Pielou indices, compared assemblage composition and indicator species among harvesting treatments and vegetation types, and analyzed correlations. We sampled 752 individuals of spiders from 33 species (six families), and 79 vascular plant species (28 families) that averaged 52% total vegetation cover. Total spider captures and overall richness were higher in DR > NPF > AR, although differences were not detected at plot level for any variable. For understory vascular plants, richness and cover were the highest on DR, followed by AR and NPF, as well as at plot level, with no affectation in indices. Likewise, highest richness and abundance occurred in NAF and NPF for spiders, and in NAF and G for vascular plants, with unique assemblages in each vegetation type despite the shared species. Assemblages also differed in harvested areas, including species of other vegetation types mainly in DR, where new conditions were generated by reduction of forest structure variables (evidenced by negative correlations), while AR maintained species composition similar to NPF, contributing to the conservation of forest specialists. Indicators occurred for both taxa in several habitats. This study highlights the importance of different vegetation types for spider and plant conservation at landscape level, while provides tools for developing monitoring strategies and conservation policies. [ABSTRACT FROM AUTHOR]