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International audience; This paper contributes to a critical re-reading of the notion of climate services. It does so by problematizing the discontinuity between young people’s commitment to climate change, and the lack of a common vision regarding climate policy among governments. In this essay, youth commitment is characterized in terms of participation in the Global Youth Climate Pact (GYCP, 2015–2022). Here, young people share projects from their own high schools and communities and participate in a citizen consultation. Most projects have achieved a good success score, increasing over the years, especially for those carried out in emerging and developing countries. Some of them were presented at the COPs. In contrast, a textual analysis of intended nationally determined contributions (INDC) illustrates divergent understandings of the Paris Agreement and exemplifies the poor results of governmental climate diplomacy. This study establishes the need to closely monitor early warning signs of climate change in conjunction with high schools and school communities. The initiatives of young people are building a civic and planetary awareness for climate change in contrast with governmental division and inertia. In this sense, climate services, directed to young people, could contribute to design a sustainable future. We approach the practices, attitudes, and commitments of young people from the angle of cooperation rather than a moral vision of responsibility. Particularly, we propose a dialogical link between the treatment of climate issues and its effects on the constitution of networks, notably as they relate to practices of action, that is, the way in which distinct groups of young people develop relationships with their environments, organize themselves, and act and transform reality.

In recently deglaciated soils, microbial organisms drive soil transformations by increasing carbon (C) and nitrogen (N) pools while depleting available phosphorous (P), thus improving plant colonization and soil development. However, the rate of soil development can vary in response to local environmental conditions that affect microbial abundance and activity. In this contribution we use observational and experimental approaches to evaluate the interplay between soil biogeochemical features and microbial abundance and function after approximately seventy years of soil development in the forefield of the Exploradores Glacier that is located at the northernmost end of the Northern Patagonian Ice Field. Our findings suggest that after approximately seventy years of soil development, microbial abundance and soil C and N accumulation increase with soil age, soil bulk density and pH decreased, and microbial activity measured as soil chlorophyll a and nifH gene abundance increased. In turn, decomposition increased with fungal abundance, showing higher values in the late stages of soil development where the soil C:N ratio was higher and soil pH was lower. Overall, biogeochemical changes along this chronosequence followed the predicted pattern, with gradual increases in soil nutrients and microbial abundance, in addition to decomposition processes.

Plant functional strategies are usually accomplished through the simultaneous expression of different traits, and hence their correlations should be promoted by natural selection. The adaptive value of correlations among leaf functional traits, however, has not been assessed in natural populations. We estimated intraspecific variation in leaf functional traits related to the primary metabolism and anti-herbivore defence in a population of Turnera velutina. We analysed whether natural selection favoured the expression of individual traits, particular combinations of traits or leaf phenotypic integration. Patterns of covariation among traits were related to water and nitrogen economy, and were similar among genotypes, but the magnitude of their phenotypic integration differed by 10-fold. Although families did not differ in the mean values of leaf functional traits, directional selection favoured low nitrogen content and low chemical defence, high content of chlorophyll, sugar in extrafloral nectar and trichome density. Families with higher phenotypic integration among leaf traits grew faster and produced more flowers. We suggest that the coordinated expression of leaf traits has an adaptive value, probably related to optimisation in the expression of traits related to water conservation and nitrogen acquisition.

Arid ecosystems are strongly limited by water availability, and precipitation plays a major role in the dynamics of all species in arid regions, as well as the ecosystem processes that occur there. However, understanding how biotic interactions mediate long-term responses of dryland ecosystems to rainfall remains very fragmented. We report on a unique large-scale field experiment spanning 25 yr and three trophic levels (plants, small mammal herbivores, predators) in a dryland ecosystem in the northern Chilean Mediterranean Region where we assessed how biotic interactions influence the long-term plant community responses to precipitation. As the most persistent ecological changes in dryland systems may result from changes in the structure, cover, and composition of the perennial vegetation, we emphasized the interplay between bottom-up and top-down controls of perennial plants in our analyses. Rainfall was the primary factor affecting the dynamics of, and interactions among, plants and small mammals. Ephemeral plant cover dynamics closely tracked short-term annual rainfall, but seemed unaffected by top-down controls (herbivory). In contrast, the response of the perennial plant cover to precipitation was mediated by (1) a complex interplay between subtle top-down (herbivory) controls that become more apparent in the long-term, (2) competition with ephemeral plants during wet years, and (3) an indirect effect of predators on subdominant shrubs and perennial herbs. This long-term field experiment highlights how climate-induced responses of arid perennial vegetation are influenced by interactions across trophic levels and temporal scales. In the face of global change, understanding how multi-trophic controls mediate dryland vegetation responses to climate is essential to properly managing the conservation of biodiversity in arid systems.

Cushion plants are life forms with a hemispherical or mat‐like, prostrate canopy well adapted to the extreme conditions of cold regions that have appealed to scientists for their ability to cope with extreme environments in most mountains, arctic, and subantarctic regions of the world. They can buffer the effects of low temperature and drought and improve soil conditions, which makes them notable facilitator species. Living at the edge in the Atacama Desert is one such species, Azorella compacta (yareta or llareta), in the Apiaceae family that can reach much over 6 m (~20 ft) in diameter with a mat‐like shape that tends to hemispherical growth form. Azorella compacta can be found in the dry Puna system, which spreads from northern Chile and Argentina to southern Peru and western Bolivia, between 3800 and 5200 m elevation, making it one of the woody plant species occurring at highest elevations in the world. In this deserted edge of the Atacama, nutrient limitation adds to other stressors such as water scarcity and high UV radiation. A compact canopy and the fact that they are embedded in resin prevent beneficiary species from growing within the cushion and condition how senesced leaves decompose inside the canopy. They can reach 3000 yr old and have to deal with episodic disturbance and herbivory events. Plants in such environments may potentially act as microbial refuges, and it could be expected that bacterial endophytes and mycorrhizal fungi have a main role in the functioning of these survival champions.

Forest ecosystems are recognized for their large capacity to store carbon (C) in their aboveground and belowground biomass and soil pools. While the distribution of C among ecosystem pools has been extensively studied, less is known about nitrogen (N) and phosphorus (P) pools and how these stocks relate to each other. There is also a need to understand how biotic and abiotic ecosystem properties drive the magnitude and distribution of C-N-P stocks. We studied a temperate rainforest in southern South America to answer the following questions: 1) how are C-N-P total stocks distributed among the different ecosystem pools?, 2) how do C:N, C:P and N:P ratios vary among ecosystem pools?, and 3) which are the main biotic and abiotic drivers of C-N-P stocks? We established 33 circular plots to estimate C, N, and P stocks in different pools (i.e. trees, epiphytes, understory, necromass, leaf litter, and soil) and a set of biotic (e.g., tree density and richness) and abiotic variables (e.g., air temperature, humidity and soil depth). We used structural equation modeling to identify the relative importance of environmental drivers on C-N-P stocks. We found that total ecosystem stocks (mean ± SE) were 1062 ± 58 Mg C ha−1, 28.8 ± 1.5 Mg N ha−1, and 347 ± 12.5 kg P ha−1. The soil was the largest ecosystem pool, containing 68%, 92%, and 73% of the total C, N, and P stocks, respectively. Compared to representative temperate forests, the soil of this forest contains the largest concentrations and stocks of C and N. The low P stock and wide soil C:P and N:P ratios suggest that P may be limiting forest productivity. The ecosystem C-N-P stocks were mainly driven by abiotic properties measured in the study area, however for N stocks, variables such as plant diversity and canopy openness were also relevant. Our results provide evidence about the importance not only of understanding the differences in C, N, and P stocks but also of the factors that drive such differences. This is key to inform conservation policies related to preserving old-growth forests in southern South America, which indeed are facing a rapid land-use change process.

Peatlands exhibit highly characteristic ecological traits and are unique complex ecosystems. Nevertheless, knowledge about southern South American peatlands is very limited. In this study, we analyzed species composition of bryophytes and lichens of Southern Hemisphere peatlands, specifically from eight peatlands of Isla Grande de Chiloe (Chiloe Island) in southern Chile (42°–43°S and 75°–73°W). Two kinds of Sphagnum peatlands were studied: natural and anthropogenic peatlands. Our results indicate the existence of clear environmental gradients affecting the structure of bryo-lichenic communities in the Sphagnum peatlands of Chiloe. Canonical correspondence analysis suggests that variation in bryophyte and lichen species composition mainly follows ombrotrophic–minerotrophic and lithotrophic-thalassotrophic gradients. Surface-water chemistry is the most significant factor accounting for changes in floristic composition among our study sites. In contrast to our expectations, bog origin (natural or anthropic) was not the most significant factor accounting for changes in floristic composition among peatlands. Other elements, such as the water source supplying peatlands or the influence of sea spray, were more relevant in the bryo-lichenic flora species occurrence in the peatlands of Chiloe. We also observed clear differences in ecological niches among species in general additive model response curves. Therefore, our results show that despite the origin, the ecology of peatlands follows common rules with peatlands from the Northern Hemisphere.

Summary During soil development, bacteria and fungi can be differentially affected by changes in soil biogeochemistry. Since the chemistry of parent material affects soil pH, nutrient availability, and indirectly litter quality, we hypothesize that parent material has an important influence on microbial community patterns during long-term soil development. In this paper, we tested for the effect of parent material, as well as, soil and litter properties upon microbial community patterns in three c. 20 000-year-old semi-arid chronosequences developed on sedimentary and volcanic (i.e. Andesitic and Dacitic) soils in the Dry Puna of Bolivia. We evaluated microbial patterns by analysing the terminal restriction fragment length polymorphism from amplified bacterial 16S rRNA genes, and the fungal internal transcribed spacer region, and quantitative real-time polymerase chain reaction. Soil and litter characteristics differed significantly between the Sedimentary and volcanic chronosequences. In particular, soil pH was alkaline in all stages of the Sedimentary chronosequence; whereas it changed from alkaline to near neutral across stages in both volcanic chronosequences. Composition of bacterial communities changed across volcanic chronosequences, and this change was associated with a reduction in soil pH and increases in litter quality, whereas no differences were found in the Sedimentary chronosequence. Fungal community composition, in contrast, did not change across any chronosequence. Relative microbial abundance, expressed as the fungal:bacterial ratio, declined across stages of the Sedimentary chronosequence in association with decreases in TC and TP, whereas in the Andesitic chronosequence decreases in fungal:bacterial ratios were related with increases in litter quality and declines in soil pH. Synthesis. Our results show the importance of parent material in affecting bacterial and fungal communities during soil development. Further, in semi-arid chronosequences, fungal:bacterial ratios tend to decline given that soil pH in young soils is rather alkaline. Our results also are consistent with the general framework that highlights the importance of above-ground (i.e. litter quality) and below-ground (i.e. soil properties) in affecting microbial relative abundance and community composition during soil development.

By affecting plant-soil feedbacks, climate change will alter plant distribution and performance and overall ecosystem functioning., Plant-soil feedbacks (PSFs) are interactions among plants, soil organisms, and abiotic soil conditions that influence plant performance, plant species diversity, and community structure, ultimately driving ecosystem processes. We review how climate change will alter PSFs and their potential consequences for ecosystem functioning. Climate change influences PSFs through the performance of interacting species and altered community composition resulting from changes in species distributions. Climate change thus affects plant inputs into the soil subsystem via litter and rhizodeposits and alters the composition of the living plant roots with which mutualistic symbionts, decomposers, and their natural enemies interact. Many of these plant-soil interactions are species-specific and are greatly affected by temperature, moisture, and other climate-related factors. We make a number of predictions concerning climate change effects on PSFs and consequences for vegetation-soil-climate feedbacks while acknowledging that they may be context-dependent, spatially heterogeneous, and temporally variable.

Forest fires can cause great changes in the composition, structure and functioning of forest ecosystems. We studied the effects of a fire that occurred >50 years ago in a temperate rainforest that caused flooding conditions in a Placic Andosol to evaluate how long these effects last; we hypothesized that the effects of fire on the soil greenhouse gas (GHG) balance could last for many years. We made monthly measurements of fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) during two years of soils in an unburned forest (UF) and a nearby site that burned >50 years ago (BS). Our results show that CO2 emissions from soils were higher in the UF than in the BS, and positively correlated with temperature and negatively with soil water content at both sites. Both sites were net CH4 sinks (higher in the UF) and fluxes correlated positively with soil water content and negatively with temperature (stronger relation in the BS). Emissions of N2O were low at both sites and showed correlation with friction velocity at the UF site. The soil GHG balance showed that the UF emitted about 80% more than the BS (5079 ± 1772 and 2815 ± 1447 g CO2-eq m−2 y−1, respectively). Combining our measured fluxes with data of CO2 net ecosystem exchange, we estimated that at the ecosystem level, the UF was a GHG sink while the BS was a source, showing a long-lasting effect of the fire and the importance of preserving these forest ecosystems.

Scientists are increasingly interested in the evolutionary responses of organisms to unpredictable, variable, and extreme climate changes. In semiarid environments, inter-annual variability in the frequency and amount of rainfall affects both the growth and recruitment of plant species, especially annuals. In these inherently variable environments, individual selection should favor demographic responses that spread the risk of mortality over time and enhance long-term reproductive success (i.e., bet-hedging strategies). However, the same processes that allow the persistence and recruitment of native species could facilitate the introduction and establishment of exotics. We assessed whether native and exotic annuals in semiarid Chile displayed similar or contrasting bet-hedging traits, and discuss mechanisms of coexistence of both types of species and their demographic variation under interannual rainfall variability driven by El Nino Southern Oscillation (ENSO). We analyzed a proxy of long-term fitness, i.e., the variability of seed density over 17 years, for the two most common native and two exotic annual plant species present in the study area. We experimentally tested whether the quality of the maternal environment (soil water supply in a given year) had an extended effect (e.g. the next year) on the proportion of seed germination or on the mean and/or variability of seed size and seed dormancy. Results showed that native and exotic species in this annual plant assemblage displayed contrasting bet-hedging strategies as evolutionary responses to variable rainfall. Although rainfall variability promotes the evolution of bet-hedging strategies, the nature of these strategies varies across species, presumably to minimize competitive exclusion. In semiarid Chile, the success of two exotic ephemerals that are components of a diverse community of native annual species seems to reflect bet-hedging germination strategies that complement rather than compete with those expressed in dominant natives.

Ecosystems where carbon fluxes are being monitored on a global scale are strongly biased toward temperate Northern Hemisphere latitudes. However, forest and moorland ecosystems in the Southern Hemisphere may contribute significantly to the global and regional C balance and are affected by different climate systems. Here, we present the first data from an old‐growth forest representative of temperate, broad‐leaved rainforests from southern South America. Carbon fluxes monitored over two years using the eddy covariance technique showed that this rainforest acts as an annual sink (−238 ± 31 g C/m2). However, there were significant pulses of carbon emission associated with dry episodes during the summer months (i.e., peak of the growing season) and periods of significant carbon fixation during the cold austral winter, indicating that the carbon balance in this forest is very sensitive to climate fluctuations. The carbon fixation surges in winter seem to be related to the mild temperatures recorded during this period of the year under the prevailing oceanic climate. Winter carbon gain was more relevant in determining the annual carbon balance than summer pulse emissions. Regarding the annual carbon balance, this southern forest resembles the patterns observed in montane tropical forests more than the behavior of narrow‐leaved evergreen temperate forests from the Northern Hemisphere. These patterns make this southern forest type relevant to understanding the mechanisms and thresholds that control ecosystem shifts from carbon sinks and sources and will provide key data to improve global dynamic vegetation models., This work was supported by FONDEQUIP AIC-37, Iniciativa Científica Milenio grant P05-002 and CONI-CYT grant PFB-23 to the Institute of Ecology and Biodiversity-Chile (IEB), FONDECYT grant 1130935 to JPQ, and the LINCGlobal research program funded by CSIC-Spain and Catholic University of Chile. The authors thank Robert Cook and Alison Boyer, who kindly provided the FLUXNET database 2015. The authors are grateful to Paul Reich (USDA) for sharing the Biome database, Sebastiaan Luyssaert for providing them with the database of CO2 balance of forest ecosystems, and an anonymous reviewer whose comments helped them to improve the manuscript. This is a contribution to the Research Program of Senda Darwin Biological Station and the Chilean Long-Term Socio-Ecological Research Network (LTSER-Chile), affiliated with ILTER, AMERIFLUX, and FLUXNET.

Through litter decomposition enormous amounts of carbon is emitted to the atmosphere. Numerous large-scale decomposition experiments have been conducted focusing on this fundamental soil process in order to understand the controls on the terrestrial carbon transfer to the atmosphere. However, previous studies were mostly based on site-specific litter and methodologies, adding major uncertainty to syntheses, comparisons and meta-analyses across different experiments and sites. In the TeaComposition initiative, the potential litter decomposition is investigated by using standardized substrates (Rooibos and Green tea) for comparison of litter mass loss at 336 sites (ranging from -9 to +26 °C MAT and from 60 to 3113 mm MAP) across different ecosystems. In this study we tested the effect of climate (temperature and moisture), litter type and land-use on early stage decomposition (3 months) across nine biomes. We show that litter quality was the predominant controlling factor in early stage litter decomposition, which explained about 65% of the variability in litter decomposition at a global scale. The effect of climate, on the other hand, was not litter specific and explained

Aim: We used fossil and phylogenetic evidence to reconstruct climatic niche evolution in Nothofagus, a Gondwana genus distributed in tropical and temperate latitudes. To assess whether the modern distribution of the genus can be explained by the tropical conservatism hypothesis, we tested three predictions: (1) species from all Nothofagus subgenera coexisted under mesothermal climates during the early Eocene, (2) tolerance to microthermal climates evolved during the Eocene-Oligocene cooling from an ancestor that grew under mesothermal conditions; and (3) the climatic niche in Nothofagus is phylogenetically conserved. Location: Australia, New Zealand, New Caledonia, Papua-New Guinea and South America. Methods: We estimated the palaeoclimate of the Early Eocene, fossil-bearing Ligorio Marquez Formation (LMF, Chile), using coexistence and leaf physiognomic analysis. We reconstructed ancestral climatic niches of Nothofagus using extant species distributions and a time-calibrated phylogeny. Finally, we used the morphological disparity index and phylogenetic generalized least squares to assess whether climatic variables follow a Brownian motion (BM) or an Ornstein-Uhlenbeck (OU) model of evolution. Results: Our palaeoclimatic estimates suggest mesothermal conditions for the LMF, where macrofossils associated with subgenera Lophozonia and possibly Fuscospora, and fossil pollen of Brassospora and Fuscospora/Nothofagus were recorded. These results are not supported by our phylogenetic analysis, which instead suggests that the ancestor of Nothofagus lived under microthermal to marginally mesothermal conditions, with tolerance to mesothermal conditions evolving only in the subgenus Brassospora. Precipitation and temperature dimensions of the realized climatic niche fit with a gradual BM or constrained OU model of evolution. Main Conclusions: Our results suggest that the use of phylogenetic reconstruction methods based only on present distributions of extant taxa to infer ancestral climatic niches is likely to lead to erroneous results when climatic requirements of ancestors differ from their extant descendants, or when much extinction has occurred. Fil: Hinojosa, Luis Felipe. Universidad De Chile. Facultad de Ciencias. Instituto de Ecología y Biodiversidad; Chile Fil: Gaxiola, Aurora. Universidad de Chile. Facultad de Ciencias. Instituto de Ecología y Biodiversidad; Chile. Universidad Católica de Chile. Facultad de Ciencias Biológicas. Departamento de Ecología; Chile Fil: Pérez, María Fernanda. Universidad de Chile. Facultad de Ciencias. Instituto de Ecología y Biodiversidad; Chile. Universidad Católica de Chile. Facultad de Ciencias Biológicas. Departamento de Ecología; Chile Fil: Quattrocchio, Mirta Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina Fil: Carvajal, Francy. Universidad De Chile. Facultad de Ciencias. Instituto de Ecología y Biodiversidad; Chile Fil: Campano, María Francisca. Universidad De Chile. Facultad de Ciencias. Instituto de Ecología y Biodiversidad; Chile Fil: Nishida, Harufumi. Chuo University. Department of Biological Sciences.; Japón Fil: Uemura, Kazuhiko. National Museum of Nature and Science. Department of Geology and Paleontology.; Japón Fil: Bustamente, Ramiro. Universidad De Chile. Facultad de Ciencias. Instituto de Ecología y Biodiversidad; Chile Fil: Arroyo, Mary T.K.. Universidad De Chile. Facultad de Ciencias. Instituto de Ecología y Biodiversidad.; Chile

Nitrogen and phosphorus are the main elements limiting net primary production in terrestrial ecosystems. When growing in nutrient-poor soils, plants develop physiological mechanisms to conserve nutrients, such as reabsorbing elements from senescing foliage (i.e. nutrient retranslocation). We investigated the changes in soil N and P in post-fire succession in temperate rainforests of southern Chile. In this area, forest recovery often leads to spatially scattered, discrete regeneration with patches varying in age, area, species richness and tree cover, representing different degrees of recovery from disturbance. We hypothesized that soil nutrient concentrations should differ among tree regenerating patches depending on the progress of forest regeneration and that nutrient resorption should increase over time as colonizing trees respond to limited soil nutrients. To evaluate these hypotheses, we sampled 40 regeneration patches in an area of 5 ha, spanning a broad range of vegetation complexity, and collected soil, tree foliage and litter samples to determine N and P concentrations. Nutrient concentrations in leaf litter were interpreted as nutrient resorption proficiency. We found that soil P was negatively correlated with all the indicators of successional progress, whereas total soil N was independent of the successional progress. Foliar N and P were unrelated to soil nutrient concentrations; however, litter N was negatively related to soil N, and litter P was positively related with soil P. Finally, foliar N:P ratios ranged from 16 to 25, which suggests that P limitation can hamper post-fire regeneration. We provide evidence that after human-induced fires, succession in temperate forests of Chile can become nutrient limited and that high nutrient retranslocation is a key nutrient conservation strategy for regenerating tree communities.

Summary 1. Recent empirical and theoretical analyses have suggested that biomes could correspond to alternative equilibrium states; one such example is the transition between forest, savanna and treeless states. 2. Fire supposes to be a key functional component of savanna ecosystems and is a powerful predictor of tree cover that can differentiate between forest and savanna ecosystems. Interestingly, empirical evidence suggests that fire occurrence drops at a threshold tree cover near 40%. Since savannas are ecosystems characterized by a discontinuous tree canopy cover immersed in a continuous grass layer a 40% of tree cover implies around 60% cover of grasses, which are the flammable component of this ecosystem. 3. In this article, we hypothesize that the observed common pattern of 40% tree cover versus 60% in grass cover often reported for savanna ecosystems is the outcome of a spatial phase transition associated with the existence of a critical percolation threshold for fire spread. 4. To test this hypothesis, we developed a spatially explicit neutral metacommunity model to explore the relationship between species cover and the emergence of percolation patterns. The model is intended to emulate savanna dynamics under neutrality assumptions. 5. Using a statistical mechanical approach, we show that a second-order phase transition behaviour is observed for the probability that a grass species develops a percolating cluster. Using a simple finite size scaling analysis, the percolation threshold pc for our model was estimated to be in the range of 0.53–0.62. 6. Synthesis. Our results point out that the emergence of a spatial phase transition associated with percolation is a robust result of neutral metacommunity dynamics with a critical threshold of space occupancy close to pc ~ 0.6, which supports our hypothesis that the empirically observed 40% tree cover (60% grass cover) is associated with a percolation threshold for C4 grasses that in turn imply the existence of a spatially connected or spanning cluster of grass cover over which fire can spread.

Resumen es: La investigacion que se desarrolla en los tres sitios fundadores de la red Chilena de Sitios de Estudios Socio-Ecologicos de Largo Plazo (LTSER-Chile) in...

Past research has demonstrated that decreased biodiversity often reduces ecosystem productivity, but variation in the shape of biodiversity–ecosystem function (BEF) relationships begets the need for a deeper mechanistic understanding of what drives these patterns. While mechanisms involving competition are often invoked, the role of facilitation is overlooked, or lumped within several less explicitly defined processes (e.g., complementarity effects). Here, we explore recent advances in understanding how facilitation affects BEF relationships and identify three categories of facilitative mechanisms that can drive variation in those relationships. Species interactions underlying BEF relationships are complex, but the framework we present provides a step toward understanding this complexity and predicting how facilitation contributes to the ecosystem role of biodiversity in a rapidly changing environment.

Aim The relationship between the proportion of species with an entire leaf margin (pE) and mean annual temperature (MAT) is one of the most powerful tools for estimating palaeotemperatures. However, phylogenetic and phytogeographic constraints on this relationship have remained unexplored. Here we investigate the pE–MAT relationship for modern floristic assemblages from southern South American forests, assess its conformity to other models and test for the existence of historical constraints on pE–MAT models. Location South America. Methods We used samples from 30 sites located in Chile between 32° and 44° S to test for a pE–MAT relationship and compared it with four regional models. We assessed the reliability of these models for predicting MAT from instrumental records in eight modern temperate-forest localities in Chile. Additionally, palaeotemperatures for Cenozoic fossil floras were estimated. To assess historical constraints in pE, we measured the phylogenetic signal in leaf margin type and the association between leaf margin and phytogeographic affiliation, defined by the distribution of genera. Results We found a significant pE–MAT relationship for Chilean forest species that differed from Australia and Northern Hemisphere models, but not from tropical South America (TSA). Temperatures for southern South American localities predicted from the new regional model – combining Chilean and TSA datasets – were more accurate than those from previous models. We also showed that leaf margin type has a strong phylogenetic signal, which was further confirmed by the highly significant effect of phytogeographic element on leaf margin type. Main conclusions Differences between the Chilean and other regional models are explained by historical legacy, as Chilean leaf margin types are strongly affected by phylogenetic closeness and phytogeographic elements. We highlight that leaf margin analyses should be conducted within the context of a flora with a shared history. Thus, we propose a new model for South America to estimate palaeotemperatures for regional fossil floras.

Summary 1. During retrogressive succession, vegetation shifts from taller forests with higher species richness to shorter woody communities of lower diversity. Studies of soil chronosequences have emphasized the role of phosphorus (P) depletion in driving these changes in community structure and composition, but neglected the possible role of poor drainage which is often associated with the oldest sites. 2. We used a fully factorial pot experiment to investigate the effects of soil water conditions and P availability on seedling relative growth rate and survival of 11 woody species associated with a 290 000-year chronosequence in southern New Zealand. Species were chosen to represent three stages of the chronosequence: young P-rich soils; intermediate-age P-depleted soils; and old P-depleted, waterlogged soils. Plants were grown in soils taken from youngest and oldest sites of the chronosequence; half the pots were freely drained whilst the other half were waterlogged. 3. Species associated with intermediate-age soils were typical ‘stress-tolerators’; those of the youngest and oldest sites were faster growing and more responsive to nutrient availability. Only the latter showed tolerance of waterlogging. Specific root length and adventitious-root production were important determinants of species’ responses to soil water conditions and nutrient supply. 4. Our study highlights that soil waterlogging and P depletion interact to influence relative growth rate and survival; P depletion is not the sole driver of ecosystem changes in the retrogressive stages of the soil chronosequence. We also show that some species associated with our retrogression did not necessarily conform to conventional views on ‘stress-tolerance’, but were well adapted to poor drainage.

Latin America (including Mexico and Central and South America) hosts a substantial proportion of global biodiversity, but suffers from increasing rates of deforestation, land degradation, and dryland expansion. Low-cost modification of local management practices integrating ecological restoration could play a major role in abating ecosystem degradation and biodiversity loss. A regional ecological restoration network would identify the major challenges, both practical and intellectual, and generate protocols for assisting land managers and stakeholders through shared databases and experience. Such a network would enhance the critical mass of practitioners working under similar, though diverse social, cultural, and ecological contexts. Una proporcion sustancial de la biodiversidad mundial se encuentra en America Latina (la cual incluye a Mexico, Centro y Sudamerica); sin embargo, esta region sufre de tasas crecientes de deforestacion, degradacion del suelo y expansion de las zonas aridas. Algunas practicas locales de manejo, con modificaciones de bajo costo que integren la restauracion ecologica, podrian jugar un papel muy importante en el abatimiento de la degradacion de los ecosistemas y en la reduccion de la biodiversidad. Una red de restauracion ecologica regional identificaria los principales retos, tanto practicos como intelectuales, y generaria los protocolos para auxiliar a los administradores y los duenos de terreno a traves de experiencias y bases de datos compartidas. Esta red incrementaria la masa critica de investigadores que trabajan en contextos sociales, historicos y ecologicos similares.

International audience; Understanding the long-term impacts of invasive mammalian browsers and granivores in mixed forests is difficult due to the many processes potentially affecting the demography of long-lived trees. We constructed individual-based spatially-explicit simulation models of two mixed conifer–angiosperm forests, growing on soils of contrasting phosphorus (P) availability, to investigate how browsing by invasive red deer (Cervus elaphus scoticus) and granivory by invasive rodents (primarily house mouse Mus musculus) might alter forest dynamics. Models were parameterized with field data. Seedling growth and survival rates were estimated inside and outside deer exclosures. Seed predation rates were estimated at high and low rodent densities in mast and non-mast seeding years. For the alluvial terrace forest, which grew on P-rich soil, our model contained 15 tree species dominated by angiosperms; our model of the P-poor marine terrace forest contained 7 species dominated by conifers. The two forest models were used to explore four 500-year scenarios: deer and rodents present, deer present and rodents absent, deer absent and rodents present, and deer and rodents absent. Our field studies revealed that the highest probabilities of seed predation by rodents occurred for two canopy species in mast years and in neighborhoods of high basal area, and that deer browsing had the greatest negative effects on the growth and survival rates of angiosperm seedlings. Our simulation models predicted that the presence of deer and rodents would reduce the abundances of canopy co-dominants, and hence total basal area, in the alluvial terrace forest. The presence of deer increased the dominance of conifers in both forests, but the effects of deer and rodents were much stronger in the alluvial terrace forest. Our study revealed two emergent properties. First, rodent- and deer-induced reductions in seedling abundances did not always translate into reduced sapling and adult tree abundances. Second, when deer changed the abundance of a canopy dominant, other species were affected by altered interspecific competition. We conclude that the effects of invasive deer and rodents will be greatest in forests growing on P-rich soils. Exclusion of deer is predicted to have greater long-term effects on forest dynamics than exclusion of rodents.

Differences in litter quality, microbial activity or abiotic conditions cannot fully account for the variability in decomposition rates observed in semiarid ecosystems. Here we tested the role of variation in litter quality, water supply, and UV radiation as drivers of litter decomposition in arid lands. And show that carry-over effects of litter photodegradation during dry periods can regulate decomposition during subsequent wet periods. We present data from a two-phase experiment, where we first exposed litter from a drought-deciduous and an evergreen shrub to natural UV levels during five, rainless summer-months and, subsequently, in the laboratory, we assessed the carry-over effects of photodegradation on biomass loss under different irrigation treatments representing the observed range of local rainfall variation among years (15 to 240 mm). Photodegradation of litter in the field produced average carbon losses of 12%, but deciduous Proustia pungens lost >25%, while evergreen Porlieria chilensis less than 5%. Natural exposure to UV significantly reduced carbon-to-nitrogen and lignin:N ratios in Proustia litter but not in Porlieria. During the subsequent wet phase, remaining litter biomass was lower in Proustia than in Porlieria. Indeed UV exposure increased litter decomposition of Proustia under low and medium rainfall treatments, whereas no carry-over effects were detected under high rainfall treatment. Consequently, for decidous Proustia carry-over effects of UV exposure were negligible under high irrigation. Litter decomposition of the evergreen Porlieria depended solely on levels of rainfall that promote microbial decomposers. Our two-phase experiment revealed that both the carry-over effects of photodegradation and litter quality, modulated by inter-annual variability in rainfall, can explain the marked differences in decomposition rates and the frequent decoupling between rainfall and litter decomposition observed in semiarid ecosystems.

Summary 1 Angiosperm trees often dominate forests growing in resource-rich habitats, whereas conifers are generally restricted to less productive habitats. It has been suggested that conifers may be displaced by angiosperms except where competition is less intense, because conifer seedlings are inherently slow growing, and are outpaced by faster-growing angiosperm species. Here we investigate whether competition with ferns and deeply shading trees also contributes to a failure of conifers to regenerate in resource-rich habitats. 2 We examined how changes in soil nutrient availability and drainage affected vegetation along the retrogressive stages of a soil chronosequence in southern New Zealand. Vegetation composition shifted from angiosperm-tree dominance on ‘recent’ alluvial terraces (< 24 ky), via coniferous-tree dominance on older marine terraces (79‐121 ky), to coniferous-shrub dominance on the oldest marine terraces (291 ky). Soil drainage deteriorated along the sequence, and N : P leaves and N : P soil indicate increasing Plimitation. Conifer species appear to be adapted to persistence on infertile and poorly drained soils. 3 The floor of the relatively fertile alluvial forests was deeply shaded ( ∼ 1% light transmission) by dense groves of tree-ferns and ground-ferns, and by large-leaved subcanopy trees. Few seedlings of any type were found on the forest floor, even in tree-fall gaps, and establishment was restricted to rotting logs and tree-fern trunks. Angiosperms were particularly successful at colonizing these raised surfaces. 4 Less shade was cast by the conifer-dominated forests on infertile marine terraces ( ∼ 5% light transmission), which lacked tall ferns. There were many opportunities for conifer establishment, with high seedling densities recorded on the forest floor and on logs. By contrast, angiosperm seedlings were mainly restricted to logs. 5 Our results suggest that several mechanisms act in concert to reduce regeneration opportunities for conifers in productive habitats. In particular, we suggest that tall ferns and deep shade are responsible for a restriction of regeneration opportunities in relatively productive forests in New Zealand, diminishing the opportunities for conifers to escape the competitive effects of fast-growing angiosperms. Thus ‘crocodiles’ may alter the outcome of the race between ‘hares’ and ‘tortoises’.

Salvage logging has been described as a controversial environmental practice in developed countries, but in developing countries this conflict has not been evaluated. We describe salvage logging of Fitzroya cupressoides, an endemic conifer of the South American temperate forests. In Chile, the Huilliche—an ethnical group—extract deadwood of Fitzroya to produce sawn timber and shingles. The objectives of this study were (i) to estimate the volume of deadwood that is removed by salvage logging performed by Huilliches and (ii) to evaluate the effects of this local activity on the regeneration of Fitzroya, especially regarding the amount of waste wood left behind. In 54 (10 10 m) plots we measured length, height and dbh of logs, snags, and stumps. We quantified the regeneration of Fitzroya by counting all individuals with heights below 2 m. Each plot was characterized by its altitude, slope, aspect, microtopography, canopy cover, and quantity of waste wood covering the forest soil. We found a total of 279.51 m 3 of deadwood of which 53.9% was rotten and 3.6% was used to make sawn timber and shingles. Contrary to expected, the number of seedlings (1‐50 cm) was positively related to waste wood. Juvenile’s density (1‐200 cm) was mainly explained by altitude, microtopography, and the interaction of these variables with slope. We concluded that salvage logging by Huilliches is an activity that removes a minimum of the ecosystem biomass. It apparently has no negative effects on the regeneration of Fitzroya, which is explained mainly by biotic and some abiotic factors, especially altitude.

Nucleation is a successional process in which extant vegetation facilitates seed dispersal and recruitment of other individuals and species around focal points in the landscape, leading to ecosystem recovery. This is an important process in disturbed sites where regeneration is limited by abiotic conditions or restrictive seed dispersal. We investigated forest recovery in a large burned area of evergreen temperate rainforest in southern Chile subjected to seasonal soil waterlogging, and assessed the relevance of nucleation processes in overcoming biotic and physical barriers for tree species regeneration. We measured richness and abundance of woody species in relation to patch size, as well as abiotic factors such as light and soil moisture within and outside patches. We found higher tree regeneration in existing patches than in open areas. We recorded an increase of patch size over time, associated with the increase in number of individuals and tree species. Soils in open areas were waterlogged, especially in winter, while patches were not. Trees in patches also acted as perches, enhancing bird-mediated seed rain. Seeds of fleshy-fruited tree species arrived first at patches and seedlings were more frequent in smaller, younger patches, while the number of seedlings of trees with wind-dispersed seeds increased in larger, older patches. Our study shows that woody species seem incapable of recruiting in open and waterlogged soils and depend strongly on extant vegetation patches to establish. In this fire-disturbed evergreen temperate forest regeneration occurs via nucleation, where new individuals contribute to a centrifugal kind of patch growth.

Extreme climatic events represent disturbances that change the availability of resources. We studied their effects on annual plant assemblages in a semi-arid ecosystem in north-central Chile. We analysed 130 years of precipitation data using generalised extreme-value distribution to determine extreme events, and multivariate techniques to analyse 20 years of plant cover data of 34 native and 11 exotic species. Extreme drought resets the dynamics of the system and renders it susceptible to invasion. On the other hand, by favouring native annuals, moderately wet events change species composition and allow the community to be resilient to extreme drought. The probability of extreme drought has doubled over the last 50 years. Therefore, investigations on the interaction of climate change and biological invasions are relevant to determine the potential for future effects on the dynamics of semi-arid annual plant communities.

Indexación: Web of Science; Scielo. La Estación Biológica Senda Darwin (EBSD) constituye un centro de investigación inmerso en el paisaje rural del norte de la Isla de Chiloé (42º S), donde fragmentos del bosque siempreverde original coexisten con praderas de uso ganadero, turberas de Sphagnum, matorrales sucesionales, plantaciones de Eucalyptus y otras formaciones de origen antropogénico. Desde 1994 hemos realizado estudios de largo plazo centrados en algunas especies de plantas (e.g., Pilgerodendron uviferum D. Don) y animales (e.g., Aphrastura spinicauda Gmelin, Dromiciops gliroides [Thomas]) catalogados como amenazados o escasamente conocidos y en ecosistemas nativos de importancia regional y global (e.g., turberas de Sphagnum, bosque Valdiviano y Nordpatagónico). Las investigaciones han considerado las respuestas de las especies y de los ecosistemas frente al cambio antropogénico del paisaje y cambio climático, así como los efectos de diferentes formas de manejo. Este escenario es semejante al de otras regiones de Chile y Latinoamérica lo que da generalidad a nuestros resultados y modelos. En este período, investigadores asociados a la EBSD han producido más de un centenar de publicaciones en revistas nacionales e internacionales y 30 tesis de pre y postgrado. Entendiendo el papel clave de los seres humanos en los procesos ecológicos de la zona rural, la EBSD ha desarrollado un programa de educación ecológica y vinculación del avance científico con la sociedad local y nacional. La integración de la EBSD a la naciente red de Sitios de Estudios Socio-Ecológicos de Largo Plazo en Chile consolidará y fortalecerá la investigación básica y aplicada que realizamos para proyectarla hacia la siguiente década. Senda Darwin Biological Station (SDBS) is a field research center immersed in the rural landscape of northern Chiloé island (42º S), where remnant patches of the original evergreen forests coexist with open pastures, secondary successional shrublands, Sphagnum bogs, Eucalyptus plantations and other anthropogenic cover types, constituting an agricultural frontier similar to other regions in Chile and Latin America. Since 1994, we have conducted long-term research on selected species of plants (e.g., Pilgerodendron uviferum) and animals (e.g., Aphrastura spinicauda, Dromiciops glirioides) that are considered threatened, poorly known or important for their ecological functions in local ecosystems, and on ecosystems of regional and global relevance (e.g., Sphagnum bogs, North Patagonian and Valdivian rain forests). Research has assessed the responses of species and ecosystems to anthropogenic land-use change, climate change, and the impact of management. During this period, more than 100 scientific publications in national and international journals, and 30 theses (graduate and undergraduate) have been produced by scientists and students associated with SDBS. Because of our understanding of the key role that humans play in ecological processes at this agricultural frontier, since the establishment of SDBS we have been committed to creative research on the communication of science to society and ecological education. The integration of SDBS to the nascent Chilean network of long-term socio-ecological research will consolidate and strengthen basic and applied research to project our work into the next decade. http://ref.scielo.org/vbm4r5

A structural and compositional definition of old-growth forest is presented, which places emphasis on the lack of recurrent human impact, the presence of a shade-tolerant canopy with emergent pioneers, and a patch area that minimises edge effects. Using this definition, we provide an overview of the current conservation status, relevance of plant–animal interactions, and unique features of nutrient fluxes in old-growth forests of southern South America. Chile hosts the largest area and latitudinal extent of old-growth temperate forest remaining in the southern hemisphere, reaching 56° S in the Cape Horn Archipelago. Despite recent public and private efforts to protect remaining old-growth forests and their endemic biodiversity, they continue to decline steeply as a result of new routes of access to commercial stands, lack of protection of coastal areas, anthropogenic fire, and expansion of monoculture-based forestry toward higher latitudes and altitudes. Pollinators (insects and birds) and vertebrate frugivores (birds and an arboreal marsupial) are important mutualists of many Chilean rain forest trees, vines and epiphytes. There is evidence to suggest that some native pollinators and animal seed vectors may be highly susceptible to changes in forest structure due to loss of old-growth forest cover. Forest fragmentation and loss of keystone, animal-pollinated emergent trees due to logging and fires, have radically changed pollinator assemblages in rural landscapes, leading to reproductive dependence on European honey bees and other exotic species. Regarding other ecosystem functions, nutrient cycles in unpolluted old-growth forests of southern Chile are characterised by strong inorganic nitrogen (N) retention and large organic N leakage to forest streams. Non-symbiotic N fixation in litter and soil tends to increase in older stands. Knowledge of these “unpolluted nutrient cycles”, particularly N and P, is still meager despite its relevance to understanding the consequences of increased global disruption of element cycles by humans. Development of baseline measurements and experiments in southern Chilean old-growth temperate forests can enhance our understanding of unpolluted ecosystem functioning.

Abstract Many authors have proposed that behavioural flexibility in the field is associated with learning ability in captivity, relative forebrain size and rate of structural evolution. In birds, the frequency of feeding innovations reported in the short notes sections of ornithology journals may be a good way to operationalize flexibility. In this paper, we examine in the birds of Australia and New Zealand the relationship between forebrain size and innovation frequency found in a previous study covering North America and the British Isles. From a methodological point of view, the two variables are highly reliable: innovation frequency per taxonomic group is similar when different readers judge innovation reports and when different editorial styles govern journals; relative forebrain size yields very similar estimates whether mean residuals from a log-log regression are used or ratios of forebrain to brainstem mass. Innovation frequency per taxon is correlated between the two Australasian zones and between these zones and the more northerly ones studied previously. Innovation frequency is also associated with relative forebrain size in Australia and, to a lesser extent, in New-Zealand; in Australia, parrots show the high frequency of innovations predicted by their large forebrain, but yield no innovations in the New Zealand sample. The forebrain/innovation trend is independent of juvenile development mode, but phylogeny appears to be an important intervening variable in Australasia, as evidenced by non-significant independent contrasts.