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Cushion plants are specialized keystone species of alpine environments that can have a positive effect on ecosystem structure and function. However, we know relatively little about how cushion plants regulate the diversity and composition of soil microbial communities, major drivers of soil processes and ecosystem functioning. Identifying what factors drive the diversity and composition of soil microbial communities in high-elevation ecosystems is also fundamental to predict how global changes will affect their conservation and the services and functions they provide. Thus, we sampled four sites along the southern Andes following the vegetation belt of Azorella cushion species. The field sites spread along a latitudinal gradient and had contrasting levels of aridity, UV-B radiation, mean temperature and soil properties. Overall, Azorella, as well as aridity and UV-B radiation, were the major drivers of the distribution, composition and diversity of soil microbial communities in the studied ecosystems of the Chilean Andes. UV-B radiation affected particularly soil fungi, while soil properties such as pH, total C and N content, essential predictors of microbial diversity globally, had a much lower effect on the composition of soil microbial communities. Understanding the factors driving the structure and composition of microbial communities, particularly the role of cushion plants and the feedbacks between plant, climate and soil is of uttermost importance for the preservation of the functionality of high-elevation ecosystems threatened by climate change.

Phenology of species, the coupling of vital activities to specific times of the year, plays a main role in ecosystem functioning and is expected to be affected by global change. We analysed the temporal structure of 52 amphibian communities in South America encompassing a latitudinal range from 7o to 34o south. Phenological modularity – species tendencies to aggregate along the months – is here introduced as a ubiquitous property of biodiversity architecture. Further, we identified an increase in phenological modularity with species richness, available energy and in communities with lower thermal dependence (i.e. the rate of change in the number of species active along the year associated with the environmental temperature). These patterns are in agreement with predictions derived from several ecological hypotheses: complexity‐stability, species‐energy and metabolic ecology. However, no direct association between modularity and the phylogenetic structure of communities was observed. A structural equation model that outperformed all the plausible alternative models considered supports these results. Modularity is reported here as a main feature of the phenology of communities that depends on environmental conditions. Here, we report for the first time a putative connection between community species richness and the degree of temporal structure – phenological modularity; the thermal dependence shows that communities at low latitudes are more vulnerable to climate change; energetic environments also promote communities with phenological modularity; and latitudinal patterns of phylogenetic community structure can give us clues of which species would be important to the conservation of community processes. These results call for further theoretical analyses to support the connection between phenological modularity, community stability and vulnerability to global change.

Top-down and bottom-up forces determine ecosystem function and dynamics. Fisheries as a top-down force can shorten and destabilize food webs, while effects driven by climate change can alter the bottom-up forces of primary productivity. We assessed the response of a highly-resolved intertidal food web to these two global change drivers, using network analysis and bioenergetic modelling. We quantified the relative importance of artisanal fisheries as another predator species, and evaluated the independent and combined effects of fisheries and changes in plankton productivity on food web dynamics. The food web was robust to the loss of all harvested species but sensitive to the decline in plankton productivity. Interestingly, fisheries dampened the negative impacts of decreasing plankton productivity on non-harvested species by reducing the predation pressure of harvested consumers on non-harvested resources, and reducing the interspecific competition between harvested and non-harvested basal species. In contrast, the decline in plankton productivity increased the sensitivity of harvested species to fishing by reducing the total productivity of the food web. Our results show that strategies for new scenarios caused by climate change are needed to protect marine ecosystems and the wellbeing of local communities dependent on their resources.

Top-down and bottom-up forces determine ecosystem function and dynamics. Fisheries as a top-down force can shorten and destabilize food-webs, while climate-change driven effects can alter the bottom-up forces of primary productivity. We assessed the response of a highly-resolved intertidal food-web to these two global-change drivers, using network analysis and bioenergetic modelling. We quantified the relative importance of artisanal fisheries as another predator species, and evaluated the independent and combined effects of fisheries and plankton-productivity changes on food-web dynamics. The food-web was robust to the loss of all harvested species but sensible to plankton-productivity decline. Interestingly, fisheries dampened the negative impacts of decreasing plankton productivity on non-harvested species, while plankton-productivity decline increased the sensitivity of harvested species to fishing. Our results show that strategies for new scenarios caused by climate change are needed to protect marine ecosystems and the wellbeing of local communities dependent on their resources.

Ecosystems functioning is based on an intricate web of interactions among living entities. Most of these interactions are difficult to observe, especially when the diversity of interacting entities is large and they are of small size and abundance. To sidestep this limitation, it has become common to infer the network structure of ecosystems from time series of species abundance, but it is not clear how well can networks be reconstructed, especially in the presence of stochasticity that propagates through ecological networks. We evaluate the effects of intrinsic noise and network topology on the performance of different methods of inferring network structure from time-series data. Analysis of seven different four-species motifs using a stochastic model demonstrates that star-shaped motifs are differentially detected by these methods while rings are differentially constructed. The ability to reconstruct the network is unaffected by the magnitude of stochasticity in the population dynamics. Instead, interaction between the stochastic and deterministic parts of the system determines the path that the whole system takes to equilibrium and shapes the species covariance. We highlight the effects of long transients on the path to equilibrium and suggest a path forward for developing more ecologically sound statistical techniques.

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.

Phanerozoic marine invertebrate richness fluctuates out of equilibrium due to pulsed adaptive evolution., Fluctuations in biodiversity, large and small, pervade the fossil record, yet we do not understand the processes generating them. Here, we extend theory from nonequilibrium statistical physics to describe the fat-tailed form of fluctuations in Phanerozoic marine invertebrate richness. Using this theory, known as superstatistics, we show that heterogeneous rates of origination and extinction between clades and conserved rates within clades account for this fat-tailed form. We identify orders and families as the taxonomic levels at which clades experience interclade heterogeneity and within-clade homogeneity of rates, indicating that families are subsystems in local statistical equilibrium, while the entire system is not. The separation of timescales between within-clade background rates and the origin of major innovations producing new orders and families allows within-clade dynamics to reach equilibrium, while between-clade dynamics do not. The distribution of different dynamics across clades is consistent with niche conservatism and pulsed exploration of adaptive landscapes.

Science advances through synthesis and integration by identifying common processes and principles from disparate observations and highlighting the unity underlying diversity. This process is exemplified by advancements in astronomy and physics in the 17th century, when Tycho Brahe’s catalog of the positions of stars, moons, planets, and comets provided the empirical foundations for Kepler’s laws of planetary motion and Newton’s law of gravity. Brahe’s natural history of the Universe led to a theory of nature that continues to shape our view of the natural world. Ecology seems poised at a transition like that of 17th century physics: the achievement of a general theory of biodiversity based on first principles. As shown by Zaoli et al. (1) in PNAS, one of the interesting aspects of this theory is that it looks a lot more like physics, particularly statistical mechanics, than classic ecology. What Tycho Brahe did for astronomy in the 17th century, von Humboldt and other great explorers did for natural history and ecology in the 19th century, with the difference that a theory equivalent to Kepler’s or Newton´s has not yet eventuated, and ecologists have remained fascinated with understanding the uniqueness of species, cataloging the varieties of organisms and studying their forms, functions, and interactions in ecological systems. Most may even think that the daunting complexity of ecological systems precludes the identification of general rules and thus the achievement even of an integrated theory, much less a unified one (e.g., ref. 2). The efforts of these early naturalists, however, led to the principle of natural selection and its subsequent mathematical formalization, within the context … [↵][1]1Email: pmarquet{at}bio.puc.cl. [1]: #xref-corresp-1-1

Cancer is a singular cellular state, the emergence of which destabilises the homeostasis reached through the evolution to multicellularity. We present the idea that the onset of the cellular disobedience to the metazoan functional and structural architecture, known as the cancer phenotype, is triggered by changes in the cell's external environment that occur with ageing: what ensues is a breach of the social contract of multicellular life characteristic of metazoans. By integrating old ideas with new evidence, we propose that with ageing the environmental information that maintains a multicellular organisation is eroded, rewiring internal processes of the cell, and resulting in an internal shift towards an ancestral condition resulting in the pseudo-multicellular cancer phenotype. Once that phenotype emerges, a new local social contract is built, different from the homeostatic one, leading to tumour formation and the foundation of a novel local ecosystem.

Larger volumes of sea ice have been thawing in the Central Arctic Ocean (CAO) during the last decades than during the past 800,000 years. Brackish brine (fed by meltwater inside the ice) is an expanding sympagic habitat in summer all over the CAO. We report for the first time the structure of bacterial communities in this brine. They are composed of psychrophilic extremophiles, many of them related to phylotypes known from Arctic and Antarctic regions. Community structure displayed strong habitat segregation between brackish ice brine (IB; salinity 2.4-9.6) and immediate sub-ice seawater (SW; salinity 33.3-34.9), expressed at all taxonomic levels (class to genus), by dominant phylotypes as well as by the rare biosphere, and with specialists dominating IB and generalists SW. The dominant phylotypes in IB were related to Candidatus Aquiluna and Flavobacterium, those in SW to Balneatrix and ZD0405, and those shared between the habitats to Halomonas, Polaribacter and Shewanella. A meta-analysis for the oligotrophic CAO showed a pattern with Flavobacteriia dominating in melt ponds, Flavobacteriia and Gammaproteobacteria in solid ice cores, Flavobacteriia, Gamma- and Betaproteobacteria, and Actinobacteria in brine, and Alphaproteobacteria in SW. Based on our results, we expect that the roles of Actinobacteria and Betaproteobacteria in the CAO will increase with global warming owing to the increased production of meltwater in summer. IB contained three times more phylotypes than SW and may act as an insurance reservoir for bacterial diversity that can act as a recruitment base when environmental conditions change.

Ever since Paget’s seed-and-soil and Ewing’s connectivity hypotheses to explain tumor metastasis (1,2), it has become clear that cancer progression can be envisaged as an ecological phenomenon. This connection has flourished during the past two decades (3–7), giving rise to important insights into the ecology and evolution of cancer progression, with therapeutic implications(8–10). Here, we take a metapopulation view of metastasis (i.e. the migration to and colonization of, habitat patches) and represent it as a bipartite network, distinguishing source patches, or organs that host a primary tumor, and acceptor patches, or organs colonized ultimately from the source through metastasis. Using 20,326, biomedical records obtained from literature, we show that: (i) the network structure of cancer ecosystems is non-random, exhibiting a nested subset pattern as has been found both in the distribution of species across islands and island-like habitats(11–13), and in the distribution of among species interactions across different ecological networks(14–16);(ii) similar to ecological networks, there is a heterogeneous distribution of degree (i.e., number of connections associated with a source or acceptor organ); (iii) there is a significant correlation between metastatic incidence (or the frequency with which tumor cells from a source organ colonize an acceptor one) and arterial blood supply, suggesting that more irrigated organs have a higher probability of developing metastasis or being invaded; (iv) there is a positive correlation between metastatic incidence and acceptor organ degree (or number of different tumor-bearing source organs that generate metastasis in a given acceptor organ), and a negative one between acceptor organ degree and number of stem cell divisions, implying that there are preferred sink organs for metastasis and that this could be related to average acceptor organ cell longevity; (v) there is a negative association between organ cell turnover and source organ degree, implying that organs with rapid cell turnovers tend to generate more metastasis, a process akin to the phenomenon of propagule pressure in ecology(17); and (vi) the cancer ecosystem network exhibits a modular structure in both source and acceptor patches, suggesting that some of them share more connections among themselves than with the rest of the network. We show that both niche-related processes occurring at the organ level as well as spatial connectivity and propagule pressure contribute to metastaticspread and result in a non-random cancer network, which exhibits a truncated power law degree distribution, clustering and a nested subset structure. The similarity between the cancer network and ecological networks highlights the importance of ecological approaches in increasing our understanding of patterns in cancer incidence and dynamics, which may lead to new strategies to control tumor spread within the human ecosystem.

The frequency of genes in interconnected populations and of species in interconnected communities are affected by similar processes, such as birth, death and immigration. The equilibrium distribution of gene frequencies in structured populations is known since the 1930s, under Wright’s metapopulation model known as the island model. The equivalent distribution for the species frequency (i.e. the species proportional abundance distribution (SPAD)), at the metacommunity level, however, is unknown. In this contribution, we develop a stochastic model to analytically account for this distribution (SPAD). We show that the same as for genes SPAD follows a beta distribution, which provides a good description of empirical data and applies across a continuum of scales. This stochastic model, based upon a diffusion approximation, provides an alternative to neutral models for the species abundance distribution (SAD), which focus on number of individuals instead of proportions, and demonstrate that the relative frequency of genes in local populations and of species within communities follow the same probability law. We hope our contribution will help stimulate the mathematical and conceptual integration of theories in genetics and ecology.

Climate change is altering phenology and distributions of many species and further changes are projected. Can species physiologically adapt to climate warming? We analyse thermal tolerances of a large number of terrestrial ectotherm (n = 697), endotherm (n = 227) and plant (n = 1816) species worldwide, and show that tolerance to heat is largely conserved across lineages, while tolerance to cold varies between and within species. This pattern, previously documented for ectotherms, is apparent for this group and for endotherms and plants, challenging the longstanding view that physiological tolerances of species change continuously across climatic gradients. An alternative view is proposed in which the thermal component of climatic niches would overlap across species more than expected. We argue that hard physiological boundaries exist that constrain evolution of tolerances of terrestrial organisms to high temperatures. In contrast, evolution of tolerances to cold should be more frequent. One consequence of conservatism of upper thermal tolerances is that estimated niches for cold-adapted species will tend to underestimate their upper thermal limits, thereby potentially inflating assessments of risk from climate change. In contrast, species whose climatic preferences are close to their upper thermal limits will unlikely evolve physiological tolerances to increased heat, thereby being predictably more affected by warming. © 2013 The Authors., This study is funded through the LINCGlobal CSIC-PUC and the NICHE project (CGL2011-26852) of the Spanish Ministry of Economy and Competitiveness. P.F.Y. is funded through a CSIC-JAE PhD studentship (2010 00735).

Climate change is expected to impact ecosystems directly, such as through shifting climatic controls on species ranges, and indirectly, for example through changes in human land use that may result in habitat loss. Shifting patterns of agricultural production in response to climate change have received little attention as a potential impact pathway for ecosystems. Wine grape production provides a good test case for measuring indirect impacts mediated by changes in agriculture, because viticulture is sensitive to climate and is concentrated in Mediterranean climate regions that are global biodiversity hotspots. Here we demonstrate that, on a global scale, the impacts of climate change on viticultural suitability are substantial, leading to possible conservation conflicts in land use and freshwater ecosystems. Area suitable for viticulture decreases 25% to 73% in major wine producing regions by 2050 in the higher RCP 8.5 concentration pathway and 19% to 62% in the lower RCP 4.5. Climate change may cause establishment of vineyards at higher elevations that will increase impacts on upland ecosystems and may lead to conversion of natural vegetation as production shifts to higher latitudes in areas such as western North America. Attempts to maintain wine grape productivity and quality in the face of warming may be associated with increased water use for irrigation and to cool grapes through misting or sprinkling, creating potential for freshwater conservation impacts. Agricultural adaptation and conservation efforts are needed that anticipate these multiple possible indirect effects.

Humans, like all organisms, are subject to fundamental biophysical laws. Van Valen predicted that, because of zero-sum dynamics, all populations of all species in a given environment flux the same amount of energy on average. Damuth’s ’energetic equivalence rule’ supported Van Valen´s conjecture by showing a tradeoff between few big animals per area with high individual metabolic rates compared to abundant small species with low energy requirements. We use metabolic scaling theory to compare variation in densities and individual energy use in human societies to other land mammals. We show that hunter-gatherers occurred at densities lower than the average for a mammal of our size. Most modern humans, in contrast, concentrate in large cities at densities up to four orders of magnitude greater than hunter-gatherers, yet consume up to two orders of magnitude more energy per capita. Today, cities across the globe flux greater energy than net primary productivity on a per area basis. This is possible by importing enormous amounts of energy and materials required to sustain hyper-dense, modern humans. The metabolic rift with nature created by modern cities fueled largely by fossil energy poses formidable challenges for establishing a sustainable relationship on a rapidly urbanizing, yet finite planet.

This chapter provides a synoptic view of the distribution, conservation and importance of the connectivity of coastal wetlands of central Chile. For this, a methodology was developed to identify coastal wetlands present in central Chile (30 °S and 41 °40’S), through the analysis of 13 multispectral images Landsat ETM + for the spring-summer seasons of 2000 and 2001. Furthermore, we analyzed the degree in which the identified wetlands are contained within the Chilean protected area network, and carried out a connectivity analysis using graph theory. This analysis, despite being preliminary, allow us to draw a number of simple conclusions, of great importance for the management and protection of these ecosystems. On one hand, the latitudinal tendencies in distribution and area of these ecosystems suggest that their average number and extension increase in the north-south direction, and that the degree of protection these sites have is relatively acceptable, but that this would greatly increase if the Priority Sites were included in the analysis. On the other hand, the connectivity analysis suggests that those organisms whose movement distances are below 10–20 km, perceive the landscape as highly fragmented and slightly heterogeneous. Finally, the analysis of the contribution of different coastal wetlands to the connectivity of the system allows us to highlight that, in general, most of the wetlands are important for maintaining connectivity of species with movement capacity below the critical limit of 10–20 km.

Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Here we review evidence that the global ecosystem as a whole can react in the same way and is approaching a planetary-scale critical transition as a result of human influence. The plausibility of a planetary-scale ‘tipping point’ highlights the need to improve biological forecasting by detecting early warning signs of critical transitions on global as well as local scales, and by detecting feedbacks that promote such transitions. It is also necessary to address root causes of how humans are forcing biological changes.

1. The area or size of an ecosystem affects the acquisition, storage and redistribution of energy and matter. Patch size reduction due to natural or anthropogenic habitat loss will not only modify species distribution and patch structure but also affect the ecosystem processes that are, in part, responsible for patch persistence. 2. In a fog-dependent forest ecosystem, trees and their architectures play essential roles in capturing and redistributing water from collection surfaces. In this paper, we address the question of how forest patch size and structure interact to determine fog water inputs and storage in a fog-inundated, coastal ecosystem in semi-arid Chile (30°S). 3. Six forest patches ranging in area from 0·2 to 36 ha on a coastal mountaintop of Fray Jorge National Park were characterized using 0·1 ha plots laid down at the centre of each forest patch. In each patch, we assessed tree basal area as a measure of forest structure, recorded daily air temperature and humidity, measured water influx from stemflow and throughfall (water that has passed through the forest canopy). Soil and litter gravimetric water contents were used as a measure of storage. 4. Total tree basal area per hectare was positively related to patch area, despite some variation at the species level. Mean and maximum air temperatures inside the patches were inversely related to patch size, with maximum temperatures differing by 2 °C on average. Annual fog water capture by trees within forest patches (net throughfall) was estimated in 296·1 mm after rain flux (about 122 mm) was subtracted. Throughfall volume and patch area were uncorrelated, but stemflow volume, soil and litter water contents scaled positively with patch area, showing a functional link between water interception and ecosystem retention. 5. Our study shows that ecosystem area in this mosaic of fog-dependent temperate forest patches can modify water fluxes and storage capacity of the ecosystem. This finding has important consequences for fragmented landscapes, where large continuous forests are fragmented into smaller patches, affecting not only the persistence of species but also the continuity of critical ecosystem processes.

Physical ecosystem engineering is the process by which some species change the distribution of materials and energy in ecosystems. Although several studies have shown that this process is a driver of local species diversity, the current challenge is predicting when and where ecosystem engineering will have large or small impacts on communities, while also explaining why impacts vary in magnitude across engineer species and environments. This study addresses this issue and proposes a series of predictions for these effects at the three spatial scales (the patch, the habitat and the landscape) along environmental gradients of physical stress. The integrative prediction of this study was that the difference in species diversity between engineered and unmodified situations (patches, habitats or landscapes) will increase as the difference in physical stress between engineered and unmodified patches becomes larger. To test the prediction, the effects of two well known high-Andean ecosystem engineers, the cushion plants Azorella madreporica and Laretia acaulis, were assessed on plant species richness in central Chile. The results support the main prediction, showing that ecosystem engineers have negative effects on species diversity at sites when the environmental modifications they perform increase physical stress for other species, while they have positive effects at sites where these habitat changes mitigate physical stress. Then, the effects of the ecosystem engineers on species diversity seem to depend on the environmental context, where larger environmental modifications are reflected in greater impacts, either positive or negative, on species diversity.

Summary 1 Ecosystem engineers are organisms that change abiotic conditions in ways that affect the performance and distribution of other species, including exotics. Several mechanisms have been proposed for the successful establishment of exotic plants in natural communities, but the positive effects that native engineer species may have on the distribution and performance of exotic plants remain unknown. 2 In this study, we propose that amelioration of extreme abiotic conditions by ecosystem engineers can make stressful habitats invadable by exotic plant species, with larger positive effects on the performance of exotic plants as environmental harshness increases. We tested this hypothesis by assessing the effects of a high-Andean ecosystem engineer, the cushion plant Azorella monantha , which is known to create habitat patches where environmental conditions are less extreme than in the surrounding habitats, on the distribution and the performance of two exotic plant species, field chickweed ( Cerastium arvense ) and common dandelion ( Taraxacum officinale ), along a an elevation gradient in the Andes of central Chile. 3 We measured and compared the abundance, biomass and survival of both exotic species within and outside cushion habitat patches at three elevations (3200 m, 3400 m and 3600 m), and evaluated whether the effects of A. monantha varied across elevations. 4 The results indicated that cushion plants positively impact the performance of both exotics, and have greater facilitative effects at higher elevations. Indeed, at the higher elevation site, C. arvense was only detected within A. monantha patches, suggesting that cushions may expand the distribution range of exotics. These results suggest that ecosystem engineering by native species could promote biological invasions in harsh environments, leading to higher abundances of invaders than those expected in the absence of engineers. 5 Given the conspicuousness of ecosystem engineering in nature, we suggest that exotic species eradication programmes might be less successful by not taking into account the facilitative effects of native engineer species on invaders. Further, we suggest that the recent proposals to use engineer species in ecosystem restoration should be aware of their potential role in promoting invasions.

The landscape (matrix) surrounding habitat fragments critically affects the biodiversity of those fragments due to biotic interchange and physical effects. However, to date, there have been only a limited number of studies on plant-animal interactions in fragmented landscapes, particularly on how tree seedling herbivory is affected by fragmentation. We have examined this question in a fog-dependent mosaic of rainforest fragments located on coastal mountaintops of semiarid Chile (30 degrees S), where the effects of the surrounding semiarid matrix and forest patch size (0.1-22 ha) on tree seedling survival were simultaneously addressed. The rainforest is strongly dominated by the endemic evergreen tree species Aextoxicon punctatum (Olivillo, approx. 80% of basal area). To assess the magnitudes and causes of Olivillo seedling mortality, we set up a field experiment where 512 tree seedlings of known age were transplanted into four forest fragments of different sizes in four 1.5 x 3-m plots per patch; one-half of each plot was fenced off with chicken wire to exclude small mammals. The plots were monitored for 22 months. Overall, 50% of the plants died during the experiment. The exclusion of small mammals from the plots increased seedling survival by 25%, with the effect being greater in smaller patches where matrix-dwelling herbivores are more abundant. This experiment highlights the important role of the surrounding matrix in affecting the persistence of trees in forest fragments. Because herbivores from the matrix cause greater tree seedling mortality in small patches, their effects must be taken into account in forest conservation-restoration plans.

The effects of energy on food web structure have been debated for at least 80 years. Nevertheless, the empirical evidence is meager, especially from terrestrial ecosystems. We analyzed long-term temporal variation in food chain length in a semiarid continental ecosystem, where productivity shows large interannual variations. Incidence of nonherbivorous prey in predator diet was used as a proxy of trophic position, allowing us to analyze the effect of productivity on food chain length within the assemblage of top predators (which comprises the most abundant and persistent top predators in the system) and to compare observed patterns at the species and assemblage levels. At the species level, the relationship between trophic position and productivity took different forms, varying in magnitude and shape. This pattern contrasts with the consistent increase in food chain length, with productivity observed at the assemblage level. Our results indicate that productivity can be a main determinant of food chain length, but not necessarily because of energy limitation. Further, the increase in food chain length with available energy probably represents an aggregate attribute, driven to a large extent by predators with higher consumption rates, rather than being the result of compensatory responses among predators.

Simple patch-occupancy models of competitive metacommunities have shown that coexistence is possible as long as there is a competition-colonization tradeoff such as that of superior competitors and dispersers. In this paper, we present a model of competition between three species in a dynamic landscape, where patches are being created and destroyed at a different rate. In our model, species interact according to a linear non-transitive hierarchy, such that species Y(3) outcompetes and can invade patches occupied by species Y(2) and this species in turn can outcompete and invade patches occupied by the inferior competitor Y(1). In this hierarchy, inferior competitors cannot invade patches of species with higher competitive ability. Analytical results show that there are regions in the parameter space where coexistence can occur, as well as regions where each of the species exists in isolation depending on species' life-history traits associated with their colonization abilities and extinction proneness as well as with the dynamics of habitat patches. In our model, the condition for coexistence depends explicitly on patch dynamics, which in turn modulate the limiting similarity for species coexistence. Coexistence in metacommunities inhabiting dynamic landscapes although possible is harder to attain than in static ones.

Tree presence in semiarid ecosystems is generally constrained by insufficient annual rainfall. However, in semiarid Chile, rainforest patches dominated by Aextoxicon punctatum are unexpectedly found on coastal mountaintops (450–600 m) at 30°S, surrounded by a xerophytic vegetation matrix that receives only 147 mm of annual precipitation. It has been proposed that these forests persist as a result of fog-water inputs. If so, then because fog-water deposition is spatially heterogeneous and shows strong edge effects, the potential environmental gradient created by the direction of fog input should determine forest structure and tree regeneration patterns. To investigate this hypothesis, we measured fog inputs, forest structural attributes (age and size distribution, basal area, and coarse woody debris), and tree regeneration in three different habitats: the windward edges (WE), leeward edges (LE), and the interior (center) of rainforest patches varying in area from 0.2 to 22 ha. Mean fog-water input was estimated from passive collectors over 1 year in WE and LE of patches. Tree regeneration was greater in the WE and forest interior (FI) and decreased toward the LE of patches, following a marked pattern of decline in fog inputs. Older trees and coarse woody debris were concentrated in the FI and LE of patches. Tree regeneration and patch structure appear to be largely controlled by fog-input direction and edge effects. We propose that forest patches may be slowly growing toward the incoming fog edge, while dying at the opposite edge.

Facilitation is a major force shaping the structure and diversity of plant communities in terrestrial ecosystems. Detecting positive plant–plant interactions relies on the combination of field experimentation and the demonstration of spatial association between neighboring plants. This has often restricted the study of facilitation to particular sites, limiting the development of systematic assessments of facilitation over regional and global scales. Here we explore whether the frequency of plant spatial associations detected from high-resolution remotely sensed images can be used to infer plant facilitation at the community level in drylands around the globe. We correlated the information from remotely sensed images freely available through Google Earth with detailed field assessments, and used a simple individual-based model to generate patch-size distributions using different assumptions about the type and strength of plant–plant interactions. Most of the patterns found from the remotely sensed images were more right skewed than the patterns from the null model simulating a random distribution. This suggests that the plants in the studied drylands show stronger spatial clustering than expected by chance. We found that positive plant co-occurrence, as measured in the field, was significantly related to the skewness of vegetation patch-size distribution measured using Google Earth images. Our findings suggest that the relative frequency of facilitation may be inferred from spatial pattern signals measured from remotely sensed images, since facilitation often determines positive co-occurrence among neighboring plants. They pave the road for a systematic global assessment of the role of facilitation in terrestrial ecosystems. Read More: http://www.esajournals.org/doi/10.1890/14-2358.1

Viticulture will not cease in major wine-growing regions in response to climate change, because vineyard managers will not let that happen. Adaptation measures will be taken to permit continued cultivation of wine grapes. These adaptation measures can place major stress on water resources and freshwater ecosystems (1).

Metabolism sustains life and controls the growth, reproduction, and longevity of living entities. As Brown et al. (2003, 2004) show, the ‘‘fire of life’’ is central to our understanding of patterns and dynamics at all levels of biological organization. However simple, it took 70 years to substantiate this statement; from Kleiber’s (1932) conclusion that the mass of the organism raised to the 3⁄4 power was the best predictor of metabolism to the model of West et al. (1997, 1999) that explains this relationship as a consequence of fundamental attributes of biological networks. This work paved the way to the Metabolic Theory of Ecology (MTE) outlined by Brown et al. (2004). We think that the theory outlined by Brown and co-workers represents a breakthrough that endows ecological sciences with a fresh perspective and a quantitative theory to tackle ecological complexity, from individuals to ecosystems. However, as with any new theory in science, it can be improved and refined.

The majority of research on biodiversity–ecosystem functioning in laboratories has concentrated on a few traits, but there is increasing evidence from the field that functional diversity controls ecosystem functioning more often than does species number. Given the importance of traits as predictors of niche complementarity and community structures, we (1) examine how the diversity sensu lato of forest trees, freshwater fishes and soil invertebrates might support ecosystem functioning and (2) discuss the relevance of productive biota for monophyletic assemblages (taxocenes). In terrestrial ecosystems, correlating traits to abiotic factors is complicated by the appropriate choice of body-size distributions. Angiosperm and gymnosperm trees, for example, show metabolic incongruences in their respiration rates despite their pronounced macroecological scaling. Scaling heterotrophic organisms within their monophyletic assemblages seems more difficult than scaling autotrophs: in contrast to the generally observed decline of mass-specific metabolic rates with body mass within metazoans, soil organisms such as protozoans show opposite mass-specific trends. At the community level, the resource demand of metazoans shapes multitrophic interactions. Hence, population densities and their food web relationships reflect functional diversity, but the influence of biodiversity on stability and ecosystem functioning remains less clear. We focused on fishes in 18 riverine food webs, where the ratio of primary versus secondary extinctions (hereafter, ‘extinction partitioning’) summarizes the responses of fish communities to primary species loss (deletions) and its consequences. Based on extinction partitioning, our high-diversity food webs were just as (or even more) vulnerable to extinctions as low-diversity food webs. Our analysis allows us to assess consequences of the relocation or removal of fish species and to help with decision-making in sustainable river management. The study highlights that the topology of food webs (and not simply taxonomic diversity) plays a greater role in stabilizing the food web and enhancing ecological services than is currently acknowledged.

Carbon, nitrogen, and phosphorus (C, N, P) stoichiometry influences the growth of plants and nutrient cycling within ecosystems. Indeed, elemental ratios are used as an index for functional differences between plants and their responses to natural or anthropogenic variations in nutrient supply. We investigated the variation in growth and elemental content of the rootless terrestrial bromeliad Tillandsia landbeckii, which obtains its moisture, and likely its nutrients, from coastal fogs in the Atacama Desert. We assessed (1) how fog nutrient supply influences plant growth and stoichiometry and (2) the response of plant growth and stoichiometry to variations in nutrient supply by using reciprocal transplants. We hypothesized that T. landbeckii should exhibit physiological and biochemical plastic responses commensurate with nutrient supply from atmospheric deposition. In the case of the Atacama Desert, nutrient supply from fog is variable over space and time, which suggests a relatively high variation in the growth and elemental content of atmospheric bromeliads. We found that the nutrient content of T. landbeckii showed high spatio-temporal variability, driven partially by fog nutrient deposition but also by plant growth rates. Reciprocal transplant experiments showed that transplanted individuals converged to similar nutrient content, growth rates, and leaf production of resident plants at each site, reflecting local nutrient availability. Although plant nutrient content did not exactly match the relative supply of N and P, our results suggest that atmospheric nutrient supply is a dominant driver of plant growth and stoichiometry. In fact, our results indicate that N uptake by T. landbeckii plants depends more on N supplied by fog, whereas P uptake is mainly regulated by within-plant nutrient demand for growth. Overall, these findings indicate that variation in fog nutrient supply exerts a strong control over growth and nutrient dynamics of atmospheric plants, which are ubiquitous across fog-dominated ecosystems.

Vegetation pattern formation is a striking characteristic of several water-limited ecosystems around the world. Typically, they have been described on runoff-based ecosystems emphasizing local interactions between water, biomass interception, growth and dispersal. Here, we show that this situation is by no means general, as banded patterns in vegetation can emerge in areas without rainfall and in plants without functional root (the Bromeliad Tillandsia landbeckii) and where fog is the principal source of moisture. We show that a simple model based on the advection of fog-water by wind and its interception by the vegetation can reproduce banded patterns which agree with empirical patterns observed in the Coastal Atacama Desert. Our model predicts how the parameters may affect the conditions to form the banded pattern, showing a transition from a uniform vegetated state, at high water input or terrain slope to a desert state throughout intermediate banded states. Moreover, the model predicts that the pattern wavelength is a decreasing non-linear function of fog-water input and slope, and an increasing function of plant loss and fog-water flow speed. Finally, we show that the vegetation density is increased by the formation of the regular pattern compared to the density expected by the spatially homogeneous model emphasizing the importance of self-organization in arid ecosystems.

Biogenic habitat creation refers to the ability of some organisms to create, maintain or destroy habitats. These habitat changes affect species diversity of natural communities, but it remains to be elucidated if this process also affects the link between ecosystem functions and species diversity. Based on the widely accepted positive relationships between ecosystem functions and species diversity, we hypothesize that these relationships should be different in biogenically created habitat patches as compared to unmodified habitat patches. We tested this hypothesis by assessing the effects of a high-Andean cushion plant, Azorella madreporica, which creates habitat patches with different environmental conditions than in the surrounding open areas with reduced vegetation cover. We used observational and experimental approaches to compare the plant biomass–species richness relationships between habitat patches created by A. madreporica cushions and the surrounding habitat without cushion plants. The observational assessment of these relationships was conducted by counting and collecting plant species within and outside cushion patches. In the experiment, species richness was manipulated within and outside cushion patches. The cushion plant itself was not included in these approaches because we were interested in measuring its effects. Results of both approaches indicated that, for a given level of species richness, plant biomass within cushions was higher than in the surrounding open areas. Furthermore, both approaches indicated that the shape of plant biomass–species richness curves differed between these habitat types. These findings suggest that habitat modifications performed by A. madreporica cushions would be positively affecting the relationships between ecosystem functions and species diversity.

The carnivore community of the altiplano ecosystem of the high Andes, including the Andean mountain cat (Leopardus jacobita) and pampas cat (Leopardus colocolo), is one of the least studied in the world. We determined the origin of 186 carnivore samples (184 faeces and two skulls) collected above 3000 m above sea level in northern Chile, including 33 from the Andean mountain cat and 75 from the pampas cat using diagnostic molecular genetic sequence variation. We determined for the first time food habits, habitat and physiographic associations, and general patterns of molecular genetic variation of the Andean mountain cat and the pampas cat in Chile. Both species had narrow dietary niches dominated by small rodents and there was a wide overlap in diet composition (0.82), suggesting low levels of prey partitioning between species. The mountain viscacha (Lagidium viscacia) made up a large proportion of the biomass of the diet of both species, especially for the Andean mountain cat (93.9% vs. 74.8% for the pampas cat), underscoring the importance of further research and conservation focus on this vanishing prey species. Although the probability of finding Andean mountain cat scats increased with altitude and slope, there was substantial geographical overlap in distribution between species, revealing that the pampas cat distribution includes high-altitude grassland habitats. The Andean mountain cat had relatively low levels of mitochondrial DNA (mtDNA) genetic variation (two mtDNA haplotypes) compared with the pampas cat (17 mtDNA haplotypes), suggestive of a distinct evolutionary history and relatively smaller historic populations. These insights will facilitate and provide tools and hypotheses for much-needed research and conservation efforts on these species and this ecosystem.

Ecosystem engineers are organisms that change the distribution of materials and energy in the abiotic environment, usually creating and maintaining new habitat patches in the landscape. Such changes in habitat conditions have been widely documented to affect the distributions and performances of other species but up to now no studies have addressed how such effects can impact the biotically driven physicochemical processes associated with these landscapes, or ecosystem functions. Based on the widely accepted positive relationship between species diversity and ecosystem functions, we propose that the effects of ecosystem engineers on other species could have an impact on ecosystem functions via two mutually inclusive mechanisms: (1) by adding new species into landscapes, hence increasing species diversity; and (2) by improving the performances of species already present in the landscape. To test these hypotheses, we focused on the effects of a high-Andean ecosystem engineer, the cushion plant Azorella monantha, by comparing the accumulation of plant biomass and nitrogen fixed in plant tissues as species richness increases in landscapes with and without the engineer species. Our results show that both ecosystem functions increased with species richness in both landscape types, but landscapes including A. monantha cushions reached higher outcomes of plant biomass and nitrogen fixed in plant tissues than landscapes without cushions. Moreover, our results indicate that such positive effects on ecosystem functions could be mediated by the two mechanisms proposed above. Then, given the conspicuousness of ecosystem engineering in nature and its strong influence on species diversity, and given the well-known relationship between species diversity and ecosystem function, we suggest that the application of the conceptual framework proposed herein to other ecosystems would help to advance our understanding of the forces driving ecosystem functioning.

Spatial fingerprints of climate change on biotic communities are usually associated with changes in the distribution of species at their latitudinal or altitudinal extremes. By comparing the altitudinal distribution of 171 forest plant species between 1905 and 1985 and 1986 and 2005 along the entire elevation range (0 to 2600 meters above sea level) in west Europe, we show that climate warming has resulted in a significant upward shift in species optimum elevation averaging 29 meters per decade. The shift is larger for species restricted to mountain habitats and for grassy species, which are characterized by faster population turnover. Our study shows that climate change affects the spatial core of the distributional range of plant species, in addition to their distributional margins, as previously reported.

A method is presented to estimate the minimum viable metapopulation size based on the basic reproductive number R 0 and the expected time to extinction τ E for epidemiological models. We exemplify our approach with two simple deterministic metapopulation models of the patch occupancy type and then proceed to stochastic versions that permit the estimation of the minimum viable metapopulation size.

Conservation priority-setting schemes have not yet combined geographic priorities with a framework that can guide the allocation of funds among alternate conservation actions that address specific threats. We develop such a framework, and apply it to 17 of the world's 39 Mediterranean ecoregions. This framework offers an improvement over approaches that only focus on land purchase or species richness and do not account for threats. We discover that one could protect many more plant and vertebrate species by investing in a sequence of conservation actions targeted towards specific threats, such as invasive species control, land acquisition, and off-reserve management, than by relying solely on acquiring land for protected areas. Applying this new framework will ensure investment in actions that provide the most cost-effective outcomes for biodiversity conservation. This will help to minimise the misallocation of scarce conservation resources., Author Summary Given limited funds for biodiversity conservation, we need to carefully prioritise where funds are spent. Various schemes have been developed to set priorities for conservation spending among different countries and regions. However, there is no framework for guiding the allocation of funds among alternative conservation actions that address specific threats. Here, we develop such a framework, and apply it to 17 of the world's 39 Mediterranean-climate ecoregions. We discover that one could protect many more plant and vertebrate species by investing in a sequence of conservation actions targeted towards specific threats, such as invasive species control and fire management, rather than by relying solely on acquiring land for protected areas. Applying this new framework will ensure investment in actions that provide the most cost-effective outcomes for biodiversity conservation., A new framework applied to 17 of the world's Mediterranean ecoregions reveals that investing in a sequence of conservation actions targeted towards specific threats will protect more species than just acquiring land for protected areas.

SUMMARYScaling relationships (where body size features as the independent variable) and power-law distributions are commonly reported in ecological systems. In this review we analyze scaling relationships related to energy acquisition and transformation and power-laws related to fluctuations in numbers. Our aim is to show how individual level attributes can help to explain and predict patterns at the level of populations that can propagate at upper levels of organization. We review similar relationships also appearing in the analysis of aquatic ecosystems (i.e. the biomass spectra) in the context of ecological invariant relationships (i.e. independent of size) such as the `energetic equivalence rule' and the `linear biomass hypothesis'. We also discuss some power-law distributions emerging in the analysis of numbers and fluctuations in ecological attributes as they point to regularities that are yet to be integrated with traditional scaling relationships and which we foresee as an exciting area of future research.