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The composition of plant functional traits varies in response to environmental conditions due to processes of community assembly and species sorting. However, there is a lack of understanding of how plant trait composition responds to environmental conditions at different spatial scales and across the plant life cycle. We investigated the trait composition of leaves (specific leaf area), seeds (seed mass) and seedlings (initial seedling height) across elevations and within elevations in relation to soil and light conditions in a tropical montane forest in southern Ecuador. We surveyed traits and communities of adult trees, seeds and seedlings on nine plots at three elevations (1000–3000 m a.s.l.) and calculated community‐weighted mean trait values to analyse trait variation across and within elevations. In addition, we measured two environmental factors (soil C/N ratio and canopy openness) to quantify local‐scale variation in environmental conditions within elevations. We found that community‐weighted means of specific leaf area, seed mass and initial seedling height decreased consistently with increasing elevation. Within elevations, mean trait values of trees, seeds and seedlings responded differently to local‐scale environmental conditions. Specific leaf area decreased with increasing soil C/N ratio, and initial seedling height decreased with increasing canopy openness. Seed mass was associated neither with soil nor with light conditions. Our findings show that broad‐scale and local‐scale processes differently shape the composition of leaf, seed and seedling traits in tropical forests, indicating a scale‐dependence in trait–environment associations. Furthermore, plant traits corresponding to different life stages were related differently to environmental conditions within elevations. Community assembly processes may therefore lead to differences in species sorting at early and late plant life stages. [ABSTRACT FROM AUTHOR]

Seed dispersal is a key component in a plant's life cycle, allowing the colonization of new habitat and eventually enabling range shifts. For animal‐dispersed plants, the behaviour of seed‐dispersing animals has direct consequences for the fate of a seed. However, there is little empirical evidence on how individual behaviour of animals affects seed dispersal.Here we investigated the effects of individual behaviour on seed dispersal distance and location by analysing movement data of spotted nutcrackers (Nucifraga caryocatactes) during harvest and scatter‐hoarding of Swiss stone pine (Pinus cembra) seeds. To assess individual variation in seed dispersal patterns, we compared daytime hourly displacement patterns across individuals. We further identified seed caching locations of individual birds and analysed their potential for pine regeneration.We found that nutcrackers showed one of two distinct behaviours: short‐distance seed dispersal and long‐distance seed dispersal. The caching locations resulting from the two behaviours differed markedly in the regeneration potential of Swiss stone pine: seeds transported over short distances were cached at high elevations with high regeneration potential within the pine's current habitat, while seeds transported over long distances were cached at low elevations with low regeneration potential outside of the pine's habitat. The behaviours were not associated with bird body mass, relative wing length or sex.Our results emphasize that intraspecific individual behaviours of seed‐dispersing animals can have far‐reaching consequences for ecosystem functions. As a major determinant of seed dispersal dynamics, individual behaviour should be taken into account for a better understanding of ecosystem functions under current and future environmental conditions. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Questions: How do seed rain biomass and richness change from old‐growth tropical forests to pastures at different elevations? How do seed mass and seed dispersal mode change from forests to pastures across these elevations? What implications do these changes have for the recovery of deforested areas in tropical mountains? Location: Old‐growth montane forests and livestock pastures along an elevational gradient (1,000–3,000 m a.s.l.), located at Podocarpus National Park, San Francisco Reserve and surrounding agricultural lands, Andes of southern Ecuador. Methods: We collected seed rain for a 3‐month period using 324 traps installed at eighteen 1‐ha plots across elevations. Half of the traps were installed in nine 1‐ha forest plots, and the other half in nine 1‐ha pasture plots. For each trap, we identified the seeds and measured seed rain biomass and richness. We also recorded seed traits and calculated community‐weighted means of seed mass and seed dispersal mode (proportion of endozoochory). Results: Forests received a higher seed rain biomass than pastures, but only at the lowest elevation. Seed rain richness did not differ between habitat types at all elevations. Community‐weighted means of seed mass and the proportion of endozoochorous species declined from forests to pastures, especially at the lower elevations. Conclusions: Although seed rain biomass and richness were overall similar between forests and pastures, large‐seeded and endozoochorous species were generally poorly represented in the seed rain of pastures compared with that of forests. These findings show that biomass and richness of seed rain may be insufficient to quantify the restoration potential of natural seed rain in deforested areas. Information on seed traits, such as seed mass and seed dispersal mode, is important to optimize restoration efforts towards the regeneration of diverse old‐growth forests along elevational gradients in tropical mountains. [ABSTRACT FROM AUTHOR]

Soil microbial diversity affects ecosystem functioning and global biogeochemical cycles. Soil bacterial communities catalyse a diversity of biogeochemical reactions and have thus sparked considerable scientific interest. One driver of bacterial community dynamics in natural ecosystems has so far been largely neglected: the predator–prey interactions between bacterial viruses (bacteriophages) and bacteria. To generate ground level knowledge on environmental drivers of these particular predator–prey dynamics, we propose an activity‐based ecological framework to simultaneous capture community dynamics of bacteria and bacteriophages in soils. An ecological framework and specifically the analyses of community dynamics across latitudinal and elevational gradients have been widely used in ecology to understand community‐wide responses of innumerable taxa to environmental change, in particular to climate. Here, we tested the hypothesis that the activity of bacteria and bacteriophages codeclines across an elevational gradient. We used metatranscriptomics to investigate bacterial and bacteriophage activity patterns at five sites across 400 elevational metres in the Swiss Alps in 2015 and 2017. We found that metabolic activity (transcription levels) of bacteria declined significantly with increasing elevation, but activity of bacteriophages did not. We showed that bacteriophages are consistently active in soil along the entire gradient, making bacteriophage activity patterns divergent from that of their putative bacterial prey. Future efforts will be necessary to link the environment‐activity relationship to predator–prey dynamics, and to understand the magnitude of viral contributions to carbon, nitrogen and phosphorus cycling when infection causes bacterial cell death, a process that may represent an overlooked component of soil biogeochemical cycles. [ABSTRACT FROM AUTHOR]

These photographs illustrate the article "Trait-based inference of ecological network assembly: a conceptual framework and methodological toolbox" by Emma-Liina Marjakangas, Gabriel Muñoz, Shaun Turney, Jörg Albrecht, Eike Lena Neuschulz, Matthias Schleuning, and Jean-Philippe Lessard published in I Ecological Monographs i . https://doi.org/10.1002/ecm.1502. We propose a conceptual framework using trait-based inference of ecological processes to improve our understanding of network assembly and our ability to predict network reassembly amid global change. Trait-based Inference of Ecological Network Assembly: A Conceptual Framework and Methodological Toolbox. [Extracted from the article]

Aim: Climate change causes shifts in species ranges globally. Terrestrial plant species often lag behind temperature shifts, and it is unclear to what extent animal‐dispersed plants can track climate change. Here, we estimate the ability of bird‐dispersed plant species to track future temperature change on a tropical mountain. Location: Tropical elevational gradient (500–3500 m.a.s.l.) in the Manú biosphere reserve, Peru. Time period: From 1960–1990 to 2061–2080. Taxa: Fleshy‐fruited plants and avian frugivores. Methods: Using simulations based on the functional traits of avian frugivores and fruiting plants, we quantified the number of long‐distance dispersal (LDD) events that woody plant species would require to track projected temperature shifts on a tropical mountain by the year 2070 under different greenhouse gas emission scenarios [representative concentration pathway (RCP) 2.6, 4.5 and 8.5]. We applied this approach to 343 bird‐dispersed woody plant species. Results: Our simulations revealed that bird‐dispersed plants differed in their climate‐tracking ability, with large‐fruited and canopy plants exhibiting a higher climate‐tracking ability. Our simulations also suggested that even under scenarios of strong and intermediate mitigation of greenhouse gas emissions (RCP 2.6 and 4.5), sufficient upslope dispersal would require several LDD events by 2070, which is unlikely for the majority of woody plant species. Furthermore, the ability of plant species to track future changes in temperature increased in simulations with a low degree of trait matching between plants and birds, suggesting that plants in generalized seed‐dispersal systems might be more resilient to climate change. Main conclusion: Our study illustrates how the functional traits of plants and animals can inform predictive models of species dispersal and range shifts under climate change and suggests that the biodiversity of tropical mountain ecosystems is highly vulnerable to future warming. The increasing availability of functional trait data for plants and animals globally will allow parameterization of similar models for many other seed‐dispersal systems. [ABSTRACT FROM AUTHOR]

Aim: Although patterns of biodiversity across the globe are well studied, there is still a controversial debate about the underlying mechanisms and their generality across biogeographic scales. In particular, it is unclear to what extent diversity patterns along environmental gradients are directly driven by abiotic factors, such as climate, or indirectly mediated through biotic factors, such as resource effects on consumers. Location: Andes, Southern Ecuador; Mt. Kilimanjaro, Tanzania. Methods: We studied the diversity of fleshy‐fruited plants and avian frugivores at the taxonomic level, that is, species richness and abundance, as well as at the level of functional traits, that is, functional richness and functional dispersion. We compared two important biodiversity hotspots in mountain systems of the Neotropics and Afrotropics. We used field data of plant and bird communities, including trait measurements of 367 plant and bird species. Using structural equation modeling, we disentangled direct and indirect effects of climate and the diversity of plant communities on the diversity of bird communities. Results: We found significant bottom‐up effects of fruit diversity on frugivore diversity at the taxonomic level. In contrast, climate was more important for patterns of functional diversity, with plant communities being mostly related to precipitation, and bird communities being most strongly related to temperature. Main conclusions: Our results illustrate the general importance of bottom‐up mechanisms for the taxonomic diversity of consumers, suggesting the importance of active resource tracking. Our results also suggest that it might be difficult to identify signals of ecological fitting between functional plant and animal traits across biogeographic regions, since different species groups may respond to different climatic drivers. This decoupling between resource and consumer communities could increase under future climate change if plant and animal communities are consistently related to distinct climatic drivers. [ABSTRACT FROM AUTHOR]

Network approaches provide insight into the complex web of interspecific interactions that structure ecological communities. However, because data on the functional outcomes of ecological networks are very rarely available, the effect of network structure on ecosystem functions, such as seed dispersal, is largely unknown. Here, we develop a new approach that is able to link interaction networks to a trait‐based seed–dispersal model to estimate community‐wide seed dispersal distances. We simulated networks, using a niche model based on size‐matching between plants and birds, that varied in the degree of niche partitioning, i.e. the overlap in interaction partners between coexisting species. We found that community‐wide dispersal distances were longest when networks had low degrees of niche partitioning. We further found that dispersal distances of plant species with small fruits peaked in models without niche partitioning, whereas dispersal distances of medium and large‐fruited plants peaked at low degrees of niche partitioning. Our simulations demonstrate that the degree of niche partitioning between species is an important determinant of the ecological functions derived from ecological networks and that simulation approaches can provide new insights into the relationship between the structural and functional components of ecological networks. [ABSTRACT FROM AUTHOR]

Plant‐fungal interactions are important for plant community assembly, but quantifying these relationships remains challenging. High throughput sequencing of fungal communities allows us to identify plant‐fungal associations at a high level of resolution, but often fails to provide information on taxonomic and functional assignment of fungi.We transplanted seeds of Pinus cembra across an elevational gradient (1850–2250 m a.s.l.) and identified environmental factors and known fungal associates important for seedling establishment and survival. We then applied null model tests to identify taxonomically unassigned fungi associated with pine recruitment.Early seedling establishment was determined by abiotic environmental factors, while seedling survival was predominantly affected by biotic environmental factors (i.e., the abundance of a fungal pathogen known from literature and the distance to adult trees). Null model tests identified known mycorrhizal partners and a large number of unknown operational taxonomic units (OTUs) associated with seedling survival, including saprotrophic and pathogenic species. These results highlight that unknown fungal OTUs, which are usually discarded from analyses, could play a crucial role for plant survival.Synthesis. We conclude that high throughput metabarcoding paired with null model tests, is a valuable approach for identifying hidden plant‐fungal associations within large and complex DNA metabarcoding datasets. Such an approach can be an important tool in illuminating the black box of plant‐microbe interactions, and thus understanding ecosystem dynamics. [ABSTRACT FROM AUTHOR]

Aim: Projecting future distributions of species under climate change remains a particular challenge for species that are trophically interacting. Interaction partners are often assumed to react differently to climate change, causing spatial mismatches in future distributions and increased extinction risks. We compare potential direct effects of climate change with combined direct and indirect effects mediated via food plants on a highly specialized bird species. Location: Europe. Taxon: European spotted nutcracker (Nucifraga caryocatactes). Methods: We used climate‐based species distribution models to project probabilities of occurrence of European spotted nutcrackers and their main food sources, Swiss stone pine (Pinus cembra) and common hazel (Corylus avellana) under climate change. We combined direct climate change effects on the bird and indirect effects via the food plants by calculating the probabilities of plants and nutcrackers occurring together. Results: We find considerable projected northward shifts in future occurrences of nutcrackers under climate change and similar effects on hazel. In contrast, projections for Swiss stone pine indicate minor altitudinal upward shifts. Combined projections of direct and indirect effects of climate change indicate less pronounced shifts of nutcrackers' occurrences, due to relatively small changes in pine's occurrences and to suitable hazel occurrence shifts. Main conclusions: Our study suggests that potential effects of climate change on the future distribution of the nutcracker might be overestimated when ignoring trophically interacting plants in future projections. Models of direct effects of climate change on nutcrackers' occurrence probabilities project greater range losses than models of combined direct and indirect effects via resource plants. Therefore, considering biotic interactions does not necessarily increase the risks that climate change may impose on species distributions, but could reduce overestimation of potential range losses in rapidly changing environments. [ABSTRACT FROM AUTHOR]

Interactions between resource and consumer species are organized in ecological networks. Species interactions in these networks are influenced by the functional traits of the interacting partners, but the generality of trait‐based interaction rules and the relationship between functional traits and a species' specialization on specific interaction partners are not yet understood. Here we combine data on eight interaction networks between fleshy‐fruited plants and frugivorous birds sampled across the tropical and subtropical Andean range. We test which combinations of morphological plant and animal traits determine trait matching between resource and consumer species in these networks. In addition, we test which of the morphological traits influence functional specialization of plant and bird species. In a meta‐analysis across network‐specific fourth‐corner analyses, we found that plant–animal trait pairs related to size matching (fruit size–beak size) and avian foraging behavior (plant height–wing shape and crop mass–body mass) were positively related in these networks. The degree of functional specialization on specific interaction partners was positively related to crop mass in plants and to the pointedness of the wing in birds. Our findings show that morphological trait matching between fleshy‐fruited plants and frugivorous birds is a general phenomenon in plant–frugivore networks across the Andes and that specific plant and bird traits can be used to approximate the degree of functional specialization. These insights into the generality of interaction rules are the base for predictions of species interactions in ecological networks, for instance in novel communities in the future, and can be applied to identify plant and animal species that fulfill specialized functional roles in ecological communities. [ABSTRACT FROM AUTHOR]

Tropical forests harbor diverse ecological communities of plants and animals that are organized in complex interaction networks. The diversity and structure of plant–animal interaction networks may change along elevational gradients and in response to human‐induced habitat fragmentation. While previous studies have analyzed the effects of elevation and forest fragmentation on species interaction networks in isolation, to our knowledge no study has investigated whether the effects of forest fragmentation on species interactions may differ along elevational gradients. In this study, we analyzed main and interaction effects of elevation and forest fragmentation on plant–frugivore interaction networks at plant and bird species level. Over a period spanning two years, we recorded plant–frugivore interactions at three elevations (1000, 2000 and 3000 m a.s.l.) and in two habitat types (continuous and fragmented forest) in tropical montane forests in southern Ecuador. We found a consistent effect of elevation on the structure of plant–frugivore networks. We observed a decrease in the number of effective bird partners of plants and, thus, a decline in the redundancy of bird species with increasing elevation. Furthermore, bird specialization on specific plant partners increased towards high elevations. Fragmentation had a relatively weak effect on the interaction networks for both plant and bird species, but resulted in a significant increase in bird specialization in fragmented forests at high elevations. Our results indicate that forest fragmentation may have stronger effects on plant–frugivore interaction networks at high compared to low elevations because bird species richness declined more steeply towards high elevations than plant species richness. We conclude that conservation efforts should prioritize the maintenance of consumer diversity, for instance by maintaining stretches of continuous forest. This applies in particular to species‐poor communities, such as those at high elevations, as the ecological processes in these communities seem most sensitive towards forest fragmentation. [ABSTRACT FROM AUTHOR]

Understanding the spatial and temporal dynamics of species assemblages is a main challenge in ecology. The mechanisms that shape species assemblages and their temporal fluctuations along tropical elevational gradients are particularly poorly understood. Here, we examined the spatio-temporal dynamics of bird assemblages along an elevational gradient in Ecuador. We conducted bird point counts at three elevations (1000, 2000 and 3000 m) on 18 1-ha plots and repeated the sampling eight times over two years (216 hours in total). For each plot, we obtained data of monthly temperatures and precipitation and recorded the overall resource availability (i.e., the sum of flower, fruit, and invertebrate resources). As expected, bird richness decreased from low to high elevations. Moreover, we found a significant decrease in bird abundance and richness and an increase in evenness between the most and least humid season at each of the three elevations. Climatic factors were more closely related to these temporal fluctuations than local resource availability. While temperature had significant positive effects on the abundance of birds at mid and high elevations, precipitation negatively affected bird abundance at low and mid elevations. Our study highlights that bird assemblages along tropical elevational gradients can show pronounced seasonal fluctuations. In particular, low temperatures and high precipitation seem to impose important constraints on birds. We conclude that potential changes in climate, due to global warming, are likely to affect the spatio-temporal dynamics of bird assemblages along tropical elevational gradients. [ABSTRACT FROM AUTHOR]

The degradation of natural forests to modified forests threatens subtropical and tropical biodiversity worldwide. Yet, species responses to forest modification vary considerably. Furthermore, effects of forest modification can differ, whether with respect to diversity components (taxonomic or phylogenetic) or to local (α-diversity) and regional (β-diversity) spatial scales. This real-world complexity has so far hampered our understanding of subtropical and tropical biodiversity patterns in human-modified forest landscapes. In a subtropical South African forest landscape, we studied the responses of three successive plant life stages (adult trees, saplings, seedlings) and of birds to five different types of forest modification distinguished by the degree of within-forest disturbance and forest loss. Responses of the two taxa differed markedly. Thus, the taxonomic α-diversity of birds was negatively correlated with the diversity of all plant life stages and, contrary to plant diversity, increased with forest disturbance. Conversely, forest disturbance reduced the phylogenetic α-diversity of all plant life stages but not that of birds. Forest loss neither affected taxonomic nor phylogenetic diversity of any taxon. On the regional scale, taxonomic but not phylogenetic β-diversity of both taxa was well predicted by variation in forest disturbance and forest loss. In contrast to adult trees, the phylogenetic diversity of saplings and seedlings showed signs of contemporary environmental filtering. In conclusion, forest modification in this subtropical landscape strongly shaped both local and regional biodiversity but with contrasting outcomes. Phylogenetic diversity of plants may be more threatened than that of mobile species such as birds. The reduced phylogenetic diversity of saplings and seedlings suggests losses in biodiversity that are not visible in adult trees, potentially indicating time-lags and contemporary shifts in forest regeneration. The different responses of taxonomic and phylogenetic diversity to forest modifications imply that biodiversity conservation in this subtropical landscape requires the preservation of natural and modified forests. [ABSTRACT FROM AUTHOR]

Front cover: The cover image of an Emerald toucanet (Aulacorhynchus prasinus) in El Bosque' Reserve, San Pedro de Vilcabamba, Ecuador is based on the Original Article Functional and phylogenetic diversity of bird assemblages are filtered by different biotic factors on tropical mountains by Dagmar M. Hanz et al., DOI: 10.1111/jbi.13489. Photo Credit: Marta Quitián. [ABSTRACT FROM AUTHOR]