Monitoring fungi in ecological restorations of coastal Indiana,U.S.A.

Monitoring of ecological restorations has rarely focused on fungi. In this study, we conduct a first‐ever monitoring of macrofungi in ecological restorations of coastal Indiana (U.S.A.) and present an approach and considerations that can be followed elsewhere. Forty‐two sites were surveyed over a 2‐year period for the presence of saprotrophic, mycorrhizal, and parasitic macrofungi. Sites included those considered to be restoration, prerestoration, or reference and were in wooded, semiwooded, or grassland habitats. With 1,103 observations, 277 species of fungi were identified. Most fungi were found in wooded habitats though some were in grassland restorations. Invasive plant cover negatively impacted fungal species richness. Monitored sites were compared to a set of reference sites using two different similarity indices (overlap and Jaccard), as well as the ratios of different fungal functional guilds, revealing that choice of index can impact how restorations are perceived to match targets. Last, we present a novel, tractable, and conservative way to assess and rank sites by the functional trait guilds of fungi. We show that such an approach can provide important additional information about the success of restorations such that functional guild ratios could be used as an indicator of restoration progress early‐on while functional values are better used in later phases.     

Not all non‐natives are equally unequal: reductions in herbivore β‐diversity depend on phylogenetic similarity to native plant community

Effects of host plant α‐ and β‐diversity often confound studies of herbivore β‐diversity, hindering our ability to predict the full impact of non‐native plants on herbivores. Here, while controlling host plant diversity, we examined variation in herbivore communities between native and non‐native plants, focusing on how plant relatedness and spatial scale alter the result. We found lower absolute magnitudes of β‐diversity among tree species and among sites on non‐natives in all comparisons. However, lower relative β‐diversity only occurred for immature herbivores on phylogenetically distinct non‐natives vs. natives. Locally in that comparison, non‐native gardens had lower host specificity; while among sites, the herbivores supported were a redundant subset of species on natives. Therefore, when phylogenetically distinct non‐natives replace native plants, the community of immature herbivores is likely to be homogenised across landscapes. Differences in communities on closely related non‐natives were subtler, but displayed community shifts and increased generalisation on non‐natives within certain feeding guilds.     

Assembly processes of trophic guilds in the root mycobiome of temperate forests

Root‐associated mycobiomes (RAMs) link plant and soil ecological processes, thereby supporting ecosystem functions. Understanding the forces that govern the assembly of RAMs is key to sustainable ecosystem management. Here, we dissected RAMs according to functional guilds and combined phylogenetic and multivariate analyses to distinguish and quantify the forces driving RAM assembly processes. Across large biogeographic scales (>1,000 km) in temperate forests (>100 plots), RAMs were taxonomically highly distinct but composed of a stable trophic structure encompassing symbiotrophic, ectomycorrhizal (55%), saprotrophic (7%), endotrophic (3%) and pathotrophic fungi (<1%). Taxonomic community composition of RAMs is explained by abiotic factors, forest management intensity, dominant tree family (Fagaceae, Pinaceae) and root resource traits. Local RAM assemblies are phylogenetically clustered, indicating stronger habitat filtering on roots in dry, acid soils and in conifer stands than in other forest types. The local assembly of ectomycorrhizal communities is driven by forest management intensity. At larger scales, root resource traits and soil pH shift the assembly process of ectomycorrhizal fungi from deterministic to neutral. Neutral or weak deterministic assembly processes are prevalent in saprotrophic and endophytic guilds. The remarkable consistency of the trophic composition of the RAMs suggests that temperate forests attract fungal assemblages that afford functional resilience under the current range of climatic and edaphic conditions. At local scales, the filtering processes that structure symbiotrophic assemblies can be influenced by forest management and tree selection, but at larger scales, environmental cues and host resource traits are the most prevalent forces.     

Defining species guilds in the Central Hardwood Forest,USA

Tree regeneration outcomes are challenging to generalize and difficult to predict. Many tree species can establish new propagules in a variety of post-disturbance environments and many different reproductive mechanisms may be used. In order to develop conceptual models that accurately reflect reproductive potential, we need a better understanding of the similarities in regeneration ecology among species. We used information from the forest ecology literature to evaluate the reproductive attributes of sixty-two tree species in the central hardwood region of the eastern United States. Each species was classified categorically for features such as flowering, seed production and dispersal, seed dormancy, germination requirements, seedling characteristics, and vegetative reproduction. Cluster analysis (Jaccard's similarity coefficient, complete linkage method) and ordination (homogeneity analysis) were used to separate nine groups (guilds) of species that had similar reproductive attributes. Individual attributes that had high variance in the first and second dimensions included: seed banking, seed dispersal, seedling shade tolerance, and seedbed requirements. Members of each guild had similar levels of reproductive specialization and guilds were either pioneer-like, opportunistic, or persistent. Pioneer guilds included: short-lived or fugitive species that colonize sites rapidly and are too shade intolerant to replace themselves; shade-tolerant species that colonize frequently disturbed sites; and stress-tolerant pioneers that survive on dry or nutrient-poor sites. Opportunistic guilds contained species that are remarkably versatile in their reproductive effort. The most flexible opportunists can colonize new sites, maintain seed in a seed bank, sprout from existing stems and persist as a seedling or sapling bank. Persistent guilds contain species that develop and maintain advance regeneration. These include: species with moderate understory tolerance that regenerate via cycles of dieback and resprouting; and more tolerant species that maintain seedling or sapling banks. Our regeneration guilds may provide a useful approach for more realistically representing large and diverse sets of tree species in forest ecosystem models.     

Bird dietary guild richness across latitudes,environments and biogeographic regions

Aim To integrate dietary knowledge and species distributions in order to examine the latitudinal, environmental, and biogeographical variation in the species richness of avian dietary guilds (herbivores, granivores, frugivores, nectarivores, aerial insectivores, terrestrial/arboreal insectivores, carnivores, scavengers, and omnivores). Location Global. Methods We used global breeding range maps and a comprehensive dietary database of all terrestrial bird species to calculate guild species richness for grid cells at 110 × 110 km resolution. We assessed congruence of guild species richness, quantified the steepness of latitudinal gradients and examined the covariation between species richness and climate, topography, habitat diversity and biogeographic history. We evaluated the potential of current environment and biogeographic history to explain global guild distribution and compare observed richness–environment relationships with those derived from random subsets of the global species pool. Results While most guilds (except herbivores and scavengers) showed strong congruence with overall bird richness, covariation in richness between guilds varied markedly. Guilds exhibited different peaks in species richness in geographical and multivariate environmental space, and observed richness–environment relationships mostly differed from random expectations. Latitudinal gradients in species richness were steepest for terrestrial/arboreal insectivores, intermediate for frugivores, granivores and carnivores, and shallower for all other guilds. Actual evapotranspiration emerged as the strongest climatic predictor for frugivores and insectivores, seasonality for nectarivores, and temperature for herbivores and scavengers (with opposite direction of temperature effect). Differences in species richness between biogeographic regions were strongest for frugivores and nectarivores and were evident for nectarivores, omnivores and scavengers when present‐day environment was statistically controlled for. Guild richness–environment relationships also varied between regions. Main conclusions Global associations of bird species richness with environmental and biogeographic variables show pronounced differences between guilds. Geographic patterns of bird diversity might thus result from several processes including evolutionary innovations in dietary preferences and environmental constraints on the distribution and diversification of food resources.     

Effects of woody plant species richness on mammal species richness in southern Africa

Aim To determine the relationship between the species richness of woody plants and that of mammals after accounting for the effect of environmental variables. Location Southern Africa, including Namibia, South Africa, Lesotho, Swaziland, Botswana, Zimbabwe, and part of Mozambique. Methods We used a comprehensive dataset including the species richness of mammals and of woody plants and environmental variables for 118 quadrats (each of 25,000 km²) across southern Africa, and used structural equation models (SEMs) and spatial regressions to examine the relationship between the species richness of woody plants and of mammal trophic guilds (herbivores, insectivores, carni/omnivores) and habitat guilds (aquatic/fossorial, ground‐living, climbers, aerial), after controlling for environment. We compared the results of SEMs with those of single‐predictor regressions (without controlling for environment) and of spatial regressions (controlling for both environment and residual spatial autocorrelation). Results The geographical variation of mammal species richness in southern Africa was strongly and positively related to that of woody plant species richness, and this relationship held for most mammal guilds even when the influence of environment and spatial autocorrelation had been accounted for. However, the effect of woody plant species richness on the richness of aquatic/fossorial species almost disappeared after controlling for environment, suggesting that the congruence in species richness patterns between these two groups results from similar responses to the same environmental variables. For many mammal guilds, the relative role of environmental predictors as measured by standardized partial regression coefficients changed depending on whether non‐spatial single‐predictor regressions, non‐spatial SEMs, or spatial regressions were used. Main conclusions Woody plants are important determinants of the species richness of most mammal guilds in southern Africa, even when controlling for environment and residual spatial autocorrelation. Environmental correlates with animal species richness as measured by simple correlations or single‐predictor regressions might not always reflect direct effects; they might, at least to some degree, result from indirect effects via woody plants. Interpretations of the strength of the effect of environmental variables on mammal species richness in southern Africa depend largely on whether spatial or non‐spatial models are used. We therefore stress the need for caution when interpreting environmental ‘effects’ on broad‐scale patterns of species richness if spatial and non‐spatial methods yield contrasting results.     

Towards novel approaches to modelling biotic interactions in multispecies assemblages at large spatial extents

Aim Biotic interactions – within guilds or across trophic levels – have widely been ignored in species distribution models (SDMs). This synthesis outlines the development of ‘species interaction distribution models’ (SIDMs), which aim to incorporate multispecies interactions at large spatial extents using interaction matrices. Location Local to global. Methods We review recent approaches for extending classical SDMs to incorporate biotic interactions, and identify some methodological and conceptual limitations. To illustrate possible directions for conceptual advancement we explore three principal ways of modelling multispecies interactions using interaction matrices: simple qualitative linkages between species, quantitative interaction coefficients reflecting interaction strengths, and interactions mediated by interaction currencies. We explain methodological advancements for static interaction data and multispecies time series, and outline methods to reduce complexity when modelling multispecies interactions. Results Classical SDMs ignore biotic interactions and recent SDM extensions only include the unidirectional influence of one or a few species. However, novel methods using error matrices in multivariate regression models allow interactions between multiple species to be modelled explicitly with spatial co‐occurrence data. If time series are available, multivariate versions of population dynamic models can be applied that account for the effects and relative importance of species interactions and environmental drivers. These methods need to be extended by incorporating the non‐stationarity in interaction coefficients across space and time, and are challenged by the limited empirical knowledge on spatio‐temporal variation in the existence and strength of species interactions. Model complexity may be reduced by: (1) using prior ecological knowledge to set a subset of interaction coefficients to zero, (2) modelling guilds and functional groups rather than individual species, and (3) modelling interaction currencies and species’ effect and response traits. Main conclusions There is great potential for developing novel approaches that incorporate multispecies interactions into the projection of species distributions and community structure at large spatial extents. Progress can be made by: (1) developing statistical models with interaction matrices for multispecies co‐occurrence datasets across large‐scale environmental gradients, (2) testing the potential and limitations of methods for complexity reduction, and (3) sampling and monitoring comprehensive spatio‐temporal data on biotic interactions in multispecies communities.     

Is a community still a community? Reviewing definitions of key terms in community ecology

Community ecology is an inherently complicated field, confounded by the conflicting use of fundamental terms. Nearly two decades ago, Fauth et al. (1996) demonstrated that imprecise language led to the virtual synonymy of important terms and so attempted to clearly define four keywords in community ecology; “community,” “assemblage,” “guild,” and “ensemble”. We revisit Fauth et al.'s conclusion and discuss how the use of these terms has changed over time since their review. An updated analysis of term definition from a selection of popular ecological textbooks suggests that definitions have drifted away from those encountered pre‐1996, and slightly disagreed with results from a survey of 100 ecology professionals (comprising of academic professors, nonacademic PhDs, graduate and undergraduate biology students). Results suggest that confusion about these terms is still widespread in ecology. We conclude with clear suggestions for definitions of each term to be adopted hereafter to provide greater cohesion among research groups.