Human impact gradient on mammalian biodiversity

Coastal birch forests in northern Norway are currently being converted to nonnative spruce plantations. Since such land use changes may cause large alterations in the birch forest ecosystems, indicators suitable for detecting and monitoring impacts need to be pursued. In this study, we used a three-table ordination method (RLQ analysis) to identify species traits in bird assemblages indicating changes in environmental attributes at stand and landscape level. RLQ analysis has the advantage of linking species traits directly to environmental attributes, hence detecting the major ecological impacts of land use change, as well as a set of species traits sensitive to these alterations. Birds and environmental attributes were sampled in six forest types in 12 different landscapes. To assess whether species traits were relatively consistent geographically and temporally, two different geographic regions and years were also included in our study design. We found the species traits investigated here to be promising indicators of land use impacts. In particular, ground nesters, cavity nesters, flycatchers, and long-distance migrants were adversely affected by conditions in elderly spruce plantations. Also, species that forage on trunks and in deciduous foliage, as well as species that eat larvae and flying insects, were related to forests with a deciduous overstory. Despite the variety of species traits reflecting ecological changes at the stand level, only the species sensitive to the reduction in area of rich birch forests responded to fragmentation effects at the landscape level. These effects of land use changes appeared to be consistent in time (years) and space (geographic regions). We argue that knowledge about trait–environmental linkages is essential when selecting indicators for monitoring land use impacts. To best separate human effects from natural fluctuations, major environmental attributes that vary naturally in time and space should also be monitored in conjunction with the indicator species traits. Finally, trait–environmental linkages could form the basis of making predictions about changes in biological and functional diversity in response to land use changes. These predictions could subsequently be evaluated in monitoring programs.

Linking species, traits and habitat characteristics of Collembola at European scale

We investigated trait-environment relationships of co-occurring aquatic Coleoptera specifically true water beetles in anthropogenic ponds from the Western Ghats, India for the first time. Our objectives were to: (1) identify species assemblages; (2) study species traits; (3) study trait-environment relationships of co-occurring species. We analysed 132 samples collected using standardised quantitative method during the years 2016 and 2017. We found 16 significant assemblages using Fager's index, where most of the pairs have body size ratio of 1.3 or more. For example,Laccophilus parvulus and Hydaticus satoipair has body size ratio of 3.98, and both are predators, indicating that body size is a function of food size. Moreover, factor analysis revealed three major swimming categories of studied beetles, namely fast swimmers, maneuverers and poor swimmers. Further, the RLQ analysis, and combined approach of RLQ and fourth-corner analysis showed that environmental variables affected species traits. For instance, odonate nymphs and submerged vegetation were positively associated with fast swimmers likeLaccophilusinefficiensandHydaticus satoi. The assemblage of congenersHydroglyphus inconstansandH. flammulatuscan be predator-mediated as these beetles showed negative association with odonate nymphs as well as competitive to obtain resource by showing positive association with chironomid larvae. Therefore, the traits studied were important for ecological performances of species in ponds. This study has also highlighted the importance of anthropogenic ponds in the Western Ghats as biodiversity refuges of ecologically unique and evolutionary old major extant lineages of water beetles.

Ecological traits and landscape characteristics predicting bird sensitivity to urbanization in city parks

Urban growth is considered to be a major driver of environmental change. Urbanisation can affect urban biodiversity in different ways. So far, most studies focused on the impact of urbanisation on single taxa in one habitat type. In this study, we used data of species inventories and GIS-based landscape elements to examine the effects of habitat size and landscape composition on the species diversity of three taxonomic groups (vascular plants, Orthoptera and Lepidoptera) in meadows and ruderal sites in the urban region of Basel, Switzerland. We also related the responses of three species traits (body size, dispersal ability and food specialisation) to habitat size in Orthoptera and Lepidoptera. We found that species of the different taxonomic groups differed in their response to habitat size and landscape composition both in meadows and ruderal sites depending on the traits examined. The species richness of Orthoptera and Lepidoptera was positively related to meadow size but not to the size of ruderal sites, while the opposite was true for plants. For Lepidoptera in ruderal sites, the percentage cover of ruderal area in the closer surroundings was a better predictor of species richness than habitat size per se. To sustain high levels of urban biodiversity, we recommend that urban planners develop adequate management strategies to satisfy the different requirements of various taxonomic groups and to increase the quality of green sites surrounding the target habitat.

Adaptive foragers and community ecology: linking individuals to communities and ecosystems

QuestionWhat is the effect of past land use and environmental gradients on plant functional traits within coastal marsh plant communities?LocationMediterranean microtidal marshes in the Llobregat Delta, NE Spain.MethodsWe used a data set collected previously comprising 45 vegetation plots with associated soil parameters, water table conditions and past land use. For each species we obtained the values or states for a set of plant functional traits: plant height, leaf dry matter content, specific leaf area, seed production, seed weight, life form and lateral expansion. To account for the effect of phylogeny, we evaluated trait diversity skewness by means of an ultrametric phylogenetic tree specifically constructed for the species studied. The association between both environmental gradients and past disturbance, and plant functional traits was tested by means of RLQ analysis.ResultsOf all the traits, only seed weight showed a phylogenetic signal; consequently, phylogeny was not included in the RLQ analysis. Conductivity was negatively correlated with seed weight, whereas water table conditions and soil ionic balance were negatively correlated with specific leaf area. Past disturbance was negatively correlated with leaf dry matter content and with lateral expansion.ConclusionsPlant traits of Llobregat Delta coastal marsh communities are conditioned by environmental gradients and by past land use. Soil ionic balance and water table conditions determine key plant functional traits such as specific leaf area. This finding also corroborates the importance of soil ionic balance as a plant life driver in microtidal Mediterranean marshes. The effect of past land use on species traits might, however, be partially indirect and mediated by associated environmental changes.

Networks of mutualistic interactions between animals and plants are considered a pivotal part of ecological communities. However, mutualistic networks are rarely studied from the perspective of species-specific roles, and it remains to be established whether those animal species more relevant for network structure also contribute more to the ecological functions derived from interactions. Here, we relate the contribution to seed dispersal of vertebrate species with their topological role in frugivore-plant interaction networks. For one year in two localities with remnant patches of Colombian tropical dry forest, we sampled abundance, morphology, behaviour and fruit consumption from fleshy-fruited plants of various frugivore species. We assessed the network topological role of each frugivore species by integrating their degree of generalization in interactions with plants with their contributions to network nestedness and modularity. We estimated the potential contribution of each frugivore species to community-wide seed dispersal, on the basis of a set of frugivore ecological, morphological and behavioural characteristics important for seed dispersal, together with frugivore abundance and frugivory degree. The various frugivore species showed strong differences in their network structural roles, with generalist species contributing the most to network modularity and nestedness. Frugivores also showed strong variability in terms of potential contribution to seed dispersal, depending on the specific combinations of frugivore abundance, frugivory degree and the different traits and behaviours. For both localities, the seed dispersal potential of a frugivore species responded positively to its contribution to network structure, evidencing that the most important frugivore species in the network topology were also those making the strongest contribution as seed dispersers. Contribution to network structure was correlated with frugivore abundance, diet and behavioural characteristics. This suggests that the species-level link between structure and function is due to the fact that the occurrence of frugivore-plant interactions depends largely on the characteristics of the frugivore involved, which also condition its ultimate role in seed dispersal.

Relating coral species traits to environmental conditions in the Jakarta Bay/Pulau Seribu reef system, Indonesia

Trait‐based approaches are becoming increasingly important in understanding the functional structure of biological communities in response to anthropogenic disturbances. Coffee is one of the most important crops in tropical regions and has gone through a process of agricultural intensification at a landscape scale that could cause the loss of species and functional diversity at a local scale. Rove beetles are diverse in Andean coffee crops and are an ideal group for evaluating the impact of the environmental heterogeneity at local and landscape scale on the functional structure of their community through identifying trait syndromes. Using a trait‐based approach with RLQ analysis, five life‐history traits of rove beetle species were studied from 27 sites in a region dominated by sun‐grown coffee in the Colombian Andes. We evaluated how environmental heterogeneity at local and landscape levels affects the functional structure of the rove beetle community, identifying groups of species with shared common traits. We found that both local and landscape variables play a crucial role in shaping the functional structure of the rove beetle community. Despite the dominance of predators and the small body size of beetle species as an indicator of the transformation processes (i.e. forest conversion to crops) that have undergone the studied coffee landscape, four trait syndromes were identified in sun‐grown coffee crops. Large and small predators, small specialist predators, medium saprophagous organisms and medium parasitoids were identified in coffee crops, supporting the idea that the high environmental heterogeneity promotes different trait syndromes in coffee crops. Synthesis and applications. Our study suggests that high environmental heterogeneity at local (small size of coffee farms) and landscape level (number of forest patches) promotes the functional structure in rove beetle communities. We discussed how trait‐based and RLQ analysis is a useful approach to evaluate the landscape simplification effect on functional diversity in tropical regions, especially with groups of highly speciose and taxonomically poorly known insects.

Oceanic islands, recognised for their isolation, high endemic species richness and unique evolutionary paths compared with their continental counterparts, are extremely susceptible to anthropogenic activities. The fragmentation of island habitats and disruption of native ecosystems has increased the risk of extinction for many endemic species, including arthropods. Extinction is not random, and some species traits may increase the probability of species entering an extinction trajectory. Studying species traits alongside International Union for Conservation of Nature (IUCN) threat levels may offer valuable insights into their vulnerability and inform targeted conservation strategies. Here, we aim to test the predictability of IUCN threat categories and conservation status based on endemic Azorean arthropods' functional traits: body size, trophic group and vertical strata occupancy. We demonstrate that species with limited vertical occupancy, particularly those restricted to ground level, are more vulnerable to extinction than those that inhabit the forest canopy. Contrary to our expectations, body size and trophic group did not appear to be direct predictors of the threat level. Overall, our findings underscore previous and ongoing effects of human activities in island ecosystems. Hence, we emphasise the need to look at species traits as predictors of future extinctions in endemic island arthropods.

Integrating species traits and habitat characteristics into models of butterfly diversity in a fragmented ecosystem

Habitat loss and fragmentation are major threats to biodiversity and can change community composition, species traits and intraspecific morphology. Calcareous grasslands are hotspots of diversity for plants and invertebrates in Europe, but habitat area and habitat amount declined strongly over the last century. It is controversially discussed how habitat area and habitat amount independently affect species assemblages, traits and morphology. With variable transects we recorded orthopteran assemblages on 22 calcareous grasslands along independent gradients of habitat area and habitat amount in a 1 km matrix. We measured male body size and wing length of two abundant grasshopper species. Orthopteran assemblages showed positive species–area and abundance–area relationships with habitat area and (extenuated) with habitat amount. We found a stronger effect of habitat area reduction on specialists and endangered species, compared to generalists and non-threatened species. The species Chorthippus biguttulus and Gomphocerippus rufus had a larger body size (fitness-related trait) in landscapes with high habitat area and habitat amount. Grasshoppers had longer wings in relation to body size (dispersal-related trait) in landscapes with a low amount of habitat. Our findings emphasize the value of large patches and landscapes with high habitat amount to (i) enhance species richness and abundances, (ii) protect threatened species, (iii) ensure long term survival of habitat-specialists and (iv) preserve individuals with high fitness traits (large body size). Conservation strategies for Orthoptera should focus on large habitats and areas with a high habitat amount.

The survival and success of alien plant species is determined by species traits (i.e., invasiveness) and the characteristics of the habitats in the region of introduction (i.e., invasibility). However, little is known about species traits as related to habitat characteristics. We assessed the characteristics of successful invaders and the interaction of environmental factors and life-history traits for alien plant species. The vascular plants were recorded from 52 agricultural landscapes in Finland. We compared the traits of native and alien plant species with Fisher’s exact test and used a three table ordination analysis, RLQ analysis, to relate species traits to environmental conditions. Species were clustered according to their position on the RLQ axes, and the clusters were tested for phylogenetic independence. The successful alien plant species were associated with life form and preferences for moisture and nitrogen, but the trait composition varied according to the habitat type. Two RLQ axes explained 80.5% of the variation, and the species traits were significantly associated with environmental variables. The clustering showed that the occurrence of alien plant species in agricultural habitats was driven by invasion history, traits related to dispersal (dispersal type, seed mass) and habitat preferences, as well as environmental features, such as geographical location, temperature and the quality and disturbance regime of the habitats. All clusters were phylogenetically non-independent. Thus, the clusters of alien species comprised species of diverse taxonomic affinities, although, they shared the traits explaining their occurrence in particular habitats. This information is useful for understanding the link between species traits and the environmental conditions of the habitats, and complexity of the invasion process.

A frequent question in invasion ecology is whether the traits of alien plant species differ from natives. This question is increasingly addressed at the plant community scale to assess the role trait differences play in community assembly. Nevertheless, there remains considerable debate as to the value of native vs. alien trait comparisons. Recommendations are made to address seven conceptual and methodological limitations in current approaches used to assess trait differences between native and alien plants: account for spatial scale dependence, make an informed choice of traits, evaluate multiple trait dimensions, incorporate intraspecific trait variation, use appropriate null models, examine environmental gradients, and assess temporal variation in trait spectra. Tackling these limitations will dramatically improve the value of native vs. alien trait comparisons. Traits should be selected based on expectations of abiotic and/or biotic constraints. Phylogenetic distances can provide valuable insights but are no substitute for the measurement of individual traits when contrasting alien and native species. An ideal set of traits would include one or more leaf, stem, seed and root traits as well as flowering phenology and plant height at maturity. Comparisons of intraspecific trait variation among native and alien species within the same plant community are rare but could improve predictions of interspecific competition and the response of communities to plant invasions. The full plant community should be examined rather than selected species subsets and comparisons between native and alien species traits are better undertaken at a neighbourhood scale. The frequency distribution of alien and native species traits may change over time through competitive exclusion as well as contemporary evolution. Repeated surveys of species abundances and traits are required to understand the consequences of trait differences between aliens and natives for plant community assembly. Analyses of the role of species traits in plant invasions need to quantify differences in a priori identified traits within communities along suitable environmental gradients and test hypothetical trait patterns against appropriate null expectations. The infrequent application of such approaches may explain the limited generalisations regarding the role of trait differences between native and alien species in the invasion of plant communities. A plain language summary is available for this article.