Search

Anthropogenic eutrophication of ecosystems is an important driver of biodiversity loss. Even protected areas (PAs) may be impacted by anthropogenic nutrients, for example, from atmospheric deposition or the provision of supplementary feeding. However, the resultant nutrient patterns, and the role of local wildlife in shaping them, remain poorly understood. We investigated anthropogenic influences on the role that red deer (Cervus elaphus) play in the nutrient balance of a PA in Denmark. We used habitat selection modeling and theoretical scenarios where we varied the proportion of energy the deer obtained from supplementary versus natural forage and compared it with the nutrients removed due to hunting. We show that the movement and distribution of the red deer population within the PA are very heterogeneous and likely influenced by the need for shelter. Moreover, depending on their reliance on supplementary feeding, deer can potentially import large amounts of nutrients to the PA, and concentrate them in localized hotspots. However, we also explore the potential for nutrient loss due to hunting activities. Such indirect anthropogenic impacts on nutrient landscapes may counteract restoration and conservation efforts. We therefore recommend incorporating anthropogenic influences on zoogeochemistry and the animal‐mediated connectivity between PAs and anthropogenically dominated landscapes into future management plans. [ABSTRACT FROM AUTHOR]

Restoration of natural processes in ecosystems is key to mitigate the biodiversity crisis. Here, we evaluate 20 Danish stream‐valley restoration projects—mainly by rewetting—in terms of successful restoration of natural wetland habitats. We used quadratic discriminant analysis and generalized linear models to compare 80 vegetation plots from the restoration projects with >60,000 natural or semi‐natural wetland reference plots. We modeled the influence of time since restoration, grazing, rewetting, and nutrient availability on (1) the probability that study plots belong to natural habitats and (2) their richness of high‐quality‐habitat indicator species. The probability of a restored wetland having developed into a natural wetland habitat—such as an alkaline fen—was generally below 10%. Also, we found only half as many indicator species in restored wetlands than in reference wetlands and we demonstrated that the number of characteristic alkaline fen species did not deviate from what could be expected under the prevailing nutrient conditions. We found a negative effect of soil nutrient availability on the number of high‐quality‐habitat indicator species and the lowest probability of plots being natural wetlands in the most nutrient rich plots. The effect of grazing was only positive in the first years after restoration and only in the most nutrient rich plots, while the effect of rewetting sites to historical hydrological conditions was generally negative. Our findings suggest that unnaturally high nutrient availability is probably the core limiting factor for successful restoration of natural wetlands and their associated plant diversity. [ABSTRACT FROM AUTHOR]

A key aspect of nature conservation is knowledge of which aspects of nature to conserve or restore to favor the characteristic diversity of plants in a given area. Here, we used a large plant dataset with >40 000 plots combined with airborne laser scanning (lidar) data to reveal the local characteristics of habitats having a high plant dark diversity—that is, absence of suitable species—at national extent (>43 000 km2). Such habitats have potential for reaching high realized diversity levels and hence are important in a conservation context. We calculated 10 different lidar based metrics (both terrain and vegetation structure) and combined these with seven different field‐based measures (soil chemistry and species indicators). We then used Integrated Nested Laplace Approximation for modelling plant dark diversity across 33 North European habitat types (open landscapes and forests) selected by the European communities to be important. In open habitat types high‐dark‐diversity habitats had relatively low pH, high nitrogen content, tall homogenous vegetation, and overall relatively homogenous terrains (high terrain openness) although with a rather high degree of local microtopographical variations. High‐dark‐diversity habitats in forests had relatively tall vegetation, few natural‐forest indicators, low potential solar radiation input and a low cover of small woody plants. Our results highlight important vegetation, terrain‐ and soil‐related factors that managers and policymakers should be aware of in conservation and restoration projects to ensure a natural plant diversity, for example low nutrient loads, natural microtopography and possibly also open forests with old‐growth elements such as dead wood and rot attacks. [ABSTRACT FROM AUTHOR]

Question: How does naturalistic grazing (trophic rewilding with large herbivores), in contrast to mowing and free succession (no grazing), affect plant community composition and species richness in temperate grassland grazed by semi‐feral cattle and horses? Location: Mols Laboratory, Denmark. Methods: We investigated grazing exclosures in the rewilding area of the Mols Laboratory, four years after its establishment. We focused on moist to dry grassland vegetation, that is, excluding scrub and woodland. Each experimental block consisted of five 5 × 9 m plots, representing four fenced treatments, that is, summer‐only grazing, winter‐only grazing, full exclosure with annual autumn mowing and full exclosure with passive succession. The matrix (the fifth treatment) was grazed by large herbivores at close‐to‐natural densities, that is, regulated bottom‐up by the carrying capacity of the area. Hence, even the seasonal grazing treatments were grazed at close‐to‐natural animal density. Quantitative plant community composition was assessed using the point‐intercept method in 25 × 25 cm quadrats, supplemented with biomass calibration models based on additional quadrats, in which above‐ground plant biomass was harvested after recording and the material sorted to species and weighed. Uniqueness was assessed as the sum of inverse range sizes for constituent species (unicity). Results: We found an appreciably higher plant species richness in grazing treatments than under both annual mowing and full exclosure, but only minor differences between seasonal grazing treatments. Uniqueness was highest in year‐round and winter‐only grazing and lowest in summer‐only grazing. The forb:graminoid ratio tended to be high in the winter‐only grazing treatment, whereas annual mowing was associated with dominance of graminoids over forbs. Full‐exclosure plots had accumulation of litter and the lowest species richness. Initial heterogeneity between plots within blocks and a systematic difference between blocks in moist and dry grasslands may have diluted treatment effects at this early point after the onset of the experiment. Data analysis using the biomass estimates derived from the calibration models yielded only minor differences in the patterns described above, when compared to the results obtained using the raw number of intercepts. Conclusions: Naturalistic grazing is a goal in itself in ecological restoration, but also proposed as an efficient management tool to promote conservation of grassland plants and communities. We found both plant species richness and the prevalence of regionally rarer species (uni) to be higher with grazing than mowing or abandonment. Similarly, the tendency for forbs to prevail under grazing may translate into enhanced floral resources for anthophilous insects. Summer‐only grazing at low density of large herbivores was not significantly different from winter‐only and year‐round grazing, but this treatment was much closer to natural grazing than intensive summer grazing typical of agri‐environmental practices.Grazing is a natural ecosystem process and, thus, restoring naturalistic grazing using feral animals may be seen as a restoration goal in itself, notwithstanding the effects on biodiversity. Nevertheless, the present study demonstrates that naturalistic grazing as a management tool may indeed create habitat for regionally uncommon species of conservation concern and probably enhance resource availability to flower‐seeking insects. [ABSTRACT FROM AUTHOR]

Wetlands are important habitats, often threatened by drainage, eutrophication, and suppression of grazing. In many countries, considerable resources are spent combatting scrub encroachment. Here, we hypothesize that encroachment may benefit biodiversity—especially under eutrophic conditions where asymmetric competition among plants compromises conservation targets. We studied the effects of scrub cover, nutrient levels, and soil moisture on the richness of vascular plants, bryophytes, soil fungi, and microbes in open and overgrown wetlands. We also tested the effect of encroachment, eutrophication, and soil moisture on indicators of conservation value (red‐listed species, indicator species, and uniqueness). Plant and bryophyte species richness peaked at low soil fertility, whereas soil fertility promoted soil microbes. Soil fungi responded negatively to increasing soil moisture. Lidar‐derived variables reflecting the degree of scrub cover had predominantly positive effects on species richness measures. Conservation value indicators had a negative relationship to soil fertility and a positive to encroachment. For plant indicator species, the negative effect of high nutrient levels was offset by encroachment, supporting our hypothesis of competitive release under shade. The positive effect of soil moisture on indicator species was strong in open habitats only. Nutrient‐poor mires and meadows host many rare species and require conservation management by grazing and natural hydrology. On former agricultural lands, where restoration of infertile conditions is unfeasible, we recommend rewilding with opportunities for encroachment toward semi‐open willow scrub and swamp forest, with the prospect of high species richness in bryophytes, fungi, and soil microbes and competitive release in the herb layer. [ABSTRACT FROM AUTHOR]

Fungal and arthropod consumers constitute the vast majority of global terrestrial biodiversity. Yet, the link from richness and composition of producer (plant) communities to the richness of consumer communities is poorly understood. Fungal and arthropod species richness could be a simple function of producer species richness at a site. Alternatively, it could be a complex function of chemical and structural properties of the producer species making up communities. We used databases on plant–fungus and plant–arthropod trophic links to derive the richness of consumer biota per associated plant species (coined link score). We assessed how well link scores could be predicted by simple attributes of plant species. Next, we used a multi‐taxon inventory of 130 sites, representing all major habitat types in a country (Denmark), to investigate whether link scores summed over plant species in communities (coined link sum) could outperform simple plant species richness as predictor of fungal and arthropod richness at the sites. We found plant species' link scores for both fungi and arthropods to be positively related to plant size, regional occupancy, nativeness and ectomycorrhizal status. Link‐based indices generally improved the prediction of richness of fungal and arthropod communities. For fungal communities, both observed link sum (from databases) and predicted link sum (from plant attributes) had high predictive power, while plant richness alone had none. For arthropod communities, predictive performance varied between functional groups. For both fungi and arthropods, richness predictions were further improved by considering abiotic habitat conditions. Our results underline the importance of plants as niche space for the megadiverse groups of arthropods and fungi. The plant–attribute approach holds promise for predicting local and regional consumer richness in areas of the world lacking detailed plant–consumer databases. [ABSTRACT FROM AUTHOR]

Large herbivores provide key ecosystem processes, but have experienced massive historical losses and are under intense pressure, leaving current ecosystems with dramatically simplified faunas relative to the long‐term evolutionary norm. Hampered by a shifting baseline, natural levels of large‐herbivore biomass are poorly understood and seldom targeted. This 'Decade of ecosystem restoration' calls for evidence‐based targets for restoring the natural diversity and biomass of large herbivores.We apply the scaling of the consumer–producer relationship to a global dataset of large‐herbivore density in natural areas. The analyses reveal that African ecosystems generally have much higher large‐herbivore biomass and also the strongest consumer–producer relationship. For Europe, Asia and South America, there are no significant relationships with primary productivity indicative of impoverished faunas. Compared to expectations from the African scaling relation, large‐herbivore biomass in ecosystems outside Africa is considerably lower than expected.Synthesis and applications. Ecological restoration and rewilding entail restoration of a natural grazing process. Our findings indicate that many nature reserves are depleted in large‐herbivore biomass, judged from their primary productivity. Meanwhile, overexploitation by seasonal livestock grazing takes place in other areas. It is thus difficult, but urgent, to reach scientific consensus regarding a natural baseline for large‐herbivore biomass. Until such agreement has been reached, we recommend to manage, or rewild, large herbivores in year‐round near‐natural grazing and without predefined density targets, but following natural and fluctuating resource availability with minimal management intervention. The establishment of experimental rewilding sites with reactive herbivore management is needed to further advance our understanding of natural grazing density. [ABSTRACT FROM AUTHOR]

Amidst the global biodiversity crisis, identifying general principles for variation of biodiversity remains a key challenge. Scientific consensus is limited to a few macroecological rules, such as species richness increasing with area, which provide limited guidance for conservation. In fact, few agreed ecological principles apply at the scale of sites or reserve management, partly because most community‐level studies are restricted to single habitat types and species groups. We used the recently proposed ecospace framework and a comprehensive data set for aggregating environmental variation to predict multi‐taxon diversity. We studied richness of plants, fungi and arthropods in 130 sites representing the major terrestrial habitat types in Denmark. We found the abiotic environment (ecospace position) to be pivotal for the richness of primary producers (vascular plants, mosses and lichens) and, more surprisingly, little support for ecospace continuity as a driver. A peak in richness at intermediate productivity adds new empirical evidence to a long‐standing debate over biodiversity responses to productivity. Finally, we discovered a dominant and positive response of fungi and insect richness to organic matter accumulation and diversification (ecospace expansion). Two simple models of producer and consumer richness accounted for 77% of the variation in multi‐taxon species richness suggesting a significant potential for generalization beyond individual species responses. Our study widens the traditional conservation focus on vegetation and vertebrate populations unravelling the importance of diversification of carbon resources for diverse heterotrophs, such as fungi and insects. [ABSTRACT FROM AUTHOR]

Species richness is the most commonly used metric to quantify biodiversity. However, examining dark diversity, the group of missing species which can potentially inhabit a site, can provide a more thorough understanding of the processes influencing observed biodiversity and help evaluate the restoration potential of local habitats. So far, dark diversity has mainly been studied for specific habitats or large‐scale landscapes, while less attention has been given to variation across broad environmental gradients or as a result of local conditions and biotic interactions. In this study, we investigate the importance of local environmental conditions in determining dark diversity and observed richness in plant communities across broad environmental gradients. Using the ecospace concept, we investigate how these biodiversity measures relate to abiotic gradients (defined as position), availability of biotic resources (defined as expansion), spatiotemporal extent of habitats (defined as continuity), and species interactions through competition. Position variables were important for both observed diversity and dark diversity, some with quadratic relationships, for example, plant richness showing a unimodal response to soil fertility corresponding to the intermediate productivity hypothesis. Interspecific competition represented by community mean Grime C had a negative effect on plant species richness. Besides position‐related variables, organic carbon was the most important variable for dark diversity, indicating that in late‐succession habitats such as forests and shrubs, dark diversity is generally low. The importance of highly competitive species indicates that intermediate disturbance, such as grazing, may facilitate higher species richness and lower dark diversity. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) is increasingly applied in ecological studies, including studies with the primary purpose of criminal investigation, in which eDNA from soil can be used to pair samples or reveal sample provenance. We collected soil eDNA samples as part of a large national biodiversity research project across 130 sites in Denmark. We investigated the potential for soil eDNA metabarcoding in predicting provenance in terms of environmental conditions, habitat type and geographic regions. We used linear regression for predicting environmental gradients of light, soil moisture, pH and nutrient status (represented by Ellenberg Indicator Values, EIVs) and Quadratic Discriminant Analysis (QDA) to predict habitat type and geographic region. eDNA data performed relatively well as a predictor of environmental gradients (R2 > 0.81). Its ability to discriminate between habitat types was variable, with high accuracy for certain forest types and low accuracy for heathland, which was poorly predicted. Geographic region was also less accurately predicted by eDNA. We demonstrated the application of provenance prediction in forensic science by evaluating and discussing two mock crime scenes. Here, we listed the plant species from annotated sequences, which can further aid in identifying the likely habitat or, in case of rare species, a geographic region. Predictions of environmental gradients and habitat types together give an overall accurate description of a crime scene, but care should be taken when interpreting annotated sequences, e.g. due to erroneous assignments in GenBank. Our approach demonstrates that important habitat properties can be derived from soil eDNA, and exemplifies a range of potential applications of eDNA in forensic ecology. [ABSTRACT FROM AUTHOR]

Plants regulate soils and microclimate, provide substrate for heterotrophic taxa, are easy to observe and identify and have a stable taxonomy, which strongly justifies their use as indicators in monitoring and conservation. However, there is no consensus as to whether plants are strong predictors of total multi‐taxon species richness. In this study, we investigate if general terrestrial species richness can be predicted by vascular plant richness and bioindication.To answer this question, we collected an extensive dataset on species richness of vascular plants, bryophytes, macrofungi, lichens, plant‐galling arthropods, gastropods, spiders, carabid beetles, hoverflies, and genetic richness (operational taxonomic units = OTUs) from environmental DNA metabarcoding. We also constructed a Conservation Index based on threatened red list species. Besides using richness of vascular plants for prediction of other taxonomic groups, we also used plant‐derived calibration of the abiotic environment (moisture, soil fertility and light conditions) as well as the degree of anthropogenic impact.Bivariate relationships between plant species richness and other species groups showed no consistent pattern. After taking environmental calibration by bioindication into account, we found a consistent, and for most groups significant, positive effect of plant richness. Plant species richness was also important for richness of fungal OTUs, Malaise OTUs and for the Conservation Index. Our multiple regression analyses revealed (a) a consistently positive effect of plant richness on other taxa, (b) prediction of 12%–55% of variation in other taxa and 48% of variation in the total species richness when bioindication and plant richness were used as predictors.Our results justify that vascular plants are strong indicators of total biodiversity across environmental gradients and broad taxonomic realms and therefore a natural first choice for biodiversity monitoring and conservation planning. [ABSTRACT FROM AUTHOR]

Abstract: Ecological trait data are essential for understanding the broad‐scale distribution of biodiversity and its response to global change. For animals, diet represents a fundamental aspect of species’ evolutionary adaptations, ecological and functional roles, and trophic interactions. However, the importance of diet for macroevolutionary and macroecological dynamics remains little explored, partly because of the lack of comprehensive trait datasets. We compiled and evaluated a comprehensive global dataset of diet preferences of mammals (“MammalDIET”). Diet information was digitized from two global and cladewide data sources and errors of data entry by multiple data recorders were assessed. We then developed a hierarchical extrapolation procedure to fill‐in diet information for species with missing information. Missing data were extrapolated with information from other taxonomic levels (genus, other species within the same genus, or family) and this extrapolation was subsequently validated both internally (with a jack‐knife approach applied to the compiled species‐level diet data) and externally (using independent species‐level diet information from a comprehensive continentwide data source). Finally, we grouped mammal species into trophic levels and dietary guilds, and their species richness as well as their proportion of total richness were mapped at a global scale for those diet categories with good validation results. The success rate of correctly digitizing data was 94%, indicating that the consistency in data entry among multiple recorders was high. Data sources provided species‐level diet information for a total of 2033 species (38% of all 5364 terrestrial mammal species, based on the IUCN taxonomy). For the remaining 3331 species, diet information was mostly extrapolated from genus‐level diet information (48% of all terrestrial mammal species), and only rarely from other species within the same genus (6%) or from family level (8%). Internal and external validation showed that: (1) extrapolations were most reliable for primary food items; (2) several diet categories (“Animal”, “Mammal”, “Invertebrate”, “Plant”, “Seed”, “Fruit”, and “Leaf”) had high proportions of correctly predicted diet ranks; and (3) the potential of correctly extrapolating specific diet categories varied both within and among clades. Global maps of species richness and proportion showed congruence among trophic levels, but also substantial discrepancies between dietary guilds. MammalDIET provides a comprehensive, unique and freely available dataset on diet preferences for all terrestrial mammals worldwide. It enables broad‐scale analyses for specific trophic levels and dietary guilds, and a first assessment of trait conservatism in mammalian diet preferences at a global scale. The digitalization, extrapolation and validation procedures could be transferable to other trait data and taxa. [ABSTRACT FROM AUTHOR]

Background: Climate change is already affecting the distributions of many species and may lead to numerous extinctions over the next century. Small-range species are likely to be a special concern, but the extent to which they are sensitive to climate is currently unclear. Species distribution modeling, if carefully implemented, can be used to assess climate sensitivity and potential climate change impacts, even for rare and cryptic species. Methodology/Principal Findings: We used species distribution modeling to assess the climate sensitivity, climate change risks and conservation implications for a threatened small-range mammal species, the Iberian desman (Galemys pyrenaicus), which is a phylogenetically isolated insectivore endemic to south-western Europe. Atlas data on the distribution of G. pyrenaicus was linked to data on climate, topography and human impact using two species distribution modeling algorithms to test hypotheses on the factors that determine the range for this species. Predictive models were developed and projected onto climate scenarios for 2070-2099 to assess climate change risks and conservation possibilities. Mean summer temperature and water balance appeared to be the main factors influencing the distribution of G. pyrenaicus. Climate change was predicted to result in significant reductions of the species' range. However, the severity of these reductions was highly dependent on which predictor was the most important limiting factor. Notably, if mean summer temperature is the main range determinant, G. pyrenaicus is at risk of near total extinction in Spain under the most severe climate change scenario. The range projections for Europe indicate that assisted migration may be a possible long-term conservation strategy for G. pyrenaicus in the face of global warming. Conclusions/Significance: Climate change clearly poses a severe threat to this illustrative endemic species. Our findings confirm that endemic species can be highly vulnerable to a warming climate and highlight the fact that assisted migration has potential as a conservation strategy for species threatened by climate change. [ABSTRACT FROM AUTHOR]

Despite the important role of fungi for ecosystems, relatively little is known about the factors underlying the dynamics of their diversity. Moreover, studies do not typically consider their dark diversity: the species absent from an otherwise suitable site. Here, we examined potential drivers of local fungal dark diversity in temperate woodland and open habitats using LiDAR and in-situ field measurements, combined with a systematically collected and geographically comprehensive macro-fungi and plant data set. For the first time, we also estimated species pools of fungi by considering both plant and fungi co-occurrences. The most important LiDAR variables for explaining fungal dark diversity were amplitude and echo ratio, which represent vegetation structure. These results suggest that the local fungal dark diversity is highest in production forests like plantations and lowest in more open forests and in open habitats with little woody vegetation. Plant species richness was the strongest explanatory factor overall and negatively correlated with local fungal dark diversity. Soil fertility showed a positive relationship with dark diversity in open habitats. These findings indicate that the local dark diversity of macro-fungi is highest in areas with a relatively high human impact (typically areas with low plant species richness and high soil fertility). Overall, this study brings novel insights into local macro-fungi dark diversity patterns, suggesting that a multitude of drivers related to both soil and vegetation act simultaneously to determine fungal dark diversity. [ABSTRACT FROM AUTHOR]

There has been much recent interest in the concept of rewilding as a tool for nature conservation, but also confusion over the idea, which has limited its utility. We developed a unifying definition and 10 guiding principles for rewilding through a survey of 59 rewilding experts, a summary of key organizations' rewilding visions, and workshops involving over 100 participants from around the world. The guiding principles convey that rewilding exits on a continuum of scale, connectivity, and level of human influence and aims to restore ecosystem structure and functions to achieve a self-sustaining autonomous nature. These principles clarify the concept of rewilding and improve its effectiveness as a tool to achieve global conservation targets, including those of the UN Decade on Ecosystem Restoration and post-2020 Global Biodiversity Framework. Finally, we suggest differences in rewilding perspectives lie largely in the extent to which it is seen as achievable and in specific interventions. An understanding of the context of rewilding projects is the key to success, and careful site-specific interpretations will help achieve the aims of rewilding., (© 2021 The Authors. Conservation Biology published by Wiley Periodicals LLC on behalf of Society for Conservation Biology.)

Monitoring insects across space and time is challenging, due to their vast taxonomic and functional diversity. This study demonstrates how nets mounted on rooftops of cars (car nets) and DNA metabarcoding can be applied to sample flying insect richness and diversity across large spatial scales within a limited time period. During June 2018, 365 car net samples were collected by 151 volunteers during two daily time intervals on 218 routes in Denmark. Insect bulk samples were processed with a DNA metabarcoding protocol to estimate taxonomic composition, and the results were compared to known flying insect richness and occurrence data. Insect and hoverfly richness and diversity were assessed across biogeographic regions and dominant land cover types. We detected 15 out of 19 flying insect orders present in Denmark, with high proportions of especially Diptera compared to Danish estimates, and lower insect richness and diversity in urbanized areas. We detected 319 species not known for Denmark and 174 species assessed in the Danish Red List. Our results indicate that the methodology can assess the flying insect fauna at large spatial scales to a wide extent, but may be, like other methods, biased towards certain insect orders.