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Aim: In this study, we assessed the importance of local‐ to landscape‐scale effects of land cover and land use on flying insect biomass. Location: Denmark and parts of Germany. Methods: We used rooftop‐mounted car nets in a citizen science project ("InsectMobile") to allow for large‐scale geographic sampling of flying insects. Volunteers sampled insects along 278 five‐km routes in urban, farmland, grassland, wetland and forest landscapes in the summer of 2018. The bulk insect samples were dried overnight to obtain the sample biomass. We extracted proportional land use variables in buffers between 50 and 1,000 m along the routes and compiled them into land cover categories to examine the effect of each land cover, and specific land use types, on insect biomass. Results: We found a negative association between urban cover and flying insect biomass (1% increase in urban cover = 1% [95% CI: −3.0 to 0.0] decrease in biomass in Denmark, and a 3% [95% CI: −3.0 to 0.0] decrease in Germany) at a landscape scale (1,000‐m buffer). In Denmark, we also found positive effects of semi‐natural land cover types, that is protected grassland (largest at the landscape scale, 1000 m) and forests (largest at intermediate scales, 250 m). Protected grassland cover had a stronger positive effect on insect biomass than forest cover did. For farmland cover, the positive association with insect biomass was not clearly modified by any variable associated with farmland use intensity. The negative association between insect biomass and urban land cover appeared to be reduced by increased urban green space. Main conclusions: Our results show that land cover has an impact on flying insect biomass with the magnitude of this effect varying across spatial scales. However, the vast expanse of grey space in urbanized areas has a direct negative impact on flying insect biomass across all spatial scales examined. [ABSTRACT FROM AUTHOR]

Policies aiming at improving biodiversity often consist of costly agri-environmental schemes, i.e. subsidized grazing or mowing of semi-natural areas. However, these practices have widely been found to be insufficient to mitigate biodiversity loss. Rewilding, i.e. restoring natural processes in self-sustaining biodiverse ecosystems, has been proposed as an alternative and is hypothesized to be a more cost-efficient approach to promote biodiversity conservation. Rewilding requires the availability of large natural areas which are not allocated for farming, forestry, and infrastructure to avoid potential conflicts over the use of the area. We perform an ex-ante private cost–benefit analysis of the establishment of four large nature reserves for rewilding in Denmark. We analyse the economic effects of changing from summer grazing in nature areas in combination with cultivated fields and forestry to the establishment of nature reserves in four case areas. We consider two scenarios involving conversion of agriculture and forestry areas into natural areas in combination with either extensive year-round cattle grazing or rewilding with wild large herbivores. In two case areas, it appears possible to establish large nature areas without incurring extra costs. Additionally, rewilding further reduces costs compared to year-round cattle grazing. Two opposing effects were dominant: increased economic rent occurred from the shift from summer grazing to year-round grazing or rewilding, while cessation of agriculture and forestry caused opportunity costs. [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]

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]

DNA metabarcoding is promising for cost-effective biodiversity monitoring, but reliable diversity estimates are difficult to achieve and validate. Here we present and validate a method, called LULU, for removing erroneous molecular operational taxonomic units (OTUs) from community data derived by high-throughput sequencing of amplified marker genes. LULU identifies errors by combining sequence similarity and co-occurrence patterns. To validate the LULU method, we use a unique data set of high quality survey data of vascular plants paired with plant ITS2 metabarcoding data of DNA extracted from soil from 130 sites in Denmark spanning major environmental gradients. OTU tables are produced with several different OTU definition algorithms and subsequently curated with LULU, and validated against field survey data. LULU curation consistently improves α-diversity estimates and other biodiversity metrics, and does not require a sequence reference database; thus, it represents a promising method for reliable biodiversity estimation. [ABSTRACT FROM AUTHOR]

The conservation status of European temperate forests is overall unfavorable, and many associated species are listed in national or European red-lists. A better understanding of factors increasing survival probability of red-listed species is needed for a more efficient conservation effort. Here, we investigated the importance of current forest cover, historical forest cover and a number of soil and climate variables on the incidence and richness of red-listed forest species in Denmark. We considered eight major taxa separately (mammals, saproxylic beetles, butterflies, vascular plants and four groups of fungi), using mainly citizen science data from several national mapping projects. Taxa were selected to represent important forest habitats or properties (soil, dead wood, forest glades and landscape context) and differ in dispersal potential and trophic strategy. For all groups, presence and richness of red-listed species was positively related with current forest cover, but - for most taxa - forest cover 200 years ago was an even better predictor. The intersection of past and current deciduous forest was used to identify the area of continuous, lost and new forest. Continuous and lost deciduous forest cover were strong predictors of red-listed species occurrence in most groups, but surprisingly species richness of butterflies and hydnoid fungi, and presence of mammals, was significantly, positively affected by coniferous forest area. The positive effect of lost deciduous forests on red-listed species, suggest an extinction debt of at least 200 years, with some areas hosting more red-listed species than the current area of old forest can sustain in the long run. Our results suggest that current priorities for forest conservation in Denmark are not efficient in protecting red-listed forest species, and that more focus should be put on conserving deciduous forest with long continuity. Furthermore, a multi-taxa approach including a wide array of organism groups with contrasting habitat affiliations, results in a more comprehensive understanding of the requirements of red-listed forest species and necessitate a more focused approach to conservation planning. [ABSTRACT FROM AUTHOR]

Question It is an old notion that pattern and process are linked in plant communities. Spatial pattern may, therefore, be a valuable indicator of community processes in space and time. Obviously, spatial aggregation may arise as the result of clonal propagation and short-distance dispersal of seeds, but it is less well known how variation in the spatial aggregation links to plant community processes and to community responses to environmental stresses, such as eutrophication and acidification. We hypothesize that intra-specific spatial aggregation may prove a useful indicator of structure and function in plant communities and, more specifically, that spatial aggregation in semi-natural grasslands will increase with increasing eutrophication and acidification. Methods The intra-specific spatial aggregation at the level of the community was estimated using pin-point data for all observed species at a site with a single parameter using the PÓlya-Eggenberger distribution. Results Intra-specific spatial aggregation correlates with biotic and abiotic gradients in the form of pH, vegetation height, species richness and species composition. The results support the hypothesis that eutrophication and acidification not only cause loss of species, but also lead to increasing intra-specific aggregation of the component species. However, there was no significant effect of N deposition, which suggests that residual nutrients from former cultivation as well as sulphur deposition override the effect of N deposition on pH and productivity in Danish acidic grasslands. Conclusion We suggest that intra-specific spatial aggregation may be used as an indicator of structure and function in plant communities and as a possible early warning indicator of future species loss. [ABSTRACT FROM AUTHOR]

The effect of atmospheric nitrogen deposition on the species richness of acid grasslands was investigated by combining data from a large Danish monitoring program with a large European data set, where a significant non-linear negative effect of nitrogen deposition had been demonstrated (). The nitrogen deposition range in Denmark is relatively small and when only considering the Danish data a non-significant decrease in the species richness with nitrogen deposition was observed. However, when both data sets were combined, then the conclusion of the European survey was further corroborated by the results of the Danish monitoring. Furthermore, by combining the two data sets a more comprehensive picture of the threats to the biodiversity of acid grasslands emerge; i.e., species richness in remnant patches of acid grassland in intensively cultivated agricultural landscapes is under influence not only from nitrogen deposition, but also from current and historical land use. [Copyright &y& Elsevier]

Invasion by alien plants has negative effects on coastal dunes. Monitoring local spread of invasive species depends on long-term data with sufficient spatial resolution. Bayesian state-space models are a new method for monitoring invasive plants based on unbalanced permanent-plot data. The method allows separation of process and sampling variance, thus enabling ecological predictions with a known degree of uncertainty. The method is applied for the invasive shrub Rosa rugosa (Japanese rose) in Danish fixed dunes. The probability of observing R. rugosa increased significantly from 0.18 to 0.28 during the period 2004-2007. The species was found in all Danish coastal regions, albeit slightly less common in northern Denmark. We discuss the advantages and limitations of using Bayesian state-space models for monitoring and predicting plant invasions using presence-absence data. [ABSTRACT FROM AUTHOR]

This study presents a meta-analysis of a collective dataset describing the succession from abandoned fields to semi-natural grassland and heathland vegetation over the past century. The study objectives were to develop a method for statistical discrimination between abandoned fields and semi-natural habitats and to analyze the probability that an abandoned field had developed into a semi-natural habitat. A statistical classification model was developed, based on lists of vascular plants from 2059 plots from Danish semi-natural grasslands and heathlands, and abandoned fields of varying age. This model was shown to discriminate effectively between abandoned fields and semi-natural habitats, and it was found to be potentially useful for the detection of abandoned fields approaching semi-natural vegetation. We suggest that the model may help clarify restoration targets and assess biological condition in formerly cultivated areas. Statistical modeling revealed that succession age, period of abandonment and succession trajectory had significant effects on the probability that abandoned fields reached the semi-natural phase. Our study indicates that restoration projects targeting grassland and heathland should take local species pools and soil fertility into account. [ABSTRACT FROM AUTHOR]

This paper describes the use of supervised methods for the classification of vegetation. The difference between supervised classification and clustering is outlined, with reference to their current use in vegetation science. In the paper we describe the classification of Danish grasslands according to the Habitats Directive of the European Union, and demonstrate how a supervised classification can be used to achieve a standardized and statistical interpretation within a local flora. We thereby offer a statistical solution to the legal problem of protection of certain selected habitat types. The Habitats Directive protects three types of Danish grassland habitats, whereas two remaining types fall outside protection. A classification model is developed, using available Danish grassland data, for the discrimination of these five types based on their species composition. This new Habitats Directive classification is compared to a previously published unsupervised classification of Danish grassland vegetation. An indicator species analysis is used to find significant indicator species for the three protected habitat types in Denmark, and these are compared to the characteristic species mentioned in the interpretation manual of the Habitats Directive. Eventually, we discuss the pros and cons of supervised and unsupervised classification and conclude that supervised methods deserve more attention in vegetation science. [ABSTRACT FROM AUTHOR]

The vegetation of abandoned arable fields on dry sandy soils was investigated in 1986 and again in 2000. Comparison of the two data sets by ordination, calibration based on indicator values, and statistical modelling revealed that the vegetation in 2000 differed significantly from the vegetation in 1986. Part of this difference could be explained by field age, but significant difference remained after correction for age. The analysis showed that species indicating nutrient-rich and acidic conditions were more abundant in the 2000 samples than expected from the age of the fields. Possible causes for the observed differences are discussed, and the role of airborne nitrogen deposition and landscape changes is emphasised. Changing course of successional processes may place serious constraints on future habitat restoration. [Copyright &y& Elsevier]

• We explore explore the Agenda2030 potential for interdisciplinary research. • We apply the SDG, their targets and four basic principle of the Agenda2030 to a national context. • We find that localised and contextualised SDG frameworks contains a great potential as a planning and policy tool/instrument. • We argue that localised and contextualised SDG frameworks should be solid anchored in evidence-based knowledge. • We conclude that the Agenda2030 may facilitate interdisciplinary research on sustainable land use. This article explores the potential of the SDG framework for interdisciplinary research. The aim is to illustrate the process of creating a shared platform of operation by the clarifying the positive and negative interactions between societal demands for land use on a national and local level. The research question is answered by making use of the systemic approach introduced by Niklas Luhmann including his arguments about autopoietic communication systems reproducing themselves. An interdisciplinary research group is firstly applying the SDG framework to the demands for sustainable land use by activating the land consolidation in Denmark. By doing so a 'national framework' anchored in the SDG framework is created. Secondly, the national framework is applied to a multifunctional land consolidation project in a Danish case area. The findings from the mapping of interactions between societal demands on a concrete case area revealed that some indicators and societal demands are more prone to conflicts than others but also on the local level there may be variations. Thus, a localised and contextualised SDG framework has shown useful insight for future projects on sustainable land use including land consolidation projects. The paper concludes that the SDG framework may be used for facilitating interdisciplinary research, however there is also a need for guidelines and examples on how to integrate the framework in academia. The paper offers a suggestion for integrating the Agenda2030 and the SDG framework in projects about sustainable land use. [ABSTRACT FROM AUTHOR]

Background: In light of the biodiversity crisis and our limited ability to explain variation in biodiversity, tools to quantify spatial and temporal variation in biodiversity and its underlying drivers are critically needed. Inspired by the recently published ecospace framework, we developed and tested a sampling design for environmental and biotic mapping. We selected 130 study sites (40 × 40 m) across Denmark using stratified random sampling along the major environmental gradients underlying biotic variation. Using standardized methods, we collected site species data on vascular plants, bryophytes, macrofungi, lichens, gastropods and arthropods. To evaluate sampling efficiency, we calculated regional coverage (relative to the known species number per taxonomic group), and site scale coverage (i.e., sample completeness per taxonomic group at each site). To extend taxonomic coverage to organisms that are difficult to sample by classical inventories (e.g., nematodes and non-fruiting fungi), we collected soil for metabarcoding. Finally, to assess site conditions, we mapped abiotic conditions, biotic resources and habitat continuity. Results: Despite the 130 study sites only covering a minute fraction (0.0005%) of the total Danish terrestrial area, we found 1774 species of macrofungi (54% of the Danish fungal species pool), 663 vascular plant species (42%), 254 bryophyte species (41%) and 200 lichen species (19%). For arthropods, we observed 330 spider species (58%), 123 carabid beetle species (37%) and 99 hoverfly species (33%). Overall, sample coverage was remarkably high across taxonomic groups and sufficient to capture substantial spatial variation in biodiversity across Denmark. This inventory is nationally unprecedented in detail and resulted in the discovery of 143 species with no previous record for Denmark. Comparison between plant OTUs detected in soil DNA and observed plant species confirmed the usefulness of carefully curated environmental DNA-data. Correlations among species richness for taxonomic groups were predominantly positive, but did not correlate well among all taxa suggesting differential and complex biotic responses to environmental variation. Conclusions: We successfully and adequately sampled a wide range of diverse taxa along key environmental gradients across Denmark using an approach that includes multi-taxon biodiversity assessment and ecospace mapping. Our approach is applicable to assessments of biodiversity in other regions and biomes where species are structured along environmental gradient. [ABSTRACT FROM AUTHOR]

We present a gradient analysis of 620 vegetation samples covering most of the floristic and environmental variation in semi-natural grassland vegetation on well-drained soils in Denmark. Vegetation was sampled using frequency in subplots. Explanatory variables were surface inclination, aspect, pH, geographical co-ordinates together with indications of soil type. Detrended Correspondence Analysis revealed four floristic gradients that could be interpreted in ecological terms by measured variables supplemented with site calibrations based on weighted averaging of Ellenberg4s indicator values. All four axes were interpreted using rank correlation statistics, and linear and non-linearmultiple regression of sample scores on explanatory variables. The first gradient was from dry calcareous to humid acidic grasslands; thesecond reflected an underlying gradient in fertility; the third reflected regional differentiation and the fourth was associated with variation in intensity of competition as indicated by association with calibrated Grime-CSR values for the plots. We applied subset ordination to the data as a supplement to traditional permutation and correlation statistics to assess the consistency of ordination results. DCA axes 1 and 2 were consistent in space and time. This gradient analysisis discussed in a context of plant strategy theory and species diversity models. Ecocline patterns lend support to the view that grazing not only favours the ruderal strategy but also the stress-tolerant strategy. The low rank of competition as an explanatory variable for the floristical gradients supports the notion that competitive effects play a subordinate role for species composition compared to microclimate and soil conditions in infertile semi-natural grasslands [ABSTRACT FROM AUTHOR]

A hierarchic classification of Danish semi-natural grassland vegetation on well-drained soils is presented. TWINSPAN was used for clustering of 614 samples of grassland vegetation showing floristic gradients and turnover in species composition in more dimensions. The optimalhierarchic level of clustering was determined by indicator species analysis. The classification was interpreted in terms of variables relating to abiotic environment and vegetation structure and to major ecoclines previously identified by gradient analysis. The 12 final clusters were compared to syntaxa of formal phytosociology and to communities in the British Vegetation Classification. Criteria for achievingfloristically homogeneous clusters without sacrificing the ecological interpretability and validity of the clusters in time and along geographical gradients are discussed [ABSTRACT FROM AUTHOR]

In this study, data from dry temperate grassland vegetation in Denmark are used to compare the predictive power of gradients obtained by ordination. One of the problems of ordination methods based on weighted averaging, namely the assumption of symmetric, unimodal response curves, is investigated by smoothing species responses to simple and complex gradients respectively. It was found that species response types to a pH gradient are diverse and often deviate from a unimodal, symmetrical shape. Bimodal responses were also found, but they disappeared when more influential gradients were considered. Many species showed truncated responses with optima near gradient ends. In order to assess the impact of unrealistic response assumptions and reported problems with instability on the performance of DCA, the predictive potentials of measured variables and coenoclines extracted by DCA were compared. Despite field data violating the assumption of unimodal response, DCA was found to extract gradients predicting species abundance better than the environmental variables available. Shortcomings and advantages of indirect and direct methods in plant ecology are discussed [ABSTRACT FROM AUTHOR]

The majority of Earth's biodiversity is unknown. This is particularly true for the vast part of soil biodiversity, which rarely can be observed directly. Metabarcoding of DNA extracted from the environment (eDNA) has become state-of-the-art in assessing soil biodiversity. For assessing fungal communities, eDNA metabarcoding is seen as an attractive alternative to classical surveying based on fruitbodies. However, it is unknown whether eDNA metabarcoding provides a representative sample of fungal diversity and census of threatened species. Therefore conservation planning and assessment are still based on fruitbody inventories. Based on a dataset of large ecological width, representing both soil eDNA metabarcoding and expert inventories of fungal fruitbodies in Denmark, we document for the first time the validity of eDNA sampling and metabarcoding as a practical inventory method and a measure of conservation value for fungi. Fruitbody data identified fewer species in total and per site, and had larger variance in site richness. Focusing on macrofungi – the class Agaricomycetes, and in turn the order Agaricales – metrics of total richness and compositional similarity converged between the methods. eDNA was suboptimal for recording the non-soil dwelling fungi such as lichens and polypores. β-Diversity was similar between methods, but more variation in community composition could be explained by environmental predictors in the eDNA data. The fruitbody survey was slightly better at finding red listed species. We find a better correspondence between biodiversity indices derived from fungal fruitbodies and DNA-based approaches than indicated in earlier studies. We argue that (historical) fungal community data based on fruitbody forays – with careful selection of taxonomic groups – may be interpreted together with modern DNA-based approaches to obtain a richer picture of the full mycobiota of the site, and for addressing historical changes. We estimated the costs of the two inventory approaches to be approximately similar for practical applications. [ABSTRACT FROM AUTHOR]

Naturally disturbed coastal dunes have become strongly reduced during the last century due to the cessation of grazing by domestic herbivores, dune stabilization initiatives, and increasing nitrogen deposition, all promoting encroachment by grasses, shrubs and woody plants. We assessed the effects of three disturbance types (burning, trampling and blowouts) on plant and arthropod species richness and composition in dry coastal dunes in Jutland, Denmark. Environmental variables, plant presence–absence and arthropod abundance were measured in 150 1 × 2 m plots along transects in blowouts, burned areas, trampled paths and their paired controls. We used Nonmetric Multidimensional Scaling (NMDS) ordination to assess differences in species composition of disturbed areas and controls. Ordination scores were used as response variables in Linear Mixed Effect (LME) models to test for the effects of disturbances on plant and arthropod composition. Indicator species analysis revealed plant and arthropod species indicative for different disturbances. Plant and arthropod species richness and the number of annual plant species generally increased with disturbance, and plant and arthropod richness and composition responded differently to different disturbances. Arthropod communities were more diverse in disturbed plots and hosted species often found in early successional habitats of potential conservation value. Disturbance promoted β-diversity, but affected plants more than arthropods, likely because of the difference in colonization potential. A combination of disturbances maximized diversity, suggesting that re-installment of a diverse disturbance regime should be considered in dune management. [ABSTRACT FROM AUTHOR]

This study presents a meta-analysis of a collective dataset describing the succession from abandoned fields to semi-natural grassland and heathland vegetation over the past century. The study objectives were to develop a method for statistical discrimination between abandoned fields and semi-natural habitats and to analyze the probability that an abandoned field had developed into a semi-natural habitat. A statistical classification model was developed, based on lists of vascular plants from 2059 plots from Danish semi-natural grasslands and heathlands, and abandoned fields of varying age. This model was shown to discriminate effectively between abandoned fields and semi-natural habitats, and it was found to be potentially useful for the detection of abandoned fields approaching semi-natural vegetation. We suggest that the model may help clarify restoration targets and assess biological condition in formerly cultivated areas. Statistical modeling revealed that succession age, period of abandonment and succession trajectory had significant effects on the probability that abandoned fields reached the semi-natural phase. Our study indicates that restoration projects targeting grassland and heathland should take local species pools and soil fertility into account.