Jesper Erenskjold Moeslund

Topographically controlled soil moisture is the primary driver of local vegetation patterns across a lowland region

Topography is recognized as an important factor in controlling plant distribution and diversity patterns, but its scale dependence and the underlying mechanisms by which it operates are not well understood. Here, we used novel high-resolution (2-m scale) topographic data from more than 30500 vegetation plots to assess the importance of topography for local plant diversity and distribution patterns across Denmark, a 43000 km2 lowland region. The vegetation data came from 901 nature conservation sites (mean size = 0.16 km2) distributed throughout Denmark, each having an average of 34 plots (five-meter radius) per site. We employed a variety of statistical measures and techniques to investigate scale dependence and mechanistic drivers operating within the study region. Ordinary Least Squares (OLS) multiple regression modeling scaled at different spatial resolutions (2 × 2, 10 × 10, 50 × 50, 100 × 100 and 250 × 250 m) was used to identify the horizontal resolution yielding the strongest vegetation–topography ...

Geographically Comprehensive Assessment of Salt-Meadow Vegetation-Elevation Relations Using LiDAR

Salt meadows are thought to be vulnerable to habitat loss under future sea-level rise (SLR) due to inundation and compression of coastal environments (coastal squeezing). The extent of this threat is poorly understood due to the lack of geographically comprehensive impact assessments. Here, we linked vegetation data for Danish salt meadows to novel very fine-resolution digital elevation models. We developed statistical models relating plant species richness and average salt tolerance to elevation at different spatial scales. The best models were used to quantify potential impacts of SLR on Danish salt-meadow vegetation under five potential 21st-century scenarios. Overall, species richness increased with elevation (average r2 = 0.21), while average salt tolerance decreased (average r2 = 0.45). Fine resolution (≤10-m) topography was required to fully represent vegetation-elevation relationships. At >50-m resolutions only feeble links were found. Under the worst scenarios 67–74% of the Danish salt-meadow area was projected to be lost. Notably, the relatively species-rich upper meadows were predicted to shrink drastically. If realized, these impacts may have severe consequences for salt-meadow biodiversity. We note that sedimentation, not accounted for here, may allow some salt meadows to partly keep up with SLR but the extent to which this will occur and where is uncertain.

Formalized classification of European fen vegetation at the alliance level

Phytosociological classification of fen vegetation (Scheuchzerio palustris-Caricetea fuscae class) differs among European countries. Here we propose a unified vegetation classification of European fens at the alliance level, provide unequivocal assignment rules for individual vegetation plots, identify diagnostic species of fen alliances, and map their distribution. 29 049 vegetation-plot records of fenswere selected fromdatabases using a list of specialist fen species. Formal definitions of alliances were created using the presence, absence and abundance of Cocktail-based species groups and indicator species. DCA visualized the similarities among the alliances in an ordination space. The ISOPAM classification algorithm was applied to regional subsets with homogeneous plot size to check whether the classification based on formal definitions matches the results of unsupervised classifications. The following alliances were defined: Caricion viridulo-trinervis (sub-halophytic Atlantic dune-slack fens), Caricion davallianae (temperate calcareous fens), Caricion atrofusco-saxatilis (arcto-alpine calcareous fens), Stygio-Caricion limosae (boreal topogenic brown-moss fens), Sphagno warnstorfii-Tomentypnion nitentis (Sphagnumbrown-moss rich fens), Saxifrago-Tomentypnion (continental to boreo-continental nitrogen-limited brown-moss rich fens), Narthecion scardici (alpine fens with Balkan endemics), Caricion stantis (arctic brown-moss rich fens), Anagallido tenellae-Juncion bulbosi (Ibero-Atlantic moderately rich fens), Drepanocladion exannulati (arcto-borealalpine non-calcareous fens), Caricion fuscae (temperate moderately rich fens), Sphagno-Caricion canescentis (poor fens) and Scheuchzerion palustris (dystrophic hollows). The main variation in the species composition of European fens reflected site chemistry (pH, mineral richness) and sorted the plots from calcareous and extremely rich fens, through rich andmoderately rich fens, to poor fens and dystrophic hollows.

Human-driven topographic effects on the distribution of forest in a flat, lowland agricultural region

Complex topography buffers forests against deforestation in mountainous regions. However, it is unknown if terrain also shapes forest distribution in lowlands where human impacts are likely to be less constrained by terrain. In such regions, if important at all, topographic effects will depend on cultural-historical factors and thus be human-driven (anthropogenic) rather than natural, except in regions where the general climate or extreme soils limit the occurrence of forests. We used spatial regression modeling to assess the extent to which topographic factors explain forest distribution (presence-absence at a 48×48 m resolution) in a lowland agricultural region (Denmark, 43,075 km2) at regional and landscape scales (whole study area and 10×10 km grid cells, respectively), how landscape-scale forest-topography relationships vary geographically, and which potential drivers (topographic heterogeneity, forest cover, clay content, coastal/inland location) determine this geographic heterogeneity. Given a moist temperate climate and non-extreme soils all landscapes in Denmark would naturally be largely forest covered, and any topographic relationships will be totally or primarily human-driven. At regional scale, topographic predictors explained only 5% of the distribution of forest. In contrast, the explanatory power of topography varied from 0%–61% at landscape scale, with clear geographic patterning. Explanatory power of topography at landscape scale was moderately dependent on the potential drivers, with topographic control being strongest in areas with high topographic heterogeneity and little forest cover. However, these conditioning effects were themselves geographically variable. Our findings show that topography by shaping human land-use can affect forest distribution even in flat, lowland regions, but especially via localized, geographically variable effects.

Using dark diversity and plant characteristics to guide conservation and restoration

Summary 1.Dark diversity is a promising concept for prioritising management efforts as it focuses on species that are present in the regional pool, but locally absent even though environmental requirements are met. Currently, we lack knowledge of what characterises species belonging to the dark diversity more often than others, although this is important knowledge for restoration and conservation actions. 2.We applied the concept to a massive national (Danish) plant diversity database, containing 236,923 records from 15,160 surveys involving 564 species. This enabled the first geographically comprehensive (43,000 km2) assessment of dark diversity, at a spatial resolution relevant for conservation and restoration planning (78 m2) across multiple terrestrial habitats, thereby maximising the practical applications of this concept. The probability for a given plant species to belong to the dark diversity was computed and logistically regressed against variables representing its ecological preferences (e.g. nutrient availability), strategies (competitor, stress tolerant, ruderal), mycorrhizal relationships, establishment capacities (seed mass) and dispersal abilities. 3.Forty-six percent of the species had a high probability (>95%) of being part of dark diversity, whereas for 7% of the species this probability was less than 60%. 4.Typical dark diversity plants tended to depend on mycorrhiza, were mostly adapted to low light and low nutrient levels, had poor dispersal abilities and were ruderals and stress intolerant. 5.Synthesis and applications. Characterising species that are more often absent from suitable sites than others (dark diversity species) has important implications for the planning and management of natural ecosystems. From our study, practitioners gain insight into the factors triggering the absence of individual plant species in a seemingly suitable habitat. We highlight the need to carefully consider mycorrhizal inoculations with a suitable assemblage of fungi to promote the establishment success of dark diversity plants. Additionally, time lags in plant species dispersal and establishment as well as spatial connectivity in fragmented habitats are central to consider in nature management although assisted migration might also aid poor dispersers. Finally, nutrient-poor localities are probably important “islets” allowing nitrophobic dark diversity plant species to thrive within agricultural landscapes that are generally nutrient rich. This article is protected by copyright. All rights reserved.

Impacts of 21st century sea-level rise on a Danish major city – an assessment based on fine-resolution digital topography and a new flooding algorithm

This study examines the potential impact of 21st century sea-level rise on Aarhus, the second largest city in Denmark, emphasizing the economic risk to the citys real estate. Furthermore, it assesses which possible adaptation measures that can be taken to prevent flooding in areas particularly at risk from flooding. We combine a new national Digital Elevation Model in very fine resolution (~2 meter), a new highly computationally efficient flooding algorithm that accurately models the influence of barriers, and geospatial data on real-estate values to assess the economic real-estate risk posed by future sea-level rise to Aarhus. Under the A2 and A1FI (IPCC) climate scenarios we show that relatively large residential areas in the northern part of the city as well as areas around the river running through the city are likely to become flooded in the event of extreme, but realistic weather events. In addition, most of the large Aarhus harbour would also risk flooding. As much of the area at risk represent high-value real estate, it seems clear that proactive measures other than simple abandonment should be taken in order to avoid heavy economic losses. Among the different possibilities for dealing with an increased sea level, the strategic placement of flood-gates at key potential water-inflow routes and the construction or elevation of existing dikes seems to be the most convenient, most socially acceptable, and maybe also the cheapest solution. Finally, we suggest that high-detail flooding models similar to those produced in this study will become an important tool for a climate-change-integrated planning of future city development as well as for the development of evacuation plans.

Dark diversity illuminates the dim side of conservation and restoration

1 Dark diversity is a promising concept for prioritizing management efforts as it focuses on missing species, i.e., species present in the regional pool, but locally absent despite suitable environmental conditions. 2 We applied the concept to a massive national plant diversity database (236,923 records from 15,160 surveys involving 564 species) to provide the first geographically comprehensive assessment of dark diversity across a large area (43,000 km2), at a spatial scale (~75 m2) relevant for conservation and restoration planning and across multiple terrestrial habitats, thus maximising its practical application potential. The likelihood for a given plant species to belong to the dark diversity pool was computed and logistically regressed against its ecological preferences (nutrient availability, pH etc.), strategies (competitor, stress tolerance, ruderal), mycorrhizal dependence and infection percentage, seed mass and maximum dispersal distance. 3 Forty-six percent of the species were absent in >95 % of the suitable sites, whereas 7 % of the species were absent in less than 60 % of sites that were deemed suitable. 4 Species that were more likely to belong to the dark diversity tended to depend on mycorrhiza, were mostly adapted to low light and nutrient levels, had poor dispersal abilities, were ruderals and had a low stress tolerance. Synthesis and applications Our findings have important implications for the planning and management of natural ecosystems requiring detailed knowledge of what triggers the presence/absence of individual plant species in a seemingly suitable habitat. We conclude that practitioners may need to carefully consider mycorrhizal inoculations with a suitable assemblage of fungi for certain plant species to become established. Also assisted migration might be necessary to help poor dispersers although spatial and temporal processes are also important to have in mind. Finally, it is important to vary nutrient loads making room for plant species to colonise both nutrient-poor and nutrient-rich localities.

Predicting provenance of forensic soil samples: soil DNA predicts habitat and environmental properties

Environmental DNA is increasingly applied in ecological studies, including forensic ecology where 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 in predicting provenance in terms of environmental conditions, habitat characteristics and geographic regions. We used linear regression for predicting environmental gradients of light, moisture, soil pH and nutrients (represented by Ellenberg Indicator Values, EIVs) and quadratic discriminant analysis (QDA) to predict habitat class and geographic region. We found high predictive power for environmental gradients (R2 > 0.73). The discriminatory power of QDA in predicting habitat characteristics varied from high accuracy in predicting certain forest types, less accurate prediction of heathland and poor accuracy for geographic region. We demonstrate the application of provenance prediction in forensic science by evaluating and discussing two mock crime scenes. Here, we supplement with plant species lists from annotated sequences. Where predictions of environmental gradients and habitat classes give an overall accurate description of a crime scene, care should be taken when interpreting annotated sequences, e.g. due to erroneous assignments in GenBank. The outlined approach clearly demonstrates that basic ecological information that can be extracted from soil eDNA, contributing to the range of potential applications of eDNA in forensic ecology.