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Following decades of declines, populations of large fish recently started to increase in the North Sea, presumably due to reduced fishing pressure. However, population recovery may be too readily claimed, since standardised sampling of fish stocks commenced only in the 1970s, well after many species had already collapsed. A true recovery must be seen from a long-term perspective. The critically endangered common skate (Dipturus batis, Rajidae) species complex is an example of a large-bodied fish that mostly disappeared before standardised monitoring took place. Here, we put the recent increase in population size into a 120-year perspective, throughout three geographical divisions in the North Sea. We analysed a large range of mostly undisclosed historical data and contemporary sources. A reconstruction of Dutch commercial landings data confirms that the species used to be very abundant between 1901 and 1920, and shows how it steadily declined from 1920 onwards until it got extirpated around 1970. Based on a quantitative analysis of standardised catch numbers from fishery-independent surveys time, we conclude that the current abundance of the species is still below historical baselines and represents a local recovery at most. We further demonstrate a prominent and consistent pattern in size distribution, with larger (mature) individuals only occurring in the northern North Sea. A large dataset on historical stomach contents from the central North Sea confirmed the diet of young common skate, which consisted predominantly of shrimps. Our review exemplifies the importance of marine historical ecology to deduce the natural richness of the North Sea.

In this Chapter we review studies that model the dynamics of tropical savannas and the effects of grazing and browsing on the vegetation. Many empirical studies illustrate the large impact that grazers and browsers can have on savanna vegetation, both directly and indirectly. We summarize this understanding in a simple model to capture the dynamics of trees, grasses, herbivores and fire in tropical savannas. This model is based on the assumption that herbivores can trigger a positive feedback mechanism between fuel load (grass biomass), fire intensity and damage of fire to trees. The positive feedback mechanism can lead to savanna vegetation where either both trees and grasses co-occur (savanna), or a state where only trees occur (i.e. woodland). As a direct relation exists between vegetation and the density of herbivores, in this model we explore what the effect is that dynamic interactions between vegetation and herbivore populations can have on the stability of savanna vegetation. By including the interactions between herbivore population growth and forage availability a negative feedback is introduced, that modifies the positive feedback resulting in reduction of the possibility that savanna vegetation shifts from tree-grass coexistence to tree-dominated vegetation. In this Chapter we demonstrate the importance of grazing and browsing in this process in tropical savannas, especially when populations of grazers and browsers are free-ranging, without movement limitations, so that herbivores can migrate to prevent food shortage during the dry season. Limitations on movement may lead to overexploitation of the vegetation by both grazers and browsers and, hence, to shifts from tree-grass coexistence to tree-dominated vegetation. The model presented in this Chapter brings together numerous studies on the influence of grazing and browsing on tropical savanna vegetation and generates predictions to be tested by future studies.

Rich fens are known for their high botanical diversity encompassing many endangered species. For decades, several management measures, including mowing and burning, have been applied to maintain a high biodiversity by means of slowing down the natural succession from calcareous rich fens to acidic poor fens or woodland. In this study, we assessed the long-term effects of these traditional management measures, and explored the effectiveness of liming as a measure to restore rich fen vegetation. Effects of summer mowing, and of burning after winter mowing, were assessed by comparing current (2013) and historical (1967) vegetation data. Effects of experimental liming, using different levels of lime addition (0, 1000, 2000, and 4000 kg Dolokal/ha), were monitored in the field during 7.5 years. Summer mowing led to more acidic and nutrient-poor conditions as indicated by a shift from rich to poor fen vegetation, including a well-developed bryophyte cover dominated by Sphagnum with some threatened species. Burning (after winter mowing) counteracted acidification but increased nutrient availability, as indicated by dominance of vascular species characteristic of productive tall-herb grasslands and a sparse bryophyte cover with common species. We conclude that the traditional measures were unable to maintain rich fen composition in the long term. Given the fact that the restoration of hydrological conditions, favouring rich fens, is not always feasible, liming could be an alternative to counteract acidification and improve rich fen conditions in the short term. This measure, however, appeared to be unsustainable as the re-establishment and dominance of Sphagnum spp. seriously complicated the development of rich fen vegetation in the longer term.

Late blight is an important disease in potato that is caused by the oomycete Phytophthora infestans. In the past, Solanum demissum late blight resistance (R) genes were introgressed into cultivated potato (Solanum tuberosum). Eleven of these resistant plants were selected to characterize the virulence spectrum of individual P. infestans isolates and to monitor the dynamics of virulence in P. infestans populations. These plants are referred to as the Mastenbroek and Black differential sets. It has long been assumed that each differential plant contained one single R gene. In the current study and previous studies, however, most Mastenbroek differential plants were shown to harbor multiple R gene(s), which blurs virulence typing of late blight isolates. In order to acquire more accurate virulence profiles, we extended the Mastenbroek differential set with Solanum spp. plants harboring reduced R gene complexity and with plants containing recently identified R genes from related but different Solanum species. In addition, a differential set of ten Genetically Modified (GM) plants harboring single late blight R genes in the same genetic background (Desiree). By analyzing the virulence spectra of recently collected isolates using both newly described differential sets, we found that the GM Desiree differential set was more accurate for isolate virulence typing than the conventional (extended) differential set. Besides, the GM Desiree differential set was shown to be useful as trap plants to isolate novel P. infestans strains and to monitor virulence towards particular R genes in P. infestans populations `on site´. Legislative restrictions are, however, limiting the use of the GM Desiree differential set.

Most hydrological studies do not account for the socio-economic influences on eco-hydrological processes. However, socio-economic developments often change the water balance substantially and are highly relevant in understanding changes in hydrological responses. In this study a multi-disciplinary approach was used to study the cascading impacts of socio-economic drivers of land use and land cover (LULC) changes on the eco-hydrological regime of the Lake Naivasha Basin. The basin has recently experienced substantial LULC changes exacerbated by socio-economic drivers. The simplified cascade models provided insights for an improved understanding of the socio-ecohydrological system. Results show that the upstream population has transformed LULC such that runoff during the period 1986–2010 was 32% higher than during the period 1961–1985. Cut-flower export volumes and downstream population growth explain 71% of the water abstracted from Lake Naivasha. The influence of upstream population on LULC and upstream hydrological processes explained 59% and 30% of the variance in lake storage volumes and sediment yield respectively. The downstream LULC changes had significant impact on large wild herbivore mammal species on the fringe zone of the lake. This study shows that, in cases where observed socio-economic developments are substantial, the use of a cascade-modeling approach, that couple socio-economic factors to eco-hydrological processes, can greatly improve our understanding of the eco-hydrological processes of a catchment.

Conservation management is expected to increase local biodiversity, but uniform management may lead to biotic homogenization and diversity losses at the regional scale. We evaluated the effects of renewed grazing and cutting management carried out across a whole region, on the diversity of plants and seven arthropod groups. Changes in occurrence over 17 years of intensive calcareous grassland management were analysed at the species level, which gave insight into the exact species contributing to regional homogenization or differentiation. Reponses were compared between species differing in habitat affinity, dispersal ability, food specialisation and trophic level. Local species richness increased over the sampling period for true bugs and millipedes, while carabid beetles and weevils declined in local species richness. Species richness remained unchanged for plants, woodlice, ants and spiders. Regional diversity and compositional variation generally followed local patterns. Diversity shifts were only to a limited extent explained by species’ habitat affinity, dispersal ability, trophic level and food specialisation. We conclude that implementation of relatively uniform conservation management across a region did not lead to uniform changes in local species composition. This is an encouraging result for conservation managers, as it shows that there is not necessarily a conflict of interest between local and regional conservation goals. Our study also demonstrates that shifts in diversity patterns differ markedly between taxonomic groups. Single traits provide only limited understanding of these differences. This highlights the need for a wide taxonomic scope when evaluating conservation management and demonstrates the need to understand the mechanisms underlying occurrence shifts.

The impact of silver nanoparticles (AgNP; at 0mg Ag/kg, 1.5mg Ag/kg, 15.4mg Ag/kg, and 154mg Ag/kg soil) and silver nitrate (AgNO3; 15.4mg Ag/kg soil) on earthworms, Lumbricus rubellus, was assessed. A 4-wk exposure to the highest AgNP treatment reduced growth and reproduction compared with the control. Silver nitrate (AgNO3) exposure also impaired reproduction, but not as much as the highest AgNP treatment. Long-term exposure to the highest AgNP treatment caused complete juvenile mortality. All AgNP treatments induced tissue pathology. Population modeling demonstrated reduced population growth rates for the AgNP and AgNO3 treatments, and no population growth at the highest AgNP treatment because of juvenile mortality. Analysis of AgNP treated soil samples revealed that single AgNP and AgNP clusters were present in the soil, and that the total Ag in soil porewater remained high throughout the long-term experiment. In addition, immune cells (coelomocytes) of earthworms showed sensitivity to both AgNP and AgNO3 in vitro. Overall, the present study indicates that AgNP exposure may affect earthworm populations and that the exposure may be prolonged because of the release of a dissolved Ag fraction to soil porewater. Environ Toxicol Chem 2014;33:743-752. © 2013 SETAC.

Key grazing lands that provide dry season forage to both resident and migrating ungulates may experience heavy grazing impacts during the dry season, thereby jeopardizing future forage productivity. In this study a herbivore exclosure experiment was used to quantify the effects of grazing by large ungulates on herbaceous regrowth and residual aboveground biomass in a fragmented key resource area; the fringe zone around Lake Naivasha, Kenya. Top-down control mechanisms were prevalent in both the dry and wet seasons suggesting the existence of a high resident herbivore density. Intense grazing significantly reduced residual biomass that in turn reduced plant regrowth. An increased frequency of defoliation reduced regrowth during the dry season demonstrating the negative effect resulting from high herbivore densities during the dry season. This study indicates that grazing exerts a higher control on regrowth than rainfall as heavily grazed residual biomass did not recover during the following wet season.

The impact of silver nanoparticles (AgNP; at 0¿mg Ag/kg, 1.5¿mg Ag/kg, 15.4¿mg Ag/kg, and 154¿mg Ag/kg soil) and silver nitrate (AgNO3; 15.4¿mg Ag/kg soil) on earthworms, Lumbricus rubellus, was assessed. A 4-wk exposure to the highest AgNP treatment reduced growth and reproduction compared with the control. Silver nitrate (AgNO3) exposure also impaired reproduction, but not as much as the highest AgNP treatment. Long-term exposure to the highest AgNP treatment caused complete juvenile mortality. All AgNP treatments induced tissue pathology. Population modeling demonstrated reduced population growth rates for the AgNP and AgNO3 treatments, and no population growth at the highest AgNP treatment because of juvenile mortality. Analysis of AgNP treated soil samples revealed that single AgNP and AgNP clusters were present in the soil, and that the total Ag in soil porewater remained high throughout the long-term experiment. In addition, immune cells (coelomocytes) of earthworms showed sensitivity to both AgNP and AgNO3 in vitro. Overall, the present study indicates that AgNP exposure may affect earthworm populations and that the exposure may be prolonged because of the release of a dissolved Ag fraction to soil porewater.

Current conservation biology suggests that across ecological time-scales specialist species existing in the recent past have left on average fewer descendant populations today than generalist species. Conversely, the speciation literature suggests that on an evolutionary time-scale specialists leave as many or more descendant lineages as generalists, i.e. they have high rates of global diversification. This begs the question: which of these two processes has more influence on the regional scale, i.e. do specialists leave more or fewer descendants than generalists within a region? Location The flora of the Netherlands. Methods We quantified niche volume of 707 plant species from coexistence data and ecological indicator values and used sister taxon comparisons to compare specialist and generalist sister taxa for the relative numbers of descendants across three temporal scales: ecological, microevolutionary and macroevolutionary. We show, first, that specialist species are more likely to be currently declining, i.e. to leave only few descendant populations. Second, specialists are less likely to be currently diversifying into intra-specific taxa. Finally, most specialist clades left fewer descendant species within a region than their generalist sister clades. These results were consistent across sublineages, unbiased by geographic sampling of lineages and environments, and held after accounting for species life histories. Differences between specialist and generalist sister clades increased with clade age, suggesting that they reflect differences in rates at which specialists left descendants (rather than differences in ecological limits to the numbers of specialists and generalists). Main conclusionsSpecialists left only few descendants within a region (i.e. the Netherlands), both at ecological, microevolutionary and macroevolutionary scales. While specialists may leave numerous evolutionary descendants at a global scale, these might be absent from most regions. Humans, by threatening specialist species, may hence further accelerate biotic homogenization with descendants of generalist lineages proliferating within regions while specialist lineages disappear.

Under the United Nations Framework Convention for Climate Change all Parties have to report on carbon emissions and removals from the forestry sector. Each Party can use its own approach and country specific data for this. Independently, large-scale models exist (e.g. EFISCEN and G4M as used in this study) that assess emissions and removals from this sector by applying a unified approach to each country, still often based on country specific data. Differences exist between the national reported values and the calculations from the large scale models. This study compares these models with national reporting efforts for 24 EU countries for the period 2000–2008, and identifies the most likely causes for differences. There are no directly identifiable single input parameters that could be targeted to fully close the gap between country and model estimates. We found that the method applied by the country (i.e. stock-difference or gain-loss) contributes significantly to differences for EFISCEN and was the best explaining variable for G4M, although for the latter it was not significant. Other variables (biomass expansion factors, harvest volumes and the way harvest losses are treated) were not found to provide a conclusive explanation for the differences between the model estimations and the country submissions in an over-al analysis. However, at the level of individual countries several different causes for differences were identified. This suggests that to really close the gap between country submissions and large scale models, close collaboration between modellers and country experts is needed, calling for openness and willingness to share relevant data and to compare GHG inventories with independent estimates. This would enable to improve the confidence both in historical GHG inventories and in the models which are needed to project the future forest sink for several policy issues.

It was shown that in the years when the numbers of the Arctic foxes are high, even though the lemming numbers are high as well, Brent geese nest considerably closer to owls' nests than in the years with low Arctic fox numbers. At values of the Arctic fox densities greater than one breeding pair per 20 km(2), the factor of lemming numbers ceases to affect the distance between owl and geese nests. This distance becomes dependent on the Arctic fox density (numbers). When the Arctic fox density is greater than the pronounced threshold, the owl-Brent internest distance is inversely and linearly related to the Arctic fox density. DOI: 10.1134/S106235901301007X [KEYWORDS: rough-legged buzzards peregrine falcons taimyr peninsula lemmings]

We give a general overview of forest inventory developments and their potential to estimate forest carbon budgets and GHG emissions. Forest inventories mostly focus on timber resources, but can be extended to cover other forest characteristics, such as forest biomass. From forest biomass, ecosystem carbon content can be derived. Forest inventory comprises of ground-based and space-based techniques, and the combination of the two provides a versatile scheme for carbon storage assessment. Large uncertainties remain in the estimation of soil carbon, as well as in the attribution and assessment of mitigation associated with the use of forest products, for example in substituting for high-energy building materials. Together, significant uncertainty remains in assessing and reporting of carbon storage and greenhouse mitigation with respect to forest-related land use and land use change.

Especially in urbanized landscapes, habitat fragmentation and increasing numbers of infrastructural features may limit genetic exchange among wildlife populations. Yet, whether this results in genetic differentiation among individuals in different habitat fragments will depend on both the species studied and the composition of the landscape. European pine martens (Martes martes) show clear spatial structure at a Europe-wide scale, but whether gene flow among habitat patches can be maintained at a more local scale in intensively urbanized areas remained unclear. Here, we analysed genotypic data from 270 pine martens sampled from locations scattered across the Netherlands, one of the most densely populated areas in the world. Using Bayesian clustering models we show that most likely maximum two large subpopulations exist in the Netherlands. We observed relatively low levels of genetic differentiation and genetic evidence of regular long-distance dispersal by juveniles that must have crossed one or multiple major highways. Our results suggest that genetic exchange among Dutch pine martens has, until 2010, not been impacted severely by the countries’ dense infrastructural network. Furthermore this species seems to have maintained its genetic diversity despite a recent demographic bottleneck. These conclusions support the idea that the effects of habitat fragmentation may strongly differ between (groups of) species, and that prioritization and optimization of management decisions thus requires direct study of the targeted species.

Species’ life-history traits underlie species–environment relationships. Therefore, analysis of species traits, combined into life-history strategies, can be used to identify key factors shaping the local species composition. This is demonstrated in a case-study on ants in chalk grasslands. We developed four life-history strategies based on traits related to reproduction, development, dispersal and synchronization that are documented in the literature. These theoretical strategies reflect different responses to certain environmental conditions. They can be characterized as generalists (G), poor dispersers (D), species whose distribution is limited to sites with high food availability (F) and species that are restricted to sites with high soil temperatures during nest founding (T). Next, we tested whether the occurrence of these strategies differed between six Dutch chalk grasslands and four reference sites situated in Germany and Belgium. We found significant differences in species numbers between sites for strategies D and T but not for strategies F and G. The differences could be explained by differences in connectivity and microhabitat conditions; species richness of strategy D decreased exponentially with increasing distance to the next nearest chalk grassland, while summer soil temperature strongly affected species richness of strategy T. From these relationships we could successfully identify the most relevant bottlenecks for the occurrence of both of these strategies in Dutch chalk grasslands. Management recommendations resulting from this analysis include adapting the management timing in Dutch chalk grasslands and focussing on counteracting habitat isolation. With this case-study we demonstrate that the life-history strategy approach is a valuable alternative to approaches that try to identify key factors by analysing the variation in environmental parameters. The main advantage of the presented alternative is the focus on mechanistically understanding species responses, allowing a comparison of processes rather than occurrences of single species.

Least weasels are highly specialized small-rodent predators. Despite the fact that they are hypothesized to play an important role in generating the lemming cycles, a key process for the functioning of the terrestrial tundra ecosystem,. very little is known about the biology of these miniature carnivores in the Arctic. At Mys Vostochny in western Taimyr, Russia, least weasels were observed for the first time during a lemming peak in 2005, but not in two subsequent years with low lemming densities. Here we report observations about weasel signs in lemming winter nests, body condition, habitat use, and diet in summer 2008, a year when lemmings had been numerous under the snow but populations crashed before the summer, and least weasels were abundant. Stable isotope analyses revealed that weasel diet was dominated by Siberian lemmings during spring. As expected, given lower resource availability when the lemming population crashed, weight (taking into account body length) was somewhat lower in 2008 than in 2005. Tracking tunnels and trapping showed that in summer least weasels mostly used sheltered habitats such as rocky outcrops and driftwood. Together with surveys of lemming winter nests, tracking tunnels appeared to be a promising method for monitoring least weasels in the Arctic tundra.

Many migratory herbivores seem to follow the flush of plant growth during migration in order to acquire the most nutrient-rich plants. This has also been hypothesized for arctic-breeding geese, but so far no test of this so-called green wave hypothesis has been performed at the individual level. During four years, a total of 30 greater white-fronted geese Anser albifrons albifrons was tracked using GPS transmitters, of which 13 yielded complete spring migration tracks. From those birds we defined stopover sites and related the date of arrival at each of these stopovers to temperature sum (growing degree days, GDD), snow cover, accumulated photoperiod and latitude. We found that geese arrived at spring stopovers close to the peak in GDD jerk; the ‘jerk’ is the third derivative, or the rate of change in acceleration, and GDD jerk maxima therefore represent the highest acceleration of daily temperature per site. Day of snow melt also correlated well with the observed arrival of the geese. Factors not closely related to onset of spring, i.e. accumulated photoperiod and latitude, yielded poorer fits. A comparison with published data revealed that the GDD jerk occurs 1–2 weeks earlier than the onset of spring derived from NDVI, and probably represents the very start of spring growth. Our data therefore suggest that white-fronted geese track the front of the green wave in spring

In the peat bogs of the Bieszczady National Park an inventory of the Black bog ant (Formica picea Nyl.) was made in order to get an impression of the probability of its survival in SE Poland. Three habitat networks are distinguished, which are situated too far from each other for (re)colonization by means of flying queens. The largest network includes five peat bogs. In two of them F. picea was found. The species was not found in peat bogs which belong to the other habitat networks. The quality of the peat bogs depends on management strategies, currently challenged by two main threats: desiccation and the influx of nutrients. This process will speed up the succession of the vegetation. As a result dwarf shrubs are encroaching on habitat areas of F. picea, where Sphagnum species are still dominating in the moss layer

The food of the last remaining population of garden dormouse (Eliomys quercinus) in the Netherlands is studied by means of analysing faecal samples, collected in the summer and autumn of the year 2010. In total 139 scat samples were collected from 51 different nest boxes. The samples were visually analysed for the presence (or absence) of different animal and vegetable food items using a stereo microscope. Millipedes (Diplopoda), beetles (Coleoptera) and snails (Gastropoda) were found to be the main animal food sources. Important vegetable food remains were the fruit pulp of apples, pears and seeds. The identified seeds were the remains of blackberries (Rubus ssp.) and elderberries (Sambucus nigra). The results were skewed by someone feeding the garden dormice with apples and pears. All the other food items were collected by the garden dormice themselves. These animal and vegetable food sources were present in more than 20% of the samples. Hymnopterans (Hymenoptera), earthworms (Lumbricidae), spiders (Araneae), harvestmen (Opiliones) and wood mice (Apodemus sylvaticus) were present in 5% to 20% of the samples. Flies (Diptera), true bugs (Heteroptera), woodlice (Isopoda), pseudoscorpions(Pseudoscorpiones), butterfly larvae (caterpillars) (Lepidoaptera), songbirds (Passeriformes) and flowers were occasionally found. Invertebrates, especially millipedes, are the staple food during the entire active feeding period.In spring and early summer the garden dormouse eats relatively more vertebrates (possibly mainly the nestlings of birds and mice), gastropods, beetles and flowers, than in August-November. The first seeds of berries were identified in the beginning of August. The occurrence of seeds increased rapidly to 90% at the end of August and then decreased to 30% in September and 0% by the end of October. Garden dormice in woods seem to depend on the rich invertebrate fauna within the litter layer. Mesotrophic mull soils have a rich fauna of medium-sized to large invertebrates and these soils are disappearing from the Savelsbos as a result of traditional management practices being abandoned. Re-establishment of species-rich wood types that produce mesotrophic mull soils could be of benefit to the remnant population of garden dormouse in the Savelsbos.

To improve the ecological functioning of riverine ecosystems, large-scale floodplain rehabilitation has been carried out in the Rhine–Meuse Delta since the 1990s. This paper evaluates changes in abundance of 93 breeding bird species over a period of 10 years in response to rehabilitation, by comparing population changes in 75 rehabilitated sites with 124 non-rehabilitated reference sites. Such quantitative, multi-species, large-scale and long-term evaluations of floodplain rehabilitation on biodiversity are still scarce, particularly studies that focus on the terrestrial component. We try to understand the effects by relating population trends to ecological and life-history traits and strategies of breeding birds. More specifically, we try to answer the question whether rehabilitation of vegetation succession or hydro-geomorphological river processes is the key driver behind recent population changes in rehabilitated sites. Populations of 35 species have significantly performed better in rehabilitated sites compared to non-rehabilitated floodplains, whereas only 8 have responded negatively to rehabilitation. Differences in effects between species are best explained by the trait selection of nest location. Reproductive investment and migratory behaviour were less strong predictors. Based on these three traits we defined eight life-history strategies that successfully captured a substantial amount of variation in rehabilitation effects. We conclude that spontaneous vegetation succession and initial excavations are currently more important drivers of population changes than rehabilitation of hydrodynamics. The latter are strongly constrained by river regulation. If rehabilitation of hydro-geomorphological processes remains incomplete in future, artificial cyclic floodplain rejuvenation will be necessary for sustainable conservation of characteristic river birds

Hollands duinen bezitten geschikt leefgebied voor bosmieren, vooral op plaatsen waar een eikenberkenbos tot ontwikkeling is gekomen, zoals in de vallei Bierlap in de duinen bij Den Haag. In dit bos hebben veel studenten tijdens de jaarlijkse cursus ecologie onderzoek verricht naar de relatie tussen bosmieren en andere soorten die in het duin leven. Daartoe werden soms dagen achtereen mieren geteld die naar en van een mierennest liepen, al of niet met een prooi in hun kaken. De laatste tien jaar is echter het aantal bosmieren teruggelopen. Getracht is de vraag te beantwoorden of dit een gevolg kan zijn van introductie van grote grazers (koeien en paarden) in het duingebied

a b s t r a c t Most seabirds live in large colonies. This fact signifies that there is an advantage in living and breeding together. Four explanations are put fore ward for this colonial behaviour, more birds have: (1) a reduced per capita predation of chicks in colonies, (2) a better anti-predator defence, (3) a more efficient forag- ing in temporally patchy environments and (4) sex ratios that are more likely to be close to one. These factors induce a strong Allee-type density-dependent relation, a positive relation between density and population growth rate at low density. Nevertheless, these Allee effects are generally ignored in seabird population studies. Therefore we study the consequences of introducing Allee-type density-dependent relations in a spatially explicit metapopulation model for the Common Tern (Sterna hirundo). Simulations show that Allee effects might be responsible for a 20-fold decline in the recolonization distances, causing patches and parts of metapopulations to effectively become more isolated. This leads to long recoloniza- tion times of empty breeding patches which consequently cause slower metapopulation expansion and recovery. Additionally, we show that the typical early warning signals, that show that a population is near its critical threshold induce by Allee effects, is less pronounced in colonies that are part of a metapopu- lation. Hence, we offer some simple equations to estimate critical densities and thresholds in a colony.

In de omgeving van Ommen komen zeldzame en kwetsbare mierensoorten voor van het geslacht Formica. Enkele soorten zijn wettelijk beschermd, onder andere de stronkmier. Deze komt in ons land vrijwel uitsluitend in deze regio voor. Op grond van de verspreidingsgegevens van de stronkmier van 1995 is de Besthmenerberg bij Ommen beschouwd als het kerngebied van de regionale metapopulatie. Het aantal nesten is echter gedurende de afgelopen 20 jaar aanzienlijk afgenomen.

In ons land zetten ongeveer 40.000 vrijwilligers zich in voor het behoud van de kwaliteit van natuur en landschap. Voor zover de doelmatigheid van het werk te wensen overlaat, kan deze worden vergroot door in een vroeg stadium doel en werkwijze met alle betrokkenen te bespreken. Dat kan het contact bevorderen tussen vrijwilligers die inventariseren en vrijwilligers die helpen bij het terreinbeheer. Wanneer het resultaat daarvan via de pers of tijdens een voorlichtingsbijeenkomst aan omwonenden van het betreffende gebied kenbaar wordt gemaakt, voorkomt dit niet alleen nodeloze drukte over impopulaire maatregelen.

Voor het beschermen en ontwikkelen van natuur wordt het steeds belangrijker de verschillende functies van natuur voor het voetlicht te brengen en daarmee coalities te sluiten met andere maatschappelijke groeperingen, die belang hebben bij één of meerdere van deze functies. Ook het verdienen van geld met natuur komt steeds prominenter op de agenda, zeker in deze tijd van draconische bezuinigingen op natuurbeheer (minstens 40% minder, oftewel ruim 300 miljoen). Dit vraag van natuurbeheerders nieuwe vaardigheden, die ook in de groene opleidingen een plaats moeten krijgen. Voormalig vliegveld Soesterberg wordt omgevormd tot een natuurgebied met ook de functie recreatie. Door de functies woningbouw en recreatie (zweefvliegen) te combineren kon er een gebied ontstaan waar cultuurhistorie, ecologie en recreatie elkaar fysiek en financieel versterken

Hosts belonging to the same species suffer dramatically different impacts from their natural enemies. This has been explained by host neighbourhood, that is, by surrounding host-species diversity or spatial separation between hosts. However, even spatially neighbouring hosts may be separated by many million years of evolutionary history, potentially reducing the establishment of natural enemies and their impact. We tested whether phylogenetic isolation of oak hosts from neighbouring trees within a forest canopy reduces phytophagy. We found that an increase in phylogenetic isolation by 100 million years corresponded to a 10-fold decline in phytophagy. This was not due to poorer living conditions for phytophages on phylogenetically isolated oaks. Neither species diversity of neighbouring trees nor spatial distance to the closest oak affected phytophagy. We suggest that reduced pressure by natural enemies is a major advantage for individuals within a host species that leave their ancestral niche and grow among distantly related species.

De huidige klimaatmodellen voorspellen voor West-Europa een verdere temperatuurstijging en meer perioden met droogte en hittegolven. Dat kan belangrijke gevolgen hebben voor het optreden van insectenplagen en daarbij zijn er zowel directe als indirecte effecten.

Extensive degradation of ecosystems, combined with the increasing demands placed on the goods and services they provide, is a major driver of biodiversity loss on a global scale. In particular, the severe degradation of large rivers, their catchments, floodplains and lower estuarine reaches has been ongoing for many centuries, and the consequences are evident across Europe. River restoration is a relatively recent tool that has been brought to bear in attempts to reverse the effects of habitat simplification and ecosystem degradation, with a surge of projects undertaken in the 1990s in Europe and elsewhere, mainly North America. Here, we focus on restoration of the physical properties (e.g. substrate composition, bank and bed structure) of river ecosystems to ascertain what has, and what has not, been learned over the last 20 years. First, we focus on three common types of restoration measures—riparian buffer management, instream mesohabitat enhancement and the removal of weirs and small dams—to provide a structured overview of the literature. We distinguish between abiotic effects of restoration (e.g. increasing habitat diversity) and biological recovery (e.g. responses of algae, macrophytes, macroinvertebrates and fishes). We then addressed four major questions: (i) Which organisms show clear recovery after restoration? (ii) Is there evidence for qualitative linkages between restoration and recovery? (iii) What is the timescale of recovery? and (iv) What are the reasons, if restoration fails? Overall, riparian buffer zones reduced fine sediment entry, and nutrient and pesticide inflows, and positive effects on stream organisms were evident. Buffer width and length were key: 5–30 m width and > 1 km length were most effective. The introduction of large woody debris, boulders and gravel were the most commonly used restoration measures, but the potential positive effects of such local habitat enhancement schemes were often likely to be swamped by larger-scale geomorphological and physico-chemical effects. Studies demonstrating long-term biological recovery due to habitat enhancement were notable by their absence. In contrast, weir removal can have clear beneficial effects, although biological recovery might lag behind for several years, as huge amounts of fine sediment may have accumulated upstream of the former barrier. Three Danish restoration schemes are provided as focal case studies to supplement the literature review and largely supported our findings. While the large-scale re-meandering and re-establishment of water levels at River Skjern resulted in significant recovery of riverine biota, habitat enhancement schemes at smaller-scales in other rivers were largely ineffective and failed to show long-term recovery. The general lack of knowledge derived from integrated, well-designed and long-term restoration schemes is striking, and we present a conceptual framework to help address this problem. The framework was applied to the three restoration types included in our study and highlights recurrent cause–effect chains, that is, commonly observed relationships of restoration measures (cause) and their effects on abiotic and biotic conditions (effect). Such conceptual models can provide useful new tools for devising more effective river restoration, and for identifying avenues for future research in restoration ecology in general.

Theoretical approaches, such as the Lotka–Volterra framework, enable predictions about long term species coexistence based on stability criteria, but generally assume temporal constancy of system equations and parameters. In real world systems, temporal variability may interfere with the attainment of stable states. Managed grassland ecosystems in Northwestern Europe experience structural periodic fluctuations in environmental conditions: the seasons. In addition, periodic disturbances such as cutting are very common. Here we show, using a Lotka–Volterra system applied to grassland species with empirically derived parameters, that seasonal variability can result in a time dependent equilibrium and redirection of displacement processes. Parameter estimates differed between species and – in most cases – between the seasons. As a result, five of the fifteen tested species combinations had different outcomes of species interactions between seasons. This indicates that systems remain in dynamic transience over the year as the equilibrium changes and the species composition of the system follows the equilibrium without ever attaining it. The non-attainment of the steady state enables coexistence of species even if there is competitive exclusion in one of the seasons. For three of the fifteen species combinations, cutting frequency affected the long-term coexistence patterns. Cutting resets the biomass of competing species and favours during regrowth those species that have a high growth rate, which can alter species coexistence in comparison to a Lotka–Volterra model without cutting. The Lotka–Volterra framework with seasonally changing empirical parameters predicts coexistence as a possible outcome of systems that in component seasons are characterised by exclusion, and vice versa.

Plant traits – the morphological, anatomical, physiological, biochemical and phenological characteristics of plants and their organs – determine how primary producers respond to environmental factors, affect other trophic levels, influence ecosystem processes and services and provide a link from species richness to ecosystem functional diversity. Trait data thus represent the raw material for a wide range of research from evolutionary biology, community and functional ecology to biogeography. Here we present the global database initiative named TRY, which has united a wide range of the plant trait research community worldwide and gained an unprecedented buy-in of trait data: so far 93 trait databases have been contributed. The data repository currently contains almost three million trait entries for 69 000 out of the world's 300 000 plant species, with a focus on 52 groups of traits characterizing the vegetative and regeneration stages of the plant life cycle, including growth, dispersal, establishment and persistence. A first data analysis shows that most plant traits are approximately log-normally distributed, with widely differing ranges of variation across traits. Most trait variation is between species (interspecific), but significant intraspecific variation is also documented, up to 40% of the overall variation. Plant functional types (PFTs), as commonly used in vegetation models, capture a substantial fraction of the observed variation – but for several traits most variation occurs within PFTs, up to 75% of the overall variation. In the context of vegetation models these traits would better be represented by state variables rather than fixed parameter values. The improved availability of plant trait data in the unified global database is expected to support a paradigm shift from species to trait-based ecology, offer new opportunities for synthetic plant trait research and enable a more realistic and empirically grounded representation of terrestrial vegetation in Earth system models.

De afgelopen jaren heeft de Nederlandse otterpopulatie zich sterk uitgebreid. Maar zowel in de uitzetgebieden als in de nieuwe kolonies ontbreekt het vaak aan ottervoorzieningen, waardoor er jaarlijks veel verkeersslachtoffers vallen. Alterra heeft binnen het huidige verspreidingsgebied de knelpuntlocaties geïnventariseerd en een lijst samengesteld met urgente knelpunten die met voorrang zouden moeten worden aangepakt.

Nature development in The Netherlands is often planned on contaminated soils or sediments. This contamination may present a risk for wildlife species desired at those nature development sites and must be assessed by specific risk assessment methods. In a previous study, we developed a method to predict ecological vulnerability in wildlife species by using autecological data and expert judgment; in the current study, this method is further extended to assess ecological vulnerability of food chains and terrestrial and aquatic habitats typical for The Netherlands. The method is applied to six chemicals: Cd, Cu, Zn, dichlorodiphenyltrichloroethane, chlorpyrifos, and ivermectin. The results indicate that species in different food chains differ in vulnerability, with earthworm-based food chains the most vulnerable. Within and between food chains, vulnerability varied with habitat, particularly at low trophic levels. The concept of habitat vulnerability was applied to a case study of four different habitat types in floodplains contaminated with cadmium and zinc along the river Dommel, The Netherlands. The alder floodplain forest habitat contained the most vulnerable species. The differences among habitats were significant for Cd. We further conclude that the method has good potential for application in mapping of habitat vulnerability. Environ. Toxicol. Chem. 2010;29:2875–2880. © 2010 SETAC

Risk maps help risk analysts and scientists to explore the spatial nature of the effects of environmental stressors such as pollutants. The development of Geographic Information Systems over the past few decades has greatly improved spatial representation and analysis of environmental information and data. Maps also constitute a powerful tool to communicate the outcome of complex environmental risk assessment to stakeholders such as the general public and policy makers. With appropriate cartography one can improve communication and thus bridge the gap between experts and users. Appropriate risk communication is pivotal to risk management, decision making and implementation and may prevent unnecessary concern about environmental pollutants. However, at present few risk maps are specifically tailored to meet the demands of such defined uses. This paper presents an overview of the most important types of risk maps that can be distinguished using examples from the scientific literature: contamination maps, exposure maps, hazard maps, vulnerability maps and 'true' risk maps. It also discusses, in a general way, the most important issues that need to be addressed when making risk maps for communication purposes: risk perception, target audience, scale and spatial aggregation and visualisation such as use of colours and symbols. Finally, some general rules of thumb are given for making environmental risk maps for communication purposes.

The overall objective of this study was to combine national forest inventory data and remotely sensed data to produce pan-European maps on growing stock and above-ground woody biomass for the two species groups “broadleaves” and “conifers”. An automatic up-scaling approach making use of satellite remote sensing data and field measurement data was applied for EU-wide mapping of growing stock and above-ground biomass in forests. The approach is based on sampling and allows the direct combination of data with different measurement units such as forest inventory plot data and satellite remote sensing data. For the classification, data from the Moderate Resolution Imaging Spectroradiometer (MODIS) were used. Comprehensive field measurement data from national forest inventories for 98,979 locations from 16 countries were used for which tree species and growing stock estimates were available. The classification results were evaluated by comparison with regional estimates derived independently from the classification from national forest inventories. The validation at the regional level shows a high correlation between the classification results and the field based estimates with correlation coefficient r = 0.96 for coniferous, r = 0.94 for broadleaved and r = 0.97 for total growing stock per hectare. The mean absolute error of the estimations is 25 m 3 /ha for coniferous, 20 m 3 /ha for broadleaved and 25 m 3 /ha for total growing stock per hectare. Biomass conversion and expansion factors were applied to convert the growing stock classification results to carbon stock in above-ground biomass. As results of the classification, coniferous and broadleaved growing stock as well as carbon stock of the above-ground biomass is mapped on a wall-to-wall basis with a spatial resolution of 500 m × 500 m per grid cell. The mapped area is 5 million km 2 , of which 2 million km 2 are forests, and covers the whole European Union, the EFTA countries, the Balkans, Belarus, the Ukraine, Moldova, Armenia, Azerbaijan, Georgia and Turkey.

An important goal of ecological compensation areas (ECAs) is to increase biodiversity in adjacent intensively managed farmland and the agricultural landscape at large. We tested whether this goal can be achieved in the case of the agri-environmental restoration scheme implemented for Swiss grassland using five large arthropod taxa (bees, true bugs, orthopterans, ground beetles and spiders) representing different ecological and functional groups. The species richness and abundance of all groups and species, respectively, was measured along 100 m transects from ECA-meadows into the adjacent intensively managed grassland at 24 sites. Species richness of all arthropod taxa except ground beetles, and the abundance of 63% of the 234 arthropod species sampled with at least five individuals were higher in ECA-meadows than in their surroundings, while the total abundance of spiders and ground beetles was higher in intensively managed meadows. The abundance of 8% of these species were only increased in the ECA-meadows themselves (“stenotopic” species) but 40% had increased abundance both in the ECA-meadows and the adjacent grassland, declining exponentially with increasing distance from ECA-meadows (“edge species”). The 90%-decay distances for these edge species differed among taxonomic groups (117 ± 18 m for true bugs, 137 ± 24 m for spiders, 152 ± 34 m for bees, 167 ± 5.7 m for orthopterans, 185 ± 34 m for ground beetles; mean ±1 standard error) and independent of taxonomic group were larger for large-sized or predacious species than for small-sized or phytophagous species. Because the average distance between neighbouring ECA-meadows in Swiss grassland is only 73 ± 4 m, the current agri-environment scheme very likely enhances arthropod diversity and possibly associated ecosystem services in the Swiss agricultural landscape at large.

Het gaat goed met de ganzen in de Lage Landen. Vrijwel alle soorten zijn, sinds het verschijnen van het vorige themanummer in 1987, in aantal toegenomen. Brandgans (Branta leucopsis) en grauwe gans (Anser anser) zijn spectaculair toegenomen en zijn in enkele decennia tijd van zeldzame bezoekers zelfs tot gewone broedvogels geworden. In dit themanummer wordt echter ook de keerzijde van deze toename van zowel overwinterende ganzen als het langere verblijf van broedganzen in het voorjaar belicht

The Common hamster (Cricetus cricetus) is a rodent, which inhabits arable land across Europe. Over the last decades, West European populations declined with more then 95%, which resulted in numerous local and regional extinctions. In the Netherlands the species went extinct in the wild in 2002, but the same year a research and reintroduction programme was started. The combination of research on the ecology of the species, monitoring, and translation of the results into practical Agri-environmental schemes (AES), resulted in a rapid population growth over the last 7 years. The Dutch project is one of the few projects in Europe which shows positive results of AES on the target species.

Vanaf 2002 zijn meer dan 80 opnamen gemaakt op de grote zandrug in de Vreugderijkerwaard aan de IJssel bij Zwolle. Deze beogen de variatie binnen het stroomdalgrasland weer te geven.

Aim - Within a region, different habitat types are characterized by different species and some habitat types have higher species diversities than others. Different habitat types are also characterized by different phylogenetic clades. However, it is not known whether – within a given region – some habitat types have species pools that are more phylogenetically diversified than others. We investigated whether species pools in contemporary habitat types represent different levels of diversification of angiosperms and, if so, whether these differences correlate with particular environmental factors. We tested these relationships in a region of recent geological origin possessing a comparatively young flora, and compared the result with standard analyses of species diversity. Location The Netherlands. Methods - We studied angiosperms across the full range of habitat types present in the Netherlands. We characterized levels of diversification represented in species pools within each of these habitat types with respect to (1) taxonomic diversification, i.e. the rate of increase of richness across taxonomic ranks (relative to a null expectation for a given species richness), and (2) cladogenic diversification, i.e. the average cladogenic distance of species from the root of a phylogenetic tree of the species pool within a given region. Results - Species pools of different habitat types represented different levels of taxonomic and cladogenic diversification. These differences were strongly correlated with the environmental characteristics of the habitat type. Greater levels of taxonomic diversification were represented in the species pools of relatively dry and open habitat types. Greater levels of cladogenic diversification were represented in habitats with both dry and weakly acidic soils. The relationship between environmental factors and taxonomic and cladogenic diversification (r2 = 0.88 and 0.76, respectively) was stronger than that between environmental factors and species richness (r2 = 0.34). Main conclusions - Within a region, species resulting from particularly high rates of diversification accumulated in particular habitat types. These habitat types represent specific contemporary abiotic environments and have a tighter relationship with levels of diversification than with species richness.

Effects of soil properties on the accumulation of metals to wood mice (Apodemus sylvaticus) were evaluated at two sites with different pH and organic matter content of the soil. pH and organic matter content significantly affected accumulation of Cd, Cu, Pb and Zn in earthworms and vegetation. For Cd, Cu and Zn these effects propagated through the food web to the wood mouse. Soil-to-kidney ratios differed between sites: Cd: 0.15 versus 3.52, Cu: 0.37 versus 1.30 and Zn: 0.33–0.83. This was confirmed in model calculations for Cd and Zn. Results indicate that total soil concentrations may be unsuitable indicators for risks that metals pose to wildlife. Furthermore, environmental managers may, unintentionally, change soil properties while taking specific environmental measures. In this way they may affect risks of metals to wildlife, even without changes in total soil concentrations. Soil properties significantly affect accumulation of heavy metals to wood mice so; risks cannot be based on total concentrations.

Recent outbreaks of highly pathogenic avian influenza (HPAI) in poultry have raised interest in the interplay between avian influenza (AI) viruses and their wild hosts. Studies linking virus ecology to host ecology are still scarce, particularly for non-duck species. Here, we link capture–resighting data of greater white-fronted geeseAnser albifrons albifronswith the AI virus infection data collected during capture in The Netherlands in four consecutive winters. We ask what factors are related to AI virus prevalence and whether there are ecological consequences associated with AI virus infection in staging white-fronted geese. Mean seasonal (low pathogenic) AI virus prevalence ranged between 2.5 and 10.7 per cent, among the highest reported values for non-duck species, and occurred in distinct peaks with near-zero prevalence before and after. Throat samples had a 2.4 times higher detection frequency than cloacal samples. AI virus infection was significantly related to age and body mass in some but not other winters. AI virus infection was not related to resighting probability, nor to maximum distance travelled, which was at least 191 km during the short infectious lifespan of an AI virus. Our results suggest that transmission via the respiratory route could be an important transmission route of AI virus in this species. Near-zero prevalence upon arrival on their wintering grounds, in combination with the epidemic nature of AI virus infections in white-fronted geese, suggests that white-fronted geese are not likely to disperse Asian AI viruses from their Siberian breeding grounds to their European wintering areas.

In dit artikel krijgt Elatine hydropiper verreweg de meeste aandacht, omdat over deze soort de rijkste historische documentatie beschikbaar is en omdat zij de grootste verscheidenheid in standplaats toont. Hoewel zij niet strikt tot het rivierengebied beperkt is, haar zwaartepunt gedurende het grootste deel van het Holoceen in de rivierdalen. Dit blijkt uit tientallen paleobotanische vondsten, die de kwalificatie 'best gedocumenteerde stroomdalplant van Nederland' wettigen.

Agricultural intensification is one of the main drivers of farmland bird declines, but effects on birds may be confounded with those of climate change. Here we examine the effects of intensification and climate change on a grassland breeding wader, the Black-tailed Godwit Limosa l. limosa, in the Netherlands. Population decline has been linked to poor chick survival which, in turn, has been linked to available foraging habitat. Foraging habitat of the nidifugous chicks consists of uncut grasslands that provide cover and arthropod prey. Conservation measures such as agri-environment schemes aim to increase the availability of chick foraging habitat but have not yet been successful in halting the decline. Field observations show that since the early 1980s, farmers advanced their first seasonal mowing or grazing date by 15 days, whereas Godwits did not advance their hatching date. Ringing data indicate that between 1945 and 1975 hatching dates advanced by about 2 weeks in parallel with the advancement of median mowing dates. Surprisingly, temperature sums at median mowing and hatching dates suggest that while the agricultural advancement before 1980 was largely due to agricultural intensification, after 1980 it was largely due to climate change. Examining arthropod abundance in a range of differently managed grasslands revealed that chick food abundance was little affected but that food accessibility in intensively used tall swards may be problematic for chicks. Our results suggest that, compared with 25 years ago, nowadays (1) a much higher proportion of clutches and chicks are exposed to agricultural activities, (2) there is little foraging habitat left when chicks hatch and (3) because of climate change, the vegetation in the remaining foraging habitat is taller and denser and therefore of lower quality. This indicates that for agri-environment schemes to make a difference, they should not only be implemented in a larger percentage of the breeding area than the current maxima of 20–30% but they should also include measures that create more open, accessible swards

Nu de opvang van de sterk toegenomen aantallen ganzen de overheid steeds meer geld gaat kosten en er steeds vaker aan beperking van de aantallen ganzen wordt gedacht, is goede demografische informatie van steeds groter belang. Hoe oud worden ganzen, hoeveel jongen krijgen ze, wat is de jaarlijkse overleving en hoeveel ganzen worden op de gehele trekroute jaarlijks geschoten

Nergens anders in Europa vinden we zulke grote aantallen ganzen als in Nederland. Zachte winters en de combinatie van geschikte voedselbronnen en veilige slaapplaatsen maken van Nederland een ideaal winterverblijf. Hoewel ganzen de naam hebben traditioneel te zijn, blijken ze flexibel in te kunnen spelen op nieuwe ontwikkelingen. Aan de hand van de landelijke ganzentellingen wordt in deze bijdrage getoond hoe de verschillende populaties zich hebben ontwikkeld en wordt er ingegaan op de internationale context waarin dat is gebeurd. Een eerste bijdrage in een themanummer "Ganzen in Nederland en Vlaanderen"

Gemiddeld raast er eens in de 10-20 jaar een zware storm over Nederland. Vaak blijven bossen hierbij niet gespaard. Bosbeheerders staan dan voor de taak in eerste instantie het meest gevaarlijke stormhout op te ruimen. Hierna komt de vraag hoeveel er in het bos achter gelaten zal worden. Bij het maken van een keuze om stormhout te ruimen of niet, kan gebruik gemaakt worden van effectentabel, die gebaseerd is op onderzoek van Alterra (rapport 1959)

Er bestond dringend behoefte aan een historisch referentiebeeld van de oorspronkelijke soortensamenstelling en verspeiding van deze graslanden in Nederland. Een dergelijke referentie is een belangrijk hulpmiddel bij de evaluatie en herstellen en ontwikkelingsbeheer en geeft door vergelijking inzicht in de kwaliteit van de huidige stroomdalgraslanden. Wij analyseerden in opdracht van het LNV (kennisnetwerk Ontwikkeling en Beheer Natuurkwaliteit; OBN) een grote verzameling historische vegetatieopnamen van Nederlandse stroomdalgraslanden (Schaffers et al. 2008). In dit artikel behandelen wij de belangrijkste resultaten.