Verheyen K.,Ghent University |
Baeten L.,Ghent University |
De Frenne P.,Ghent University |
Bernhardt-Romermann M.,Goethe University Frankfurt |
And 18 more authors.
Journal of Ecology | Year: 2012
Atmospheric nitrogen (N) deposition is expected to change forest understorey plant community composition and diversity, but results of experimental addition studies and observational studies are not yet conclusive. A shortcoming of observational studies, which are generally based on resurveys or sampling along large deposition gradients, is the occurrence of temporal or spatial confounding factors. We were able to assess the contribution of N deposition versus other ecological drivers on forest understorey plant communities by combining a temporal and spatial approach. Data from 1205 (semi-)permanent vegetation plots taken from 23 rigorously selected understorey resurvey studies along a large deposition gradient across deciduous temperate forest in Europe were compiled and related to various local and regional driving factors, including the rate of atmospheric N deposition, the change in large herbivore densities and the change in canopy cover and composition. Although no directional change in species richness occurred, there was considerable floristic turnover in the understorey plant community and a shift in species composition towards more shade-tolerant and nutrient-demanding species. However, atmospheric N deposition was not important in explaining the observed eutrophication signal. This signal seemed mainly related to a shift towards a denser canopy cover and a changed canopy species composition with a higher share of species with more easily decomposed litter. Synthesis. Our multi-site approach clearly demonstrates that one should be cautious when drawing conclusions about the impact of atmospheric N deposition based on the interpretation of plant community shifts in single sites or regions due to other, concurrent, ecological changes. Even though the effects of chronically increased N deposition on the forest plant communities are apparently obscured by the effects of canopy changes, the accumulated N might still have a significant impact. However, more research is needed to assess whether this N time bomb will indeed explode when canopies will open up again. © 2011 The Authors. Journal of Ecology © 2011 British Ecological Society.
Ewald J.,Weihenstephan-Triesdorf University of Applied Sciences |
Hennekens S.,Wageningen University |
Wohlgemuth T.,Swiss Federal Institute of forest |
Jansen F.,University of Greifswald |
And 10 more authors.
Tuexenia | Year: 2013
Within the last 30 years the role of nitrogen in Central European forests has changed fundamentally from limiting resource to environmental problem. As the retrospective tracking of nutrient availability by soil chemical and biogeochemical measurements faces serious problems, bioindication based on understorey species composition is indispensable for monitoring broad-scale eutrophication. Based on a broad survey of more than 100,000 forest vegetation plots accessible in electronic data-bases from Germany and adjacent countries, we calculated unweighted average Ellenberg nutrient values (mN) as a proxy of plant-available macronutrients. Based on the quantiles of the frequency distribution of mN in a regionally stratified sample, we define five trophic classes, which can be used to compare dimensionless mN values. We studied spatial patterns of average nutrient values within 17 regions and compared the periods from 1899 to 1975 and 1976 to 2006. After 1975 eutrophic (mN > 5.67) and hypertrophic (mN > 6.28) conditions were common everywhere except in the Alps and Saxony-Anhalt, but very oligotrophic conditions (mN > 3.44) were still widespread in regions with nutrient-poor bedrock. Before 1975 mN of plots had been lower than after 1975 in all but the southeastern regions. Between the pre-and post-1975 data the proportion of hypertrophic plots increased from 5.7 to 11.8%, and that of very oligo-trophic plots decreased from 14.6 to 8.3%. To remove bias resulting from uneven distribution, the dataset was stratified by five tree layer dom-inance types, period and region and resampled. In pre-1975 plots medians of mN increased in the order Pinus sylvestris, Quercus spp., Picea abies, Fagus sylvatica and Alnus spp, whereas the increase of mN was highest in forest types with historically low nutrient values. Therefore, the widespread change in mN must be attributed to the pronounced vegetation changes in Quercus and Pinus stands, indicating the importance of land-use change, i.e. recovery of nutrient cycles after hundreds of years of exploita-tion through coppicing, grazing and litter use. The analysis confirms eutrophication as a megatrend of modern vegetation change and demonstrates the high research potential of linking vegetation plot databases across large regions.
Vught I.,Research Institute for Nature and Forest |
de Charleroy D.,Research Institute for Nature and Forest |
van Liefferinge C.,Agency for Nature and Forests |
Coenen E.,Flemish Environment Agency |
Coeck J.,Research Institute for Nature and Forest
Journal of Applied Ichthyology | Year: 2011
Until 2003 Cottus perifretum was believed to be extinct from the Demer River basin in Flanders, Belgium. However, that year a relict population of this bullhead species was found in the Dorpbronbeek. The Research Institute for Nature and Forest (INBO) and the Agency for Nature and Forests (ANB) launched a conservation project to preserve this population by re-introducing cultured progeny to the Zevenbronnenbeek. This headwater stream was carefully selected from seven evaluated potential locations within the Demer River basin based on water and habitat quality and food availability. In October 2008, 1220 cultured age 0+ bullhead were released. To enlarge the chance for success, ceramic roof tiles were added to the stream as artificial spawning substrates. In 2009, the success of the re-introduction was assessed. The recaptured fish had grown since their release and were in visual good condition, but most important, natural reproduction occurred. © 2011 Blackwell Verlag, Berlin.
Louette G.,Research Institute for Nature and Forest |
Adriaens D.,Research Institute for Nature and Forest |
Adriaens P.,Research Institute for Nature and Forest |
Anselin A.,Research Institute for Nature and Forest |
And 5 more authors.
Journal for Nature Conservation | Year: 2011
Natura 2000 targets the sustainable conservation of Europe's biodiversity. An important cornerstone of Natura 2000 is the Habitats Directive, which is currently implemented across European member states. However, straightforward implementation is not obvious since the favourable conservation status of habitats and species needs to be achieved at the member state level, while conservation objectives need to be formulated at the protected site level. To bridge this gap, we propose to start from regional conservation objectives before site level objectives are formulated. These regional conservation objectives have the advantage of providing a framework according to which conservation objectives can be allocated both within and outside the protected sites of the Natura 2000 network. Especially since they all contribute to the national or regional conservation status. Recently, Flanders (northern Belgium) has adopted this approach and has quantified conservation objectives at the regional scale. As the current regional conservation status of habitats and species is mostly unfavourable, regional conservation objectives entail a drastic increase in area (42%) for habitats, and active conservation measures for 78% of the species. We are convinced that the method outlined here, may substantially contribute to a helpful discussion about implementing and streamlining Natura 2000 across European member states. © 2011 Elsevier GmbH.
Genetic rescue and the increase of litter size in the recovery breeding program of the common hamster (Cricetus cricetus) in the Netherlands. Relatedness, inbreeding and heritability of litter size in a breeding program of an endangered rodent
La Haye M.J.J.,Radboud University Nijmegen |
La Haye M.J.J.,Wageningen University |
Koelewijn H.P.,Wageningen University |
Koelewijn H.P.,Nunhems Netherlands BV |
And 4 more authors.
Hereditas | Year: 2012
Reduced genetic variation is a severe threat for long-term persistence of endangered animals. Immigration or translocation of new individuals may result in genetic rescue and increase the population viability of the endangered population or species. Unfortunately, studying genetic rescue in wild populations is very difficult, but breeding programs of endangered species can contribute to our knowledge of the diverse effects of genetic rescue. A recovery breeding program of common hamsters in the Netherlands enabled the study of genetic rescue in an endangered rodent as a few wild hamsters from two nearby and also highly threatened populations were added to the breeding stock. Litter size increased over the years, but no relation between inbreeding levels and litter size was found. Average litter size benefited from the genetic variation introduced by a hamster from Germany, but hamsters from Belgium had no effect on litter size. Rather than alleviating inbreeding depression the genetic rescue effect observed in this population seems to originate from the introduction of beneficial alleles by the German male. Breeding programs using several populations may increase the success of reintroductions and long-term persistence of these populations. © 2013 The Authors.