State of the art review on climate change impacts on natural ecosystems and adaptation

Climate change has become unavoidable and the Netherlands has started to adapt the water systems and coastal defense to reduce vulnerability to the effects of climate change. These strategies to make the Netherlands climate-proof will also have its impact on nature and ecosystem functioning, in addition to the direct impacts of climate change. This report provides a state-of-the-art review of national and international research with respect to climate change impacts and adaptation, relevant to natural ecosystems in the Netherlands. This review is intended to serve as a reference of current available knowledge and will assist in programming new research required for climate-proofing the Netherland

Field Simulation of Global Change: Transplanting Northern Bog Mesocosms Southward

A large proportion of northern peatlands consists of Sphagnum-dominated ombrotrophic bogs. In these bogs, peat mosses (Sphagnum) and vascular plants occur in an apparent stable equilibrium, thereby sustaining the carbon sink function of the bog ecosystem. How global warming and increased nitrogen (N) deposition will affect the species composition in bog vegetation is still unclear. We performed a transplantation experiment in which mesocosms with intact vegetation were transplanted southward from north Sweden to north-east Germany along a transect of four bog sites, in which both temperature and N deposition increased. In addition, we monitored undisturbed vegetation in control plots at the four sites of the latitudinal gradient. Four growing seasons after transplantation, ericaceous dwarf shrubs had become much more abundant when transplanted to the warmest site which also had highest N deposition. As a result ericoid aboveground biomass in the transplanted mesocosms increased most at the southernmost site, this site also had highest ericoid biomass in the undisturbed vegetation. The two dominant Sphagnum species showed opposing responses when transplanted southward; Sphagnum balticum height increment decreased, whereas S. fuscum height increment increased when transplanted southward. Sphagnum production did not differ significantly among the transplanted mesocosms, but was lowest in the southernmost control plots. The dwarf shrub expansion and increased N concentrations in plant tissues we observed, point in the direction of a positive feedback toward vascular plant-dominance suppressing peat-forming Sphagnum in the long term. However, our data also indicate that precipitation and phosphorus availability influence the competitive balance between Sphagnum, dwarf shrubs and graminoids

Effects of elevated CO2 and increased N deposition on bog vegetation in the Netherlands = [Gevolgen van een verhoogde atmosferische CO2-concentratie en N-depositie voor hoogveenvegetatie in Nederland]

Ombrotrophic bogs are important long-term sinks for atmospheric carbon. Changes in species composition of the bog plant community may have important effects on carbon sequestration, because peat mosses ( Sphagnum ) contribute more to peat accumulation than vascular plants. The aim of this study was to investigate the effects of elevated atmospheric carbon dioxide (CO 2 ) and increased nitrogen (N) deposition on bog vegetation in the Netherlands, with special attention to the relationship between peat mosses and vascular plants.Three experiments were conducted, one outdoors and two in the greenhouse, in which peat monoliths were exposed to different levels of atmospheric CO 2 and N deposition. The outdoor experiment was part of the European BERI project, which used MiniFACE technology for creating elevated CO 2 conditions. The vegetation response in all three experiments was followed for two or three growing seasons. In addition, evapotranspiration and the partitioning of 15 N-labelled N deposition among Sphagnum , vascular plants and peat was measured.The results showed, for the first time, that elevated CO 2 benefits growth of Sphagnum , but not necessarily at the cost of vascular plant growth. Increases in vascular plant biomass were non-significant, and were apparently restricted by the faster Sphagnum height growth and/or nutrient limitation. Sphagnum can take advantage of elevated CO 2 because its growth is less nutrient limited than that of vascular plants. Reductions in evapotranspiration at elevated CO 2 in summer would further benefit Sphagnum , as its growth is very sensitive to changes in moisture availability. During three growing seasons of N addition, the Sphagnum layer became saturated with N, resulting in a larger availability of N and better growth of vascular plants. After reaching a cover of about 60% vascular plants reduced Sphagnum growth through increased shading.These changes in relative abundances of peat mosses versus vascular plants, in response to treatments and interactions between species, have implications for carbon sequestration in peat bogs. As elevated CO 2 favours Sphagnum growth, it is expected that carbon sequestration in bogs increases with increasing levels of atmospheric CO 2 . In contrast, increased N deposition will likely reduce carbon sequestration by increasing the relative abundance of vascular plants.Key words:15 N tracer, BERI, competitive interactions, elevated CO 2 , evapotranspiration, global change, MiniFACE, N deposition, ombrotrophic bog vegetation, plant species compostion, Sphagnum , vascular plants</p

De toendra smelt

Een kwart van het landoppervlak van het noordelijk halfrond heeft permafrost in de bodem, vooral in Canada en Siberië. De permafrost vormt een meters dikke, ondoordringbare laag. Alleen de bovenste decimeters van de toendra ontdooien in de zomer. Maar dit gebied is erg kwetsbaar voor verstoring. Een kleine verandering kan een groot effect hebben. Dat ontdekten Monique Heijmans en haar collega’s van de leerstoelgroep Natuurbeheer en Plantenecologie. Zij verwijderden de struikjes in een vijftal proefveldjes en volgden die percelen een aantal jaren. Het effect was dramatisch: de permafrost, de permanent bevroren ondergrond, begon te ontdooien en de toendra zakte in elkaar

Effects of elevated CO2 and increased N deposition on bog vegetation in the Netherlands = [Gevolgen van een verhoogde atmosferische CO2-concentratie en N-depositie voor hoogveenvegetatie in Nederland]

Ombrotrophic bogs are important long-term sinks for atmospheric carbon. Changes in species composition of the bog plant community may have important effects on carbon sequestration, because peat mosses ( Sphagnum ) contribute more to peat accumulation than vascular plants. The aim of this study was to investigate the effects of elevated atmospheric carbon dioxide (CO 2 ) and increased nitrogen (N) deposition on bog vegetation in the Netherlands, with special attention to the relationship between peat mosses and vascular plants.Three experiments were conducted, one outdoors and two in the greenhouse, in which peat monoliths were exposed to different levels of atmospheric CO 2 and N&nbsp;deposition. The outdoor experiment was part of the European BERI project, which used MiniFACE technology for creating elevated CO 2 conditions. The vegetation response in all three experiments was followed for two or three growing seasons. In addition, evapotranspiration and the partitioning of 15 N-labelled N&nbsp;deposition among Sphagnum , vascular plants and peat was measured.The results showed, for the first time, that elevated CO 2 benefits growth of Sphagnum , but not necessarily at the cost of vascular plant growth. Increases in vascular plant biomass were non-significant, and were apparently restricted by the faster Sphagnum height growth and/or nutrient limitation. Sphagnum can take advantage of elevated CO 2 because its growth is less nutrient limited than that of vascular plants. Reductions in evapotranspiration at elevated CO 2 in summer would further benefit Sphagnum , as its growth is very sensitive to changes in moisture availability. During three growing seasons of N&nbsp;addition, the Sphagnum layer became saturated with N, resulting in a larger availability of N&nbsp;and better growth of vascular plants. After reaching a cover of about 60% vascular plants reduced Sphagnum growth through increased shading.These changes in relative abundances of peat mosses versus vascular plants, in response to treatments and interactions between species, have implications for carbon sequestration in peat bogs. As elevated CO 2 favours Sphagnum growth, it is expected that carbon sequestration in bogs increases with increasing levels of atmospheric CO 2 . In contrast, increased N&nbsp;deposition will likely reduce carbon sequestration by increasing the relative abundance of vascular plants.Key words:15 N&nbsp;tracer, BERI, competitive interactions, elevated CO 2 , evapotranspiration, global change, MiniFACE, N&nbsp;deposition, ombrotrophic bog vegetation, plant species compostion, Sphagnum , vascular plant

Swift recovery of Sphagnum nutrient concentrations after excess supply

Although numerous studies have addressed the effects of increased N deposition on nutrient-poor environments such as raised bogs, few studies have dealt with to what extent, and on what time-scale, reductions in atmospheric N supply would lead to recovery of the ecosystems in question. Since a considerable part of the negative effects of elevated N deposition on raised bogs can be related to an imbalance in tissue nutrient concentrations of the dominant peat-former Sphagnum, changes in Sphagnum nutrient concentration after excess N supply may be used as an early indicator of ecosystem response. This study focuses on the N and P concentrations of Sphagnum magellanicum and Sphagnum fallax before, during and after a factorial fertilization experiment with N and P in two small peatlands subject to a background bulk deposition of 2 g N m(-2) year(-1). Three years of adding N (4.0 g N m(-2) year(-1)) increased the N concentration, and adding P (0.3 g P m(-2) year(-1)) increased the P concentration in Sphagnum relative to the control treatment at both sites. Fifteen months after the nutrient additions had ceased, N concentrations were similar to the control whereas P concentrations, although strongly reduced, were still slightly elevated. The changes in the N and P concentrations were accompanied by changes in the distribution of nutrients over the capitulum and the stem and were congruent with changes in translocation. Adding N reduced the stem P concentration, whereas adding P reduced the stem N concentration in favor of the capitulum. Sphagnum nutrient concentrations quickly respond to reductions in excess nutrient supply, indicating that a management policy aimed at reducing atmospheric nutrient input to bogs can yield results within a few years