Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2019
Authors
Jan Magnusson Stephanie Eisner Shaochun Huang Cristian Lussana Giulia Mazzotti Richard Essery Tuomo Saloranta Stein BeldringAbstract
Climate models show that global warming will disproportionately influence high‐latitude regions and indicate drastic changes in, among others, seasonal snow cover. However, current continental and global simulations covering these regions are often run at coarse grid resolutions, potentially introducing large errors in computed fluxes and states. To quantify some of these errors, we have assessed the sensitivity of an energy‐balance snow model to changes in grid resolution using a multiparametrization framework for the spatial domain of mainland Norway. The framework has allowed us to systematically test how different parametrizations, describing a set of processes, influence the discrepancy, here termed the scale error, between the coarser (5 to 50‐km) and finest (1‐km) resolution. The simulations were set up such that liquid and solid precipitation was identical between the different resolutions, and differences between the simulations arise mainly during the ablation period. The analysis presented in this study focuses on evaluating the scale error for several variables relevant for hydrological and land surface modelling, such as snow water equivalent and turbulent heat exchanges. The analysis reveals that the choice of method for routing liquid water through the snowpack influences the scale error most for snow water equivalent, followed by the type of parametrizations used for computing turbulent heat fluxes and albedo. For turbulent heat exchanges, the scale error is mainly influenced by model assumptions related to atmospheric stability. Finally, regions with strong meteorological and topographic variability show larger scale errors than more homogenous regions.
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Authors
Katharina Strobl Johannes Kollmann Leonardo H. TeixeiraAbstract
Ecological restoration has great potential for reversing anthropogenic degradation, as it aims at the simultaneous recovery of several ecosystem functions and services. However, it can be challenging to evaluate multiple restoration targets based on a high number of indicators, and this calls for a multifunctionality approach. Multifunctionality is an integrated measure of the relative supply of multiple ecosystem functions or services. As temporal aspects are of key importance for ecosystem recovery, we analyzed multifunctionality against time since restoration. We used rewetted peatlands in a mountainous region in Central Germany as a study case. Restored peatlands are expected to become multifunctional, while their recovery is rather slow. We investigated to what extent rewetted peatlands recover, and how time since restoration controls the simultaneous development of multiple ecosystem properties. We studied restored peatlands with respect to plant diversity, water table, peat decomposition, water holding capacity, and nutrient level using a chronosequence of 0–18 yr after restoration. We analyzed the development of individual properties and of a combined index. We further compared the recovery of restored sites at different ages to an intact reference peatland and to a theoretical optimum value, defined as the mean of the eleven most desirable values observed. Eleven out of 13 peatland properties and the combined index significantly evolved with time since restoration. Nevertheless, we could not observe a consistent trend of multiple properties if aiming at highest levels of functioning, whereas there was progress with time if low or intermediate functioning is targeted. Our results show that not all functions of restored peatlands can recover to the most desirable extent within 18 yr. However, the average functionality and some individual properties achieved levels comparable to the reference site, highlighting that improvement is possible. While the integrated assessment informs about the degree of ecosystem recovery, an additional analysis of individual properties helps understanding ecosystem‐specific dynamics, which are needed for making decisions on potential future management.
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Richard Meadow Tor J. Johansen Gunda Thöming Annette Folkedal Schjøll Belén Cotes Christian NansenAbstract
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Arne HermansenAbstract
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Authors
Junbin Zhao Sparkle L. Malone Steven. F. Oberbauer Paulo C. Olivas Jessica L. Schedlbauer Christina L. Staudhammer Gregory StarrAbstract
Climate change has altered global precipitation patterns and has led to greater variation in hydrological conditions. Wetlands are important globally for their soil carbon storage. Given that wetland carbon processes are primarily driven by hydrology, a comprehensive understanding of the effect of inundation is needed. In this study, we evaluated the effect of water level (WL) and inundation duration (ID) on carbon dioxide (CO2) fluxes by analysing a 10‐year (2008–2017) eddy covariance dataset from a seasonally inundated freshwater marl prairie in the Everglades National Park. Both gross primary production (GPP) and ecosystem respiration (ER) rates showed declines under inundation. While GPP rates decreased almost linearly as WL and ID increased, ER rates were less responsive to WL increase beyond 30 cm and extended inundation periods. The unequal responses between GPP and ER caused a weaker net ecosystem CO2 sink strength as inundation intensity increased. Eventually, the ecosystem tended to become a net CO2 source on a daily basis when either WL exceeded 46 cm or inundation lasted longer than 7 months. Particularly, with an extended period of high‐WLs in 2016 (i.e., WL remained >40 cm for >9 months), the ecosystem became a CO2 source, as opposed to being a sink or neutral for CO2 in other years. Furthermore, the extreme inundation in 2016 was followed by a 4‐month postinundation period with lower net ecosystem CO2 uptake compared to other years. Given that inundation plays a key role in controlling ecosystem CO2 balance, we suggest that a future with more intensive inundation caused by climate change or water management activities can weaken the CO2 sink strength of the Everglades freshwater marl prairies and similar wetlands globally, creating a positive feedback to climate change.