Does atmospheric nitrogen deposition lead to greater nitrogen and carbon accumulation in coastal sand dunes?

Atmospheric nitrogen (N) deposition is thought to accelerate ecological succession, causing a loss of diversity in species-rich dune grasslands and hampering restoration goals. We tested whether elevated atmospheric N deposition results in faster accumulation of soil C and soil N, using three high-resolution chronosequences of up to 162 years in coastal sand dunes with contrasting N deposition and soil base status (high N deposition calcareous and acidic dunes in Luchterduinen, the Netherlands (LD) and low N deposition calcareous dunes in Newborough, UK (NB)). We also used the process model CENTURY to evaluate the relative contribution of N deposition, climate, and soil pH. In contrast to our hypothesis we found that accumulation of soil C and N was greatest at the low N deposition site NB. Model simulations indicated a negative interaction between high N deposition and symbiotic N2 fixation. From this we conclude that high N deposition suppresses and replaces N2 fixation as a key N source. High N deposition led to lower soil C:N only in the early stages of succession (<20 years). The data also revealed accelerated acidification at high N deposition, which is a major concern for restoration of dune grasslands. More data are needed from acidic dunes from low N deposition areas to assess pH effects on soil C and N pools. Therefore, while N accumulation in soils may not be an issue, both acidification and plant community change due to elevated availability of mineral N remain major conservation problems. Restoration in degraded dune grasslands should focus on maintaining habitat suitability, rather than N removal from soil pools

Ecological restoration of rich fens in Europe and North America: from trial and error to an evidence-based approach

Fens represent a large array of ecosystem services, including the highest biodiversity found among wetlands, hydrological services, water purification and carbon sequestration. Land use change and strong drainage has severely damaged or annihilated these services in many parts of North America and Europe, which urges the need of restoration plans at the landscape level. We review the major constraints for the restoration of rich fens and fen water bodies in agricultural areas in Europe and disturbed landscapes in North America: 1) habitat quality problems: drought, eutrophication, acidification, and toxicity, 2) recolonization problems: species pools, ecosystem fragmentation and connectivity, genetic variability, invasive species, and provide possible solutions. We discuss both positive and negative consequences of restoration measures, and their causes. The restoration of wetland ecosystem functioning and services has, for a long time, been based on a trial and error approach. By presenting research and practice on the restoration of rich fen ecosystems within agricultural areas, we demonstrate the importance of biogeochemical and ecological knowledge at different spatial scales for the management and restoration of biodiversity, water quality, carbon sequestration and other ecosystem services, especially in a changing climate. We define target processes that enable scientists, nature managers, water managers and policy makers to choose between different measures and to predict restoration prospects for different types of deteriorated fens and their starting conditions

Uranium Vertical and Lateral Distribution in a German Forested Catchment

The natural measurements of uranium (U) are important for establishing natural baseline levels of U in soil. The relations between U and other elements are important to determine the extent of geological origin of soil U. The present study was aimed at providing a three-dimensional view of soil U distribution in a forested catchment (ca. 38.5 ha) in western Germany. The evaluated data, containing 155 sampled points, each with four major soil horizons (L/Of, Oh, A, and B), were collected from two existing datasets. The vertical U distribution, the lateral pattern of U in the catchment, and the occurrence of correlations between U and three groups of elements (nutrient elements, heavy metals, and rare earth elements) were examined. The results showed the median U concentration increased sevenfold from the top horizon L/Of (0.14 mg kg−1) to the B horizon (1.01 mg kg−1), suggesting a geogenic origin of soil U. Overall, soil U concentration was found to be negatively correlated with some plant macronutrients (C, N, K, S, Ca) but positively with others (P, Mg, Cu, Zn, Fe, Mn, Mo). The negative correlations between U and some macronutrients indicated a limited accumulation of plant-derived U in soil, possibly due to low phytoavailability of U. Positive correlations were also found between U concentration and heavy metals (Cr, Co, Ni, Ga, As, Cd, Hg, Pb) or rare earth elements, which further pointed to a geogenic origin of soil U in this forested catchment

Calcium and iron as key drivers of brown moss composition through differential effects on phosphorus availability

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o-PO₄ (A), NO₃^- (B) and NH₄⁺ (C) concentrations per vegetation type in porewater 2 days before the experiment, in inundation water during the experiment, and in porewater 2 days after the experiment.

<p>Sample means with standard deviations are indicated (<i>n</i> = 5). Statistical information is provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144006#pone.0144006.t003" target="_blank">Table 3</a>. For abbreviations see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144006#pone.0144006.t001" target="_blank">Table 1</a>.</p

Water table (A) and Cl-concentrations (B) per vegetation type in porewater 2 days before the experiment, in inundation water during the experiment, and in porewater 2 days after the experiment.

<p>Sample means with standard deviations are indicated (<i>n</i> = 5). Statistical information is provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144006#pone.0144006.t003" target="_blank">Table 3</a>. For abbreviations see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144006#pone.0144006.t001" target="_blank">Table 1</a>.</p

Effects of location, season, vegetation type and their interactions on the water table and porewater chemistry at <i>T</i> = 0 of each yearly experiment.

<p>Effects of location, season, vegetation type and their interactions on the water table and porewater chemistry at <i>T</i> = 0 of each yearly experiment.</p

Average porewater ratios of [alkalinity]/[Cl], and [Ca]/[Cl] in winter and summer, before and after inundation.

<p>Average porewater ratios of [alkalinity]/[Cl], and [Ca]/[Cl] in winter and summer, before and after inundation.</p

Initial water tables and porewater characteristics for the different areas and vegetation types for combined seasons.

<p>Initial water tables and porewater characteristics for the different areas and vegetation types for combined seasons.</p