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In their natural state, river floodplains are heterogeneous and dynamic ecosystems that may retain and remove large quantities of nitrogen from surface waters. We compared the soil nitrogen dynamics in different types of habitat patches in a restored and a channelized section of a Thur River floodplain (northeast Switzerland). Our objective was to relate(More)
Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta-analysis of studies at 48 sites across four continents that used enriched 15N isotope tracers in order to synthesize(More)
RATIONALE The use of stable nitrogen (N) isotope ratios (δ(15)N values) in dendroecological studies is often preceded by an extraction procedure using organic solvents to remove mobile N compounds from tree-rings. Although these mobile N compounds may be capable of distorting potential environmental signals in the tree-ring δ(15)N values, recent(More)
In Valais, Switzerland, Scots pines (Pinus sylvestris L.) are declining, mainly following drought. To assess the impact of drought on tree growth and survival, an irrigation experiment was initiated in 2003 in a mature pine forest, approximately doubling the annual precipitation. Tree crown transparency (lack of foliage) and leaf area index (LAI) were(More)
The analysis of 15N in aqueous samples requires the concentration of dissolved nitrogen (N) into a small volume that can be analysed by mass spectrometry. This is conveniently achieved by the NH3 diffusion technique, where NH4+ is captured on small acidified filters enclosed in PTFE. NO3- can be analysed the same way by reducing it to NH4+ with Devarda's(More)
The response of specific groups of organisms, like Collembola to atmospheric nitrogen (N) deposition is still scarcely known. We investigated the Collembola community in a subalpine forest (Alptal, Switzerland) as subjected for 12 years to an experimentally increased N deposition (+25 on top of ambient 12 kg N ha(-1) year(-1)). In the 0-5 cm soil layer,(More)
To determine the relationship between phloem transport and changes in phloem water content, we measured temporal and spatial variations in water content and sucrose, glucose and fructose concentrations in phloem samples and phloem exudates of 70- and 30-year-old Norway spruce trees (Picea abies (L.) Karst.). Large temporal and spatial variations in phloem(More)
Climate warming may alter ecosystem nitrogen (N) cycling by accelerating N transformations in the soil, and changes may be especially pronounced in cold regions characterized by N-poor ecosystems. We investigated N dynamics across the plant-soil continuum during 6 years of experimental soil warming (2007-2012; +4 °C) at a Swiss high-elevation treeline site(More)
Being tolerant to heat and drought, oaks are promising candidates for future forestry in view of climate change in Central Europe. Air warming is expected to increase, and drought decrease soil N availability and thus N supply to trees. Here, we conducted a model ecosystem experiment, in which mixed stands of young oaks (Quercus robur, Q. petraea and Q.(More)
Despite numerous studies on nitrogen (N) cycling in forest ecosystems, many uncertainties remain, particularly regarding long-term N accumulation in the soil. Models validated against tracer isotopic data from field labeling experiments provide a potential tool to better understand and simulate C and N interactions over multiple decades. In this study, we(More)