1,720,962 research outputs found
dendrometer_and_climate_daily_2019-2022
No full textDaily time series of stem diameter measurements, taken with high-resolution dendrometers (DC2 and DC3, Ecomatik, Munich, Germany). Measurements were taken on the 20 IMP plots of the RTG2300, i.e. quintets 3, 4, 6 and 8. Per plot, four trees per species were equipped with a dendrometer. The data set also contains variables derived from dendrometer data with the treenetproc R package, including growth, maximum daily shrinkage and daily minimum tree water deficit. Additionally, the data set includes environmental variables, which were gathered on the study plots and used for modeling of tree water deficit, such as precipitation, VPD, temperature and soil moisture. For detailed description of the data columns, see the metadata excel-file.
Data is processed using the treenetproc R package, which includes exclusion of outliers, correction of jumps and calculation of variables, such as tree water deficit and irreversible growth. Then, it was summarized to daily values and merged with climate data.
This data set covers years 2019-2022
Precipitation_stable_water_isotopes_2021-2022
No full textTime series of stable water isotope data from precipitation/throughfall samples, taken from custom-built rain collectors on the RTG2300 IMP plots (quintets 3, 4, 6, 8) and the nearby open-sky climate-stations. One collector per plot. The obtained water samples were analyzed for the isotopic compositions of hydrogen and oxygen at the Center for Stable Isotope Research and Analysis (KOSI, Georg-August-University Göttingen, Germany), using a high temperature conversion analyzer (TC/EA, Thermo Electron Corporation, Bremen, Germany) coupled via a Con-Flo III interface to a Delta V Plus isotope ratio mass spectrometer (Thermo Electron Corporation, Bremen, Germany)
Stable_water_isotopes_2022
No full textThe data set contains stable water isotope data measured on water extracted from (1) soil samples of different depths and (2) tree xylem of suberized twigs of 12 different trees. Samples were taken (1) with a Pürckhauer soil corer and (2) by tree climbers on RTG2300 plots 6.1, 6.2 and 6.3 during summer 2022 in weekly intervals and were extracted using cryogenic vacuum distillation.
The obtained water samples were analyzed for the isotopic compositions of hydrogen and oxygen at the Center for Stable Isotope Research and Analysis (KOSI, Georg-August-University Göttingen, Germany), using a high temperature conversion analyzer (TC/EA, Thermo Electron Corporation, Bremen, Germany) coupled via a Con-Flo III interface to a Delta V Plus isotope ratio mass spectrometer (Thermo Electron Corporation, Bremen, Germany)
Stable_water_isotopes_2021
No full textSoil and xylem samples were taken once in summer 2021 from all plots of quintets 3, 4, 6, 8 of the RTG2300 sites. We took stem cores at breast height from n=8 trees (1 core per tree) and 4 soil cores, each in the middle between a pair of trees. Soil cores were separated in 7 depth intervals. Water was extracted from all samples using cryogenic vacuum distillation and subsequently analyzed for the isotopic compositions of hydrogen and oxygen at the Center for Stable Isotope Research and Analysis (KOSI, Georg-August-University Göttingen, Germany), using a high temperature conversion analyzer (TC/EA, Thermo Electron Corporation, Bremen, Germany) coupled via a Con-Flo III interface to a Delta V Plus isotope ratio mass spectrometer (Thermo Electron Corporation, Bremen, Germany). Gravimetric water content was calculated from fresh and oven-dried (105°C) sample weight
Dual-isotope tracer experiment (2H, 15N), 2023
No full textIsotopic data associated with the publication "De‐Coupled Water and Nitrogen Translocation From Subsoil to Canopy of Temperate Forest Trees" by Klara Mrak, Christina Hackmann et al.
A dual-isotope pulse-chase tracer experiment was conducted in two temperate forests in Germany. Tracer solution enriched in 2H and 15N was applied at 60 cm soil depth or below the litter layer. Uptake of the tracer by neighboring mature forest trees was tracked over time (4, 5, 6, and 14 weeks after labelling) by sampling xylem water and foliage of the target trees
Local neighborhood affects stem rehydration under drought: evidence from mixtures of European beech with two different conifers
No full textAbstract Mixed-species forests are, for multiple reasons, promising options for forest management in Central Europe. However, the extent to which interspecific competition affects tree hydrological processes is not clear. High-resolution dendrometers capture sub-daily variations in stem diameter; they can simultaneously monitor stem growth (irreversible changes in diameter) and water status (reversible changes) of individual trees. Using the information on water status, we aimed to assess potential effects of tree species mixture, expressed as local neighborhood identity, on night-time rehydration and water stress. We deployed 112 sensors in pure and mixed forest stands of European beech, Norway spruce, and Douglas fir on four sites in north-western Germany, measuring stem diameter in 10-minute intervals for a period of four years (2019–2022). In a mixture distribution model, we used environmental variables, namely soil matric potential, atmospheric vapor pressure deficit, temperature, precipitation, and neighborhood identity to explain night-time rehydration, measured as the daily minimum tree water deficit (TWDmin). TWDmin was used as a daily indicator of water stress and the daily occurrence of sufficient water supply, allowing for stem growth (potential growth). We found that species and neighborhood identity affected night-time rehydration, but the impacts varied depending on soil water availability. While there was no effect at high water availability, increasing drought revealed species-specific patterns. Beech improved night-time rehydration in mixture with Douglas fir, but not in mixture with spruce. Douglas fir however, only improved rehydration at a smaller share of beech in the neighborhood, while beech dominance tended to reverse this effect. Spruce was adversely affected when mixed with beech. At species level and under dry conditions, we found that night-time rehydration was reduced in all species, but beech had a greater capacity to rehydrate under high to moderate soil water availability than the conifers, even under high atmospheric water demand. Our study gives new insights into neighborhood effects on tree water status and highlights the importance of species-specific characteristics for tree-water relations in mixed-species forests. It shows that drought stress of European beech can be reduced by admixing Douglas fir, which may point towards a strategy to adapt beech stands to climate change
Water consumption of beech, spruce and Douglas fir in pure and mixed stands in a wet and a dry year – Testing predictions of the iso/anisohydry concept
No full texthttp://dx.doi.org/10.13039/501100001655 Deutscher Akademischer Austauschdiensthttp://dx.doi.org/10.13039/501100001659 German Research Foundatio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
De‐Coupled Water and Nitrogen Translocation From Subsoil to Canopy of Temperate Forest Trees
No full textABSTRACT Water and nitrogen (N) transport from soil to canopy play a central role in tree functioning, yet direct evidence for their timing and coupling in mature forests remains scarce. We report results from a paired dual‐isotope ( 2 H, 15 N) tracer experiment in a temperate forest, comparing water and nitrate uptake patterns across tree species (Douglas fir, European beech), soil textures (loamy, sandy) and rooting depths (surface, subsoil). Using simultaneous double tracer injections into the lower rooting zone, followed by canopy xylem sap and foliage sampling over 2 months, we quantified the appearance of water and nitrate in xylem sap and foliage, supported by sap flow measurements to estimate transit times. Water reached the canopy faster than nitrogen, revealing a marked asynchrony in resource translocation for both species and sites—the first such field observation. Douglas fir showed greater subsoil water and nitrate uptake on sandy than on loamy soil, and higher subsoil uptake compared to beech under identical conditions. Tree species, soil texture and soil depth jointly govern water and nitrate uptake dynamics, as well as their temporal decoupling. These findings provide novel field‐based evidence of asynchronous water and nitrate transport, advancing our understanding of tree ecophysiology and nutrient cycling under field conditions.Summary statement Dual‐isotope tracing in situ shows faster transport of water than nitrate from soil to canopy of mature trees, indicating effects of root function, soil texture and species traits. Douglas fir exhibits greater subsoil water and nitrate uptake on sandy than on loamy soils and higher uptake than beech under similar soil conditions.ABSTRACT Water and nitrogen (N) transport from soil to canopy play a central role in tree functioning, yet direct evidence for their timing and coupling in mature forests remains scarce. We report results from a paired dual‐isotope ( 2 H, 15 N) tracer experiment in a temperate forest, comparing water and nitrate uptake patterns across tree species (Douglas fir, European beech), soil textures (loamy, sandy) and rooting depths (surface, subsoil). Using simultaneous double tracer injections into the lower rooting zone, followed by canopy xylem sap and foliage sampling over 2 months, we quantified the appearance of water and nitrate in xylem sap and foliage, supported by sap flow measurements to estimate transit times. Water reached the canopy faster than nitrogen, revealing a marked asynchrony in resource translocation for both species and sites—the first such field observation. Douglas fir showed greater subsoil water and nitrate uptake on sandy than on loamy soil, and higher subsoil uptake compared to beech under identical conditions. Tree species, soil texture and soil depth jointly govern water and nitrate uptake dynamics, as well as their temporal decoupling. These findings provide novel field‐based evidence of asynchronous water and nitrate transport, advancing our understanding of tree ecophysiology and nutrient cycling under field conditions.Summary statement Dual‐isotope tracing in situ shows faster transport of water than nitrate from soil to canopy of mature trees, indicating effects of root function, soil texture and species traits. Douglas fir exhibits greater subsoil water and nitrate uptake on sandy than on loamy soils and higher uptake than beech under similar soil conditions.Deutsche Forschungsgemeinschaft https://doi.org/10.13039/50110000165
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