8 results on '"Becker, Joscha N."'
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2. Climate–land-use interactions shape tropical mountain biodiversity and ecosystem functions
- Author
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Peters, Marcell K., Hemp, Andreas, Appelhans, Tim, Becker, Joscha N., Behler, Christina, Classen, Alice, Detsch, Florian, Ensslin, Andreas, Ferger, Stefan W., Frederiksen, Sara B., Gebert, Friederike, Gerschlauer, Friederike, Gütlein, Adrian, Helbig-Bonitz, Maria, Hemp, Claudia, Kindeketa, William J., Kühnel, Anna, Mayr, Antonia V., Mwangomo, Ephraim, Ngereza, Christine, Njovu, Henry K., Otte, Insa, Pabst, Holger, Renner, Marion, Röder, Juliane, Rutten, Gemma, Schellenberger Costa, David, Sierra-Cornejo, Natalia, Vollstädt, Maximilian G. R., Dulle, Hamadi I., Eardley, Connal D., Howell, Kim M., Keller, Alexander, Peters, Ralph S., Ssymank, Axel, Kakengi, Victor, Zhang, Jie, Bogner, Christina, Böhning-Gaese, Katrin, Brandl, Roland, Hertel, Dietrich, Huwe, Bernd, Kiese, Ralf, Kleyer, Michael, Kuzyakov, Yakov, Nauss, Thomas, Schleuning, Matthias, Tschapka, Marco, Fischer, Markus, and Steffan-Dewenter, Ingolf
- Published
- 2019
- Full Text
- View/download PDF
3. Legume and Non-legume Trees Increase Soil Carbon Sequestration in Savanna
- Author
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Becker, Joscha N., Gütlein, Adrian, Cornejo, Natalia Sierra, Kiese, Ralf, Hertel, Dietrich, and Kuzyakov, Yakov
- Published
- 2017
4. Biomass, Morphology, and Dynamics of the Fine Root System Across a 3,000-M Elevation Gradient on Mt. Kilimanjaro
- Author
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Sierra Cornejo, Natalia, Hertel, Dietrich, Becker, Joscha N., Hemp, Andreas, and Leuschner, Christoph
- Subjects
root:shoot ratio ,fine root biomass ,Plant Science ,root economics spectrum ,lcsh:Plant culture ,afroalpine heathland ,fine root production ,shoot ratio ,savannah ,tropical montane forest [afroalpine heathland ,root traits ,root] ,lcsh:SB1-1110 ,tropical montane forest ,Original Research - Abstract
Fine roots (≤2 mm) consume a large proportion of photosynthates and thus play a key role in the global carbon cycle, but our knowledge about fine root biomass, production, and turnover across environmental gradients is insufficient, especially in tropical ecosystems. Root system studies along elevation transects can produce valuable insights into root trait-environment relationships and may help to explore the evidence for a root economics spectrum (RES) that should represent a trait syndrome with a trade-off between resource acquisitive and conservative root traits. We studied fine root biomass, necromass, production, and mean fine root lifespan (the inverse of fine root turnover) of woody plants in six natural tropical ecosystems (savanna, four tropical mountain forest types, tropical alpine heathland) on the southern slope of Mt. Kilimanjaro (Tanzania) between 900 and 4,500 m a.s.l. Fine root biomass and necromass showed a unimodal pattern along the slope with a peak in the moist upper montane forest (~2,800 m), while fine root production varied little between savanna and upper montane forest to decrease toward the alpine zone. Root:shoot ratio (fine root biomass and production related to aboveground biomass) in the tropical montane forest increased exponentially with elevation, while it decreased with precipitation and soil nitrogen availability (decreasing soil C:N ratio). Mean fine root lifespan was lowest in the ecosystems with pronounced resource limitation (savanna at low elevation, alpine heathland at high elevation) and higher in the moist and cool forest belt (~1,800–3,700 m). The variation in root traits across the elevation gradient fits better with the concept of a multi-dimensional RES, as root tissue density and specific root length showed variable relations to each other, which does not agree with a simple trade-off between acquisitive and conservative root traits. In conclusion, despite large variation in fine root biomass, production, and morphology among the different plant species and ecosystems, a general belowground shift in carbohydrate partitioning is evident from 900 to 4,500 m a.s.l., suggesting that plant growth is increasingly limited by nutrient (probably N) shortage toward higher elevations. Open-Access-Publikationsfonds 2020 peerReviewed
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- 2020
5. Biomass, Morphology, and Dynamics of the Fine Root System Across a 3,000-M Elevation Gradient on Mt. Kilimanjaro
- Author
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Sierra Cornejo, Natalia, primary, Hertel, Dietrich, additional, Becker, Joscha N., additional, Hemp, Andreas, additional, and Leuschner, Christoph, additional
- Published
- 2020
- Full Text
- View/download PDF
6. Legume and Non-legume Trees Increase Soil Carbon Sequestration in Savanna
- Author
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Becker, Joscha N., primary, Gütlein, Adrian, additional, Sierra Cornejo, Natalia, additional, Kiese, Ralf, additional, Hertel, Dietrich, additional, and Kuzyakov, Yakov, additional
- Published
- 2016
- Full Text
- View/download PDF
7. The Ebergoetzen Measurement Site: Linking Biogeochemical Cycles and Soil Development in a Central European Beech Forest.
- Author
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Becker, Joscha N., Hughes, Harold, Grotheer, Jürgen, Zeppenfeld, Thorsten, and Sauer, Daniela
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SOIL formation , *BIOGEOCHEMICAL cycles , *EUROPEAN beech , *HUMUS , *SOIL solutions - Abstract
Climatic changes affect soil formation and biogeochemical processes on various spatial and temporal scales. This alters the interaction and feedback mechanism between long-term soil development and present biogeochemical cycles. To identify these mechanistic transformations and thus implications on soil function and ecosystem services, continuous and highly resolved observations are fundamental.In spring 2017, we established the Ebergoetzen measurement site in order to investigate biogeochemical processes and related soil formation under two distinct microclimatic conditions. The sites is located in a small valley on Triassic sandstone bedrock with active soil acidification and early-stage podsolization. The area is covered by a ~50-year-old beech forest (Fagus sylvatica) and separated into two topographical units: a south-facing slope and a north-facing slope. Both slopes were equipped with a state-of-the-art sensor network to monitor environmental parameters and biogeochemical fluxes. Soil moisture and temperature, as well as climatic parameters are continuously monitored. Each slope was equipped with suction plates to collect soil water (-150 hPa) at four different soil depths (15, 30, 50 and 70 cm). Soil solution is collected on a bi-weekly basis and analyzed for carbon and nutrient concentrations. Additional litter traps (0.5 m²) were installed and sampled regularly to estimate the seasonal element inputs from solid matter. Dissolved element and nutrient inputs are quantified in samples from 12 stem-flow and throughfall collectors. Twelve individual trees were equipped with sap-flow meters to continuously monitor water uptake by trees.At the north-facing slope, soil temperature and evapotranspiration were seasonally reduced compared to the south-facing slope, leading to higher water availability and leaching, thus lower soil pH values – and a potential deceleration of biochemical turnover. Based on these initial conditions, we plan to assess annual and interannual fluctuations and relate these changes to soil development processes, such as soil organic matter transformation and relocation within the profile, as well as changes in the plant-soil interactions and effects on the biogenic silicon cycle. An SQL-database was designed to automatically collect and structure all data and make it available for possible collaborations and large-scale comparisons. [ABSTRACT FROM AUTHOR]
- Published
- 2019
8. Application of planar optodes to measure CO2 gradients in the rhizosphere of unsaturated soils.
- Author
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Holz, Maire, Becker, Joscha N., Oburger, Eva, and Daudin, Gabrielle
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WATERLOGGING (Soils) , *SOIL moisture , *SOILS , *SOIL respiration , *RHIZOSPHERE , *OPTODES - Abstract
Soil CO2 efflux is a major pathway in the global C cycle and comprises root respiration as well as microbial respiration. Soil respiration is therefore tightly linked to root activity and C release from roots as root exudates are rapidly decomposed by soil microorganisms. As the rhizosphere is characterized by high C turnover rates and high spatial variability of processes, a method is needed to account for this spatial and temporal variability of CO2 production in the rhizosphere. Planar optodes were previously applied to measure the distribution of pH and O2 in the rhizosphere. So far, CO2 measurements were only a few times successfully conducted in saturated soils, although the importance of soil CO2 respiration is usually higher under aerobic conditions. We therefore tested whether planar optodes can be applied to measure CO2 in the rhizosphere of unsaturated soils. Maize (zea mays) plants were grown in 5 rhizoboxes filled with sandy soil. After four weeks, planar optodes sensitive to CO2 (PreSens GmbH, SF-CD2R - range: 0 – 1 % pCO2) were attached to the rhizosphere surface. We selected 2-5 positions with visibly growing roots per box and attached 20-40 cm² optodes at each position. The CO2 concentration was measured at three different volumetric soil water contents (VWC), a) 21%, b) 28% and c) after saturation at 38%. The change of CO2 signal was monitored over a period of 15 hours after saturation of samples to test the optode equilibration time. The obtained images were calibrated and analyzed using ImageJ v. 1.51 (NIH).Gradients of CO2 were clearly visible around root tips. Around mature root parts, the increase of CO2 was only half as strong as for young root parts, likely due to high root respiration in the growing root parts and due to microbial decomposition of root exudates. The equilibration time for the rhizosphere was 10 hours, while in bulk soil equilibrium was not reached after 15 hours. This suggests that optodes should be attached to samples and equilibrated for at least 15 hours prior to measurements. Soil moisture had a strong effect on the measured CO2 concentration. For 21% VWC the average CO2 concentration was 0.23 µmol CO2 l-1 while it was 0.38 µmol CO2 l-1 for 28% VWC and increased to 1.47 µmol CO2 l-1 after saturating the samples to 38% VWC. For 28% and 38% VWCs, CO2 gradients were clearly visible around the roots, while no gradients were detectable at VWC of 21%. This is likely due to the increased diffusion of CO2 into the optodes under higher VWC. Statistical comparisons between VWC levels were highly sensitive, indicating that small changes in soil WC will greatly affect the measured CO2 concentration and thus may be a strong confounding variable for treatment comparisons in unsaturated soils. However, provided that the soil moisture is kept constant in all samples, optode measurements of CO2 can be used in moist soil samples to quantify relative differences in CO2 concentration between treatments. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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