@inproceedings{FischerGypserSubbotinaetal., author = {Fischer, Thomas and Gypser, Stella and Subbotina, Maria and Veste, Maik}, title = {Hydraulic and nutritional feedback controls surface patchiness of biological soil crusts at a post-mining site}, series = {European Geosciences Union, General Assembly 2015, Vienna, Austria, 13 April - 17 May 2015}, booktitle = {European Geosciences Union, General Assembly 2015, Vienna, Austria, 13 April - 17 May 2015}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @inproceedings{HirschBonhageBauriegeletal., author = {Hirsch, Florian and Bonhage, Alexander and Bauriegel, Albrecht and Schneider, Anna and Raab, Alexandra and Raab, Thomas and Gypser, Stella}, title = {Occurrence, soil parameters and genesis of Rhodic Arenosols ('Fuchserden') in northeastern Germany}, series = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @misc{HirschBonhageBauriegeletal., author = {Hirsch, Florian and Bonhage, Alexander and Bauriegel, Albrecht and Schneider, Anna and Raab, Thomas and Raab, Alexandra and Gypser, Stella}, title = {The occurrence, soil parameters and genesis of rubified soils ('Fuchserden') of northeastern Germany}, series = {Catena}, volume = {175}, journal = {Catena}, issn = {0008-7769}, doi = {10.1016/j.catena.2018.11.039}, pages = {77 -- 92}, language = {en} } @misc{FischerGypserSubbotinaetal., author = {Fischer, Thomas and Gypser, Stella and Subbotina, Maria and Veste, Maik}, title = {Synergic hydraulic and nutritional feedback mechanisms control surface patchiness of biological soil crusts on tertiary sands at a post-mining site}, series = {Journal of Hydrology and Hydromechanics}, volume = {62}, journal = {Journal of Hydrology and Hydromechanics}, number = {4}, issn = {0042-790X}, doi = {10.2478/johh-2014-0038}, pages = {293 -- 302}, abstract = {In a recultivation area located in Brandenburg, Germany, five types of biocrusts (initial BSC1, developed BSC2 and BSC3, mosses, lichens) and non-crusted mineral substrate were sampled on tertiary sand deposited in 1985- 1986 to investigate hydrologic interactions between crust patches. Crust biomass was lowest in the non-crusted substrate, increased to the initial BSC1 and peaked in the developed BSC2, BSC3, the lichens and the mosses. Water infiltration was highest on the substrate, and decreased to BSC2, BSC1 and BSC3. Non-metric multidimensional scaling revealed that the lichens and BSC3 were associated with water soluble nutrients and with pyrite weathering products, thus representing a high nutrient low hydraulic feedback mode. The mosses and BSC2 represented a low nutrient high hydraulic feedback mode. These feedback mechanisms were considered as synergic, consisting of run-off generating (low hydraulic) and run-on receiving (high hydraulic) BSC patches. Three scenarios for BSC succession were proposed. (1) Initial BSCs sealed the surface until they reached a successional stage (represented by BSC1) from which the development into either of the feedback modes was triggered, (2) initial heterogeneities of the mineral substrate controlled the development of the feedback mode, and (3) complex interactions between lichens and mosses occurred at later stages of system development.}, language = {en} } @misc{GypserSchuetzeFreese, author = {Gypser, Stella and Sch{\"u}tze, Elisabeth and Freese, Dirk}, title = {Crystallization of single and binary iron- and aluminum hydroxides affect phosporus desorption}, series = {Journal of Plant Nutrition and Soil Science}, volume = {182}, journal = {Journal of Plant Nutrition and Soil Science}, number = {5}, issn = {1522-2624}, doi = {10.1002/jpln.201700543}, pages = {741 -- 750}, abstract = {In acidic soils, phosphorus availability is affected by its strong affinity for mineral surfaces, especially Fe- and Al-hydroxides. Plant roots have developed adaptive strategies to enhance the availability of phosphorus, including producing and exuding low molecular weight organic acids with a high affinity for phosphorus that competes with high molecular weight organic ligands formed during humification and mineralization. The aim of this study was to characterize the kinetics and mechanism of phosphorus desorption from Fe- and Al-hydroxides of variable crystallinity, as well as binary Fe:Al-hydroxide mixtures. Long-term desorption experiments (56 days) were conducted with CaCl₂, CaSO₄, citric acid, and humic acid as competitive sorptives. CaCl₂ and CaSO₄ were selected as general inorganic sorptives and citric and humic acids were selected as organic ligands produced by organisms in the rhizosphere or following humification. The cumulative phosphorus desorption increased following the order CaCl₂< CaSO₄< humic acid < citric acid. Amorphous ferrihydrite and Fe-rich Fe:Al-hydroxides exhibited much less desorption when exposed to inorganic solutions than the crystalline and Al-rich Fe:Al-hydroxide mixtures. Models of the desorption data suggest phosphorus desorption with citric acid is diffusion- controlled for ferrihydrite and Fe-rich amorphous Fe:Al-hydroxides. When humic acid was the sorptive, metal-organic complexes accumulated in the solution. The results suggest organic compounds, especially citric acid, are more important for liberating phosphorus from Fe- and Al-minerals than inorganic ions present in the soil solution.}, language = {en} } @inproceedings{GypserFreese, author = {Gypser, Stella and Freese, Dirk}, title = {Mechanisms of adsorption and desorption of phosphorus on crystalline iron, aluminum, manganese (hydr)oxides as well as iron and calcium phosphates in comparison to amorphous iron-aluminum compounds}, series = {8th International Phosphorus Workshop IPW8, Rostock, Germany, September 12-16, 2016}, booktitle = {8th International Phosphorus Workshop IPW8, Rostock, Germany, September 12-16, 2016}, editor = {Kr{\"a}mer, Inga and H{\"a}berle, Stephanie}, address = {Rostock}, doi = {10.12754/procs-2016-ipw8}, pages = {S. 73}, abstract = {Inorganic phosphorus (P) plays an important role as plant nutrient in fertilizers, but also as a major pollutant to aquatic ecosystems by leaching from arable land. The mobility and bioavailability of P depends on adsorption, desorption and precipitation processes at soil mineral surfaces. In the soil matrix, P can be found in the forms of iron, aluminum or calcium complexes, adsorbed on mineral surfaces. P reactions in soil, especially the fixation on iron and aluminum (hydr) oxides, have been thoroughly studied. But the much slower process of P release has to be attended as well regarding the prospective supply of fertilizers and the use of plant available P pools in arable soils. The P adsorption ability of pedogenic oxides depends on their crystallinity, while soils contain both crystalline minerals such as goethite or ferrihydrite, as well as amorphous iron and aluminum compounds. In this study, long-term adsorption and desorption experiments were carried out to investigate the P binding mechanism during the sorption processes at certain time steps. For adsorption experiments, various experimental conditions such as pH, P ionic strength, competitive ions such as SO4 2- and Ca2+ as well as time will be considered. For desorption experiments, a Flow-Through-Reactor-Technique will be applied to investigate desorption kinetics and processes under nearly natural conditions without disturbance of the mineral-solution interface. Additionally, the release of P from the iron and calcium phosphates vivianite and hydroxyapatite, a main supplier of inorganic P and model substance for bone char, will be investigated. By using Fourier-Transformation-Infrared-Spectroscopy, changes of P binding mechanisms during ad- and desorption processes and easily as well heavily purgeable P can be detected. Aim is to identify fundamental processes of P fixation and mobilization as well as to specify similarities and differences of P binding on crystalline and amorphous reactive surfaces of pedogenic oxides.}, language = {en} } @misc{GypserFreese, author = {Gypser, Stella and Freese, Dirk}, title = {Phosphorus release from vivianite and hydroxyapatite by organic and inorganic compounds}, series = {Pedosphere}, volume = {30}, journal = {Pedosphere}, number = {2}, issn = {1002-0160}, doi = {10.1016/S1002-0160(20)60004-2}, pages = {190 -- 200}, abstract = {Based on recent mining rates and the exhaustion of global phosphorus (P) reserves, there is a need to mobilize P already stored in soils, and its recovery from secondary resources such as Ca- and Fe-phosphates is important. The Ca-phosphate hydroxyapatite forms a good fertilizer source, while vivianite is formed in waterlogged soils and sediments. During sludge treatment, the formation of vivianite has been identified, being mainly Fe-phosphate. Long-term P release from both hydroxyapatite and vivianite was studied using different inorganic (CaCl2 and CaSO4) and organic (citric and humic acid) reagents during batch experiments. Reagents CaCl2 and CaSO4 represent the soil solution, while citric and humic acids as organic constituents affect P availability in the rhizosphere and during the process of humification. Additionally, the flow-through reactor (FTR) technique with an infinite sink was used to study the long-term P release kinetics. The cumulative P release was higher by organic acids than by inorganic compounds. The cumulative P release rates were higher in the FTR with CaCl2 as compared to the batch technique. The infinite sink application caused a continuously high concentration gradient between the solid and liquid phases, leading to higher desorption rates as compared to the batch technique. The predominant amount of the total P released over time was available for a short term. While inorganic anion exchange occurred at easily available binding sites, organic acids affected the more heavily available binding sites, which could be embedded within the mineral structure. The results showed that organic compounds, especially citric acid, play a superior role as compared to the inorganic constituents of the soil solution during the recovery of already stored P from the tertiary phosphates vivianite and hydroxyapatite.}, language = {en} } @misc{GypserHirschSchleicheretal., author = {Gypser, Stella and Hirsch, Florian and Schleicher, Anja M. and Freese, Dirk}, title = {Impact of crystalline and amorphous iron- and aluminum hydroxides on mechanisms of phosphate adsorption and desorption}, series = {Journal of Environmental Sciences}, volume = {70}, journal = {Journal of Environmental Sciences}, doi = {10.1016/j.jes.2017.12.001}, pages = {175 -- 189}, language = {en} } @inproceedings{MykhailovaRaabGypseretal., author = {Mykhailova, Larysa and Raab, Thomas and Gypser, Stella and Fischer, Thomas}, title = {Development and hydrology of biological soil crusts -- first results from a surface inoculation experiment}, series = {European Geosciences Union, General Assembly 2016, Vienna, Austria, 17 April - 22 May 2016}, booktitle = {European Geosciences Union, General Assembly 2016, Vienna, Austria, 17 April - 22 May 2016}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @misc{MantovaniVesteGypseretal., author = {Mantovani, Dario and Veste, Maik and Gypser, Stella and Halke, Christian and Koning, Laurie Anne and Freese, Dirk and Lebzien, Stefan}, title = {Transpiration and biomass production of the bioenergy crop Giant Knotweed Igniscum under various supplies of water and nutrients}, series = {Journal of Hydrology and Hydromechanics}, volume = {62}, journal = {Journal of Hydrology and Hydromechanics}, number = {4}, issn = {0042-790X}, doi = {10.2478/johh-2014-0028}, pages = {316 -- 323}, abstract = {Soil water availability, nutrient supply and climatic conditions are key factors for plant production. For a sustainable integration of bioenergy plants into agricultural systems, detailed studies on their water uses and growth performances are needed. The new bioenergy plant Igniscum Candy is a cultivar of the Sakhalin Knotweed (Fallopia sachalinensis), which is characterized by a high annual biomass production. For the determination of transpiration-yield relations at the whole plant level we used wicked lysimeters at multiple irrigation levels associated with the soil water availability (25, 35, 70, 100\%) and nitrogen fertilization (0, 50, 100, 150 kg N ha-1). Leaf transpiration and net photosynthesis were determined with a portable minicuvette system. The maximum mean transpiration rate was 10.6 mmol m-2 s-1 for well-watered plants, while the mean net photosynthesis was 9.1 μmol m-2 s-1. The cumulative transpiration of the plants during the growing seasons varied between 49 l (drought stressed) and 141 l (well-watered) per plant. The calculated transpiration coefficient for Fallopia over all of the treatments applied was 485.6 l kg-1. The transpiration-yield relation of Igniscum is comparable to rye and barley. Its growth performance making Fallopia a potentially good second generation bioenergy crop.}, language = {en} } @misc{GypserHerppichFischeretal., author = {Gypser, Stella and Herppich, Werner B. and Fischer, Thomas and Lange, Philipp and Veste, Maik}, title = {Photosynthetic characteristics and their spatial variance on biological soil crusts covering initial soils of post-mining sites in Lower Lusatia, NE Germany}, series = {Flora}, volume = {Vol. 220}, journal = {Flora}, issn = {0367-2530}, doi = {10.1016/j.flora.2016.02.012}, pages = {103 -- 116}, abstract = {Following surface disturbance, quaternary sands are the basic substrate for soil development in the Lusatian reclamation area. These substrates mostly contain few organic matter and, hence, are nutrient poor. Accumulation of soil carbon is an important factor for ecosystem development, where biological soil crusts initially influence soil processes and promote ecosystem succession. The compositional structures of biological soil crusts at various developmental stages and their photosynthetic properties were investigated on two former open-cast lignite sites, currently under reclamation, an artificial sand dune in Welzow S{\"u}d, and a forest plantation in Schlabendorf S{\"u}d (Brandenburg, Germany). As development of biological soil crusts progressed, their contents of organic carbon and total chlorophyll increased. The ratio of these parameters, however, varied with the relative contribution of lichens and mosses in particular. Also maximum photochemical efficiency, net photosynthesis and respiration increased with crustal development. An additional evaluation of NDVI and chlorophyll fluorescence images showed that especially moss-dominated biocrusts had higher photosynthetic capacity compared to green algae-dominated biocrusts or soil lichens, so the photosynthetic capacity showed to be highly species-specific. The ratio of gross photosynthesis to respiration indicated a higher ecological efficiency of biocrusts dominated by green algae than of lichen-dominated biocrusts. The occurrence of soil lichens reduced net CO2 fixation and increased CO2 release due to the enhanced mycobiontic respiration. During crustal succession, the rise of photosynthesis-related parameters is not necessarily linear as a result of the highly heterogenic distribution of the different crustal organisms between biocrusts of similar developmental stages as well as between those growing at the two study sites. Therefore, the evaluation of relevant ecophysiological parameters highlighted that not all biocrust-forming organisms similarly contribute to the ecophysiological behavior of biological soil crusts. Nevertheless, the occurrence of the biological soil crusts promoted soil formation and accumulation of soil carbon in initial soils.}, language = {en} } @misc{GypserVesteFischeretal., author = {Gypser, Stella and Veste, Maik and Fischer, Thomas and Lange, Philipp}, title = {Infiltration and water retention of biological soil crusts on reclaimed soils of former open-cast lignite mining sites in Brandenburg, north-east Germany}, series = {Journal of hydrology and hydromechanics}, volume = {64}, journal = {Journal of hydrology and hydromechanics}, number = {1}, doi = {10.1515/johh-2016-0009}, pages = {1 -- 11}, abstract = {Investigations were done on two former open-cast lignite mining sites under reclamation, an artificial sand dune in Welzow S{\"u}d, and a forest plantation in Schlabendorf S{\"u}d (Brandenburg, Germany). The aim was to associate the topsoil hydrological characteristics of green algae dominated as well as moss and soil lichen dominated biological soil crusts during crustal succession with their water retention and the repellency index on sandy soils under temperate cli-mate and different reliefs. The investigation of the repellency index showed on the one hand an increase due to the cross-linking of sand parti-cles by green algae which resulted in clogging of pores. On the other hand, the occurrence of moss plants led to a de-crease of the repellency index due to absorption caused by bryophytes. The determination of the water retention curves showed an increase of the water holding capacity, especially in conjunction with the growth of green algae layer. The pore-related van Genuchten parameter indicate a clay-like behaviour of the developed soil crusts. Because of the inho-mogeneous distribution of lichens and mosses as well as the varying thickness of green algae layers, the water retention differed between the study sites and between samples of similar developmental stages. However, similar tendencies of water retention and water repellency related to the soil crust formation were observed. Biological soil crusts should be considered after disturbances in the context of reclamation measures, because the ini-tial development of green algae biocrusts lead to an increasing repellency index, while the occurrence of mosses and a gain in organic matter enhance the water holding capacity. Thus, the succession of biocrusts and their small-scale succes-sion promote the development of soil and ecosystem.}, language = {en} } @misc{GypserVesteFischeretal., author = {Gypser, Stella and Veste, Maik and Fischer, Thomas and Lange, Philipp}, title = {Formation of soil lichen crusts at reclaimed post-mining sites, Lower Lusatia, North-east Germany}, series = {Graphis Scripta}, volume = {27}, journal = {Graphis Scripta}, number = {1-2}, issn = {0901-7593}, pages = {3 -- 14}, abstract = {Biological soil crusts were investigated at reclaimed post-mining sites near Welzow and Schlabendorf in Lower Lusatia (Brandenburg, Germany). Various development stages from initial biological soil crusts built up by green algae, to more developed soil crusts with mosses, as well as moss-soil lichen crusts, were classified. The spatial-temporal dynamics during the development resulted in a moss-lichens cover with discrete patches of pioneer organisms like green algae in between. At the study sites, 13 species of terricolous lichens were identified. The formation of the biological soil crust is important for the accumulation of soil organic matter in the first millimeters of the topsoil of these pioneer ecosystems. A correlation between cryptogamic biomass and soil carbon content were found.}, language = {en} } @misc{AhmedGypserFreeseetal., author = {Ahmed, Ashour A. and Gypser, Stella and Freese, Dirk and Leinweber, Peter and K{\"u}hn, Oliver}, title = {Molecular level picture of the interplay between pH and phosphate binding at the goethite-water interface}, series = {Physical Chemistry Chemical Physics}, volume = {22}, journal = {Physical Chemistry Chemical Physics}, number = {45}, issn = {1463-9084}, doi = {10.1039/d0cp04698a}, pages = {26509 -- 26524}, abstract = {The soil pH plays a substantial role in controlling phosphorus (P) adsorption and mobilization. These processes are strongly affected by the phosphate interaction strength with P-fixing soil minerals such as goethite. The target of the current contribution is to draw a molecular level picture of the interplay between pH and phosphate binding at the goethite-water interface via a joint experimental-theoretical approach. Periodic density functional theory (DFT) calculations were carried out to provide a molecular level understanding of the pH dependence of P adsorption. To validate the modeling approach, adsorption experiments of phosphate at goethite were performed in the pH range of 4-12. There was agreement between experiments and simulations in the description of the adsorption behavior by two pH-dependent successive stages. The adsorption increases along the pH change from 4 to 8. A further increase of pH leads to a decrease of adsorption. By comparing with literature data it is concluded that the first stage will be observed only if there is no significant change of the surface charge at low pH. Moreover, the molecular modeling results point to the abundance of the monodentate (M) binding motif at both extremely low and high pH ranges. Otherwise, the bidentate (B) one is predominant along the intermediate pH range. These observations could resolve the existing debate about the assignment of phosphate-goethite binding motifs. Furthermore, the results point to a decrease of pH upon phosphate sorption due to an induced acidification of soil solution. The present joint experimental-theoretical approach provides a better understanding and description of the existing phosphate sorption experiments and highlights new findings at the atomistic/molecular scale.}, language = {en} } @misc{GypserSchuetzeFreese, author = {Gypser, Stella and Sch{\"u}tze, Elisabeth and Freese, Dirk}, title = {Single and binary Fe- and Al-hydroxides affect potential phosphorus mobilization and transfer from pools of different availability}, series = {Soil Systems}, volume = {5}, journal = {Soil Systems}, number = {2}, doi = {10.3390/soilsystems5020033}, pages = {1 -- 21}, abstract = {Phosphorus (P) fixation is a global problem for soil fertility and negatively impacts agricultural productivity. This study characterizes P desorption of already fixed P by using KCl, KNO3, histidine, and malic acid as inorganic and organic compounds, which are quite common in soil. Goethite, gibbsite, and ferrihydrite, as well as hydroxide mixtures with varying Fe- and Al-ratio were selected as model substances of crystalline and amorphous Fe- and Al-hydroxides. Especially twoand multi-component hydroxide systems are common in soils, but they have barely been included in desorption studies. Goethite showed the highest desorption in the range from 70.4 to 81.0\%, followed by gibbsite with values in the range from 50.7 to 42.6\%. Ferrihydrite had distinctive lower desorption in the range from 11.8 to 1.9\%. Within the group of the amorphous Fe-Al-hydroxide mixtures, P desorption was lowest at the balanced mixture ratio for 1 Fe: 1 Al, increased either with increasing Fe or Al amount. Precipitation and steric effects were concluded to be important influencing factors. More P was released by crystalline Fe-hydroxides, and Al-hydroxides of varying crystallinity, but desorption using histidine and malic acid did not substantially influence P desorption compared to inorganic constituents.}, language = {en} } @misc{SchuetzeGypserFreese, author = {Sch{\"u}tze, Elisabeth and Gypser, Stella and Freese, Dirk}, title = {Kinetics of phosphorus release from vivianite, hydroxyapatite, and bone char influenced by organic and inorganic compounds}, series = {Soil Systems}, volume = {4}, journal = {Soil Systems}, number = {1}, issn = {2571-8789}, doi = {10.3390/soilsystems4010015}, pages = {1 -- 20}, abstract = {The availability of P is often insuffcient and limited by accumulation in soils. This led to the necessity of solutions for the recovery as well as recycling of secondary P resources. Batch experiments were conducted with CaCl2 and citric acid to characterize P release kinetics from vivianite, hydroxyapatite, and bone char. While the P release during the CaCl2 treatment was so low that only vivianite and hydroxyapatite showed a slightly higher release with increasing CaCl2 concentration, the increase of dissolved P was more pronounced for citric acid. The application of citric acid resulted in a 32,190-fold higher P release for bone char. Fourier-transform infrared spectroscopic data suggested higher instability of hydroxyapatite than for bone char. The kinetic data showed that bone char, especially at a lower particle size, had a higher long-term P release than hydroxyapatite or vivianite. The suitability of hydroxyapatite and bone char as a poorly soluble, but sustainable P source is better than that of vivianite. However, the efficiency as a P fertilizer is also dependent on present soil P mobilization processes. The results underline the importance of the accessibility of fertilized or naturally bound P for plant roots to benefit from the excretion of organic acids.}, language = {en} } @misc{AhmedGypserLeinweberetal., author = {Ahmed, Ashour A. and Gypser, Stella and Leinweber, Peter and Freese, Dirk and K{\"u}hn, Oliver}, title = {Infrared Spectroscopic Characterization of Phosphate Binding at the Goethite-Water Interface}, series = {Physical Chemistry Chemical Physics}, volume = {21}, journal = {Physical Chemistry Chemical Physics}, issn = {1463-9084}, doi = {10.1039/C8CP07168C}, pages = {4421 -- 4434}, abstract = {The interaction between phosphates and soil mineral surfaces, such as Fe- and Al-(oxyhydr)oxides, plays a crucial role in the P immobilization and thus its availability for plants. The reactions of phosphates with Fe-hydroxides and especially goethite have been studied extensively. But a molecular-level picture about the phosphate binding mechanism at the goethite-water interface is still lacking. Therefore, in the current contribution we have explored the molecular binding mechanism for the adsorbed phosphate at the goethite-water interface by performing sorption kinetics experiments for orthophosphate and characterizing the adsorbed species by FT-IR spectroscopy. In parallel, periodic DFT calculations have been performed to explore the interaction mechanism as well as to calculate the IR spectra for monodentate (M) and bidentate (B) orthophosphate complexes at two different goethite surface planes (010 and 100) in the presence of water. In general, our interaction energy results give evidence that the mono-protonated B phosphate complex is more favored to be formed at the goethite-water interface although the M motif could exist as a minor fraction. Moreover, it was found that water plays an important role in controlling the phosphate adsorption process at the goethite surfaces. The interfacial water molecules form H-bonds (HBs) with the phosphate as well as with the goethite surface atoms. Further, some water molecules form covalent bonds with goethite Fe atoms while others dissociate at the surface to protons and hydroxyl groups. The present theoretical assignment of IR spectra introduces a benchmark for characterizing experimental IR data for the adsorbed KH2PO4 species at the goethite-water interface. In particular, IR spectra of the mono-protonated (2O+1Fe) B complex at the 010 goethite surface plane and the M complex at the 100 goethite surface plane were found to be consistent with the experimental data. In order to explore the role of different abundancies of surface planes and binding motifs, IR spectra obtained from weighted averages have been analyzed. Results confirmed the above conclusions drawn from interaction energy calculations.}, language = {en} } @misc{KochGuppyAmelungetal., author = {Koch, Maximilian and Guppy, Christopher and Amelung, Wulf and Gypser, Stella and Bol, Roland and Seidel, Sabine and Siebers, Nina}, title = {Insights into ³³phosphorus utilisation from Fe- and A-hydroxides in Luvisol and Ferralsol subsoils}, series = {Soil Research}, volume = {57}, journal = {Soil Research}, number = {5}, issn = {1838-6768}, doi = {10.1071/SR18223}, pages = {447 -- 458}, abstract = {There is currently relatively little available information on subsoil phosphorus (P) use for crop production as a function of soil order. In this study, a rhizobox experiment was performed using subsoils of two reference soil groups, an Orthic Ferralsol and a Haplic Luvisol. To evaluate the immediate P uptake by wheat (Triticum aestivum L.) from different subsoil P pools during 14 days of growth, subsoil bands were spiked with KH₂PO₄ solution associated to Fe-hydroxide (³³P-Fe), to Al-hydroxide (³³P-Al), in free form (³³P-OrthoP), or in trace amounts without any additional ³¹P (³³P-NoP). At the beginning of the experiment, the soil water content was set at 75\% of water-holding capacity, corresponding to an initial soil matric potential of -12 ± 1 kPa. During plant growth, soil moisture decreased in both soils, but soil matric potentials in both soils did not drop below field capacity (-33 kPa; pF 2.5). The shoot dry weights of the Ferralsol were 1.2 to 1.8 times those of the Luvisol. Despite elevated soil P availability in the Luvisol, shoot P concentrations did not differ between the two soils. The amount of ³³P taken up by the shoots from the oxide phases was 15\% to 40\% greater in the Ferralsol treatments than in those in the Luvisol treatments. It was concluded that the more favourable physical soil conditions facilitated ³³P uptake from both oxidic phases from the Ferralsol subsoil relative to the Luvisol subsoil, despite better P phytoavailability in the latter.}, language = {en} } @misc{KleefeldGypserHerppichetal., author = {Kleefeld, Andreas and Gypser, Stella and Herppich, Werner B. and Bader, Georg and Veste, Maik}, title = {Identification of spatial pattern of photosynthesis hotspots in moss- and lichen-dominated biological soil crusts by combining chlorophyll fluorescence imaging and multispectral BNDVI images}, series = {Pedobiologia}, volume = {68}, journal = {Pedobiologia}, issn = {1873-1511}, doi = {10.1016/j.pedobi.2018.04.001}, pages = {1 -- 11}, abstract = {Although biological soil crusts can be found in open landscapes worldwide, their species composition depends on soil properties such as texture and pH, on microclimate, and their respective developmental stage. In addition, local variations in water holding capacity and/or chemical properties of soils influence the formation of spatial patterns and different types of biocrusts on the landscape level. For the evaluation of biocrusts functions and their impact on soil carbon pools, the analysis of the interrelationship between photosynthetic activity and the variations of spatial distribution pattern and types of biocrust is indispensable. For this purpose, an image processing approach was applied that combined chlorophyll fluorescence analyses and multispectral BNDVI to comprehensively characterize the spatial patterns of photosynthetic hotspots in biological soil crusts. For image analysis, five biological soil crust samples with different ratios of substrate, mosses and lichens were collected on an inland dune system in Lieberose, dominated by the moss Polytrichum piliferum, and the lichens Cladonia fimbriata and C. coccifera. RGB-images of the biocrusts were taken with a standard consumer camera Nikon 5200, BNDVI images with a modified Canon S110 NIR camera and chlorophyll fluorescence images with a modular open FluorCAM FC 800-O/1010, respectively. BNDVI and Fv/Fm were nearly in the same range for all biocrust samples related to the total surface area. Although mosses showed higher BNDVI than lichens within the separate biocrust samples. F0 and Fm increased with species coverage and with advancing biocrust development. Overlapping of BNDVI with F0 and Fm images showed that not all crustal organisms contribute to BNDVI and chlorophyll fluorescence. The overlapping areas of BNDVI and F0 ranged between 13\% and 29\%, that of BNDVI and Fm between 17\% and 47\%. Matching of RGB, BNDVI and CFI allows visualizing spatial pattern with high or low photosynthesis in biocrusts.}, language = {en} } @inproceedings{GypserFischerLangeetal., author = {Gypser, Stella and Fischer, Thomas and Lange, Philipp and Veste, Maik}, title = {Impact of biocrust succession on water retention and repellency on open-cast lignite mining sites under reclamation in Lower Lusatia, NE-Germany}, series = {European Geosciences Union, General Assembly 2016, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2016, Vienna, Austria}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, abstract = {Mining activities can strongly affect ecosystem properties by destruction of naturally developed soils and removal of vegetation. The unstructured substrates show high bulk densities, compaction, low water infiltration rates, reduced water holding capacities and higher susceptibility to wind and water erosion. In the initial stage of the ecosystem development, the post-mining sites are open areas without or with a low cover of higher vegetation. It is well-known that biocrusts are able to colonize the soil surface under such extreme conditions without human support and affect soil hydrological processes such as water infiltration, run-off or re-distribution. Investigations were conducted on two former lignite open-cast mining sites, an artificial sand dune on the reclaimed watershedWelzow "Neuer Lugteich" and a reforestation area in Schlabendorf (Brandenburg, north-east Germany). The aim was to relate the hydrological characteristics of the topsoil to successional stages of biological soil crusts on reclaimed soils and their influence on repellency index and water holding capacity compared to pure mining substrate. Our study emphasized the influence of changing successional stages and species composition of biological soil crusts, forming a small-scale crust pattern, on water repellency and retention on sandy soils in temperate climate. Different successional stages of soil crusts were identified from initial scattered green algae crusts, dominated by Zygogonium spec. and Ulothrix spec., and more developed soil crusts containing mosses such as Ceratodon purpureus and Polytrichum piliferum. Lichens of the Genus Cladonia were more pronouncedly contributed to biocrusts at later and mature stages of development. The repellency index on the one hand increased due to the cross-linking of sand particles by the filamentous green algae Zygogonium spec. which resulted in clogging of pores, and on the other hand decreased with the occurrence of moss plants due to absorption caused by bryophytes. The determination of the water retention curves showed an increase of the water holding capacity, especially in conjunction with the growth of green algae layer. The absorption capacity of soil crust biota as well as a decreased pore diameter in the green algae layers positively affected the water retention of crusted soil compared to pure substrate. The occurrence of bryophytes with later succession weakened the repellent behavior of the biocrusts, increased infiltration, and might have affected the run-off at small-scale on biocrusts. Certainly, the biological soil crusts showed water repellent properties but no distinctive hydrophobic characteristics. On both locations, similar trends of water repellency and retention related to crustal formation were observed, in spite of different relief, reclamation time and inhomogeneous distribution of crustal organisms.}, language = {en} } @misc{DietzKueppersWachendorfetal., author = {Dietz, Miriam and K{\"u}ppers, Manfred and Wachendorf, Magnus and Stefan, Thorsten and Veste, Maik and Gypser, Stella}, title = {Modelling photosynthesis and carbon fluxes of moss- and lichen-dominated biological soil crusts in temperate dry acid grasslands in Brandenburg}, series = {Gf{\"O} 2019, Science Meets Practice, 49th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, university of M{\"u}nster, 9-13 September 2019}, journal = {Gf{\"O} 2019, Science Meets Practice, 49th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, university of M{\"u}nster, 9-13 September 2019}, address = {M{\"u}nster}, pages = {223}, abstract = {Top soils in temperate climates are regularly covered by cryptogames. Depending on the climatic and environmental conditions and their development stage, these biocrusts are built up by different species of cyanobacteria, bacteria, green algae, mosses, liverworts, lichens and fungi, which crosslink the uppermost soil particles. Biocrusts create a thin surface layer of high biotic activity, with high C and nutrient pools and fluxes to deeper soil layers, where the soil tends to be biotically and biogeochemically less active. Changes in soil structure, e.g. due to the accumulation of organic material and the ability of biological nitrogen fixation, result in significant feedback and control of biogeochemical processes. We analysed the response of photosynthesis and respiration to changing temperature and light in two moss-and lichen-dominated soil crusts from a dry acid grassland in the vicinity of a pine forest in Brandenburg, Germany. For the estimation of carbon fluxes, we combined lab-based CO2 gas exchange measurements and continuous determination of biocrust drying and rewetting cycles under field conditions. These experiments facilitated the development of an empirical photosynthesis model that allows for an estimation of the carbon dynamics of biological soil crusts based on their ecophysiological performance.}, language = {en} } @misc{GypserDiezBoellietal., author = {Gypser, Stella and Diez, Miriam and Boelli, Daniel and Wachendorf, Magnus and K{\"u}ppers, Manfred and Veste, Maik}, title = {Monitoring of biocrust development and physiological activity in disturbed ecosystems in Central Europe}, series = {Biocrust 4 - 4th International Workshop on Biological Soil Crusts}, volume = {2019}, journal = {Biocrust 4 - 4th International Workshop on Biological Soil Crusts}, address = {North Stradbroke Island, Queensland , Australia}, doi = {10.13140/RG.2.2.11042.99523}, pages = {1}, abstract = {In many ecosystems of the earth, biocrusts influence the successive development of vegetation through their influence on the soil formation. This change in soil structure, e.g. due to the accumulation of organic material and the ability of biological nitrogen fixation, results in significant feedback and controls of ecosystem processes, especially in arid regions. In Brandenburg, located in NE Germany, the dry grasslands on sand dunes and the post-mining landscapes, characterized by edaphic drought and lack of nutrients as well as disturbances, are ecologically interesting locations for investigations of the biocrusts. In recent years, the species composition, structure, N-fixation, C-fluxes, and accumulation as well as their soil hydrological properties of biocrusts have been characterized and ecophysiological measurements of biocrust activity and CO2 exchange of different biocrust types under standardized environmental conditions have been performed in the laboratory. These ecophysiological measurements were correlated for the first time with NDVI measurements using a modified consumer camera, thus enabling a spatial analysis of the photosynthesis hotspots and a transfer from the lab into the landscape. The development and physiological activity of biocrusts are significantly influenced by microclimatic boundary conditions and moisture-dry cycles. The duration of these moisture phases is decisive for their spatial and temporal development and for the differentiation of the developmental stages. The permanent recording of moisture in the biocrusts in the uppermost millimeters using a newly developed biocrust wetness sensor in combination with NDVI measurements enable detailed information about biocrust activities and carbon fluxes. These continuous measurements of NDVI and physiological activity with PRI sensors allows determining seasonal activity phases in relation to microclimatological site conditions. More recent technological developments in sensor technology make it possible to carry out detailed and cost-effective investigations of the biocrust activity over the course of the year.}, language = {en} } @misc{GypserVeste, author = {Gypser, Stella and Veste, Maik}, title = {Hotspot biocrusts: Combining chlorophyll fluorescence and NDVI to analyze spatial and temporal variations of photosynthesis}, series = {Gf{\"O} 2019, Science Meets Practice, 49th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, university of M{\"u}nster, 9-13 September 2019}, journal = {Gf{\"O} 2019, Science Meets Practice, 49th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, university of M{\"u}nster, 9-13 September 2019}, pages = {199}, abstract = {Biological soil crusts (biocrusts) play an important role as pioneering organisms on initial soils and in open landscapes after natural and human disturbances. Even though they only cover the topsoil, biocrusts are key drivers for biogeochemical and ecological processes and influencing ecosystem development. Microclimatic conditions, texture, water holding capacity, and chemical soil properties lead to the formation of spatial patterns. Sandy nutrient-poor soils in pine forests in the open-cast lignite mining district in Brandenburg are covered by biocrust, dominated by different functional types and species (e.g. algae, mosses, lichens). The photosynthetic activity of these poikilohydric organisms, strongly depending on moisture, affects biocrust function and their impact on soil C pools and dynamics. Therefore, the evaluation of photosynthesis in relation to the spatial distribution pattern variation is fundamental. For this purpose, we combined different remote sensing techniques, spectral reflectance sensors, and chlorophyll fluorescence imaging to analyze the photosynthetic dynamics in relation to biocrust species composition and wetness. Desiccation of the biocrusts was detected with a miniature moisture sensor and related to their activity. A low-cost consumer grade camera was used to determine NDVI and to map the distribution and heterogeneity of chlorophyll for a comprehensive characterization of spatial photosynthetic activity pattern. Basic as well as maximum fluorescence, the maximum photochemical efficiency, and NDVI decreased during desiccation of the biocrusts, whereby moss and moss/lichen biocrusts showed higher water holding capacities relative to green algae biocrusts. The combination of different sensor technologies is a powerful tool for monitoring long-term biocrust development and their implication for soil C dynamics.}, language = {en} } @misc{AhmedGypserLeinweberetal., author = {Ahmed, Ashour A. and Gypser, Stella and Leinweber, Peter and Freese, Dirk and K{\"u}hn, Oliver}, title = {New insights into IR spectroscopic characterization of phosphate binding at the goethite-water interface}, series = {IPW9, ETH Zurich, Switzerland, 8-12 July, 2019 - Abstracts}, journal = {IPW9, ETH Zurich, Switzerland, 8-12 July, 2019 - Abstracts}, address = {Z{\"u}rich}, pages = {108}, abstract = {Facing the projected peak phosphorus (P) scenario, substantial research activities have been triggered to improve our knowledge towards a more efficient and sustainable use of P resources. One major factor playing a role in the P immobilization and thus its availability for plants is the strong interaction between phosphates and soil mineral surfaces, such as Fe- and Al-(oxyhydr)oxides. The reactions of phosphates with Fe-hydroxides and especially goethite have been studied extensively. But a molecular-level picture of the phosphate binding mechanism at the goethite-water interface is still lacking. Therefore, in the current contribution we have explored the molecular binding mechanism for the adsorbed phosphate at the goethite-water interface by performing sorption kinetics experiments for orthophosphate and characterizing the adsorbed species by FT-IR spectroscopy. In parallel, periodic quantum mechanical calculations, at the density functional theory (DFT) level, have been performed to explore the interaction mechanism as well as to calculate the IR spectra for monodentate (M) and bidentate (B) orthophosphate complexes with goethite at two different goethite surface planes (010 and 100) in the presence of water. In general, our interaction energy results give evidence that the mono-protonated B phosphate complex is more favored to be formed at the goethite-water interface although the M motif could exist as a minor fraction. Moreover, it was found that water plays an important role in controlling the phosphate adsorption process at the goethite surfaces. The interfacial water molecules form H-bonds (HBs) with the phosphate as well as with the goethite surface atoms. Further, some water molecules form covalent bonds with goethite Fe atoms while others dissociate at the surface to protons and hydroxyl groups. The present theoretical assignment of IR spectra introduces a benchmark for characterizing experimental IR data for the adsorbed KH2PO4 species at the goethite-water interface. In particular, IR spectra of the mono-protonated (2O+1Fe) B complex at the 010 goethite surface plane and the M complex at the 100 goethite surface plane were found to be consistent with the experimental data. In order to explore the role of different abundancies of surface planes and binding motifs, IR spectra obtained from weighted averages have been analyzed. Results confirmed the above conclusions drawn from interaction energy calculations. Moreover, the soil solution pH effect on the phosphate binding mechanism to goethite surface has been explored as well.}, language = {en} } @inproceedings{KochKruseEichlerLoebermannetal., author = {Koch, Maximilian and Kruse, Jens and Eichler-L{\"o}bermann, Bettina and Gypser, Stella and Flavel, R. and Guppy, Christopher and Zimmer, Dana and Leinweber, Peter and Siebers, Nina}, title = {Phosphorus bioavailability in soil profiles of a long-term fertilizer experiment: The evaluation of their bioaccessibility}, series = {Abstracts der DBG Jahrestagung 2017, 02.-07. Sept. 2017, G{\"o}ttingen}, booktitle = {Abstracts der DBG Jahrestagung 2017, 02.-07. Sept. 2017, G{\"o}ttingen}, pages = {1}, abstract = {Global agricultural productivity depends on the use of finite phosphorus (P) resources of which not only the topsoil, but also subsoil, can hold immense reserves. To assess potential soil contribution to plant nutrition, we compared the P status of Stagnic Cambisol profiles in experimental plots that received different P fertilizer applications (control, triple superphosphate (TSP), compost, compost+TSP) for 16 years. Sequential fractionation was combined with P K-edge X-ray absorption near edge structure (XANES) spectroscopy to identify the chemical P speciation. Fertilized topsoils (21 to 69 kg P ha-1 a-1) showed P reserves larger by a factor of 1.2 to 1.4, and subsoil P reserves larger by a factor of 1.3 to 1.5 than those of the control. P-XANES revealed the predominance of inorganic P species such as moderately labile Fe- (46 to 92\%), Al- (0 to 40\%), and Ca- (0 to 15\%) P compounds besides organic P (0 to 13\%) in all treatments. The fertilizer application slightly altered P speciation throughout the profiles, but the type of fertilizer had no significant effect on it. Optimal plant growth requirements are restricted by the exchangeable P from the solid phase within the soil solution. Therefore, ongoing research focuses on the accessibility of P from P loaded amorphous Fe- and Al-hydroxides, previously identified as the predominant abiotic P forms. To assess their P desorption potential, P-33 rhizotron experiments combined with P-33 isotopic exchange kinetics (IEK) are underway. Preliminary results indicated that besides differences in P binding capacity of soil hydroxides, physical soil parameters, such as the matric potential, strongly control soil P availability, thus plant P acquisition rates can vary among different soil types. Our results gained new detailed information about P bioavailability under agricultural practice. The investigations towards P bioaccessibility may contribute to improved interpretation of soil P tests and reduced fertilizer recommendations.}, language = {en} } @inproceedings{GypserVeste, author = {Gypser, Stella and Veste, Maik}, title = {Biological soil crusts as driver for ecosystem structures and functions on reclaimed post-mining sites in Lower Lusatia, Germany}, series = {9th International Symposium on Ecosystem Behavior BIOGEOMON, Litomysl, Czech Republic, August 20-24, 2017}, booktitle = {9th International Symposium on Ecosystem Behavior BIOGEOMON, Litomysl, Czech Republic, August 20-24, 2017}, editor = {Nov{\´a}k, Martin and Kr{\´a}m, Pavel and Step{\´a}nov{\´a}, M.}, pages = {33 -- 34}, language = {en} } @inproceedings{GypserSlazakFreese, author = {Gypser, Stella and Slazak, Anna and Freese, Dirk}, title = {Impact of crystallization of iron and aluminium hydroxides on the mechanisms of phosphate binding}, series = {9th International Symposium on Ecosystem Behavior BIOGEOMON, Litomysl, Czech Republic, August 20-24, 2017}, booktitle = {9th International Symposium on Ecosystem Behavior BIOGEOMON, Litomysl, Czech Republic, August 20-24, 2017}, editor = {Nov{\´a}k, Martin and Kr{\´a}m, Pavel and Step{\´a}nov{\´a}, M.}, pages = {366 -- 367}, language = {en} } @inproceedings{GypserVeste, author = {Gypser, Stella and Veste, Maik}, title = {Application of chlorophyll fluorescence, CO2 gas exchange, and NDVI for the detection of spatial variances of photosynthesis of biological soil crusts on anthropogenic degraded soils}, series = {3rd International Workshop on Biological Soil Crusts BIOCRUST3, September 26-30, 2016, Star Hall-Moab, Utah, USA}, booktitle = {3rd International Workshop on Biological Soil Crusts BIOCRUST3, September 26-30, 2016, Star Hall-Moab, Utah, USA}, pages = {24 -- 25}, abstract = {Degradation of soils and the destruction of vegetation as a result of anthropogenic disturbances affect ecosystem functions and properties worldwide. In Brandenburg (NE Germany) various ecosystems were degraded by different human activities like surface mining and military activities on sand dunes. These resulted in degraded open landscapes with an initial soil development. These new ecosystems are characterized by a high vulnerability to erosion, low water holding capacity, lack of nutrients, or low pH. For rehabilitation of degraded soils and vegetation, these post-mining and mobile sand dunes need specific restoration measures, but beside inappropriate soil characteristics, insufficient water availability can limit plant growth. Even located in the temperate zone of Europe, Brandenburg belongs to the driest regions in Germany and faces long drought periods. In this context, the determination of the influence of biocrusts on carbon accumulation during initial ecosystem succession, small-scale investigations on photosynthetic capacity and active phase regarding biocrust formation and developmental stage, which vary from initial green algae-crusts to biocrusts dominated by soil lichens or mosses, are necessary. Hence, succession of biocrusts result in a spatiotemporal heterogeneity and distribution pattern. We could show that varying species abundance, composition, and crust succession affect photosynthetic capacity, and hence, carbon fixation capability. Different spatial hotspots could be analyzed under field conditions and monitored during the season. Long-term measurements of climatic parameters, which include radiation, temperature, precipitation, and desiccation of biocrusts, will be linked to photosynthetic performances under lab conditions. This spatial model can help to understand the impact of biocrusts on carbon accumulation in initial soils. Due to the potential to colonize soil surface under harsh conditions without human support, advantages of biocrusts can be used systematically as a supporting rehabilitation measure for physical stabilization, gain of organic carbon, and hence, facilitates the growth of indigenous vegetation during primary succession.}, language = {en} } @misc{GypserVeste, author = {Gypser, Stella and Veste, Maik}, title = {Importance of P limitation for the C:N:P ratio in Robinia plantations on marginal sites}, series = {Gf{\"O} 2019, Science Meets Practice, 49th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, university of M{\"u}nster, 9-13 September 2019}, journal = {Gf{\"O} 2019, Science Meets Practice, 49th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, university of M{\"u}nster, 9-13 September 2019}, editor = {Thiede, Julia and Klein-Rauthake, Theresa}, pages = {82}, abstract = {Due to disturbances of soils after open-cast lignite mining activities in the Lusatian mining district, Northeast Germany, large areas covered with excavated and dumped material. These initial soils are characterized by a lack of nutrients and organic matter which is why Robinia pseudoacacia was established during reclamation of those marginal sites. As a pioneer species, Robinia is well suitable for the establishment on reclaimed forest ecosystems due to the N fixation capability and its ability to grow on a nutrient-poor sandy substrate with low water holding capacity. Since the N requirement of the Robinia can be covered by symbiotic nodule bacteria, P is important as a growth-limiting nutrient. Even though the total and available P in soils increased with the age of the plantings (planted between 1995 and 2007), the ratio of available to total P decreased relative to younger plantings. Despite the accumulation of organic matter and the decomposition of organic bound P, the bioavailability is affected by ad- and desorption processes, especially on Fe- and Al-hydroxides. It was hypothesized that the P demand of young trees, initially provided by a one-time fertilizer application, exceeds the P supply by mineralization over time. As a first step, kinetics of P desorption from synthetic Fe- and Al-hydroxides were characterized by using humic acid as a model organic compound, to detect fast and slow releasable P over time. At the Robinia sites, soil samples were examined at different depth with regard to their C, N and P concentrations. From the first results, we can conclude that the P availability and its limitation influences the growth performance of Robinia as well as the N-fixing symbiotic bacteria and, thus, the C:N:P ratio as a long-term effect on an ecosystem scale.}, language = {en} } @misc{VesteGypser, author = {Veste, Maik and Gypser, Stella}, title = {{\"O}kologische Funktionen und Dienstleistungen biologischer Bodenkrusten in Offenlandschaften - Fluch oder Segen?}, series = {Gf{\"O} 2019, Science Meets Practice, 49th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, university of M{\"u}nster, 9-13 September 2019}, journal = {Gf{\"O} 2019, Science Meets Practice, 49th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, university of M{\"u}nster, 9-13 September 2019}, address = {M{\"u}nster}, pages = {166}, abstract = {Initiale und n{\"a}hrstoffarme {\"O}kosysteme wie Grasl{\"a}nder und Offenlandschaften haben aus Sicht des Naturschutzes einen hohen Wert f{\"u}r die Landschaft und sind in der intensiv genutzten Kulturlandschaft Mitteleuropas selten geworden. Gerade Bergbaufolgelandschaften, aber auch gest{\"o}rte Binnend{\"u}nen, bieten Potenzial f{\"u}r die Entwicklung von initialen Lebensr{\"a}umen und Landschaften. Die obersten Millimeter der Bodenoberfl{\"a}che dieser {\"O}kosysteme werden durch Biokrusten besiedelt. Gebildet werden diese komplexen Lebensgemeinschaften aus einer Vielzahl von Cyanobakterien, Gr{\"u}nalgen, Moosen, Pilzen, Bakterien und Flechten. Diese Organismen „verkleben" die Bodenoberfl{\"a}che und beeinflussen als „{\"O}kosystem en miniature" maßgeblich die {\"o}kosystemaren Prozesse und die weitere Vegetationsentwicklung. Der Eintrag von C und N sowie die Akkumulation von organischem Material f{\"o}rdert die Bodenentwicklung in der initialen Phase. W{\"a}hrend der Sukzession der Biokrusten entwickeln sich die komplexen biotischen Prozesse des N-Kreislaufes mit R{\"u}ckkopplungen auf die N{\"a}hrstoffversorgung. Ausgeschiedene Exopolysaccharide, die eine Verbindung mit den Bodenpartikeln eingehen, verkleinern nach Regen den Porenraum der Bodenoberfl{\"a}che und vermindern die Infiltration. Besonders Moos- und Flechten-Krusten unterbinden bei geringen Niederschlagsintensit{\"a}ten die Infiltration in tiefere Bodenschichten. Konkurrenz und die großfl{\"a}chige Versiegelung der Bodenoberfl{\"a}che haben zudem negative Auswirkungen auf die Keimung und Etablierung von h{\"o}heren Pflanzen. Diese biotischen Interaktionen f{\"u}hren bei gesteuerten Sukzessionen auf Renaturierungsfl{\"a}chen zu {\"A}nderungen der Vegetationsentwicklung. Somit wird die Bedeutung der Biokrusten f{\"u}r die Renaturierungs{\"o}kologie z.T. kontrovers diskutiert. Klein- und großr{\"a}umige St{\"o}rungen hingegen sind als integraler Bestandteil der {\"O}kosystementwicklung einzuschließen.}, language = {de} } @inproceedings{HalkeGypserMantovanietal., author = {Halke, Christian and Gypser, Stella and Mantovani, Dario and Lebzien, Stefan and Freese, Dirk and Veste, Maik}, title = {Yield, transpiration and growth of the new bioenergy crop IGNISCUM Candy under different water regimes}, series = {Gf{\"O} 43rd Annual Meeting, Building bridges in ecology, linking systems, scales and disciplines, September 9 to 13, 2013, Potsdam, Germany}, booktitle = {Gf{\"O} 43rd Annual Meeting, Building bridges in ecology, linking systems, scales and disciplines, September 9 to 13, 2013, Potsdam, Germany}, editor = {Jeltsch, Florian and Joshi, Jasmin}, pages = {32 -- 33}, abstract = {There is a growing global need to produce more energy and reducing greenhouse gas emissions. One possible source of renewable energy in parts of Europe is the use of crop for bioenergy production. Currently, maize dominates the biogas production. For a diversified production of substrates alternative crops needs to be evaluated for their sustainable utilization and ecological integration into agro-systems. The new bioenergy plants IGNISCUM Candy and IGNISCUM Basic are cultivars of the Sakhalin Knotweed (Fallopia sachalinensis, Fam. Polygonaceae), which are characterized by a high annual biomass production. Information on the crop production of this species is rare. Hence, understanding plant response to the combinations of water and nutrients availability is crucial for the development of sustainable plant production. In greenhouse experiments we investigate the interrelations between nutrient supply, biomass production, and plant ecophysiology. For the determination of yield-transpiration relations at whole plant level we used a wick lysimeter system, which allows us to study plant growth under controlled water regimes and to calculate the plant transpiration. The irrigation is supplied by an automatic drip irrigation system and computer-controlled in relation to the volumetric soil water content. Four different water treatments associated to the SWC range from well-watered to drought stressed plants. The influence of plant sizes on plant water use was investigated under different nitrogen supply. The fertilizer applied is calcium ammonium nitrate (N) and the rates for the four treatments are 0, 50, 100, 150 kg N/ha at the beginning of the growing season. Plant transpiration is calculated on the basis of water input, storage and drainage in weekly intervals. The cumulative transpiration of the plants during the growing season is between 49 L (drought stressed) and 141 L (well-watered) per plant, respectively. We calculated a transpiration coefficient of 525 Liters per kg dry biomass.}, language = {en} } @misc{GypserFreese, author = {Gypser, Stella and Freese, Dirk}, title = {Mobilization of P from crystalline and amorphous Fe- and Al-hydroxides}, series = {EGU General Assembly 2020}, journal = {EGU General Assembly 2020}, doi = {10.5194/egusphere-egu2020-2871}, language = {en} }