TY  - JOUR
A1  - Puppe, Daniel
A1  - Ehrmann, Otto
A1  - Kaczorek, Danuta
A1  - Wanner, Manfred
A1  - Sommer, Michael
T1  - The protozoic Si pool in temperate forest ecosystems - Quantification, abiotic controls and interactions with earthworms
JF  - Geoderma : an international journal of soil science
N2  - Biogenic silicon (BSI) pools influence Si cycling in terrestrial ecosystems. As research has been focused mainly on phytogenic BSi pools until now, there is only little information available on quantities of other BSi pools. There are no systematic studies on protozoic Si pools - here represented by idiosomic testate amoebae (TA) - and abiotic and biotic influences in temperate forest ecosystems. We selected ten old forests along a strong gradient in soil forming factors (especially parent material and climate), soil properties and humus forms. We quantified idiosomic Si pools, corresponding annual biosilicification, plant-available and amorphous Si fractions of topsoil horizons. Furthermore, we analyzed the potential influences of abiotic factors (e.g. soil pH) and earthworms on idiosomic Si pools.
 While idiosomic Si pools were relatively small (up to 5 kg Si ha(-1)), annual biosilicification rates of living TA (17-80 kg Si ha(-1)) were comparable to or even exceeded reported data of annual Si uptake by trees. Soil pH exerted a strong, non-linear control on plant-available Si. Surprisingly, no relationship between Si supply and idiosomic Si pools could be found (no Si limitation). Instead, idiosomic Si pools showed a strong, negative relationship to earthworm biomasses, which corresponded to humus forms. We concluded that earthworms control idiosomic Si pools in forest soils by direct (feeding, competition) and/or indirect mechanisms (e.g. change of habitat structure). Earthworms themselves were strongly influenced by soil pH: Below a threshold of pH 3.8 no endogeic or anecic earthworms existed. As soil pH is a result of weathering and acidification idiosomic Si pools are indirectly, but ultimately controlled by soil forming factors, mainly parent material and climate. (C) 2014 Elsevier B.V. All rights reserved.
KW  - Biogenic silica
KW  - Testate amoebae
KW  - Biosilicification
KW  - Terrestrial Si cycle
KW  - Si fractions
KW  - Humus forms
Y1  - 2015
U6  - https://doi.org/10.1016/j.geoderma.2014.12.018
SN  - 0016-7061
SN  - 1872-6259
VL  - 243
SP  - 196
EP  - 204
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Ehrmann, Otto
A1  - Puppe, Daniel
A1  - Wanner, Manfred
A1  - Kaczorek, Danuta
A1  - Sommer, Michael
T1  - Testate amoebae in 31 mature forest ecosystems - Densities and micro-distribution in soils
JF  - European journal of protistology
N2  - We studied testate amoebae and possible correlated abiotic factors in soils of 31 mature forest ecosystems using an easily applicable and spatially explicit method. Simple counting on soil thin-sections with a light microscope resulted in amoeba densities comparable to previously reported values, i.e. 0.1 x 10(8) to 11.5 x 10(8) individuals m(-2) (upper 3 cm of soil). Soil moisture and soil acidity seem to be correlated with amoeba densities. At sites of moderate soil moisture regimes (SMR 2-7) we found higher densities of testate amoebae at pH < 4.5. At wetter sites (SMR >= 8) higher individual densities were recorded also at less acidic sites. The in situ description of amoebae, based on the analysis of a complete soil thin-section, showed a relatively uniform spatial micro-distribution throughout the organic and mineral soil horizons (no testate amoeba clusters). We discuss the pros and cons of the soil thin-section method and suggest it as an additional tool to improve knowledge of the spatial micro-distribution of testate amoebae.
KW  - Microhabitats
KW  - Soil thin-section
KW  - Soil moisture regimes
KW  - Soil reaction
Y1  - 2012
U6  - https://doi.org/10.1016/j.ejop.2012.01.003
SN  - 0932-4739
VL  - 48
IS  - 3
SP  - 161
EP  - 168
PB  - Elsevier
CY  - Jena
ER  - 
TY  - JOUR
A1  - Wanner, Manfred
A1  - Elmer, Michael
A1  - Sommer, Michael
A1  - Funk, Roger
A1  - Puppe, Daniel
T1  - Testate amoebae colonizing a newly exposed land surface are of airborne origin
JF  - Ecological indicators : integrating monitoring, assessment and management
N2  - We hypothesized that at the very beginning of terrestrial ecosystem development, airborne testate amoebae play a pivotal role in facilitating organismic colonization and related soil processes. We, therefore, analyzed size and quantity of airborne testate amoebae and immigration and colonization success of airborne testate amoebae on a new land surface (experimental site "Chicken Creek", artificial post-mining water catchment). Within an altogether 91-day exposure of 70 adhesive traps, 12 species of testate amoebae were identified to be of airborne origin. Phryganella acropodia (51% of all individuals found, diameter about 35-45 mu m) and Centropyxis sphagnicola (23% of all individuals found, longest axis about 55-68 mu m), occurred most frequently in the adhesive traps. We extrapolated an aerial amoeba deposition of 61 individuals d(-1) m(-2) (living and dead individuals combined). Although it would be necessary to have a longer sequence (some additional years), our analysis of the "target substrate" of aerial immigration (catchment site) may point to a shift from a stochastic (variable) beginning of community assembly to a more deterministic (stable) course. This shift was assigned to an age of seven years of initial soil development. Although experienced specialists are necessary to conduct these time-consuming studies, the presented data suggest that terrestrial amoebae are suitable indicators for initial ecosystem development and utilization.
KW  - Artificial water catchment
KW  - Immigration by air
KW  - Biological indicator
Y1  - 2015
U6  - https://doi.org/10.1016/j.ecolind.2014.07.037
SN  - 1470-160X
SN  - 1872-7034
VL  - 48
SP  - 55
EP  - 62
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Wehrhan, Marc
A1  - Puppe, Daniel
A1  - Kaczorek, Danuta
A1  - Sommer, Michael
T1  - Spatial patterns of aboveground phytogenic Si stocks in a grass-dominated catchment
BT  - results from UAS-based high-resolution remote sensing
JF  - Biogeosciences : BG
N2  - Various studies have been performed to quantify silicon (Si) stocks in plant biomass and related Si fluxes in terrestrial biogeosystems. Most studies are deliberately designed on the plot scale to ensure low heterogeneity in soils and plant composition, hence similar environmental conditions. Due to the immanent spatial soil variability, the transferability of results to larger areas, such as catchments, is therefore limited. However, the emergence of new technical features and increasing knowledge on details in Si cycling lead to a more complex picture at landscape and catchment scales. Dynamic and static soil properties change along the soil continuum and might influence not only the species composition of natural vegetation but also its biomass distribution and related Si stocks. Maximum likelihood (ML) classification was applied to multispectral imagery captured by an unmanned aerial system (UAS) aiming at the identification of land cover classes (LCCs). Subsequently, the normalized difference vegetation index (NDVI) and ground-based measurements of biomass were used to quantify aboveground Si stocks in two Si-accumulating plants (Calamagrostis epige-jos and Phragmites australis) in a heterogeneous catchment and related corresponding spatial patterns of these stocks to soil properties. We found aboveground Si stocks of C. epige-jos and P. australis to be surprisingly high (maxima of Si stocks reach values up to 98 g Sim(-2)), i.e. comparable to or markedly exceeding reported values for the Si storage in aboveground vegetation of various terrestrial ecosystems. We further found spatial patterns of plant aboveground Si stocks to reflect spatial heterogeneities in soil properties. From our results, we concluded that (i) aboveground biomass of plants seems to be the main factor of corresponding phytogenic Si stock quantities, and (ii) a detection of biomass heterogeneities via UAS-based remote sensing represents a promising tool for the quantification of lifelike phytogenic Si pools at landscape scales.
Y1  - 2021
U6  - https://doi.org/10.5194/bg-18-5163-2021
SN  - 1726-4170
SN  - 1726-4189
VL  - 18
IS  - 18
SP  - 5163
EP  - 5183
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Schaller, Jörg
A1  - Puppe, Daniel
A1  - Kaczorek, Danuta
A1  - Ellerbrock, Ruth
A1  - Sommer, Michael
T1  - Silicon cycling in soils revisited
JF  - Plants : open access journal
N2  - Silicon (Si) speciation and availability in soils is highly important for ecosystem functioning, because Si is a beneficial element for plant growth. Si chemistry is highly complex compared to other elements in soils, because Si reaction rates are relatively slow and dependent on Si species. Consequently, we review the occurrence of different Si species in soil solution and their changes by polymerization, depolymerization, and condensation in relation to important soil processes. We show that an argumentation based on thermodynamic endmembers of Si dependent processes, as currently done, is often difficult, because some reactions such as mineral crystallization require months to years (sometimes even centuries or millennia). Furthermore, we give an overview of Si reactions in soil solution and the predominance of certain solid compounds, which is a neglected but important parameter controlling the availability, reactivity, and function of Si in soils. We further discuss the drivers of soil Si cycling and how humans interfere with these processes. The soil Si cycle is of major importance for ecosystem functioning; therefore, a deeper understanding of drivers of Si cycling (e.g., predominant speciation), human disturbances and the implication for important soil properties (water storage, nutrient availability, and micro aggregate stability) is of fundamental relevance.
KW  - andosols
KW  - clay neoformation
KW  - crop yield
KW  - land use change
KW  - micro
KW  - aggregate stability
KW  - phytoliths
KW  - sediments
KW  - silicon cycling
KW  - silicon
KW  - extraction methods
KW  - silicon pore water speciation
Y1  - 2021
U6  - https://doi.org/10.3390/plants10020295
SN  - 2223-7747
VL  - 10
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Puppe, Daniel
A1  - Höhn, Axel
A1  - Kaczorek, Danuta
A1  - Wanner, Manfred
A1  - Wehrhan, Marc
A1  - Sommer, Michael
T1  - How big is the influence of biogenic silicon pools on short-term changes in water-soluble silicon in soils? Implications from a study of a 10-year-old soil-plant system
JF  - Biogeosciences
N2  - The significance of biogenic silicon (BSi) pools as a key factor for the control of Si fluxes from terrestrial to aquatic ecosystems has been recognized for decades. However, while most research has been focused on phytogenic Si pools, knowledge of other BSi pools is still limited. We hypothesized that different BSi pools influence short-term changes in the water-soluble Si fraction in soils to different extents. To test our hypothesis we took plant (Calamagrostis epigejos, Phragmites australis) and soil samples in an artificial catchment in a post-mining landscape in the state of Brandenburg, Germany. We quantified phytogenic (phytoliths), protistic (diatom frustules and testate amoeba shells) and zoogenic (sponge spicules) Si pools as well as Tironextractable and water-soluble Si fractions in soils at the beginning (t(0)) and after 10 years (t(10)) of ecosystem development. As expected the results of Tiron extraction showed that there are no consistent changes in the amorphous Si pool at Chicken Creek (Huhnerwasser) as early as after 10 years. In contrast to t(0) we found increased water-soluble Si and BSi pools at t(10); thus we concluded that BSi pools are the main driver of short-term changes in water-soluble Si. However, because total BSi represents only small proportions of water-soluble Si at t(0) (< 2 %) and t(10) (2.8-4.3 %) we further concluded that smaller (< 5 mu m) and/or fragile phytogenic Si structures have the biggest impact on short-term changes in water-soluble Si. In this context, extracted phytoliths (> 5 mu m) only amounted to about 16% of total Si con-tents of plant materials of C. epigejos and P. australis at t(10); thus about 84% of small-scale and/or fragile phytogenic Si is not quantified by the used phytolith extraction method. Analyses of small-scale and fragile phytogenic Si structures are urgently needed in future work as they seem to represent the biggest and most reactive Si pool in soils. Thus they are the most important drivers of Si cycling in terrestrial biogeosystems.
Y1  - 2017
U6  - https://doi.org/10.5194/bg-14-5239-2017
SN  - 1726-4170
SN  - 1726-4189
VL  - 14
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - GEN
A1  - Puppe, Daniel
A1  - Höhn, Axel
A1  - Kaczorek, Danuta
A1  - Wanner, Manfred
A1  - Wehrhan, Marc
A1  - Sommer, Michael
T1  - How big is the influence of biogenic silicon pools on short-term changes in water-soluble silicon in soils?
BT  - Implications from a study of a 10-year-old soil–plant system
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - The significance of biogenic silicon (BSi) pools as a key factor for the control of Si fluxes from terrestrial to aquatic ecosystems has been recognized for decades. However, while most research has been focused on phytogenic Si pools, knowledge of other BSi pools is still limited. We hypothesized that different BSi pools influence short-term changes in the water-soluble Si fraction in soils to different extents. To test our hypothesis we took plant (Calamagrostis epigejos, Phragmites australis) and soil samples in an artificial catchment in a post-mining landscape in the state of Brandenburg, Germany. We quantified phytogenic (phytoliths), protistic (diatom frustules and testate amoeba shells) and zoogenic (sponge spicules) Si pools as well as Tironextractable and water-soluble Si fractions in soils at the beginning (t(0)) and after 10 years (t(10)) of ecosystem development. As expected the results of Tiron extraction showed that there are no consistent changes in the amorphous Si pool at Chicken Creek (Huhnerwasser) as early as after 10 years. In contrast to t(0) we found increased water-soluble Si and BSi pools at t(10); thus we concluded that BSi pools are the main driver of short-term changes in water-soluble Si. However, because total BSi represents only small proportions of water-soluble Si at t(0) (< 2 %) and t(10) (2.8-4.3 %) we further concluded that smaller (< 5 mu m) and/or fragile phytogenic Si structures have the biggest impact on short-term changes in water-soluble Si. In this context, extracted phytoliths (> 5 mu m) only amounted to about 16% of total Si con-tents of plant materials of C. epigejos and P. australis at t(10); thus about 84% of small-scale and/or fragile phytogenic Si is not quantified by the used phytolith extraction method. Analyses of small-scale and fragile phytogenic Si structures are urgently needed in future work as they seem to represent the biggest and most reactive Si pool in soils. Thus they are the most important drivers of Si cycling in terrestrial biogeosystems.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 633 
KW  - brook experimental forest
KW  - protozoic Si pool
KW  - testate amebas
KW  - biochemical cycle
KW  - temperate forest
KW  - amorphous silica
KW  - dissolution
KW  - carbon
KW  - phytoliths
KW  - surface
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-417141
IS  - 633
SP  - 5239
EP  - 5252
ER  - 
TY  - JOUR
A1  - Puppe, Daniel
A1  - Sommer, Michael
T1  - Experiments, uptake mechanisms, and functioning of silicon foliar fertilization
BT  - a review focusing on Maize, Rice, and Wheat
JF  - Advances in Agronomy ; 152
N2  - Silicon (Si) is considered as a quasiessential element for higher plants as its uptake increases plant growth and resistance against abiotic as well as biotic stresses. Foliar application of fertilizers generally is assumed to be a comparably environment-friendly form of fertilization because only small quantities are needed. The interest in foliar fertilization and the use of Si as a fertilizer in general increased significantly within the last decades, but there are only few publications dealing with the foliar application of Si at all. In the present review, the effects of Si foliar fertilization, including nano-Si fertilizers, on the three most important crops on a global scale, that is, maize, rice, and wheat, are summarized. Additionally, different pathways (i.e., cuticular pathways, stomata, and trichomes) of foliar uptake and functioning of Si foliar fertilizers against biotic (i.e., fungal diseases and harmful insects), as well as abiotic (i.e., water stress, macronutrient imbalance, and heavy metal toxicity) stressors are discussed. Future research should especially focus on (1) the gathering of empirical data from field and greenhouse experiments, (2) the intensification of co-operations between practitioners and scientists, (3) interdisciplinary research, and (4) the analysis of results from multiple studies (meta-analysis, big data) to fully understand effects, uptake, and functioning of Si foliar fertilizers and to evaluate their potential in modern sustainable agriculture concepts.
Y1  - 2018
SN  - 978-0-12-815171-6
U6  - https://doi.org/10.1016/bs.agron.2018.07.003
SN  - 0065-2113
VL  - 152
SP  - 1
EP  - 49
PB  - Elsevier
CY  - San Diego
ER  - 
TY  - JOUR
A1  - Kaczorek, Danuta
A1  - Puppe, Daniel
A1  - Busse, Jacqueline
A1  - Sommer, Michael
T1  - Effects of phytolith distribution and characteristics on extractable silicon fractions in soils under different vegetation - An exploratory study on loess
JF  - Geoderma : an international journal of soil science
N2  - The significance of phytoliths for the control of silicon (Si) fluxes from terrestrial to aquatic ecosystems has been recognized as a key factor. Humankind actively influences Si fluxes by intensified land use, i.e., agriculture and forestry, on a global scale. We hypothesized phytolith distribution and assemblages in soils of agricultural and forestry sites to be controlled by vegetation (which is directed by land use) with direct effects on extractable Si fractions driven mainly by phytolith characteristics, i.e., dissolution status (dissolution signs) and morphology (morphotype proportions). To test our hypothesis we combined different chemical extraction methods (calcium chloride, ammonium oxalate, Tiron) for the quantification of different Si fractions (plant available Si, Si adsorbed to/occluded in pedogenic oxides/hydroxides, amorphous Si) and microscopic techniques (light microscopy, confocal laser scanning microscopy, scanning electron microscopy) for detailed analyses of phytoliths extracted using gravimetric separation (physical extraction) from exemplary loess soils of agricultural (arable land and grassland/meadow) and forestry (beech and pine) sites in Poland. We found differences in dissolution signs, morphotype proportions, and vertical distribution of phytoliths in soil horizons per site. In general, dominant morphotypes of assignable phytoliths in the studied soil profiles were elongate phytoliths and short cells, both of which are typical for grass-dominated vegetation. However, the organic layers of forest soils were dominated by globular phytoliths, which are typical indicators for mosses. As expected soil horizons under different vegetation generally were characterized by differences in extractable Si fractions, especially in the upper soil horizons. However, phytogenic Si pools counter-intuitively showed no correlations with chemically extracted Si fractions and soil pH at all. Our findings indicate that it is necessary to combine microscopic analyses and Si extraction techniques for examinations of Si cycling in biogeosystems, because extractions of Si fractions alone do not allow drawing any conclusions about phytolith characteristics or interactions between phytolith pools and chemically extractable Si fractions and do not necessarily reflect phytogenic Si pool quantities in soils and vice versa.
KW  - Phytolith dissolution
KW  - Phytolith morphotypes
KW  - Si extraction
KW  - Surface roughness parameters
KW  - Si cycling
Y1  - 2019
U6  - https://doi.org/10.1016/j.geoderma.2019.113917
SN  - 0016-7061
SN  - 1872-6259
VL  - 356
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Puppe, Daniel
A1  - Kaczorek, Danuta
A1  - Wanner, Manfred
A1  - Sommer, Michael
T1  - Dynamics and drivers of the protozoic Si pool along a 10-year chronosequence of initial ecosystem states
JF  - Ecological engineering : the journal of ecotechnology
N2  - The size and dynamics of biogenic silicon (BSi) pools influence silicon (Si) fluxes from terrestrial to aquatic ecosystems. The research focus up to now was on the role of plants in Si cycling. In recent studies on old forests annual biosilicification rates of idiosomic testate amoebae (i.e. TA producing self-secreted silica shells) were shown to be of the order of Si uptake by trees. However, no comparable data exist for initial ecosystems. We analyzed the protozoic BSi pool (idiosomic TA), corresponding annual biosilicification rates and readily available and amorphous Si fractions along a 10-year chronosequence in a post-mining landscape in Brandenburg, Germany.
 Idiosomic Si pools ranged from 3 to 680 g Si ha(-1) and were about 3-4 times higher at vegetated compared to uncovered spots. They increased significantly with age and were related to temporal development of soil chemical properties. The calculation of annual biosilicification resulted in maxima between 2 and 16 kg Si ha(-1) with rates always higher at vegetated spots. Our results showed that the BSi pool of idiosomic TA is built up rapidly during the initial phases of ecosystem development and is strongly linked to plant growth. Furthermore, our findings highlight the importance of TA for Si cycling in young artificial ecosystems. (C) 2014 Elsevier B.V. All rights reserved.
KW  - Idiosomic Si pool
KW  - Amorphous silica
KW  - Terrestrial ecosystem development
KW  - Artificial catchment
KW  - Si fractions
KW  - Biosilicification
Y1  - 2014
U6  - https://doi.org/10.1016/j.ecoleng.2014.06.011
SN  - 0925-8574
SN  - 1872-6992
VL  - 70
SP  - 477
EP  - 482
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Puppe, Daniel
A1  - Wanner, Manfred
A1  - Sommer, Michael
T1  - Data on euglyphid testate amoeba densities, corresponding protozoic silicon pools, and selected soil parameters of initial and forested biogeosystems
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The dataset in the present article provides information on protozoic silicon (Si) pools represented by euglyphid testate amoebae (TA) in soils of initial and forested biogeosystems. Protozoic Si pools were calculated from densities of euglyphid TA shells and corresponding Si contents. The article also includes data on potential annual biosilicification rates of euglyphid TA at the examined sites. Furthermore, data on selected soil parameters (e.g., readily-available Si, soil pH) and site characteristics (e.g., soil groups, climate data) can be found. The data might be interesting for researchers focusing on biological processes in Si cycling in general and euglyphid TA and corresponding protozoic Si pools in particular.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1039 
KW  - silicon cycling
KW  - biogenic silica
KW  - terrestrial biogeosystems
KW  - biosilicification
KW  - Euglyphida
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-471160
SN  - 1866-8372
IS  - 1039
ER  - 
TY  - JOUR
A1  - Puppe, Daniel
A1  - Wanner, Manfred
A1  - Sommer, Michael
T1  - Data on euglyphid testate amoeba densities, corresponding protozoic silicon pools, and selected soil parameters of initial and forested biogeosystems
JF  - Data in brief
N2  - The dataset in the present article provides information on protozoic silicon (Si) pools represented by euglyphid testate amoebae (TA) in soils of initial and forested biogeosystems. Protozoic Si pools were calculated from densities of euglyphid TA shells and corresponding Si contents. The article also includes data on potential annual biosilicification rates of euglyphid TA at the examined sites. Furthermore, data on selected soil parameters (e.g., readily-available Si, soil pH) and site characteristics (e.g., soil groups, climate data) can be found. The data might be interesting for researchers focusing on biological processes in Si cycling in general and euglyphid TA and corresponding protozoic Si pools in particular.
KW  - Silicon cycling
KW  - Biogenic silica
KW  - Terrestrial biogeosystems
KW  - Biosilicification
KW  - Euglyphida
Y1  - 2018
U6  - https://doi.org/10.1016/j.dib.2018.10.164
SN  - 2352-3409
VL  - 21
SP  - 1697
EP  - 1703
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Wanner, Manfred
A1  - Seidl-Lampa, Barbara
A1  - Höhn, Axel
A1  - Puppe, Daniel
A1  - Meisterfeld, Ralf
A1  - Sommer, Michael
T1  - Culture growth of testate amoebae under different silicon concentrations
JF  - European journal of protistology
N2  - Testate amoebae with self-secreted siliceous shell platelets ("idiosomes") play an important role in terrestrial silicon (Si) cycles. In this context, Si-dependent culture growth dynamics of idiosomic testate amoebae are of interest. Clonal cultures of idiosomic testate amoebae were analyzed under three different Si concentrations: low (50 mu mol L-1), moderate/site-specific (150 mu mol L-1) and high Si supply (500 mu mol L-1). Food (Saccharomyces cerevisiae) was provided in surplus. (i) Shell size of four different clones of idiosomic testate amoebae either decreased (Trinema galeata, Euglypha filifera cf.), increased (E. rotunda cf.), or did not change (E. rotunda) under the lowest Si concentration (50 mu mol Si L-1). (ii) Culture growth of idiosomic Euglypha rotunda was dependent on Si concentration. The more Si available in the culture medium, the earlier the entry into exponential growth phase. (iii) Culture growth of idiosomic Euglypha rotunda was dependent on origin of inoculum. Amoebae previously cultured under a moderate Si concentration revealed highest sustainability in consecutive cultures. Amoebae derived from cultures with high Si concentrations showed rapid culture growth which finished early in consecutive cultures. (iv) Si (diluted in the culture medium) was absorbed by amoebae and fixed in the amoeba shells resulting in decreased Si concentrations. (C) 2016 Elsevier GmbH. All rights reserved.
KW  - Amoebal silicon
KW  - Sommer et al. 2006
KW  - Biosilicification
KW  - Consumption
KW  - Culture growth dynamics
KW  - Euglyphida
KW  - Terrestrial Si cycle
Y1  - 2016
U6  - https://doi.org/10.1016/j.ejop.2016.08.008
SN  - 0932-4739
SN  - 1618-0429
VL  - 56
SP  - 171
EP  - 179
PB  - Royal Society of Chemistry
CY  - Jena
ER  - 
TY  - JOUR
A1  - Puppe, Daniel
A1  - Kaczorek, Danuta
A1  - Schaller, Jörg
A1  - Barkusky, Dietmar
A1  - Sommer, Michael
T1  - Crop straw recycling prevents anthropogenic desilication of agricultural soil-plant systems in the temperate zone
BT  - results from a long-term field experiment in NE Germany
JF  - Geoderma : an international journal of soil science
N2  - Due to the fact that silicon (Si) increases the resistance of plants against diverse abiotic and biotic stresses, Si nowadays is categorized as beneficial substance for plants. However, humans directly influence Si cycling on a global scale. Intensified agriculture and corresponding harvest-related Si exports lead to Si losses in agricultural soils. This anthropogenic desilication might be a big challenge for modern agriculture. However, there is still only little knowledge about Si cycling in agricultural systems of the temperate zone, because most studies focus on rice and sugarcane production in (sub)tropical areas. Furthermore, many studies are performed for a short term only, and thus do not provide the opportunity to analyze slow changes in soil-plant systems (e.g., desilication) over long periods. We analyzed soil and plant samples from an ongoing long-term field experiment (established 1963) in the temperate zone (NE Germany) to evaluate the effects of different nitrogen-phosphoruspotassium (NPK) fertilization rates and crop straw recycling (i.e., straw incorporation) on anthropogenic desilication in the long term. Our results clearly show that crop straw recycling not only prevents anthropogenic desilication (about 43-60% of Si exports can be saved by crop straw recycling in the long term), but also replenishes plant available Si stocks of agricultural soil-plant systems. Furthermore, we found that a reduction of N fertilization rates of about 69% is possible without considerable biomass losses. This economy of the need for N fertilizers potentially can be combined with the benefits of crop straw recycling, i.e., enhancement of carbon sequestration via straw inputs and prevention of anthropogenic desilication of agricultural soil-plant systems. Thus crop straw recycling might have the potential to act as key management practice in sustainable, low fertilization agriculture in the temperate zone in the future.
KW  - Sustainable crop production
KW  - Straw incorporation
KW  - Phytoliths
KW  - Silicon exports
KW  - Plant available Si
Y1  - 2021
U6  - https://doi.org/10.1016/j.geoderma.2021.115187
SN  - 0016-7061
SN  - 1872-6259
VL  - 403
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Puppe, Daniel
A1  - Leue, Martin
A1  - Sommer, Michael
A1  - Schaller, Jörg
A1  - Kaczorek, Danuta
T1  - Auto-fluorescence in phytoliths
BT  - a mechanistic understanding derived from microscopic and spectroscopic analyses
JF  - Frontiers in Environmental Science
N2  - The detection of auto-fluorescence in phytogenic, hydrated amorphous silica depositions (phytoliths) has been found to be a promising approach to verify if phytoliths were burnt or not, especially in archaeological contexts. However, it is unknown so far at what temperature and how auto-fluorescence is induced in phytoliths. We used fluorescence microscopy, scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared spectroscopy to analyze auto-fluorescence in modern phytoliths extracted from plant samples or in intact leaves of winter wheat. Leaves and extracted phytoliths were heated at different temperatures up to 600 degrees C. The aims of our experiments were i) to find out what temperature is needed to induce auto-fluorescence in phytoliths, ii) to detect temperature-dependent changes in the molecular structure of phytoliths related to auto-fluorescence, and iii) to derive a mechanistic understanding of auto-fluorescence in phytoliths. We found organic compounds associated with phytoliths to cause auto-fluorescence in phytoliths treated at temperatures below approx. 400 degrees C. In phytoliths treated at higher temperatures, i.e., 450 and 600 degrees C, phytolith auto-fluorescence was mainly caused by molecular changes of phytolith silica. Based on our results we propose that auto-fluorescence in phytoliths is caused by clusterization-triggered emissions, which are caused by overlapping electron clouds forming non-conventional chromophores. In phytoliths heated at temperatures above about 400 degrees C dihydroxylation and the formation of siloxanes result in oxygen clusters that serve as non-conventional chromophores in fluorescence events. Furthermore, SEM-EDX analyses revealed that extractable phytoliths were dominated by lumen phytoliths (62%) compared to cell wall phytoliths (38%). Our findings might be not only relevant in archaeological phytolith-based examinations, but also for studies on the temperature-dependent release of silicon from phytoliths and the potential of long-term carbon sequestration in phytoliths.
KW  - fluorescence microscopy
KW  - FTIR spectroscopy
KW  - SEM-EDX
KW  - burnt phytoliths;
KW  - carbon sequestration
Y1  - 2022
U6  - https://doi.org/10.3389/fenvs.2022.915947
SN  - 2296-665X
VL  - 10
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Puppe, Daniel
A1  - Höhn, Axel
A1  - Kaczorek, Danuta
A1  - Wanner, Manfred
A1  - Sommer, Michael
T1  - As time goes by-Spatiotemporal changes of biogenic Si pools in initial soils of an artificial catchment in NE Germany
JF  - Applied soil ecology : a section of agriculture, ecosystems & environment
KW  - Biogenic silica
KW  - Diatom frustule
KW  - Testate amoeba shell
KW  - Sponge spicule
KW  - Initial ecosystem
Y1  - 2016
U6  - https://doi.org/10.1016/j.apsoil.2016.01.020
SN  - 0929-1393
SN  - 1873-0272
VL  - 105
SP  - 9
EP  - 16
PB  - Elsevier
CY  - Amsterdam
ER  -