@article{EhrmannPuppeWanneretal.2012,
  author    = {Ehrmann, Otto and Puppe, Daniel and Wanner, Manfred and Kaczorek, Danuta and Sommer, Michael},
  title     = {Testate amoebae in 31 mature forest ecosystems - Densities and micro-distribution in soils},
  series = {European journal of protistology},
  volume    = {48},
  journal   = {European journal of protistology},
  number    = {3},
  publisher = {Elsevier},
  address   = {Jena},
  issn      = {0932-4739},
  doi       = {10.1016/j.ejop.2012.01.003},
  pages     = {161 -- 168},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}
@article{PuppeEhrmannKaczoreketal.2015,
  author    = {Puppe, Daniel and Ehrmann, Otto and Kaczorek, Danuta and Wanner, Manfred and Sommer, Michael},
  title     = {The protozoic Si pool in temperate forest ecosystems - Quantification, abiotic controls and interactions with earthworms},
  series = {Geoderma : an international journal of soil science},
  volume    = {243},
  journal   = {Geoderma : an international journal of soil science},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0016-7061},
  doi       = {10.1016/j.geoderma.2014.12.018},
  pages     = {196 -- 204},
  year      = {2015},
  abstract  = {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.},
  language  = {en}
}