Auswirkungen mehrjähriger ökologischer Bewirtschaftung auf ausgewählte Bodeneigenschaften, dargestellt am Beispiel des Versuchsfeldes Gülzow

The effects of ecological vs. conventional farming on several biological, chemical and physical soil properties were investigated at the arable test site Gülzow (Northeast Germany). After ten years of ecological farming increased activities of dehydrogenase, β-glucosidase and alkaline phosphatase in the soil were measured. Low effects on the chemical soil properties like content of Corg, Nt and soil organic matter and no significant effects on physical soil properties like density, porosity and water retention were observed. -- (Sprache des Volltextes: Deutsch

Auswirkungen mehrjähriger ökologischer Bewirtschaftung auf ausgewählte Bodeneigenschaften

The effects of ecological vs. conventional farming on several biological, chemical and physical soil properties were investigated at the arable test site Gülzow (Northeast Germany). After ten years of ecological farming increased activities of dehydrogenase, β-glucosidase and alkaline phosphatase in the soil were measured. Low effects on the chemical soil properties like content of Corg, Nt and soil organic matter and no signifi-cant effects on physical soil properties like density, porosity and water retention were observed

Transgene effects on rhizodeposition: Evidence from molecular-chemical screening by Pyrolysis-Field Ionisation Mass Spectrometry (Py-FIMS)

Rhizodeposition plays an important role in the C and N cycle of ecosystems, since it essentially reflects the interaction between plant, soil and soil microorganisms. The molecular-chemical characterisation of rhizodeposition is often limited to selected compound classes (e.g., carbohydrates and amino acids). A more comprehensive analytical approach is based on the molecular-chemical “fingerprint” revealed by Pyrolysis-Field Ionisation Mass Spectrometry (Py-FIMS).

The presented results give evidence of specific effects in conjunction with soil type, crop, variety, transgenes and mycorrhizal colonisation on the molecular-chemical composition of rhizodeposition. The experiments included various crops (maize, potato, vetch, willow and poplar), which were grown in leaching vessels under controlled environmental conditions on different soil types. The experimental design covered different varieties for maize, trangenes (vetch and potato) and inoculation with mycorrhizal fungi (poplar). All rhizodeposits were leached at defined growth stages and analysed by Py-FIMS.

The Py-FIMS data evaluation by multivariate statistics enabled a clear discrimination by all factors. Among these factors soil type and the crop had the largest effect on the molecular-chemical composition. By contrast, variety and transgene effects were subordinated.
The results of the multivariate statistics for crops, grown on the same soil (maize, potato, vetch), revealed 23 mass signals with highest discriminating power (P<0.001, multiple F-test). About 90 % of those signals can be assigned to known substances, based on our mass spectrometric in-house library and/or the literature. Further investigation will be focused on structural elucidation of the previously unassigned mass signals.
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Diversität von Ektomykorrhizapilzen unter Pioniervegetation auf einem küstennahen Regosol

Die natürliche Pioniervegetation auf küstennahen Regosolen in Norddeutschland umfasst mehrere Wirtspflanzen von Ektomykorrhizapilzen, wie z.B. Salix, Populus und Pinus spp.. Ektomykorrhizapilze können auf diesen stark erosionsgefährdeten Standorten durch die Ausbildung von abziehenden Hyphen bzw. Rhizomorphen zur Stabilisierung der Oberböden beitragen. In der vorliegenden Untersuchung wurde die Diversität von Ektomykorrhizen an Salweiden (Salix caprea) auf einem küstennahen Regosol in einem Zeitraum von zwei Jahren morphologisch-anatomisch beschrieben und die beteiligten Pilzpartner über die Sequenzierung der rDNA identifiziert. Es wurden 11 Arten aus 8 Gattungen von Asco- und Basidiomyceten nachgewiesen, deren Verbreitung einer zeitlichen Dynamik unterlag. Dunkel pigmentierte Tomentella spp. (Thelephoraceae) und kurz-Distanz Explorationstypen dominierten die Ektomykorrhizierung der Salweiden jedoch unabhängig vom Probenahmetermin

Site-dependent relationships between fungal community composition, plant genotypic diversity and environmental drivers in a Salix biomass system

Soil fungi are strongly affected by plant species or genotypes since plants modify their surrounding environment, but the effects of plant genotype diversity on fungal diversity and function have not been extensively studied. The interactive responses of fungal community composition to plant genotypic diversity and environmental drivers were investigated in Salix biomass systems, posing questions about: (1) How fungal diversity varies as a function of plant genotype diversity; (2) If plant genotype identity is a strong driver of fungal community composition also in plant mixtures; (3) How the fungal communities change through time (seasonally and interannually)?; and (4) Will the proportion of ECM fungi increase over the rotation? Soil samples were collected over 4 years, starting preplanting from two Salix field trials, including four genotypes with contrasting phenology and functional traits, and genotypes were grown in all possible combinations (four genotypes in Uppsala, Sweden, two in Rostock, Germany). Fungal communities were identified, using Pacific Biosciences sequencing of fungal ITS2 amplicons. We found some site-dependent relationships between fungal community composition and genotype or diversity level, and site accounted for the largest part of the variation in fungal community composition. Rostock had a more homogenous community structure, with significant effects of genotype, diversity level, and the presence of one genotype (“Loden”) on fungal community composition. Soil properties and plant and litter traits contributed to explaining the variation in fungal species composition. The within-season variation in composition was of a similar magnitude to the year-to-year variation. The proportion of ECM fungi increased over time irrespective of plant genotype diversity, and, in Uppsala, the 4-mixture showed a weaker response than other combinations. Species richness was generally higher in Uppsala compared with that in Rostock and increased over time, but did not increase with plant genotype diversity. This significant site-specificity underlines the need for consideration of diverse sites to draw general conclusions of temporal variations and functioning of fungal communities. A significant increase in ECM colonization of soil under the pioneer tree Salix on agricultural soils was evident and points to changed litter decomposition and soil carbon dynamics during Salix growth

Site-Effects Dominate the Plant Availability of Nutrients under Salix Species during the First Cutting Cycle

Fast-growing willows (Salix spp.) provide alternative sources of renewable energy generation, but need an adequate nutrient availability in the soil for high biomass production. In general, species mixtures can be more nutrient-efficient than pure cultures, but this is scarcely known for Salix spp. Therefore, this study evaluates the nutrient availability and P mobilization under two willow species, Salix dasyclados var. 'Loden' and S. schwerinii x viminalis var. 'Tora', grown as pure and mixed cultures at non-fertilized former arable sites in Germany (Stagnic Cambisol) and Sweden (Vertic Cambisol). The plant availability of potassium (K), magnesium (Mg) and phosphorus (P) and soil phosphatase activities in the topsoil were measured in spring of the year of planting (initial) and under 4 years-old stocks (one year after the first 3-year cutting cycle). The initial plant availability of the nutrients significantly differed between the sites and the two sampling dates at both sites. The plant availability of K and Mg was optimal to high at both sites and sampling dates, but rather low for P (after 4 years <= 5 mg P 100 g(-1) soil). The plant-available P and K content in soil significantly decreased within the 4 years of willow growth at both sites. The acid and alkaline phosphatase activity in the soil of the German site (Rostock) was significantly lower after 4 years of willow growth, but differed not significantly between the two sampling dates at the Swedish site (Uppsala). Higher activity of acid phosphatase compared to alkaline phosphatase was recorded in the soils at both test sites based on the site-specific soil pH (<7). The slight decrease of plant availability of P after 4 years of Salix growth in pure culture differed not significantly between the different species. Mixed growth did not decrease the plant availability of P within this period, although no significant difference in the biomass production of pure and mixed growth was observed. This was valid at both sites, and therefore, seems independent of the site-specific differences in soil and climate conditions. The general validity of the assumptions should be tested also for other species mixtures and soil conditions in the future before site-adapted growth designs can be recommended in biomass production of Salix

Galectin-1, an Endogenous Lectin Produced by Thymic Epithelial Cells, Induces Apoptosis of Human Thymocytes

Galectin-1, a β-galactoside binding protein, is produced by thymic epithelial cells and binds to human thymocytes. We have previously reported that galectin-1 induces the apoptosis of activated T lymphocytes. Because the majority of thymocytes die via apoptosis while still within the thymus, we tested whether galectin-1 could induce the apoptosis of these cells. We now report that in vitro exposure to galectin-1 induced apoptosis of two subsets of CD4lo CD8lo thymocytes. The phenotypes of susceptible thymocytes were consistent with that of both negatively selected and nonselected cells. Galectin-1–induced apoptosis was enhanced by preexposure of thymocytes to antibody to CD3, suggesting that galectin-1 may be a participant in T-cell– receptor mediated apoptosis. In contrast, pretreatment of thymocytes with dexamethasone had no effect on galectin-1 susceptibility. We noted that 71% of the cells undergoing apoptosis after galectin-1 treatment had a DNA content greater than 2N, indicating that proliferating thymocytes were most sensitive to galectin-1. We propose that galectin-1 plays a role in the apoptosis of both negatively selected and nonselected thymocytes, and that the susceptibility of thymocytes to galectin-1 is regulated, in part, by entry or exit from the cell cycle

Changes in SOM under short-rotation forestry with fast-growing tree species

Soil carbon storage is strongly affected by land use and land use change. Afforestation with fast growing tree species on former arable soils may increase soil organic carbon (SOC) contents due to the reduction in soil cultivation frequency. The DFG-funded project „The mycorrhiza-mediated pathway for soil organic matter (SOM) formation and consequences for the SOM turnover under short rotation forestry“ investigates two major types of mycorrhiza formation as a function of land use and the importance of composition, stability and storage of SOM. In our subproject we compared SOC stocks of ongoing short rotation forestry (SRF) and former forestry fields (f-SRF). This leads to the following questions: i) Is there a long-term increase in carbon storage under current SRF schemes; and ii) Is this carbon storage under SRF sustainable; what are the consequences of transforming forest soils back into arable land? Two current (SRF) and two former (f-SRF) (Populus nigra x P. maximowiczii) test sites in different temporal stages of change were selected, with corresponding reference sites (REF)in each case. We found an accumulation of SOC in topsoil of current long-term SRF in comparison to REF, but lower carbon content in the subsoil. In former SRF sites accumulation of SOC was not detectable and we found no increase in the total SOC stocks per site. Effects are marked by soil treatment. Variance in total accumulation of SOC occurs in spatial distribution of investigated areas and was effected by its annual variabilities. Combined, the investigations results in following: i) SRF changes the carbon distribution in the anthric horizon. However, a total carbon storage change could not be detected. ii) The differences in carbon distribution were quickly removed by planting

Bodenökologische Auswirkungen der Kurzumtriebswirtschaft mit Pappeln und Weiden in Mecklenburg-Vorpommern

Anhand zweier langjähriger Kurzumtriebs-plantagen in Mecklenburg-Vorpommern wurden die Managementvarianten Kurz-umtriebswirtschaft mit den schnellwachsen-den Baumarten Pappel und Weide, Acker-land und Rückführung von Kurzumtriebs-plantage in Ackerland (Umbruch) hinsichtlich ausgewählter Bodeneigenschaften unter-sucht. Als Prüfparameter dienten die Gehal-te an den pflanzenverfügbaren Nährstoffen Phosphor, Kalium und Magnesium, die Ge-halte an organischer Substanz und Gesamt-stickstoff sowie die pH-Werte. An beiden Standorten zeigten sich spezifische Ma-nagementeffekte und Tiefendifferenzierun-gen, die angesichts des zu erwartenden größer- flächigen Anbaus von Energieholz und bei der Vervollkommnung des Produkti-onsverfahrens zu berücksichtigen sind