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Steinau an der Straße, Germany

Chojnicki B.H.,University of Life Sciences in Poznan | Michalak M.,University of Life Sciences in Poznan | Acosta M.,University of Life Sciences in Poznan | Juszczak R.,University of Life Sciences in Poznan | And 3 more authors.
Polish Journal of Environmental Studies | Year: 2010

The assessment of net ecosystem exchange (NEE) and respiration of ecosystem (Reco) of terrestrial ecosystems is necessary to improve our knowledge about the carbon cycle. The aims of this paper were to present reliable measurements of CO2 fluxes of a temperate bog ecosystem located in Poland using a closed dynamic chamber system and to obtain a daily dynamic course of CO 2 fluxes over the 2007 vegetation season. Measurements of CO 2 fluxes were carried out at Rzecin peatland ecosystem located in northwestern Poland using the set of two chambers (dark and transparent). Reco during the experiment period ranged from 2.65 to 14.76 μmolCO 2·m-2·s-1. The daily run of NEE was inversed to PPFD and the values of NEE varied from 0.06 to -11.82 μmolCO2·m-2·s-1. We found differences between NEE and Reco in the wetland ecosystem with respect to term of measurements. The PPFD, air and soil temperatures explain most temporal variability of CO2 fluxes at Rzecin. But vegetation structure, its phenology and water-level depth seem also to play important roles. The chamber technique is a useful tool for determining carbon dioxide exchange between wetland surface and the atmosphere.

Knierim A.,University of Hohenheim | Knierim A.,Leibniz Center for Agricultural Landscape Research | Boenning K.,ZALF | Caggiano M.,French National Institute for Agricultural Research | And 5 more authors.
Outlook on Agriculture | Year: 2015

Recently, Agricultural Knowledge and Innovation Systems (AKISs) have gained considerable attention in scientific and political forums in the European Union (EU). AKIS is considered a key concept in identifying, analysing and assessing the various actors in the agricultural sector as well as their communication and interaction for innovation processes. Using qualitative expert interviews and organizational mapping, the features of national AKISs were investigated in selected EU member states (Belgium, France, Ireland, Germany, Portugal and the UK). The authors present the different national AKISs and compare them qualitatively with regard to their institutional settings, their overall policy frameworks and their coordinating structures. Conclusions are drawn with regard to AKIS appraisal in general and the usefulness of the AKIS concept, particularly for the understanding and evaluation of policy-induced innovation in agriculture.

Leuschner C.,University of Gottingen | Wulf M.,ZALF | Wulf M.,University of Potsdam | Bauchler P.,Tauernallee 13 | Hertel D.,University of Gottingen
Ecosystems | Year: 2014

Forest (or tree) age has been identified as an important determinant of the carbon (C) storage potential of forest soils. A large part of Central Europe's current forested area was affected by land use change with long periods of cultivation in past centuries suggesting that the organic C stocks in the soil (SOC) under recent forest may partly be legacies of the past and that stand age effects have to be distinguished from forest continuity effects (that is, the time since re-afforestation). We examined the influence of mean tree age and forest continuity on the SOC pool and the stores of total N and available P, Ca, Mg, and K in the soil (mineral soil and organic layer) across a sample of 14 beech (Fagus sylvatica) forests on sandy soil with variable tree age (23-189 years) and forest continuity (50-year-old afforestation to ancient ('permanent') forest, that is, >230 years of proven continuity). Ancient beech forests (>230 years of continuity) stored on average 47 and 44% more organic C and total N in the soil than recent beech afforestation (50-128 years of continuity). Contrary to expectation, we found large and significant C and N pool differences between the forest categories in the mineral soil but not in the organic layer indicating that decade- or century-long cultivation has reduced the subsoil C and nutrient stores while the organic layer element pools have approached a new equilibrium after only 50-128 years. PCA and correlation analyses suggest that forest continuity cannot be ignored when trying to understand the variation in soil C stocks between different stands. Forest clearing, subsequent cultivation, and eventual re-afforestation with beech resulted in similar relative stock reductions of C and N and, thus, no change in soil C/N ratio. We conclude that the continuity of forest cover, which may or may not be related to tree age, is a key determinant of the soil C and nutrient stores of beech forests in the old cultural landscape of Central Europe. © 2013 Springer Science+Business Media New York.

Leuschner C.,University of Gottingen | Wulf M.,ZALF | Wulf M.,University of Potsdam | Bauchler P.,Tauernallee 13 | Hertel D.,University of Gottingen
Forest Ecology and Management | Year: 2013

In the diluvial lowlands of northern Germany, the Netherlands and northern Poland, an estimated ~5 Mio ha of Scots pine plantations (Pinus sylvestris) has been established on sandy soil in the last 250years replacing the former temperate broad-leaved forests after extended periods of cultivation in the Middle Ages. We examined the effect of variable stand continuity of pine plantations (recent vs. ancient: 51-128 vs. >230years) on the soil organic carbon (SOC) store and soil nutrient capital in comparison to ancient beech forests (>230years of continuity) which represent the potential natural forest vegetation. Recent and ancient pine stands had c. 75% larger organic layer C stores than ancient beech forests, while the total C stock in the soil (organic layer and mineral soil to 100cm) was ~25% larger in the beech forests due to higher C concentrations in 0-50cm depth of the mineral soil. The soil stores of Ntot were ~50% and the exchangeable Ca, K and Mg pools about three times larger under beech than under the pine stands. Resin-exchangeable P was enriched in the soils under ancient pine stands probably due to manuring in the past. After clear-cut and long cultivation, it may take>230years of forest presence to restore the greatly reduced mineral soil C and N pools. The C and N sequestration potential of the soils appeared to be particularly small under pine indicating a pronounced tree species (pine vs. beech) effect on soil C and N dynamics. We conclude that, in the face of rising greenhouse gas emissions, the limited soil C and nutrient storage potential of Scots pine plantations on sandy soils needs consideration when selecting suitable tree species for future forestry. © 2013 Elsevier B.V.

Rees R.M.,Scotland's Rural College | Augustin J.,ZALF | Alberti G.,University of Udine | Ball B.C.,Scotland's Rural College | And 30 more authors.
Biogeosciences | Year: 2013

Nitrous oxide emissions from a network of agricultural experiments in Europe were used to explore the relative importance of site and management controls of emissions. At each site, a selection of management interventions were compared within replicated experimental designs in plot-based experiments. Arable experiments were conducted at Beano in Italy, El Encin in Spain, Foulum in Denmark, Logärden in Sweden, Maulde in Belgium, Paulinenaue in Germany, and Tulloch in the UK. Grassland experiments were conducted at Crichton, Nafferton and Peaknaze in the UK, Gödöllö in Hungary, Rzecin in Poland, Zarnekow in Germany and Theix in France. Nitrous oxide emissions were measured at each site over a period of at least two years using static chambers. Emissions varied widely between sites and as a result of manipulation treatments. Average site emissions (throughout the study period) varied between 0.04 and 21.21 kgN2O-N ha-1 yr-1, with the largest fluxes and variability associated with the grassland sites. Total nitrogen addition was found to be the single most important determinant of emissions, accounting for 15% of the variance (using linear regression) in the data from the arable sites (p <0.0001), and 77% in the grassland sites. The annual emissions from arable sites were significantly greater than those that would be predicted by IPCC default emission factors. Variability of N 2O emissions within sites that occurred as a result of manipulation treatments was greater than that resulting from site-to-site and year-to-year variation, highlighting the importance of management interventions in contributing to greenhouse gas mitigation. © Author(s) 2013.

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