Drainage of peatlands for agriculture causes an increase of CO2 flux from peat decomposition, contributing to national CO2 emission. The reverse process, i.e. for re-creation of wetlands, reduces the CO2 flux, but increases the CH4 flux. We developed a process model (PEATLAND) to simulate these fluxes from peat soils subject to different water-table management scenarios. The model combines primary production, aerobic decomposition of soil organic matter (including the soil-parent material, peat), CH4 formation, oxidation, and transport. Model input requires specification of water table and air temperature data sets, vegetation parameters such as primary production and parameters related to gas transport, and basic soil physical data.

Validation using closed flux-chamber measurements of CO2 and CH4 from five different sites in the western Netherlands shows that seasonal changes in fluxes of CO2 and CH4 are correctly modelled. However, the CO2 submodel underestimates peat decomposition when peat decomposition rates obtained from laboratory incubation experiments are used as input. Field decomposition rates are considerably higher. This is attributed to enhancement of decomposition by the addition of easily decomposable material from root exudation (’priming effect’). Model experiments indicate that 1) drainage increases the CO2 production from peat decomposition strongly; 2) restoring a high water table may decrease the total greenhouse gas flux by a small amount although the CH4 flux increases strongly; 3) a warmer climate may cause higher greenhouse gas fluxes from peat soils resulting in a positive feedback to climate warming, and 4) high vegetation productivity in fen meadows may stimulate peat decomposition by the priming effect.

Time-stratigraphic interpretations of Late Pliocene to Early Pleistocene sediments from onshore locations and from marginal marine settings of the North Sea Basin often refer to the subdivision of the Dutch and British ’Quaternary’ regional stratigraphic stages. Since age control for these stages and their stage boundaries are based on relative dating methods, in this study pollen, dinoflagellate cysts and foraminiferal assemblages were investigated to correlate the regional stratigraphic stages independently to the global chronostratigraphy and the paleomagnetic timescale. The data were obtained from eight boreholes located in the depocentre setting of the Late Pliocene North Sea Basin comprising a 1000 m thick sedimentary succession. The British Gedgravian and Waltonian stages, the Dutch Reuverian to Brunssumian as well as published foraminiferal zones (NSB 14, FB and the lower part of the FA2 zone) fall within the Zanclean and Piacenzian. The lower boundaries of the Pre-Ludhamian and Pretiglian stages and of the NSB 14 to 15 zones are close to the paleomagnetic Gauss-Matuyama boundary. The Pre-Ludhamian, Ludhamian, Thurnian and the Pretiglian, Tiglian A and Tiglian B stages presumably cover the marine isotope stages 103 to 95. It is proposed that the Ludhamian, Thurnian and the Tiglian A were short lasting, warm, periods during which sea level highstand facilitated sedimentary deposition at the marginal areas of the North Sea Basin. The lower boundary of the paleomagnetic Olduvai subchron is situated in the Tiglian Cl-4b stage while the TC4c stage is found within the Olduvai subchron. Foraminiferal NSB 15 and NSB 16 zone as well as the upper part of the FA2 and FA1 zone fall within the Gelasian and cover the Matuyama chron as well as the lower part of the Olduvai subchron. Comparison with formerly dated North Sea sediments shows a good agreement between foraminiferal zonations on a broader scale but significant differences in absolute ages occur. Strontium isotope values indicate approximately 1 Ma younger ages as expected from our chronostratigraphic model. This discrepancy is explained by the dominance of freshwater from river discharge contributing high amounts of eroded material to the basin, leading to an increase of the 87Sr/86Sr ratio in the shelf-sea water.

Information on the vegetation and landscape history of a region is often limited, and available data are hard to interprete. A concept is presented here on how a more comprehensive picture of the structure and development of landscapes and vegetations of the past can be gained by integrating the information of several disciplines. Archaeological field methods have been combined with methods used in landscape studies (geology, soil science, micromorphology) and vegetation studies (ecology, palynology and dendrochronology).

This concept has been applied and tested during an integrated study of a buried woodland at Zwolle-Stadshagen (Province of Overijssel, the Netherlands). Many large wood remnants were found in a peat layer preserved below a thick clay deposit. The wood remnants were dated by using dendrochronology to the period between ca. 150 BC and AD 580 (ca. 2200 - 1400 cal. BP). Two phases could be distinguished in the development of the peat. The woodland consisted of a closed stand with ash, alder and oak as main species, in the first phase mostly resembling an alder carr, and in the second one the near-extinct Filipendulo-Alnetum Passage et Hofmann 1968. No evidence of exploitation of the woodland by man nor of animal foraging was found.

The followed integrated procedure has led to a more substantiated reconstruction of the palaeo-environment with its wetland wood, but also of the influence of human activities on the palaeo-landscape and its woodlands, that could not have been obtained otherwise.

Dendrochronology has been used to date sub-fossil wood excavated from former wetland woods located in Zwolle-Stadshagen, the Netherlands. Tree-ring analysis was performed on oak and ash to gain insight into changes in the growth dynamics of the trees resulting from changes in external site conditions, particularly hydrology. In addition population dynamics of oak and ash were studied by observing the temporal distribution and mean age of the oak and ash trees in the period when the woodland existed. The results showed that woodlands with oak and ash at Zwolle-Stadshagen existed at least for a period of about 700 years, from ca. 150 BC to AD 580 (ca. 2200 - 1400 cal. BP). The oak and ash were slowly growing and showed alternating phases of normal and depressed growth. Growth depressions occurred with a frequency of about 20 to 40 years. Almost all of these depressions were synchronous with those in oaks from other - mainly wetland areas - in NW Europe. Consequently, a regional (climate) factor must be considered responsible for this phenomenon. By taking into account the specific growth conditions in wetland woods it is very likely that this factor is linked to site hydrology. Around AD 300 (ca. 1650 cal. BP) a remarkable shift in population dynamics occurred in both oak and ash with many new trees establishing. This indicates a period of striking changes in site hydrology preceding the collapse of the woodland starting around AD 530 (ca. 1420 cal. BP).