Integrated observations and modelling of greenhouse gas budgets at the ecosystem level in the Netherlands

Within the framework of the Bsik research programme Climate Changes Spatial Planning (CCSP) research has been carried out to improve estimates of greenhouse gas (GHG) emissions (GHG) from land use and land management in space and time, to reduce the uncertainty in such GHG emission estimates, to identify measures to reduce GHG emissions from land-use and to apply and further develop innovative methods to measure the emissions of N2O and CH4 in particular.

CO2 emissions show a quite regular and predictable seasonal and daily variability mainly related to light and temperature. Temporal variability of N2O emission is characterized by low background emissions interspersed with rather rare but extremely high emission peaks mainly triggered by precipitation and application of fertilizer. Temporal variability of CH4 emission is very large as well, but the causes of this variability are less clear. Spatial variability of N2O and CH4 emissions is to some extent caused by differences in groundwater level and land and soil management intensity.

The objective to upscale flux estimates from the landscape level to country-wide level was achieved for CO2 and N2O but not for CH4. In particular improvement of water table information is important for upscaling of CH4 fluxes, while all models will profit from updated information on the rapidly changing peat soils in the Netherlands.
We have found that the rewetting of agricultural peatland can turn areas from a GHG source into a sink. Summer emissions from large shallow lakes are higher than those from intensively and extensively managed polders but lower than those from drainage ditches within the polders.
The current innovative measurement methods (EC, REA and DEC) for N2O and CH4 fluxes are accurate but not yet economically efficient. For CO2 there are accurate and economically efficient methods in place.