UK GHG Flux Network – Peatlands

Peatlands occupy 12% of the UK territory and can store large amounts of carbon (C). However, drainage, peat extraction, and other management activities have turned these ecosystems into greenhouse gas (GHG) emitters. Currently, peatlands account for ~ 4% of the UK’s total annual GHG emissions. Eddy covariance is considered the best method to measure landscape scale GHG exchange (CO2, CH4, N2O), between the Earth’s surface and the atmosphere. Recently many flux towers have been installed on UK peatlands under different land-use and in different condition, with some undergoing restoration. In total there are currently 30 operating, with 9 in Scotland (SCO2FLUX managed by The James Hutton Institute, JHI) and 21 across England, Wales and Northern Ireland (managed by UKCEH), including the Auchencorth Moss ICOS site. As part of the projects, NERC-MOTHERSHIP and SRC-CENTREPEAT, these peatland sites are being harmonised into a network. The data is being analysed using standard protocols in order to generate a powerful dataset to examine the exchange of CO2 and CH4 over UK peatlands. Some of the topics being investigated are: the spatial and temporal variability of emissions for all peatland classifications; the main drivers and controlling mechanisms of GHG exchange, such as the effect of water table depth on gas exchange and restoration impacts (e.g. raising water levels in agricultural peatlands); the value and effectiveness of restoration techniques (e.g. the timeline of recovery in the transition from forest to bog); improving the modelling of peatlands in JULES and other land-surface models; ground-proofing data for Earth observation techniques; assessing the contribution of peatlands to achieving net zero; examining the impact of wildfire on restoration from forest to bog. An overview of the network of sites and some highlights of the analysis to date will be presented

Estimating CO2 flux of croplands for bottom-up budgeting

International audienceAgricultural crops play a significant role in the diurnal and seasonal cycle of atmospheric CO2 over the growing season. The evolution of CO2 flux over space and time for various crops need to be determined for establishing any (mid-)continental atmospheric CO2 budget as it is intended to be done in the North American Carbon Program. Flux towers and the ancillary measurements are critical for regional analysis and understanding of dynamics of CO2 and energy exchange. They provide ground-truth data for remote sensing observations, information for verifying process-based models and for interpreting aircraft and tall tower concentration measurements. Several instrumented towers are monitoring CO2 and energy fluxes from agricultural crops such as corn, wheat, soybean, sugar beet, rape seed, and rice paddies for various locations through networks such as Ameriflux, CarboEurope, and Japanflux. Our objectives are (i) to prepare an exhaustive inventory of the eddy flux measurements carried out (past and present) reporting the crop types, agro-climatic conditions, soil type and slope, management practices and type of measurements (fluxes and the so-called ancillary ones) along with any relevant methodological problems encountered in flux measurements above short canopy crop and (ii) to compare different temporal series (30-min, daily, 10 days) of flux measurements acquired through the growing season in order to stress the commonalities and the differences in the functional response of the various crops in relation to climate, and management practices

Estimating CO2 flux of croplands for bottom-up budgeting

International audienceAgricultural crops play a significant role in the diurnal and seasonal cycle of atmospheric CO2 over the growing season. The evolution of CO2 flux over space and time for various crops need to be determined for establishing any (mid-)continental atmospheric CO2 budget as it is intended to be done in the North American Carbon Program. Flux towers and the ancillary measurements are critical for regional analysis and understanding of dynamics of CO2 and energy exchange. They provide ground-truth data for remote sensing observations, information for verifying process-based models and for interpreting aircraft and tall tower concentration measurements. Several instrumented towers are monitoring CO2 and energy fluxes from agricultural crops such as corn, wheat, soybean, sugar beet, rape seed, and rice paddies for various locations through networks such as Ameriflux, CarboEurope, and Japanflux. Our objectives are (i) to prepare an exhaustive inventory of the eddy flux measurements carried out (past and present) reporting the crop types, agro-climatic conditions, soil type and slope, management practices and type of measurements (fluxes and the so-called ancillary ones) along with any relevant methodological problems encountered in flux measurements above short canopy crop and (ii) to compare different temporal series (30-min, daily, 10 days) of flux measurements acquired through the growing season in order to stress the commonalities and the differences in the functional response of the various crops in relation to climate, and management practices

Ecosystem process models at multiple scales for mapping tropical forest productivity

Quantifying mass and energy exchanges within tropical forests is essential for understanding their role in the global carbon budget and how they will respond to perturbations in climate. This study reviews ecosystem process models designed to predict the growth and productivity of temperate and tropical forest ecosystems. Temperate forest models were included because of the minimal number of tropical forest models. The review provides a multiscale assessment enabling potential users to select a model suited to the scale and type of information they require in tropical forests. Process models are reviewed in relation to their input and output parameters, minimum spatial and temporal units of operation, maximum spatial extent and time period of application for each organization level of modelling. Organizational levels included leaf-tree, plot-stand, regional and ecosystem levels, with model complexity decreasing as the time-step and spatial extent of model operation increases. All ecosystem models are simplified versions of reality and are typically aspatial. Remotely sensed data sets and derived products may be used to initialize, drive and validate ecosystem process models. At the simplest level, remotely sensed data are used to delimit location, extent and changes over time of vegetation communities. At a more advanced level, remotely sensed data products have been used to estimate key structural and biophysical properties associated with ecosystem processes in tropical and temperate forests. Combining ecological models and image data enables the development of carbon accounting systems that will contribute to understanding greenhouse gas budgets at biome and global scales