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Research Call

DAFM Reference


DAFM Award

DAFM National Call 2011 11/C/208 UCD, (TCD, UL, Teagasc) €818,001

Project Title:

Monitoring and Assessment of critical biomass removal in Irish forests

Project Coordinator:

Dr. Thomas Cummins

Project Abstract

Critical Biomass Removal is a new concept, the level of biomass removal from forests that can be sustained without causing harm, according to current knowledge. Increased harvesting of forest biomass, such as branches and foliage (in addition to main-stem logs currently removed) is increasing as a source of carbon-neutral biofuel. Removing biomass also removes nutrients, needed for the next growth of trees. The ForSite project is assessing the nutrient impact of increased biomass harvesting in Irish forests, by developing databases of nutrient exchanges, and a tool for forest managers and policymakers to assess biomass-harvesting scenarios using this new concept of critical biomass removal. Nutrients move in a partially-closed cycle in the forest, through organic-matter decomposition and tree growth. Net nutrient inputs to the forest come from atmospheric deposition (mostly precipitation), and from soil-mineral weathering. ForSite is quantifying these inputs, using long-term monitoring of deposition at three sites, and with new surveys and analysis to measure soil-mineral weathering rates for the first time. These measurements will be combined with climate maps, and with new soil maps for Ireland from the recently published Teagasc Soil Information System survey. Nutrients leave the forest in overland flow and drainage water. By monitoring soil-solution composition (based on 20 years data, 1991–2010), and by modelling soil-water flow and runoff (under way), we are quantifying this nutrient exchange. Nutrients removed in managed harvesting operations can be predicted, based on known quantities of plant material, and existing and improved values for the nutrient content of forest components (under way). By calculating the net nutrient balance, it will be possible to guide management planning to avoid exceeding critical biomass removal. The sustainability of residue removal has been assessed by modelling these element balances, and published based on information available at end of 2014. Indications are that for the nutrient elements magnesium and potassium, inputs in deposition and weathering balance those removed in harvest. For Calcium, however, increased harvest was predicted to have an impact, though a relatively small one, in view of the uncertainties remaining in these estimates.

Final Report: