Duration: 2010-2013
Research Programme: Bioenergy from Forests
Climate change represents one of the greatest environmental, social and economic threats facing to our planet. To mitigate this threat, renewable fuels for energy production are in a great interest. There is now also a great financial incentive to increase the use of forest biomass for bioenergy purposes. Therefore whole-tree harvesting (WTH), in which tree tops, branches and stumps are also harvested, is in increase use in addition to traditional stem-only harvesting (SOH). It is hypothesized that WTH might reduce nutrients leaching to waters. However the disturbance of the forest floor might increase leaching of nutrients and trace metals.
The overall objective is to determine if final harvesting of drained peatland forests will bring about a significant release and transport of trace metals (Cd,Cu,Hg,Ni,Pb,Zn) from the surface layer of peat to watercourses where they would pose an eco-toxicological risk. Anthropogenic emissions of these metals to the atmosphere have increased enormously since pre-industrial times. Once in the atmosphere, the trace metals are transported considerable distances and reaching the ground as wet and dry deposition. Because of the high binding affinity of organic matter, the surface layers of organic soils have become particularly enriched in trace metals. In Finland, there is c. 10 Mha of peatlands of which 4.9 Mha has been drained for forest production purposes. Within the next 10-30 years, much of these drained peatland forests are due to be harvested.
We plan to carry out catchment investigative study to assess the duration and attenuation of harvesting effects on trace metal release and loading to watercourses, and quantify the removal of trace metals associated with the harvested biomass. We plan to have 8 catchment areas, half of the areas are underlain by granitic lithologies and other half by black shale, rich in trace metals.
After calibration, 3 catchments in both black shale and granite areas will be treated (WTH and SOH), one area in both bedrock types remain as a control area. Changes in the mass balance of each metal, relevant physico-chemical properties of the peat, interstitial and drainage waters, and changes
in structure the microbial community will be determined. We plan to use innovative techniques, including diffusive gradients in thin films (DGT) buried in the peat and retrieved over time to determine changes in trace metal speciation and fluxes in situ, and phospholipid fatty acid (PLFA) analysis to determine changes in microbial community structure. We plan to compliment the empirical data with modeling, including mass balance thermodynamic equilibrium speciation (MINEQL+) and runoff modeling.
Our approach will be cross-disciplinary (forest ecosystem, soil, environmental geochemistry and peatland scientists, and environmental analytical chemists) and integrated (atmosphere-vegetation-soil-bedrock-runoff).
The research team consists of scientists from the University of Helsinki (Dept. of Forest Sciences), the University Oulu (Dept. of chemistry), Geological Survey of Finland (GTK) and Finnish Environemnet Institute (SYKE).
Project leader:
Ukonmaanaho, Liisa
The Finnish Forest Research Institute,
Vantaa Unit,
PL 18, FI-01301 VANTAA, FINLAND
Phone: +358 10 211 5115 Telefax: +358 10 211 2103
E-mail: liisa.ukonmaanaho@metla.fi
Other researchers: Fritze, Hannu, VA (2012), Kiikkilä, Oili, VA (2011-12), Lauren, Ari, JO (2011), Nieminen, Tiina, VA (2010-12), Piispanen, Juha, OU (2010-12), Pyhtilä, Heidi, OU (2010-12)
Updated 24.05.2012
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