Project 10: Assessing the effects of forest harvest on natural climate solutions
Supervisors: Dr Andrew Tanentzap and Erika C. Freeman
The forestry sector will likely play a major role in climate change mitigation and the removal of atmospheric CO 2 by shifting to wood building materials and producing wood-derived biochar and biofuels. However, these strategies will necessitate an increase in the total production of forest products. Given that global carbon management commitments rely, in significant part, on negative emissions, the calculus of Earth system trade-offs in the forest sector must be examined carefully. One under-examined Earth system component is the linkage between terrestrial and aquatic ecosystems. The importance of this linkage is underlain by the fact that the largest terrestrial reservoir of C is soil organic matter (OM). This global reservoir stores at least three times as much C as the atmosphere or plant biomass. Therefore, if the soil is increasingly disturbed by mechanized harvest or if the interactions of water flow paths and OM-rich soil layers increase as a result of forestry-induced changes to the hydrological cycle, there is a heightened potential for loss of terrestrial C to inland waters with concomitant effects on aquatic ecosystem health. This project will examine the chemical properties of OM in stream water from over 200 Canadian headwater streams in an area with historical forest harvest. The aim is to develop a deeper understanding of how forest harvest disturbance influences stream water carbon in harvested Landscapes.
We aim to address three environmental and conservation priorities. First, monitoring how water quality changes with human impacts in surrounding catchments is a primary objective in many environmental monitoring programmes. As surface waters are often sourced by drinking water treatment plants, a major determinant of treatment strategies is the composition of OM which can be inferred from fluorescence properties measured in this study. Second, OM is central to the functioning of freshwater ecosystems that support Earth’s life system. It does so by increasing the attenuation of solar radiation, altering contaminant toxicity and increasing nutrient pools. The movement of OM through freshwaters is also one of the largest natural fluxes in the global carbon cycle. By altering the path of water through the landscape, forest harvest may alter the properties of OM and therefore its role in freshwater ecosystem function with potentially negative consequences to aquatic ecosystem health. Several OM properties are measured as part of this study and we aim to infer information about hydrological pathways from changes to these metrics. Lastly, this project will contribute to the time-sensitive understanding of how forest harvest contributes to changes in the carbon quantity and quality in streams. With detailed land-use metrics, forest harvest history, and OM properties measured we aim to better understand the potential unintended consequences of harvesting forests in order to achieve climate targets.
The Role of the Intern
The intern will perform statistical analyses of chemical data collected from Canadian streams (2019) and corresponding modelled landscape metrics and forest harvest history in order to generate a better understanding of the link between harvest and stream water quality. This will be a continuation of course work for the student and therefore their start-up training needs will be minimal. The student will be integrated within the DAB by being introduced and working alongside 1 student and researchers with statistics and machine learning expertise and will receive direct supervision and practical experience with the coding pipeline, statistical analysis, and data presentation.
Expected Outputs
We expect that given a month of analysis time, a thorough statistical analysis of the relationship between stream carbon and surrounding land use will be completed and contribute to a planned publication.
Key References
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- Rockström, J. et al. A roadmap for rapid decarbonization. Science (80-. ). 355, 1269–1271 (2017).
- Sohi, S. P. Carbon Storage with Benefits. Science (80-. ). 338, 1034 LP-1035 (2012). 9. Lawton, G.
- Welcome to the age of wood. New Sci. 241, 33–37 (2019).
- Heck, V., Gerten, D., Lucht, W. & Popp, A. Biomass-based negative emissions difficult to reconcile with planetary boundaries. Nat. Clim. Chang. 8, 151–155 (2018).
- Schulze, E. D., Körner, C., Law, B. E., Haberl, H. & Luyssaert, S. Large-scale bioenergy from additional harvest of forest biomass is neither sustainable nor greenhouse gas neutral. GCB Bioenergy 4, 611–616 (2012).
- Brienen, R. J. W. et al. Long-term decline of the Amazon carbon sink. Nature 519, 344– 348 (2015).
- Büntgen, U. et al. Limited capacity of tree growth to mitigate the global greenhouse effect under predicted warming. Nat. Commun. 10, 2171 (2019).
- Scharlemann, J. P., Tanner, E. V., Hiederer, R. & Kapos, V. Carbon Management Global soil carbon: understanding and managing the largest terrestrial carbon pool. (2014). doi:10.4155/cmt.13.77
- Cambi, M., Certini, G., Neri, F. & Marchi, E. The impact of heavy traffic on forest soils: A review. For. Ecol. Manage. 338, 124–138 (2015).
- Kreutzweiser, D. P., Hazlett, P. W. & Gunn, J. M. Logging impacts on the biogeochemistry of boreal forest soils and nutrient export to aquatic systems: A review. Environ. Rev. 16, 157–179 (2008).
- Campeau, A. et al. Current forest carbon fixation fuels stream CO2 emissions. Nat. Commun. 10, 1876 (2019).
