Turkey Lakes Watershed Study reference list: 2008

08-01  Ueno, D., C. Darling, M. Alaee*, G. Pacepavicius, C. Teixeira, L. Campbell, R.J. Letcher, A. Bergman, and G. Marsh.  Hydroxylated Polybrominated Diphenyl Ethers (OH-PBDEs) in the abiotic environment: surface water and precipitation from Ontario, Canada.  Environ.Sci.Technol. 42, 1657-1664, 2008. (*Author of correspondence).

Summary: The TLW was the “northern remote site” in Ontario that was  sampled for hydroxylated polybrominated diphenyl ethers in rain and snow during 2002-2004.  OH-PBDEs have been used in flame retardants, polyurethane foams and fabric backing, and when entering the environment during use and disposal, may affect human health.  Concentrations measured at the TLW were lower than in more southerly industrialized areas, but the study concludes that OH-PBDEs are ubiquitous in the abiotic environment.

08-02  Zhang, L. A. Wiebe, R.Vet, C. Mihele, J.M. O’Brien, S. Iqbal, Z. Liang.  Measurements of reactive oxidized nitrogen at eight Canadian rural sites.  Atmos. Environ. 42, 8065-8078, 2008.

Summary: The TLW was one of eight rural sites sampled between 2001 and 2005 to study partitioning of tropospheric reactive oxidized nitrogen (NOy) across eastern Canada.  Differences in budgets and partitioning of the eight chemical species comprising NOy were observed between populated and remote (Algoma) areas. On average, NOx contributed 50-80% to total NOy during cold seasons and 30-60% during warm and hot seasons.

08-03  White*, M.S., M.A. Xenopoulos, K. Hogsden, R.A. Metcalfe, P.J. Dillon.  Natural lake level fluctuation and associated concordance with water quality and aquatic communities within small lakes of the Laurentian Great Lakes region.  Hydrobiologia 613, 21-31, 2008. (*Contact D.S. Jeffries for correspondence).

Summary: With three other areas in the Laurentian Great Lakes Watershed, the TLW was part of a study to reveal patterns of the effects of water level fluctuation on water quality and aquatic communities.  Significant correlations with some water quality parameters were observed (DOC, Ca, Conductivity, pH, SO₄) while only macroinvertebrates were significantly affected by water level fluctuations.  Thus factors that disturb natural water levels such as climate change and water regulation could have damaging effects on lake ecosystems.

08-04  Webster*, K.L., I.F. Creed, F.D. Beall and R.A. Bourbonnière.  Sensitivity of catchment-aggregated estimates of soil carbon dioxide efflux to topography under different climatic conditions.  J. Geophys. Res. 113, G03040, 14pp, 2008. (*Contact D.S. Jeffries for correspondence).

Summary: Patterns of soil respiration are important in estimating regional carbon budgets in a forested landscape.  Two catchments at the TLW of differing topographic features were examined and it was found that a minimum of three features (upland, transition and wetland) were needed for accurate estimates of catchment-aggregated soil respiration (CAR).  The critical transition zone had the highest rates of soil respiration under all climatic scenarios.  Contributions to CAR become higher under warmer and drier conditions.

08-05  Zhang, J.  Long-term patterns of dissolved organic carbon in boreal lakes.  MSc. Thesis, Department of Biology, University of Saskatchewan, Saskatoon.  94pp,  Appendix, 2008.

Summary: Regional and global variables in relation to DOC dynamics were analyzed at 5 sites in 55 lakes, including the TLW.  Among key variables that best explained the variation in long-term DOC patterns were total solar radiation and precipitation, although not at the TLW site.  A general model was developed to compare the response of DOC to regional variables, but since the TLW had no variables in common with the other sites, it was excluded.  Nova Scotia was found to dominate the model in strength of response to changes of environmental variables, while Dorset and ELA had only weak contributions to the general model.

08-06  Fleming, R.L. and K.A. Baldwin. Effects of harvest intensity and aspect on a boreal transition tolerant hardwood forest. I. Initial postharvest understory composition. Canadian Journal of Forest Research 38 (4), 685-697, doi:10.1139/X07-198, 2008.

Summary: Disturbance effects on plant communities largely reflect the degree of overstory removal, soil disturbance, and attendant vegetation destruction. Partial and complete canopy removal and soil disturbance were assessed for their post-harvest impact on vascular plant cover, community responses, indicator species and diversity on north or south facing plots at the TLW 3-years after harvest. Community composition and diversity were primarily related to soil disturbance and aspect related radiation exposure. Canopy opening did not have major influences on its own. Logging-related soil disturbance thus seems to be the predominant silviculture factor (over canopy opening) affecting understory community response and diversity. Prominent aspect related changes suggest that responses will be site and species specific.

08-07  Webster, K.L., I.F. Creed, R.A. Bourbonnière and F.D. Beall. Controls on the heterogeneity of soil respiration in a tolerant hardwood forest. Journal of Geophysical Research 113, G03018, doi:10.1029/2008JG000706, 2008.

Summary: The spatial and temporal distribution of soil respiration (Rs) in forested landscapes and its control by environmental conditions and carbon pools has not been sufficiently investigated. An Rs monitoring strategy targeting different topographic features within the TLW revealed that critical transition zones yielded significantly larger Rs than adjacent upland or wetland portions of the catchments. Environmental conditions (soil temperature and moisture) explained the majority of variance in Rs. This study highlighted the critical transition zone as major sites of Rs because of the existing synchronicity between optimal temperature and moisture conditions during the growing season and the large pool of high quality substrate.

08-08  Creed, I.F., F.D. Beall, T.A. Clair, P.J. Dillon and R.H. Hesslien. Predicting export of dissolved organic carbon from forested catchments in glaciated landscapes with shallow soils. Global Biogeochemical Cycles 22, GB4024, doi:10.1029/2008GB003294, 2008.

Summary: This study presents a simple model of dissolved organic carbon (DOC) loading to surface waters that is applicable to headwater catchments in forested regions on glaciated landscapes. Several watersheds, including the TLW, were assessed for annual DOC export, which was found to vary widely. It was hypothesized that the proportion of wetlands within the catchments would explain the majority of variation in average annual DOC export across catchments. Digital terrain analysis was used to identify wetlands using a digital elevation model. The proportion of wetlands explained 63% of the variance in average annual DOC export, which increased to 89% with the inclusion of regional climatic indicators.  DOC export can be predicted accurately from headwater catchments in forested regions on glaciated landscapes using a simple model based on proportion of wetlands and climatic variables.

08-09  Krezek, C.C., J.M. Buttle, F.D. Beall, R.D. Moore, I.F. Creed, P.K. Sibley, U. Silins, K.J. Devito and C.A. Mendoza. HydroEcological Landscapes and Processes Project: A National-scale Forest Hydrology Initiative. Streamline Watershed Management Bulletin 12: 33-38. 2008.

Summary: The HydroEcological Landscapes and Processes (HELP) project identifies commonalities and differences in terrestrial-aquatic linkages across Canada’s forest landscapes through an analytically based classification system that will be the framework for quantifying hydrologic, geomorphic and ecologic processes for forested landscapes across the country. The HELP project combines results from multiple forest hydrology research sites in different ecozones across Canada including the TLW.

08-10  Jeziorski, A., N.D. Yan, A.M. Paterson, A.M. DeSellas, M.A. Turner, D.S. Jeffries, B. Keller, R.C. Weeber, D.K. McNicol, M.E. Palmer, K. McIver, K. Arseneau, B.K. Ginn, B.F. Cumming and J.P. Smol. The widespread threat of calcium decline in fresh waters. Science 322: 1374-1377.  2008.

Summary: The consequences of declining calcium concentrations in softwater boreal lakes for aquatic biota have not yet been reported. By examining crustacean zooplankton remains preserved in lake sediment cores this study documented near extirpations of calcium-rich Daphnia species, which are keystone herbivores in pelagic food webs, concurrent with declining lake-water calcium. The TLW lakes were part of the 770 Canadian Shield lakes examined, that showed 62% of the lakes with calcium concentrations approaching or below the threshold at which laboratory Daphnia populations suffer reduced survival and fecundity. The ecological impacts of environmental calcium loss are likely to be both widespread and pronounced.

08-11  Casson, N.J. Rain induced bursts of denitrification activity account for differences in dissolved nitrogen export from forested catchments. MSc. Thesis, Department of Biology, University of Western Ontario, London. 67pp, 2 appendices, 2008.

Summary: This study sought to explain the discrepancy in dissolved N stream export between C35 and C38 at the TLW in terms of greater gaseous N export from more prevalent wet soils in C38. Minimal N2O efflux was observed on days without rain. However, on days with rain, N2O efflux was observed, with a linear increase in the rate of N2O efflux from wet soils per millimetre of rain. Intensive monitoring of the wetland soil profile suggested that rain delivers water to the surface layers of the wetland creating an oxygen poor environment where accumulated NO3 is transformed to N2O then N2. This study suggests that rain can produce substantial bursts of N2O and N2 from forest soils and that failure to account for gaseous N export may lead to an underestimation of N export from forested catchments.

08-12  Rams, A.P. Shifts in the magnitude and partitioning of atmospheric versus aquatic carbon export in response to changing climatic conditions. MSc. Thesis, Department of Biology, University of Western Ontario, London.  64pp, 4 appendices, 2008.

Summary: The aim of this thesis was to determine whether changes in meteorological conditions have caused changes in the magnitude and partitioning of atmospheric vs. aquatic C export from C38 at the TLW during the growing seasons from 2003 to 2007. Soil organic carbon pools, the sorption capacity, and the potential saturation of the sorption capacity by dissolved forms of C along an upland-wetland-stream transect were determined. Soil water samples and soil surface CO₂ efflux were collected on the same transect. Stream water samples were collected along with continuous monitoring of water table depth and catchment discharge. Total C export during the growing season increased over the five years of sampling, with greater increases observed in atmospheric losses of C as compared to aquatic losses in the form of DOC.