N.T. Roulet

article

The direct and indirect effects of inter-annual meteorological variability on ecosystem carbon dioxide exchange at a temperate ombrotrophic bog

T.A. Teklemariam, P.M. Lafleur, T.R. Moore, N.T. Roulet, more

Agricultural and Forest Meteorology > 2010 > 150 > 11 > 1402-1411

The link between inter-annual variability (IAV) in ecosystem CO ₂ exchange and meteorological conditions was evaluated using a decade (June 1998 to October 2008) of eddy covariance (EC) and meteorological data recorded at the Mer Bleue peatland, a large ombrotrophic bog located in Ontario, Canada (45.40°N lat., 75.50°W long.). Year-to-year variability in meteorology was particularly marked...

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Assessing long‐term hydrological and ecological responses to drainage in a raised bog using paleoecology and a hydrosequence

J. Talbot, P.J.H. Richard, N.T. Roulet, R.K. Booth

Journal of Vegetation Science > 21 > 1 > 143 - 156

Question: We studied vegetation succession after drainage in a bog, as an analogue for potential persistent water table drawdown due to climate change. We asked: (1) how does bog vegetation change following a long‐term water table lowering and (2) how are effects of drainage on hydrology and vegetation distributed temporally and spatially? Location: Mer Bleue peatland, Ontario, Canada (45.41°N,...

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Antecedent moisture conditions and catchment morphology as controls on spatial patterns of runoff generation in small forest catchments

A.L. James, N.T. Roulet

Journal of Hydrology > 2009 > 377 > 3-4 > 351-366

Although existing empirical studies of runoff generation in headwater catchments have provided evidence of runoff mechanisms, contributing sources and active flowpaths from forest catchments around the world, our understanding of how hydrologic and biological processes vary and aggregate in space within headwater systems remains poor. In this study, we examine the spatial patterns of storm runoff...

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Using direct and indirect measurements of leaf area index to characterize the shrub canopy in an ombrotrophic peatland

O. Sonnentag, J. Talbot, J.M. Chen, N.T. Roulet

Agricultural and Forest Meteorology > 2007 > 144 > 3-4 > 200-212

Leaf area index (LAI) is an important ecological parameter that characterizes the interface between a vegetation canopy and the atmosphere. Indirect measurements of LAI using optical techniques such as the LAI-2000 plant canopy analyzer have been routinely conducted for different vegetation canopies including forests and agricultural crops. However, little attention has been paid to shrub canopies...

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Ecosystem Respiration in a Cool Temperate Bog Depends on Peat Temperature But Not Water Table

P.M. Lafleur, T.R. Moore, N.T. Roulet, S. Frolking

Ecosystems > 2005 > 8 > 6 > 619-629

Ecosystem respiration (ER) is an important but poorly understood part of the carbon (C) budget of peatlands and is controlled primarily by the thermal and hydrologic regimes. To establish the relative importance of these two controls for a large ombrotrophic bog near Ottawa, Canada, we analyzed ER from measurements of nighttime net ecosystem exchange of carbon dioxide (CO₂) determined by eddy covariance...

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Groundwater flow patterns in a large peatland

C.J.D. Fraser, N.T. Roulet, M. Lafleur

Journal of Hydrology > 2001 > 246 > 1-4 > 142-154

Groundwater flow patterns and geochemistry were studied in the Mer Bleue bog, near Ottawa, Ontario, Canada. Groundwater flow patterns alternated between recharge, i.e. head gradients producing flow from the surface of the peatland to the deeper peat, and discharge, i.e. head gradients indicating flow from the deeper peat towards the surface of the peatland, during the summer of 1998. The patterns...

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Spatial and temporal dynamics of mercury in Precambrian Shield upland runoff

C.J. Allan, A. Heyes, N.T. Roulet, V.L. St. Louis, more

Biogeochemistry > 2001 > 52 > 1 > 13-40

Methylated and total Hg, and TOC concentrations were measured in precipitation and runoff in a first order Precambrian Shield watershed, and in precipitation, throughfall, shallow groundwater and runoff in a zero Precambrian Shield watershed. Plots dominated by open lichen-covered bedrock and another containing small patches of conifer forest and thin discontinuous surficial deposits were monitored...

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Uncertainty in Predicting the Effect of Climatic Change on the Carbon Cycling of Canadian Peatlands

T.R. Moore, N.T. Roulet, J.M. Waddington

Climatic Change > 1998 > 40 > 2 > 229-245

Northern peatlands play an important role globally in the cycling of C, through the exchange of CO2 with the atmosphere, the emission of CH4, the production and export of dissolved organic carbon (DOC) and the storage of C. Under 2 × CO2 GCM scenarios, most Canadian peatlands will be exposed to increases in mean annual temperature ranging between 2 and 6° C and increases in mean annual precipitation...

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Sinks and sources of methylmercury in a boreal catchment

Brian A. Branfireun, D. Hilbert, N.T. Roulet

Biogeochemistry > 1998 > 41 > 3 > 277-291

A simple, catchment-scale, cascade model was used toassess the importance of sinks and sources ofmethylmercury (MeHg) in a boreal catchment thatcontains a forested upland, a lowland peatland and asmall lake. The three compartment model was run usingrealistic flow rates and atmospheric loading of MeHg,and the model was constrained by observedconcentrations of MeHg in each compartment. Assumingno internal...

article

Groundwater flow and dissolved carbon movement in a boreal peatland

J.M. Waddington, N.T. Roulet

Journal of Hydrology > 1997 > 191 > 1-4 > 122-138

Measurement of the groundwater flux and the consequent advection of dissolved carbon (DOC (dissolved organic carbon), CH ₄ and CO ₂ ) were made in a boreal peatland in northern Sweden in summer 1993. The early summer gradients in hydraulic head indicated a downward flux of water in the peatland, but after a persistent mid-summer dry period the gradients changed to produce an outward...

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Search results for: N.T. Roulet

The direct and indirect effects of inter-annual meteorological variability on ecosystem carbon dioxide exchange at a temperate ombrotrophic bog

Assessing long‐term hydrological and ecological responses to drainage in a raised bog using paleoecology and a hydrosequence

Antecedent moisture conditions and catchment morphology as controls on spatial patterns of runoff generation in small forest catchments

Using direct and indirect measurements of leaf area index to characterize the shrub canopy in an ombrotrophic peatland

Ecosystem Respiration in a Cool Temperate Bog Depends on Peat Temperature But Not Water Table

Groundwater flow patterns in a large peatland

Spatial and temporal dynamics of mercury in Precambrian Shield upland runoff

Uncertainty in Predicting the Effect of Climatic Change on the Carbon Cycling of Canadian Peatlands

Sinks and sources of methylmercury in a boreal catchment

Groundwater flow and dissolved carbon movement in a boreal peatland

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