Impacts of high precipitation on the energy and water budgets of a humid boreal forest

Isabelle, Pierre‐Érik; Nadeau, Daniel F.; Anctil, François; Rousseau, Alain N.; Jutras, Sylvain; Music, Biljana

doi:10.1016/j.agrformet.2019.107813

Cited by 28 publications

(33 citation statements)

References 88 publications

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“…Despite high precipitation, only 45% − 48% returns back to the atmosphere. Isabelle et al [20] in a study at the same sites found that E appeared to be capped even in the presence of high precipitation. The excess of P generates runoff or recharge of ground water, indicating that the availability of soil water is probably not a limiting factor for E T .…”

Section: E T /E At the Seasonal Scalementioning

confidence: 89%

“…This study was conducted in a region representative of the humid boreal forest, namely Montmorency Forest in eastern Canada (47 • 17 18 N; 71 • 10 05.4 W) [20]. This region is under the influence of a continental subarctic climate with a short and cool growing season occurring between June and October [51].…”

Section: Study Sitementioning

confidence: 99%

“…A recent study by Isabelle et al [20] at a humid boreal forest in eastern Canada found the mean cumulative annual E to be ≈ 550 mm, the highest amongst a total of 15 sites across the boreal biome, despite representing a rather modest fraction of the mean annual precipitation (≈ 1600 mm). In humid boreal forests, where tree growth and E T rate are not limited by water availability, one may expect a relatively large E T /E ratio.…”

Section: Introductionmentioning

confidence: 96%

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The Dynamics of Transpiration to Evapotranspiration Ratio under Wet and Dry Canopy Conditions in a Humid Boreal Forest

Hadiwijaya

Pépin

Isabelle

et al. 2020

Forests

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Humid boreal forests are unique environments characterized by a cold climate, abundant precipitation, and high evapotranspiration. Transpiration ( E T ), as a component of evapotranspiration (E), behaves differently under wet and dry canopy conditions, yet very few studies have focused on the dynamics of transpiration to evapotranspiration ratio ( E T / E ) under transient canopy wetness states. This study presents field measurements of E T / E at the Montmorency Forest, Québec, Canada: a balsam fir boreal forest that receives ∼ 1600 mm of precipitation annually (continental subarctic climate; Köppen classification subtype Dfc). Half-hourly observations of E and E T were obtained over two growing seasons using eddy-covariance and sap flow (Granier’s constant thermal dissipation) methods, respectively, under wet and dry canopy conditions. A series of calibration experiments were performed for sap flow, resulting in species-specific calibration coefficients that increased estimates of sap flux density by 34 % ± 8 % , compared to Granier’s original coefficients. The uncertainties associated with the scaling of sap flow measurements to stand E T , especially circumferential and spatial variations, were also quantified. From 30 wetting–drying events recorded during the measurement period in summer 2018, variations in E T / E were analyzed under different stages of canopy wetness. A combination of low evaporative demand and the presence of water on the canopy from the rainfall led to small E T / E . During two growing seasons, the average E T / E ranged from 35 % ± 2 % to 47 % ± 3 % . The change in total precipitation was not the main driver of seasonal E T / E variation, therefore it is important to analyze the impact of rainfall at half-hourly intervals.

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Section: E T /E At the Seasonal Scalementioning

confidence: 89%

Section: Study Sitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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The Dynamics of Transpiration to Evapotranspiration Ratio under Wet and Dry Canopy Conditions in a Humid Boreal Forest

Hadiwijaya

Pépin

Isabelle

et al. 2020

Forests

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“…They are equipped with eddy covariance sensors (IRGASON, Campbell Scientific, UT, USA) that measure turbulent fluxes of heat and water vapour (snow sublimation and evapotranspiration), and CNR4 net radiometers (Kipp and Zonen, Delft, the Netherlands). Further details about the flux towers is provided by Isabelle et al [55]. An intensive manual snow survey was conducted during winters 2016-2017 (W1) and 2017-2018 (W2) around each snow-profiling station, for a total of 1061 observations.…”

Section: Methodsmentioning

confidence: 99%

“…Due to past logging operations, there are several patches of forest clearings accompanied by spatially varying stand structures ( Figure 1). For detailed descriptions of the study area, please refer to Parajuli et al [51], Isabelle et al [52,55] and Hadiwijaya et al [54]. turbulent and radiative fluxes between the canopy and the atmosphere.…”

Section: Study Areamentioning

confidence: 99%

Does Data Availability Constrain Temperature-Index Snow Models? A Case Study in a Humid Boreal Forest

Parajuli

Nadeau

Anctil

et al. 2020

Water

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Temperature-index (TI) models are commonly used to simulate the volume and occurrence of meltwater in snow-fed catchments. TI models have varying levels of complexity but are all based on air temperature observations. The quality and availability of data that drive these models affect their predictive ability, particularly given that they are frequently applied in remote environments. This study investigates the performance of non-calibrated TI models in simulating the subcanopy snow water equivalent (SWE) of a small watershed located in Eastern Canada, for which some distinctive observations were collected. Among three relatively simple TI algorithms, the model that performed the best was selected based on the average percent bias (Pbias of 24%) and root mean square error (RMSE of 100 mm w.e.), and was designated as the base TI model. Then, a series of supplemental tests were conducted in order to quantify the performance gain that resulted from including the following inputs/processes to the base TI model: subcanopy incoming radiation, canopy interception, snow surface temperature, sublimation, and cold content. As a final test, all the above modifications were performed simultaneously. Our results reveal that, with the exception of snow sublimation (Pbias of 5.4%) and snow surface temperature, the variables mentioned above were unable to improve TI models within our sites. It is therefore worth exploring other feasible alternatives to existing TI models in complex forested environments.

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Exploring the spatiotemporal variability of the snow water equivalent in a small boreal forest catchment through observation and modelling

Parajuli

Nadeau

Anctil

et al. 2020

Hydrological Processes

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In snow-fed catchments, it is crucial to monitor and model the snow water equivalent (SWE), particularly when simulating the melt water runoff. SWE distribution can, however, be highly heterogeneous, particularly in forested environments. Within these locations, scant studies have explored the spatiotemporal variability in SWE in relation with vegetation characteristics, with only few successful attempts. The aim of this paper is to fill this knowledge gap, through a detailed monitoring at nine locations within a 3.49 km 2 forested catchment in southern Québec, Canada (47 N, 71 W). The catchment receives an annual average of 633 mm of solid precipitation and is predominantly covered with balsam fir stands. Extracted from intensive field campaign and high-resolution LiDAR data, this study explores the effect of fine scale forest features (tree height, tree diameter, canopy density, leaf area index [LAI], tree density and gap fraction) on the spatiotemporal variability in the SWE distribution. A nested stratified random sampling design was adopted to quantify small-scale variability across the catchment and 1810 manual snow samples were collected throughout the consecutive winters of 2016-17 and 2017-18. This study explored the variability of SWE using coefficients of variation (CV) and relating to the LAI. We also present existing spatiotemporal differences in maximum snow depth across different stands and its relationship with average tree diameter. Furthermore, exploiting key vegetation characteristics, this paper explores different approaches to model SWE, such as multiple linear regression, binary regression tree and neural networks (NN).We were unable to establish any relationship between the CV of SWE and the LAI.However, we observed an increase in maximum snow depth with decreasing tree diameter, suggesting an association between these variables. NN modelling (Nash-Sutcliffe efficiency [NSE] = 0.71) revealed that, snow depth, snowpack age and forest characteristics (tree diameter and tree density) are key controlling variables on SWE.Using only variables that are deemed to be more readily available (snow depth, tree height, snowpack age and elevation), NN performance falls by only 7% (NSE = 0.66).

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Impacts of high precipitation on the energy and water budgets of a humid boreal forest

Cited by 28 publications

References 88 publications

The Dynamics of Transpiration to Evapotranspiration Ratio under Wet and Dry Canopy Conditions in a Humid Boreal Forest

The Dynamics of Transpiration to Evapotranspiration Ratio under Wet and Dry Canopy Conditions in a Humid Boreal Forest

Does Data Availability Constrain Temperature-Index Snow Models? A Case Study in a Humid Boreal Forest

Exploring the spatiotemporal variability of the snow water equivalent in a small boreal forest catchment through observation and modelling

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