Comparative surface energy budgets in western and central subarctic regions of Canada

Natural Boreal saline fens provide analogues for reclaimed wetland systems constructed with sodium‐rich tailings materials. These natural analogues can improve our understanding of vegetative controls on dominant ecohydrological processes (i.e. evapotranspiration (ET)) in constructed landscapes. Therefore, the objective of this study is to characterize ET within a natural boreal saline fen over a growing season to determine the primary hydro‐climatic controls using community‐scale ET measurements targeting dominant vegetation communities within different microforms along with environmental controls. ET rates were highest during periods of peak vegetation growth and temperatures between June and August, with rates decreasing slightly in July. Vegetation species' physiology was the dominant variable governing ET. The more salt tolerant species maintained higher ET rates despite the lower leaf area index and water table levels found within these species. The lower ET rates measured in July can be attributed to high water tables from above average precipitation causing soil inundation and salt stress, increasing stomatal closure. However, community plots containing Triglochin maritima maintained transpiration rates under the coupled stress conditions. Therefore, this is a potentially important species for use in boreal reclamation planting schemes. Last, the findings emphasize that the dominant vegetation selected for reclamation projects must coincide with the materials used (peat and subsurface materials), as results within this study demonstrate that some native boreal fen species (Calamagrostis inexpansa, Hordeum jubatum, and Juncus balticus) were unable to maintain transpiration rates during flood and saline conditions that can occur within the mining area of this region. Copyright © 2015 John Wiley & Sons, Ltd.

show abstract

Controls on evapotranspiration at a subarctic sedge fen

Eaton

Rouse

2001

Hydrological Processes

View full text Add to dashboard Cite

Abstract:In this study, 10 years of summertime data collected at a representative sedge fen in the Hudson Bay Lowland (HBL) are used to investigate the energy and water balance dynamics of subarctic wetlands. The summertime climatic characteristics at the study site during the 10 year study period are also examined. It is shown that mean cumulative summertime precipitation P avg for the study decade closely approximates the 30 year mean P avg . However, the mean summertime air temperature T avg for the study decade is 1°C higher than the 30 year mean T avg .To examine the energy and water balance dynamics at the study site, the variation in each of their respective components throughout the study decade is considered. Little variation is observed in cumulative summertime net radiation Q Ł cum and cumulative summertime ground heat flux Q Gcum ; however, substantial year-to-year variation is evident in cumulative summertime water deficit WD cum , cumulative summertime precipitation P cum , cumulative summertime sensible heat flux Q Hcum , and cumulative summertime latent heat flux Q Ecum . It is noted that the variability in Q Ecum is particularly significant because it consumes the largest proportion of the available summertime energy, and is the largest component of the summertime water balance at this subarctic wetland.Past research has suggested that Q Ł , P, and T have the most influence on summertime Q E at high-latitude wetlands. To test this hypothesis at our study site, Q Ecum , P cum , T avg and Q Ł cum from each year in the study decade were examined. It is observed that high Q Ecum is associated with high P cum , T avg and Q Ł cum , and that low Q Ecum is associated with low P cum and T avg . To identify the hydroclimatological variables that are most responsible for controlling Q Ecum dynamics at the sedge fen, a stepwise linear regression was performed. This analysis indicates that P cum and Q Ł cum are the most important hydroclimatological controls over Q Ecum . However, it is demonstrated that the variability in P cum is more responsible than the variability in Q Ł cum for the variability in Q Ecum during the study decade because of its higher coefficient of variation. The results of this study have broader applicability to wetlands in other parts of the subarctic ecoregion, including the Mackenzie River Basin (MRB). For example, past studies have shown similarities in the energy balance regimes at wetland sites from the HBL and MRB.

show abstract

Comparative surface energy budgets in western and central subarctic regions of Canada

Cited by 23 publications

References 15 publications

Synoptic controls on the surface energy and water budgets in sub-arctic regions of Canada

Synoptic controls on the surface energy and water budgets in sub-arctic regions of Canada

Characterizing dominant controls governing evapotranspiration within a natural saline fen in the Athabasca Oil Sands of Alberta, Canada

Controls on evapotranspiration at a subarctic sedge fen

Contact Info

Product

Resources

About