Pierre River Mine Project

WATER AENV SIRS 15 – 43
Section 12.1
iii. Clarify the responses of key vegetation species, based on observations in
adjacent undisturbed wetlands, to characterize hydro-dynamic changes
within remaining affected wetlands; and,
iv. Clarify the responses of key plant communities, based on observations in
adjacent undisturbed wetlands, to characterize hydro-dynamic changes
within remaining affected wetlands.
Response 25d i. A direct comparison between the hydro-dynamic character of affected
wetlands in the Pierre River Mine LSA and adjacent undisturbed wetlands
should not be made, because site-specific factors will influence the
hydrodynamic character of those wetlands. However, certain hydrological
influences are expected to be similar. For example, it is known that
hydrology influences the physical and chemical parameters in wetlands,
which in turn influence the establishment and maintenance of wetland types
and wetland processes. Given the major role of hydrology in wetlands
function, changes in hydrology can affect aspects of wetland ecology, such as
water chemistry, vegetation species composition and diversity (Thormann et
al. 1998; Whitehouse and Bayley 2005; Locky and Bayley 2006; Laitinen et
al. 2008).
The relationship between water table depth and peatlands (e.g., fens and
bogs) type is particularly close, with seasonal and annual water fluctuations
influencing vegetation species composition in these wetlands (Thormann et
al. 1998; Whitehouse and Bayley 2005).
In general, the hydrological regime in wetlands is influenced by the wetland
water budget, a character that is dynamic in space and time. The potential
water storage capacity, geologic setting and climate will determine how a
wetland responds to hydrologic changes related to oil sands development.
Accordingly, the effects on peatlands because of water drawdown in the
Pierre River Mine LSA are specific to those particular wetlands for such
aspects as natural drainage, topography and hydrogeology, because they have
dynamic and generally site-specific effects across the LSA. These dynamic
and site-specific effects are addressed by developing detailed wetlands
monitoring programs in the predicted drawdown area.
In general, the influence of hydrology on peatlands can be summarized as
follows:
• wetlands type (e.g., fens, bog, swamps) and wetlands succession is
controlled by water source, rate of water flow and water table
fluctuations, which in turn may affect nutrient availability, alkalinity and
the accumulation or decomposition of organic substrate (Devito and
Mendoza 2006)
• water table fluctuations naturally occur within the upper layer of peat
(acrotelm) in fen and bog wetlands because it has high hydraulic
April 2010 Shell Canada Limited 12-33
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