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If the timing of river discharge shifts, it may lead to a strong impact on groundwater levels.
This is especially the case in valleys that have major rivers flowing through them. For the
Xeni Gwet’in, the rivers of such importance would include the Chilcotin, Chilko and Taseko
Rivers. In addition, peak flow in many BC rivers is predicted to shift to an earlier date,
combined
with a prolonged and lower baseflow period. Such a shift in peak flow would
force groundwater levels to shift by the same interval.
Another important factor is the projected higher incidence of extreme events. Generally,
heavy rain events result in less groundwater recharge, because the ground is not able to
absorb the increased precipitation fast enough. The result will be greater runoff, more
flooding, etc., which it is difficult to quantify with accuracy in hydrologic models. Similarly,
extended periods of drought would lead to dry soil conditions, which in some cases can
result in less groundwater infiltration. So despite the fact that BC, as a whole, is projected to
become wetter, some of this additional precipitation may fall as heavy rainfall and,
consequently, the amount of groundwater recharge could decrease.
5.2. Forest and Vegetation
This section provides a summary of the larger Study Background Report on Climate Impacts
on forest and vegetation prepared by Orman Consulting. For the full report, please see
Annex 2. The methodology for the assessment carried out is provided in section 2.3 above.
In brief, climate projections based on the worst case emissions (A1F1) scenario were used
to describe possible effects on the forests of the Xeni Gwet’in Territory by 2050. The
projected climate variable changes by 2020 and 2050 are presented along with climate
normals (1960‐1999) by Biogeoclimatic (BEC) subzone. Although the model predicts
changes to climate envelopes as classified by the BEC system, the changes do not represent
changes to the forest ecosystem itself. Potential changes to the forest are inferred with the
help of expert opinion and literature reviews 49.
Forests of the Xeni Gwet’in Territory
The XGCA ecosystem, including its wildlife, is somewhat adapted to periods of climate
extremes, whether very severe winters or summer drought periods. In the winter, strong
winds called “Chinooks” (warm drying winds) periodically blows from the west, causing
rapid warming and snow melting, as they also do in the foothills of the Rocky Mountains.
Many plant and animal species have evolved and survived in areas like the XGCA because of
their resiliency to extreme climate variations. Other species have not done so well, largely in
part due to man‐induced habitat alternations or destruction, rather than climate extremes
and
so have either been extirpated or put on the threatened or endangered list, provincially
and/or federally.
The forests of British Columbia are classified using the Biogeoclimatic Ecological
Classification (BEC) System mentioned earlier. This classification system is a framework for
understanding the important components of terrestrial ecological systems. These
components include climate, site factors, and associated vegetation. The BEC system uses
vegetation, soils, and topography
to infer the regional climate of a geographic area. Areas of
49 This simplistic approach was taken due to the budget constraints of this project. Models are now being
developed that will project effects of climate change on vegetation (Campbell et al. 2009).
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