32 CityTREES
The flow of water and gravel into the forest edge of the cutblock following removal of the trees. Snow and rain, some of which
is captured by the canopy of trees, was now falling directly to the ground in the cutblock. The slow infiltration rate of the
compacted gravel led to extensive gravel deposition in the forest following minor Manitoban rains. Photo by Alex Martin
2012). Having previously grown in a dense stand
of homogenous height, the trees were exposed
to forces that they had not previously encoun-
tered, thus increasing the risk of windthrow
(Mitchell, 1995). While silvicultural best practices
offer guidance for abating windthrow risks, we do
not often discuss these issues within best prac-
tices of managing trees during construction.
Second, the square cutblock case illustrates the
impacts that canopy cover loss can have on urban
runoff. In forest hydrology, ablation of snow from
the canopy of trees during the winter reduces the
amount of throughfall (Varhola et al., 2010). During
the summer, the canopy of trees reduces the impact
of rain on soils and particle displacement. A site
now topped with gravel and compacted by vehi-
cles—as was the case with the cutblock described
here—has a slower infiltration rate than the original
forest soils. Tree loss also reduces the transpiration
at the macro-scale, resulting in more water being
retained in the soil. All of these factors, as well as
the lack of water uptake from the now cleared trees,
results in increased runoff. We can see this runoff
transporting and depositing gravel into the forest as
it is channeled in the gravel edges of the cutblock.
This story offers insight for practicing arborists and
urban foresters about the impact that tree removal
can have on hydrological cycles and the suscepti-
bility of trees to windthrow when force dynamics
are changed as a result of tree removals. The story
also demonstrates the politicization of tree removals.
In the absence of community engagement and
without consulting a forester or an arborist with
expertise in windthrow dynamics, the municipality
put itself in a negative light to the community.
In closing this three-part series on rural urban
forestry with the importance of community engage-
ment and the impact that tree loss can have on
communities, I hope these three stories—one
historical and two personal anecdotes—demon-
strate that conflicts can occur in urban forestry
as they do in conventional forestry. Further, com-
munity engagement that is inclusive and bridges
language barriers is imperative, and examining pre-
vious failures presents an opportunity for lifelong
learning. Together, we progress forward towards
a more sustainable and inclusive future.
