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elevant landscape attribute, a response surface ranging from 0 to
1 dictates the relationship between habitat quality and the status of
the attribute.
Road density is consistently identified in empirical research as being
negatively associated with wolverine habitat, and was included as
a habitat quality attribute in the wolverine HSI. Research in lowland
boreal forests of central Canada and northwestern USA found
mortality risk to increase within home ranges where road density
exceeded 0.44 km/km 2 (Justina Ray, pers. comm., Rowland et al.
2003). The relationship between road density and wolverine is
probably not a well-defined threshold, but rather a gradual impact
(i.e., habitat quality declines with higher road density). The influence
of road density on habitat quality was represented by a linear
relationship where habitat quality equals 1 (i.e., 100%) when road
density equals 0, dropping to 0.5 (50%) when road density equals
0.44 km/km 2 , and 0 when road density equals 0.88 km/km 2 . The
relationship is consistent with the finding that wolverine are unlikely
to occupy home ranges with road densities greater than 0.44 km/
km 2 . The relationship also helps to incorporate the finding from the
boreal lowlands study (Dawson et al. 2010) that denning sites are
likely to be 7 km from roads (i.e., there is a negative impact of roads
over and above the 1 km buffer). The availability of denning sites
is therefore negatively related with road density. When assessing
habitat quality, road density was calculated at the tertiary watershed
scale. Rowland et al. (2003) suggest that the watershed scale is
appropriate when planning wolverine conservation.
Road density is
consistently identified
in empirical research
as being negatively
associated with
wolverine habitat.
Other potential habitat quality attributes such as forest age or
human density were not included in the HSI. Forest age does not
seem to be an important determinant of wolverine habitat, given
that cuts and burns were not selected for or against relative to other
cover types in northwestern Ontario (Bowman et al. 2010). Human
density in the study area is unlikely to reach levels that are detrimental
to wolverine (beyond the negative relationship already captured
by the road density relationship). Rowland et al. (2003) propose a
human density threshold of 3.9/km 2 for northwestern USA, which is
substantially higher than the current population density in the study
area (< 0.2 people/km 2 ).
3.4.2.3 Habitat suitability
For each tertiary watershed, habitat suitability was calculated as the
sum of the products of each cover type’s habitat availability and the
watershed’s habitat quality (based on road density).
A Fork in the Road: Future Development in Ontario’s Far North
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