Spatial Analysis

Constraints:

The only constraint employed in this assessment of Grizzly Bear habitat suitability is water-based. The assumptions here are:
1. Grizzly Bears are land-based and thus do not live in water.
2. Virtually any land area is possible Grizzly Bear habitat, but the qualities of these areas differ. BTMs were used to create
Boolean maps of ocean and fresh water systems including lakes, reservoirs and wide portions of major rivers called WATERCON using RECLASS. This was used to mask out from the study area.
 

Factors:

1) Proximity to Fresh Water Bodies

All living organisms cannot live without water, Grizzly Bears are no exception. DISTANCE operator was used
in IDRISI to perform distance operation to fresh water sources (BTMs). The resulting map WATERDIST was then
fed through the FUZZY operation and mapped with sigmoidal monotonically decreasing function to habitat
suitability. Habitat suitability decreases sigmoidally from 150 metres to 1000 metres and then, above 1000 meters
it becomes equally unsuitable.

2) Slope

Prime Grizzly Bear habitat is located in the gentle sloped valley bottoms close to fresh water sources. SURFACE
operation calculated slopes from the Digital Elevation Models (DEMs), the result was fed through FUZZY with
monotonically decreasing linear relationships, parameters 0 degree and 30 degree indicating the most suitable areas
with slopes below 30 degrees.

3) Elevation

Grizzly Bears generally stay below the tree line, where food and water is more abundant. DEMs were used to map
linear decreasing relationship between elevation and habitat suitability, with parameters 150m and 1000m using
FUZZY indicating the areas above 1000 meters as equally unsuitable.

4) Land Cover

The 19 land-use classes determined by the Ministry of Environment used here were reclassified based on the
literature review findings from various Grizzly Bear habitat studies. Forests were given the highest rating, with
Old Growth topping the list as prime Grizzly Bear habitat at maximum suitability of 255. Areas with human
activities/settlements were given lowest scores accordingly. Less ideal natural habitats like alpine/glaciers were
also given lower scores.

5) Proximity to Human Activity

Human activity sites like recreation sites, ski resorts and golf courses are not ideal Grizzly Bear habitat. But this is
more tolerated than permanent/long term human settlements. DISTANCE & FUZZY operations were performed
with a minimum distance of 370 meters from the human activity sites.

6) Proximity to Human Settlements

Grizzly Bears will change its’ behaviour around humans. This is a rather complex relationship that we shall generalize
as Proximity to Human Settlements. That is, habitat suitability increases further away from human contact. This factor
was given different parameters as permanent/long term human contact has a greater impact on Grizzly Bears than
short-term human activities. DISTANCE & FUZZY operations were performed indicating 1000 meters as a
minimum distance from human settlements.

7) Proximity to Old Forest

The Central Coast of British Columbia is known to sustain large numbers of Grizzly Bear populations because of
its’ relatively intact temperate rainforests, one of the largest in the world. This supports the hypothesis that Grizzly
Bears thrive in Old Forests. This is the consequence of old forests having spatial and structural complexities that are
lacking in the young/plantation forests. These create micro/macro habitats within the forests that encourage bio-diversity.
Also, from a conservation point of view, we would like to see more of the Great Bear Rainforest protected.
DISTANCE & FUZZY operations were performed to show that the suitability decreases as the distance from old
forest increases.

Multiple-Criteria Evaluation:

Weights were calculated with the pair-wise comparison matrix for all factors:
 
 

	Water	Slope	Elevation	Oldfor	Humactiv	Humsettl	Forest
Water	1
Slope	1/3	1
Elevation	1	1	1
Oldfor	1/3	1/3	1/5	1
Humactiv	1	1	1	5	1
Humsettl	1	1	1/3	3	1/3	1
Forest	1/3	1/3	1/3	1	1/3	1/3	1

IDRISI is rather inflexible with the pair-wise comparison values in the matrix because it
does not allow entering custom weight ratios. Multiple Criteria Evaluation was performed as the final step towards
Grizzly Bear habitat suitability map and then, this final map  was reclassified to highlight only the high quality
grizzly bear habitats.

Grizzly Bear Habitat Suitability Assessment Map
High Quality Grizzly Bear Habitat Map
 

Results
 

Primarily, our analysis was focused on eight watersheds located in the central coast of British Columbia. The main
assumptions drawn from the analysis indicate that the most suitable watershed in the this region is Kitasu River
watershed, while Bela Coola River watershed was recognized as the least suitable. However, the viability of these
watersheds depends upon many factors highlighted here and their suitability index may serve only as a qualitative
measure.

Grizzly Bear Habitat Suitability by Watershed Map

Below is the table that shows the final quantitative results of our analysis. Initially, the original area of each watershed was calculated and then, the high quality habitat areas (>200) were added. Then, all watersheds were ranked  based on these calculations. As we can see, Kitasu Bay and Laredo Inlet watersheds have the highest percentage of high quality habitat,
whereas Owikeno Lake and Bella Coola River watersheds have the lowest percentage.
 
 

High Quality Watershed Ranking by Area

Watershed Name	Watershed Area (sq.km)	High Quality Habitat	Rank by Total Area	% Area High Quality	Rank by %
BELA	2490.47375	24.11625	8	0.968339859	8
KHTZ	3497.319553	167.8818784	7	4.80030137	6
KTSU	943.0636249	418.6441207	4	44.39192751	1
LRDO	2342.905874	538.2725611	1	22.97457047	2
NASC	4134.018106	492.2812549	2	11.90805754	4
NECL	3340.174086	475.0470068	3	14.22222299	3
NIEL	3864.125694	352.6433751	5	9.126084476	5
OWIK	8293.673125	230.879375	6	2.783801236	7

 

However, the Bella Coola River watershed  should not be ignored based on its low degree of suitability. It is clearly visible that this watershed serves as a corridor to the more remote watersheds located northward and therefore, it provides a good quality habitat for grizzly bear. Moreover, the supervised classification used in our analysis was arbitrary and focused on high quality habitats, but it does not suggest that lower suitability habitats should be ignored.

When considering the ranking based on the total area of high quality habitat, we recognize the Laredo Inlet and Nascall River watersheds as the most viable habitats, while Khuze River and Bella Coola River watersheds belong to the least suitable habitats.
Generally,  the habitat suitability depends on the size of  watersheds and their location,  so that larger watersheds situated closer to the coast have higher suitability level. Even though the Kitasu Bay watershed is relatively small, its remote location on the coast has a significant impact on its suitability.

The general trend observed indicates that the suitability of the watersheds decreases as they are farther inland. Moreover, the high quality habitats become smaller and fragmented in the watersheds located farther from the coast. However, the linkage to other watersheds is clearly observed mainly through the major rivers and more frequently, through the dense network of smaller streams farther inland.