For example, the old- growth trees have extremely long roots that help prevent erosion of the soil along the banks of the many fish streams.
Keeping these banks intact is important because these streams are home to salmon, which are the bear's main food source.
In return, the bear's feeding habits nurture the forest.
As the bears eat the salmon, they discard the skin and bones in great amounts on the forest floor, which provide vital nutrients.
These produce lush vegetation that sustains thousands of other types of life forms, from birds to insects and more.
Today the spirit bear lives off the coast of the province of British Columbia on a few islands.
There is great concern for their survival since it is estimated that less than two hundred of these white bears remain.
The best way to protect them is to make every effort to preserve the delicate balance of their forest environment - in other words, their ecosystem.
The greatest threat to the bear's existence is the loss of its habitat.
Over many years, logging companies have stripped the land by cutting down a large number of trees.
In addition, they have built roads which have fractured the areas where the bear usually feeds and many hibernation sites have also been lost.