NATURAL HISTORY

FLORA

Forest Park is located within what is known as the Western Hemlock zone. In its natural, undisturbed condition, this zone is populated by three primary tree species: Douglas-fir, western hemlock and western red cedar.

Forest Park remains in a semi-natural condition and has maintained all of the western hemlock zone's naturally evolved, characteristic plants. However, one change is significant today. Instead of being dominated by evergreen trees, the park is clothed with a preponderence of red alder and bigleaf maple trees. Primarily due to extensive logging, evergreen trees have declined appreciably while hardwood species have proliferated.

FAUNA

Due to Forest Park's significant size and its continuous, unfragmented habitat, it boasts an incredible diversity of wildlife for an urban park. Over one hundred twelve species of birds and sixty-two species of mammals call Forest Park home. Currently, a tenuous corridor of natural vegetation  connects the park's northwestern end to less developed areas and, ultimately, Oregon's Coast Range.

GEOLOGY

Landslides have been a major factor in the recent geologic history of Forest Park. What is known as Portland Hills silt overlies Columbia River basalt, creating a very unstable formation, especially when wet.

Considering the somewhat soggy winter climate of western Oregon, this makes for a poor foundation material. Ironically, the propensity for landslides has been a significant factor in the preservation of Forest Park. A number of development schemes have been thwarted by unstable slopes.