Ecology of Olympic National Park
Olympic National Park is located in the Pacific Northwest corner of the United States on the Olympic Peninsula in Washington State.
Various factors such as erosion, tsunamis, glaciers, and fires have shaped the park’s unique landscape, which includes mountains, coasts, rivers, and even rainforests. These different regions contribute to the wide range in elevation found throughout the park, with the lowest elevations at sea-level in the coastal regions and the highest elevation reaching 7,980 feet (2,432 meters) at the peak of Mt. Olympus.
The changes in elevation throughout the park, along with variations in other climate conditions such as precipitation, contribute greatly to the biodiversity found at Olympic National Park. The highly variable climate conditions in the park have led to the formation of several different biotic communities (groups of organisms that interact with each other). Biotic communities are typically defined by the types of plants present and the abiotic conditions. Olympic National Park is comprised of six principle biotic communities: coastal forests, lowland forests, temperate rain forest, montane forests, subalpine, and alpine. Throughout these communities, there are over 1,450 vascular plant species and hundreds of non-vascular plant species including mosses, liverworts, and hornworts.
The USGS Olympic Field Station, part of the Forest and Rangeland Ecosystem Science Center (FRESC), collaborates with the National Park Service and other agencies within Olympic National Park.
Biotic Communities and Plant Species
Coastal Forests
Coastal forest communities can be found surrounding the 73 miles of coastline at Olympic National Park. Milder temperatures and abundant rain help support these dense forests, which are defined by their diverse trees, shrubs, and understory species. Some common species include the Sitka spruce (Picea sitchensis), western hemlock (Tsuga heterophylla), evergreen huckleberry (Vaccinium ovatum), and deer and sword ferns (Blechnum spicant and Polystichum munitum). Fallen branches and trees from these forests contribute to the driftwood and logs found scattered across the beaches of the park.
Lowland Forests
Similar to coastal forests, lowland forests also have milder temperatures and abundant rainfall. These climate conditions, along with the deeper soils found in this community, support the tall, wide trees found throughout the community. This community is often referred to as an old growth forest, which are defined by the following characteristics: trees over 200 years old, abundant downed wood, multi-layered canopies, and snags (standing dead trees). Old growth refers predominantly to the Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) trees found in the lowland forests. Other common species include shrubs such as the coast red elderberry (Sambucus racemosa) and huckleberries (Vaccinium spp.) and understory species such as violets (Viola spp.) and star flowers (Trientalis borealis).
Temperate Rain Forests
As implied from their name, temperate rain forest communities are defined by the large amount of rain they receive. At Olympic National Park, the rain forests receive between 140 to 167 inches of rain every year. Similar to coastal and lowland forests, temperate rain forests at Olympic National Park have moderate temperatures. The moisture allows non-vascular plants, such as mosses and spike mosses, to flourish. Epiphytic mosses, or mosses that grow on other plants and absorb water from the air or rain, are abundant throughout the rain forests of Olympic. Additionally, dead wood and nurse logs cover the floors of the rain forests and contribute to its biodiversity by providing essential nutrients and habitats. After large trees die and fall to the ground, they begin to decay. In the long process of decaying, they provide shelter and nutrients for new germinating seeds, mosses, fungi, mammals, amphibians, and insects. Common tree species include the Sitka spruce, Douglas fir, western hemlock, bigleaf maple (Acer macrophyllum), and vine maple (Acer circinatum). Common epiphytes include the licorice fern (Polypodium glycyrrhiza), cat-tail moss (Isothecium stoloniferum), and lungwort (Lobaria spp.). Understory species include the Oregon oxalis (Oxalis oregana), sword and lady ferns (Polystichum munitum and Athyrium felix-femina), and stair-step moss (Hylocomium splendens).
Montane Forests
Continuing up the mountains of Olympic National Park, the montane forest biotic community can be found at elevations between approximately 1,500 and 4,000 feet. On the western windward sides of the mountain slopes, the higher air moisture due to facing the ocean favors the growth of western hemlocks and silver firs (Abies amabilis). On the sunnier and drier slopes to the east and south, Douglas firs, which have adaptations for fire-resistance, dominate. On these drier slopes, wildfires started by lightning strikes play a large role in shaping the forest through ecological succession. These natural fires clean out understory species and create space for a new generation of plants. Common shrubs and wildflowers found in the montane forests include salal (Gaultheria shallon), bearberry (Arctostaphylos uva-ursi), coralroot (Corallorhiza mertensiana), and bead lily (Clintonia uniflora).
Subalpine
As you continue to climb up the mountains of Olympic National Park, the temperatures drop and environmental factors such as snow and wind play a large role in shaping the ecology of the subalpine forests. Subalpine forest communities occur between approximately 5000 and 6000 feet in elevation. These communities serve as a transition between the flourishing montane forests below and the barren alpine biome above, with trees getting shorter and shorter as the elevation rises and climate conditions become too insurmountable for survival. Despite the cooler temperatures and frequent snows in the winters, subalpine communities are also sometimes affected by wildfires in the drier summer seasons. Common species include the Alaska yellow-cedar (Chaemaecyparis nootkatensis), mountain hemlock (Tsuga mertensiana), and subalpine fir (Abies lasiocarpa).
Alpine
At the highest points of Olympic National Park, the alpine biotic community experiences cold temperatures, strong winds, and shallow soils—difficult living conditions for most plants. However, some wildflowers have been able to survive and thrive in these conditions through adaptations such as growing low to the ground, evolving waxy or hairy leaves, and storing energy in bulbs or tap roots during the winter. These strategies help them avoid losing moisture to winds, conserve moisture, and fuel regrowth in the springtime, respectively. Some wildflower species include Flett’s violet (Viola fletti), Piper’s bellflower (Campanula piperi), and scalloped onion (Allium crenulatum).
Mosses and Lichens
Throughout Olympic National Park, mosses and lichens play an important role in many different ecosystems. Mosses are non-vascular plants, meaning they don’t have specialized structures like stems and roots to transport water. Lichens are the product of a symbiotic relationship between fungi and green algae or cyanobacteria. Mosses and lichens can be found living on and hanging from trees and on the forest floors, and they play the essential role of providing soil and moisture for other plants in the forest.
Animal Species
Birds
Throughout Olympic National Park, there are about 300 species of birds, including the winter wren, sooty grouse, tufted puffin, woodpeckers, and hummingbirds, just to name a few. The park is also home to several threatened or endangered species of birds, including the northern spotted owl (threatened), western snowy plover (threatened), marbled murrelet (threatened), and short-tailed albatross (endangered). However, many efforts across multiple agencies are being employed to help these species survive and expand their populations. The Northwest Forest Plan, signed in 1994 collaboratively by the Forest Service, Bureau of Land Management, EPA, and NPS, called for the continued monitoring of the spotted owl. The plan has also helped to guide conservation measures such as planning timber harvesting and removing barred owls that outcompete spotted owls for their habitats.
Mammals
Olympic National Park is home to 62 terrestrial species of mammals. Some terrestrial species include mountain lions, black bears, voles, bats, and beavers. There are also several species that are endemic to the Olympic Peninsula, meaning they only exist there, including the snow mole, Mazama pocket gopher, Olympic chipmunk, and Olympic marmot. These species were able to uniquely evolve on the Olympic Peninsula because past geological barriers, such as glaciers, isolated them from outside populations. Wolves were also once abundant throughout the park but were eradicated by humans in the early 1900s.
Olympic National Park also houses 29 species of marine mammals. Some common species of marine mammals throughout the park include seals, sea lions, whales, and otters. Similarly to the wolves, sea otters were also once abundant throughout the ocean waters that fall within the park boundaries but were hunted to extinction in the early 1900s. The sea otter population was reintroduced and able to recover due to conservation efforts between 1969 and 1970.
Amphibians and Reptiles
Olympic National Park is home to 13 species of amphibians, including eight salamander and five frog species. Throughout their entire lifecycles, amphibians are reliant on the presence of water. Because amphibians don’t have amniotic eggs like other vertebrates, their eggs don’t have protective coverings, making them susceptible to drying out. The larval stage is also dependent on water, with most tadpoles only being able to survive in water and having gills. Even after metamorphosis, where the species often gain the ability to live on land, adult amphibians have porous skin that allows for gas exchange. Because of this heavy dependence on water, the high moisture in Olympic National Park makes it an ideal habitat for amphibians. They can often be found under decaying downed trees or alongside streams and ponds at high and low elevations of the park. Some amphibian species found at the park include the northwestern salamander (Ambystoma gracile), Olympic torrent salamander (Rhyacotriton olympicus), and pacific tree frog (Pseudacris regilla).
Olympic National Park is also home to four species of reptiles: one lizard and three snake species. Unlike amphibians, reptiles often thrive in warmer, drier climates where they can better regulate their body temperatures. However, some species still persist on the Olympic Peninsula, including the northern alligator lizard (Elgaria coerulea), rubber boa (Charina bottae), common garter snake (Thamnophis sirtalis), and northwestern garter snake (Thamnophis ordinoides). None of these snakes are venomous.
Fish
There are 37 species of native fish in Olympic National Park, including five species of salmon, the Olympic mud minnow, and trout. These fish, and more specifically the anadromous fish, play a critical role in transferring nutrients throughout the park. An anadromous fish, such as salmon, is one that migrates between freshwater rivers and oceans to lay eggs in the same streams where they were born. Through this migration, the fish transport nutrients from the ocean to river and terrestrial ecosystems, providing a critical food source for other animals such as bears, eagles, and otters. They also contribute to the biogeochemical cycles of carbon, nitrogen, and phosphorus throughout the park
Invertebrates
Olympic National Park is home to thousands of invertebrates, including insects, spiders, worms, and mollusks. Though these creatures are small, they play a huge role in the ecosystems they occupy throughout the park. Invertebrates play a key role in decomposing downed trees and cycling nutrients, pollinating flowers, and providing a key source of food for many other animals.
Coastline and Climate Change
Coastline
Along the beachfront of Olympic National Park, the coastlines are teeming with life. As the tide recedes twice each day, the rocks beneath the waves are revealed, along with the tidepools that they house. Within the tidepools, visitors can discover a wide variety of plant and animal species, including algae, seaweed, anemones, sea stars, and crabs.
As climate change continues to shape our world, however, these coastlines are at risk of being damaged due to sea-level rise. A research study by the USGS used a coastal vulnerability index (CVI) to map where the park may be most vulnerable to sea-level rises. This data is critical in deciding where to allocate resources to best conserve as many species and natural habitats as possible. Additionally, the USGS conducted a natural resource condition assessment to identify any potential issues in the park related to resource conservation.
Climate change has the potential to drastically impact the other biotic communities of Olympic National Park as well. The USGS conducted a case study on Olympic National Park to assess the sensitivity of certain areas to adapt to climate change.