Geography of the Hoh Rainforest

• Brian Moody

The Hoh Rainforest

The Hoh Rainforest is located on the Olympic Peninsula in Northwestern Washington state, USA (Encyclopedia Britannica, 2014). It lies on the west side of Olympic National Park, surrounded by the Olympic National Forest (Encyclopedia Britannica, 2014). The absolute location is between 47-48 degrees North latitude and 123-124.5 degrees West longitude (Broker, 1994).

Temperatures within the Hoh Rainforest range from the 20s (Fahrenheit) up to 80 Fahrenheit (USDA, 2014). The temperature ranges fluctuate by season with nighttime winter temperatures reaching the coldest point into the 20s. Winter daytime temperatures hover in the 40s (USDA, 2014). Spring temperatures range from 35-60 Fahrenheit (USDA, 2014). Summer temperatures range from the low 50s at night to daytime temperatures range between 65-80 degrees Fahrenheit (USDA, 2014). Fall temperatures can fluctuate between 35-65 degrees Fahrenheit (USDA, 2014).

As the name suggests, the Hoh Rainforest experiences an extensive amount of precipitation. The precipitation can take the form of rain or snow, with the latter typically occurring significantly only at higher elevations (Marietta College, 2014). The Hoh Rainforest experiences 140-170 inches (12-14 feet) of annual precipitation (National Park Service, 2014).

Temperature and precipitation in the Hoh Rainforest are influenced primarily by mountains and the Pacific Ocean (National Park Service, 2011). While not a part of the Olympic National Park, home of the Hoh Rainforest the Cascade Mountains play a major role in temperature regulation within the park (National Park Service, 2011).

The Cascade Mountains protect the Hoh Rainforest from masses of cold air brought down by polar jet streams from Canada (National Park Service, 2011). As a result, most of the polar air stays east of the Cascades, resulting in warmer temperatures within the Hoh Rainforest (National Park Service, 2011).

The Pacific Ocean is simply the largest temperature moderator of the Hoh Rainforest (National Park Service, 2011). The Pacific Ocean also plays a critical role in precipitation levels experienced in the region as maritime polar air masses are pushed inland by westerly wind patterns (Christopherson, 2010).

The Olympic Mountains are another major influence over temperature and precipitation levels in the Hoh Rainforest. The mountain range causes orographic lifting to occur (National Park Service, 2011). As air is pushed inland from the ocean, air pressure decreases, pushing it upward as it approaches the mountains (Christopherson, 2010). Simultaneously, the air increases in elevation and gets colder (Christopherson, 2010). Precipitation then occurs when the atmosphere reaches 100% relative humidity as a result of moisture entering it from the ocean (Christopherson, 2010). Most of this precipitation is experienced on the windward side of the Olympic Mountains (National Park Service, 2011).

The Hoh Rainforest has not experienced any extreme weather events, with the exception of flooding which will be addressed in an upcoming section of this paper. It is worth noting, that while the Pacific coast of Washington is susceptible to tsunamis, the Hoh Rainforest is situated far enough inland to be protected from such an extreme weather event.

The Hoh Rainforest is classified as a marine west coast climate type (Christopherson, 2010). It is therefore characterized by few temperature extremes and plenty of precipitation in all month of the year (Encyclopedia Britannica, 2014).

The Hoh Rainforest is made up geologically of sedimentary and extrusive igneous rock (Christopherson, 2010). Sedimentary rocks are formed from the processes of weathering, transportation, and deposition (Christopherson, 2010). Within the Hoh Rainforest, the sedimentary rock make up consists of shale and limestone (Broker, 1994). The outward igneous rock composition is a result of lava seamounts (Broker, 1994).

The major tectonic activity experienced in the Hoh Rainforest was plate tectonic activity (Broker, 1994). The land altering processes of faulting and glaciations are responsible for the formation of the peaks and valleys of the Hoh Rainforest (Broker, 1994). Additionally, the creation of the Strait of Juan de Fuca and Puget Sound are results of glacial advances and retreats (Broker, 1994).

The topography and prominent features of the Hoh Rainforest and surrounding area consists of valleys, lakes, and mountains. There are 5 major valleys in the Olympic Peninsula region: Soleduck Valley, Bogachiel River Valley, Hoh River Valley, Queets River Valley, and Quinault River Valley (Broker, 1994). There are also 5 lowland lakes made by glacial activity: Lake Ozette, Lake Crescent, Lake Cushman, Lake Wynoochee, and Lake Quinault (Broker, 1994). The Olympic Mountain Range provides a mountainous terrain associated with the surrounding area (Broker, 1994).

The major structural controls of the Hoh Rainforest are the mountains within and surrounding the area, primarily the Olympic Mountain Rang. The structural formation of the mountains helps develop a radial drainage pattern (Christopherson, 2010). This pattern occurs when streams flow off a central peak or dome (Christopherson, 2010). As streams within the area flow down the Olympic Mountains, they drain into the Hoh River. The peak discharge ever estimated for the Hoh River is 60,000cfs occurring on October 17, 2003 (US Department of the Interior, 2004). The mean daily flow of the Hoh River is 2,524cfs (US Department of the Interior, 2004).

The Hoh rainforest is subjected to flooding by the incumbent Hoh River (NIFC, 2007). While flooding occurred only 1-2 times per decade prior to 1970, the recurrence has elevated to 3 times per year (US Department of the Interior, 2004). The increase in flooding has been blamed primarily on human influence through the introduction of rip rap for bank stabilization; the rip rap while stabilizing the bank also speeds river flow creating higher discharge rates and flood conditions downstream (NIFC, 2007). Other factors contributing to increased flood recurrence include changes in weather patterns and deforestation (US Department of the Interior, 2004). The increase in deforestation for road construction and timber harvesting has not only created impervious surfaces that speed stormwater flow into the Hoh River, but has also decreased canopy cover which helps slow the speed of precipitation reducing the amount of runoff reaching the river system (US Department of the Interior, 2004).

The Hoh Rainforest is belongs to the temperate rainforest biome (Marietta College, 2014). The vegetation characteristics of the ecosystem are evergreen and deciduous trees on windward slopes and redwoods (Marietta College, 2014). Indicator plant species of the temperate Hoh Rainforest are mature strands of conifers, including: Douglas Fir, Western Red Cedar, Mountain Hemlock, Western Hemlock, Sitka Spruce, and Lodgepole Pine (Marietta College, 2014). The dominant deciduous tree species is the Big-leaf Maple, while mosses, lichens and epiphytes are also hey indicator species of the biome (Marietta College, 2014). The indicator animal species of the temperate Hoh Rainforest include slugs, birds such as the Clark’s Nutcracker and Blue Grouse, and Roosevelt Elk (Marietta College, 2014).

The ecosystem of the Hoh Rainforest is characterized primarily by rain or precipitation and moderate temperatures (National Park Service, 2014). Other key characteristics include: large old trees, dead wood, epiphytes, nurse logs, and Roosevelt Elk (National Park Service, 2014). The temperate rainforest is the fourth most productive ecosystem type; it has a net primary production rate of 600-2500g/sm/yr (Christopherson, 2010). The ecosystem provides an abundance of ecosystem services. The trees of the rainforest filter air by capturing carbon dioxide and other pollutants (National Park Service, 2014). Additionally, the trees help manage stormwater by capturing and slowing precipitation in the canopy and water absorption and filtration by plant roots (National Park Service, 2014). The Hoh Rainforest provides much to animals and humans in the way of habitat and recreation (National Park Service, 2014).

There are four distinct habitats in the Olympic National Park and Forest (Broker, 1994). First, there are the marine and estuarine coastal areas (Broker, 1994). Second is the temperate rainforest (Broker, 1994). The third habitat is the alpine meadows and unvegetated glacial peaks (Broker, 1994). Finally, the national park and forest contains the rain shadow forest and field habitat (Broker, 1994).

The dominate plant communities within the Hoh Rainforest are large old coniferous trees, including Douglas Fir, Western Red Cedar, Mountain Hemlock, Western Hemlock, Sitka Spruce, and Lodgepole Pine (Broker, 1994). Dominant deciduous trees of the Hoh Rainforest include Big-leaf Maple, Vine Maple, Red Alder, and Black Cottonwood (Broker, 1994). Ferns, mosses, and lichens are also dominant plant types within the ecosystem (Broker, 1994). The dominant animal species within the Hoh Rainforest are fish, such as trout, amphibians, and primary consumers, such as Roosevelt Elk and Black-tailed Deer (Broker, 1994).

The Hoh Rainforest follows a food chain and web similar to that of all temperate rainforest. The food chain and web progress beginning with producers like grasses and blackberries (Christopherson, 2010). The primary consumers such as deer and elk consume the producers (Christopherson, 2010). Secondary consumers, such as black bears, tick, or insects then feed off or on the primary consumers (Christopherson, 2010). Meanwhile, tertiary consumers like birds feed on the secondary consumers (Christopherson, 2010). Decomposers, such as soil bacteria and fungi feed on each of the previously mentioned members of the food chain and web, as they breakdown the plant animal remains (Christopherson, 2010). The producers are then fed by the decomposers, starting the chain and web over again (Christopherson, 2010).

The Spotted Owl is an example of an animal occupying a niche within the Hoh Rainforest (Broker, 1994). To thrive, the Spotted Owl has very specific habitat requirements consisting of. “dense, mature strands of trees and a minimum of 3000 acres of contiguous forested land with mature, multi-layered, multi-aged canopy, large snags, deformed branches for perches, and internal defects for nest cavities,” (Broker, 1994). The Hoh Rainforest therefore is the ideal place for this animal population to exist.

Many symbiotic relationships exist within the Hoh Rainforest. Such relationships are often illustrated by fungi and plant species. An example occurring in the Hoh Rainforest are the fungi, Conk’s and Turkey Tails feeding off organic matter on trees (Broker, 1994).

The Human-Land relationship within the Hoh Rainforest can be both positive and negative. Recreational activities like camping, hiking, birding, and fishing are all examples of the positive relationship between humans and the rainforest (National Park Service, 2014). Conversely, clear-cutting and logging illustrate the negative relationship between man and the Hoh Rainforest (National Park Service, 2014). Such actions are responsible for landslides, the choking of rivers and streams with sediment caused by downed logs, and diminished wildlife habitats (National Park Service, 2014).

The ecosystem of the Hoh Rainforest is of stable, high quality. The area is home to many endangered species, such as Spotted Owls, Marbled Mureletts, fishers, salmon, and Bull Trout (Olympic Coast Alliance, 2005). Each of these species depend on the highest quality forest conditions and their presence reflects the stability and quality of the Hoh Rainforest (Olympic Coast Alliance, 2005). The major threat to the Hoh Rainforest ecosystem and the species within is logging (Olympic Coast Alliance, 2005). Many conservation strategies have been implemented in an effort to control logging in the rainforest. The most successful strategy has been to include the Hoh Rainforest in the Olympic National Park, Olympic National Forest, Olympic Experimental Forest, and Quinault Indian Reservation (Olympic Coast Alliance, 2005). Inclusion in these larger systems provides rigid and strict regulation over logging within the Hoh Rainforest.

References:

Broker, Stephen P. (1994). Climate and Ecology. Yale-New Haven Teachers Institute. Retrieved from http://www.yale.edu/ynhti/curriculum/units/1994/5/94.05.04.x.html.

Christopherson (2010), Elemental Geosystems, 7th Ed.

Marietta College, Department of Biology and Environmental Sciences. (2014). Biomes of the World. Retrieved from http://www.marietta.edu/~biol/biomes/temprain.htm.

Marine West Coast Climate.(2014). InEncyclopædia Britannica. Retrieved fromhttp://www.britannica.com/EBchecked/topic/365348/marine-west-coast-climate.

Northwest Indian Fisheries Commission (NIFC). (2007). Hoh River Flooding: Needs of Fish and People Must be Balanced. Retrieved from http://nwifc.org/2007/12/hoh-river-flooding-needs-of-fish-and-people-must-be-balanced/.

National Park Service. (2014). Olympic National Park Washington. Retrieved from http://www.nps.gov/olym/planyourvisit/visiting-the-hoh.htm.

National Park Service. (2011). Olympic National Park: Weather and Climate Retrieved from http://www.nps.gov/olym/planyourvisit/upload/weather.pdf.

Olympic Coast Alliance (2005). Olympic Coast Rainforest. Retrieved from http://www.olympiccoast.org/rainforest.html.

Olympic National Park.(2014). InEncyclopædia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/428124/Olympic-National-Park

United States Department of Agriculture, Forest Service. (2014). Olympic National Forest. Retrieved from http://www.fs.usda.gov/detail/olympic/about-forest/?cid=fsbdev3_049559.

U.S. Department of the Interior, Bureau of Reclamation Technical Service Center (2004). Geomorphic Assessment of Hoh River in Washington State. Retrieved from http://www.ecy.wa.gov/programs/sea/sma/cma/pdf/Hoh_CMZ.pdf.

Radical Botany (2014). Restoring the Connection Between Native Plants and Humans. Retrieved from radicalbotany.com/category/fungi-and-mushrooms/.