The Marine West Coast Forest is a Level I ecoregion of North America designated by the Commission for Environmental Cooperation (CEC) in its North American Environmental Atlas. The region includes parts of Alaska, the Yukon, British Columbia, Washington, Oregon, and California.
Topography/geography/soil
The region is strongly influenced by the large mountain ranges stretching throughout most of the coast. Changes in elevation cause changes in plant/animal diversity, this can be exemplified through observing the alpine tundra's vegetation which consists of shrubs, herbs, mosses, and lichens; while lower elevations, the temperate coastal forest hold magnificently large trees such as western hemlock, California redwood, and the red alder. These differences are in direct correlation with the availability of oxygen, and other nutrients at higher elevations. The mountains also create rain-shadow areas due to the clouds having to release their precipitation in order to get over the mountains, or be blocked all together. Trees, which perform better under stress, grow in these areas such as the Douglas fir. As for the soil, the region generally has a thin podzol soil, causing it to be extremely acidic. Farmers must compensate by applying fertilizers and lime to lower the acidic levels for agricultural viability. Digging even deeper the then soil within the region will reveal mostly igneous and sedimentary rock. Colluvium and morainal deposits make up most of the surface materials. Mountains, which so intensely affect the region, are massive formations resulting from upheaval caused by continental collisions
Climate
The climate of the marine west coast forests is humid. According to the Köppen climate classification System, this climate is very damp throughout most of the year, receiving a great amount of rainfall along with heavy cloud cover. The marine climate can also be defined with its narrow range of temperatures throughout the year. Precipitation is ample and consistent in the marine west coast, with many days of rainfall and a large annual accumulation. Many areas in the marine west coast climate have more than 150 days of rainfall per a year, along with averaging around 50 to 250 centimeters per a year of total rainfall (Britannica, 2013). The average temperatures of areas within the marine west coast forests usually range from 10 °C to 15 °C (Britannica, 2013).
These mild temperatures are in collaboration with the moderating effect of ocean bodies on air temperatures due to the constant influx of oceanic air influencing the marine west coast throughout the year (Ritter, 2009). The marine west coast is located in the path of westerly winds from the ocean that contribute to its cloudy skies, significant amount of precipitation, and mild temperatures (Hollow, 2001). The rainfall, seasons, and temperature are all dependent on each other and are all affected by the global circulatory pattern.
Hydrology
The main watersheds in the region are the Puget Sound and Columbia River Watershed. Due to the region’s proximity to the Pacific Ocean, this ecoregion experiences large amounts of precipitation annually, creating a very humid and wet climate. The majority of river and stream activity is directly influenced by the annual precipitation patterns. In the rainy season from October to May, most of the low elevation rivers and streams experience peak run off levels. Rivers and streams at higher elevation are more influenced by snow melt and therefore experience peak run off from late spring into early summer due to the snow melt. The permeability levels of bedrock in the area of interest dictate surface water in the region. Volcanic parent material, as found in Oregon, tends to result in lower levels of ground water due to the low permeability of the rock. Although areas with volcanic parent material may have fewer ground water aquifers, these areas tend to have better developed stream networks and higher stream drainage levels (Moore, 765). Areas with newer volcanic bedrock have higher levels of permeability, and are therefore more likely to have ground water aquifers. These areas will experience lower stream drainage densities and less developed stream networks due to the greater rate of ground water recharge (Moore, 765).