I. Background: PNW forests

Warmer temperature, ultimately, results in climate changes such as more precipitation, desertification, intense weathers, and seasonal timing shifts. In this blog, precipitation patterns will be the focus of discussion, particularly in  the forests of Washington state and moreover the Pacific Northwest region. The region of interest is a temperate rainforest biome, where changes in precipitation pattern will most likely affect water availability of vegetation. (This topic was chosen because RAIN is definitely a feature of Seattle and most importantly, in hopes to share some insights into what is really up with the environment we are living in!!)  

Before we learn about the impacts of climate change on the forests of the Pacific Northwest, this page will familiarize us to a brief background and the current climate of the location. The most noticeable feature of the Pacific Northwest is the mountains. On the Pacific coast, the Coastal Ranges consist of the Willapa Hills and the infamous Olympic Mountains located in the southwest and northwest, respectively. Moving inward, we find another range of mountains called the Cascade Range. This range is composed of currently-dormant volcanic cones like Mt. Adams, Mt. Baker, Mt. Helen’s, and the highest mountain in Washington State, Mt. Rainier. All these beautiful ranges of mountains sustain a large forest ecosystem we are interested in. The region that lies between the two ranges is characterized by a depression named the Western Corridor; most of Washington’s major cities are concentrated here: Tacoma, Vancouver, Bellevue, and Seattle. Moving on to low elevation, the flattest region of the state is the Columbia Plateau on the southern- center.

http://vulcan.wr.usgs.gov/LivingWith/Historical/LewisClark/Maps/map_lewis_clark_pacific_northwest.html

Another topographic feature of the Pacific Northwest, especially Washington, is rivers and lakes. They contribute a large variety of resources that Washington heavily depends on. Fishery and hydroelectric power are just two of the resources.  Washington’s two main rivers are Snake and Columbia River, which is the longest and most powerful one that ranks 2^nd after Mississippi River in average discharge.  Also, the lakes provide water storage, flood control, and electricity through approximately 90 dams. (Refer to a nicely-labeled topographic map of the Pacific Northwest above)

Overall, these topographical features affect the current climate conditions of the Pacific Northwest. The Cascade Range is the major barrier that divides the region’s climate, ecology, and economics. The west of the Cascades, where most of the population resides, is impacted by direct human interactions e.g., forestry and dam building. The climate is characterized with abundant winter rain and dry summers. The area is densely covered with moist conifer forests, oak forests, grasslands, river valleys, coastal salt marshes, and freshwater wetlands. Currently, constant commercial logging and land conversion over the past century has resulted in 80 to 90% loss of old forests from the original extent.

http://www.usgcrp.gov/usgcrp/nacc/education/pnw/pnw-edu-2.htm

Eastern side of the Cascades is another story. This area is very dry, unlike the wet west, with abundant sunshine and little precipitation that leads to frequent occurrence of forest fires that generates open forests, consisting of various firs and spruce. High elevations are composed of alpine meadows and lower elevations with woodlands, grasslands, sagebrush steppe, deserts and lava fields. The lowlands in this area are fertile for tree fruits and therefore, it continues to maintain the title as the “Fruit Bowl” of Washington. However, the east is also influenced by human interactions, mostly regarding agriculture, fire suppression, and grazing. The biggest impacts have been targeted on to the prairie grasslands that have been converted to crop fields, sagebrush steppe into agriculture. The remaining grassland and sagebrush steppe transformed into woodlands due to grazing.

Now that we are acquainted with the basics, we will further explore in details about the tree phenology of the Pacific Northwest on the next page; how it will shift with climate change, and the potential consequence called trophic mismatch.