Biodiversity may be used to mean variety at the genetic, species or ecosystem level.

Species living a particular area, including their genetic variants and the unique ecosystems or plant communities that develop, are of inherent value. These assemblages of species represent the products of millions of years of adaptation and evolution within a dynamic landscape. They are quite literally irreplaceable. Each locally adapted species represents a unique genetic variant, that if lost, will not be seen again.

Some areas are significant for the richness of their flora, and in our area include high elevation grasslands (balds) and the Columbia River corridor. The Columbia Coast does not live in isolation. Other areas of high diversity within 100 miles of the coast are the Olympic Mountains and Columbia Gorge.

Vectors for Introduced Species
Humans, with an amazing capacity to tot other species from place to place, have done much to reduce biodiversity and homogenize ecosystems around the world.

Just as the Columbia River acts as a corridor to promote diversity in the regional flora, it also acts as a vector, bringing new species to the region through modern shipping. Plant hunting along freshwater tideflats can be particularly rewarding, for new species that are sighted, and frustrating, trying to figure out where in the world they have come from and correctly identify them.

Water carries more than fish, barges and ships. It carries seeds downstream from urban and agricultural areas upriver, including common reed, reed canary grass, purple nutsedge, purple loosestrife. Ballast water may also carry foreign animals such as zebra mussel, European green crab, Chinese mitten crab, to name a few potentially devastating species now in or approaching our area that have been carried around the world in water ballast.

Agriculture, particularly of ruminants, brings dozens of new forage species into natural landscapes. Forage seed mixes often contain "weedy" species that were as undesirable in their old habitats as they are in the new. Seeds also accompany hay, cereal feeds and animals as they are transported from one area to another.

Urbanization as it is generally practiced, virtually eliminates native vegetation and replaces it with a palette of species from around the world. These include a collection of species used to grow lawns, vegetables, and a wide variety of ornamentals, all with their attendant weeds. Alterations to soil hydrology, fertility, aeration, and the use of impervious surfaces collectively result in the permanent loss of all but the toughest natives.

Habitat Breakdown
Hydrological changes are intended to dry out landscapes, lowering water tables, reducing water storage capacity and creating upland-like conditions for farming, grazing and urban development. Collectively these changes result in long term loss of wetland habitat and capacity, which often goes unnoticed until floods, wetter winters and resulting displacement of humans or property damage comes to community notice. Practices include ditching, diking, filling, groundwater pumping, and alternatively, the creation of lakes by impounding water behind dams.

Road building is the single most destructive step taken in otherwise pristine habitats. Roads may alter hydrology by damming off small streams, replacing open streambeds with culverts, or running along flood plains, act as a permanent source of new sediments during winter rain events. By opening the soil, bringing in rock and gravel from other sites, and allowing regular vehicular traffic, roads allow the transport of seeds and vegetative progules from other areas. The result is that a group of common, mostly European species of grasses and herbs can now be found on most roadsides throughout the region. Sadly, they often spread into nearby forests, meadows, marshes and riparian areas.

Industrial foresty magnifies road disturbance and the possibility of weed seed transmission by regularly clearing off the land, opening up soils, disturbing duff layers, burning, and replanting.

Changes in disturbance regimes include fire and flood suppression.

Disturbed Habitats
These habitats are common throughout the region. Road building, industrial timberland management, agriculture, shipping, and urbanization bring a familiar collection of predominately European species. Upland species include dandelion, hairy cats'ear, velvetgrass, orchard-grass, Queen Anne's lace, tansy ragwort, English plantain, ribwort, quack-grass, and many others. Wetland species include purple loosestrife, canary reedgrass, creeping buttercup, smooth cordgrass, giant knotweed, and common reed. Woody species include Scots broom, several blackberries, gorse, ivy and holly.