"Nature Guide Journal"

Autumn has arrived on the Oregon Coast, and although the days are growing shorter, they may seem warmer. Since fall marks the transition from northern winds of summer to the southern winds of winter, we often experience less wind–and warmer-feeling–days.

Autumn also marks the end of our dry season.

Those unfamiliar with the Pacific Northwest often equate "Oregon" with "rains all the time." In truth, Portland, Oregon receives less annual precipitation than does New York City. The real difference lies in timing: The east coast of the US receives precipitation fairly evenly throughout the year, while the west coast has wet winters and dry summers.

Seasonal precipitation, combined with moderate temperatures, give the Pacific Northwest much of its ecological character. Visitors often comment on our brown lawns, mossy roofs, wildfires, and dark forests–all brought about by the wet-winters/dry-summers phenomenon.

Large scale agricultural irrigation is less common in the eastern US than in the western; crispy-brown lawns are less common, too. Moss on roofs is more common here because moss can tolerate drying out and remaining dormant once during the year, when followed by wet and mild winter growing conditions. The repeated mini-droughts of the east coast are more stressful to these pioneering plants.

Dry summers set the stage for wildfire in the west. And fire plays an important role in establishing and maintaining certain plant communities. Besides cleaning out weeds, pests, and disease, fire trims back some plants–which usually reseed or resprout, while giving others more space.

The local native people regularly burned particular areas to control certain shrubs and encourage edible grass-land plants such as camas and brodiaea. Additionally, some plant species actually benefit from regular light fire, most notably the Ponderosa pines of Central Oregon.

Drought-induced fires can also "reset" the succession from one plant community to another. A hot fire in a northwest forest can open the ground to the light and turn a dark forest floor into a sunlit meadow that welcomes species that languish in the shadows–Douglas fir, for example.

Our region's signature coniferous ("conifer" = "needle-leafed") forests are evidence of our wet-winters/dry-summers phenomenon, as well. In contrast to the thirstier broad-leaved trees of the eastern forests, our conifers better tolerate months of little moisture.

(Tables showing average monthly temperatures and rainfall for Coos Bay are posted on the climate page.)