For me it is a time of rejuvenation and also my favorite season. With the shift of the California Current, rains begin to fall in California after a summer of drought. The high country along the Pacific Slope finds snow returning. While we retreat inside our homes, native plants and animals must adjust to the changes. Some birds migrate, mammals might hibernate, and some plants shed their leaves and “hibernate” for winter in their own way.
What follows is a journey across the Pacific Slope to four favorite fall hikes–excellent for colorful foliage. I’ve also included some of the plant species that will be found.
San Gabriel River National Monument
Blackrock-High Rock Desert National Conservation Area
Conifers possess highly derived adaptations that allow them to flourish on continental land masses north and south of the 45th parallel—to the arctic tree line. They also grow in similar regions with decreasing latitude, like the various cordilleras of western North America. Though they comprise less than 1% of all plant species (~630), they define 30% of the forests on Earth. In order to survive in colder climates conifers must be able to handle temperature and moisture extremes. As a cat preens its fur, most conifers care for their needles. These waxy progeny are coddled when energy is diverted from other tree functions to maintain needles—often for many years. This heavy investment must allow needles to endure both high and low temperatures while at the same time regulating water loss during the warmer months. Also, because most conifers are evergreen, they are not inhibited by late spring or even summer frosts which might otherwise kill the leaves of a less cold-adapted species. Angiosperms–many of which are deciduous–generally inhabit lower elevations and warmer regions where they spend less time and energy in leaf production and maintenance and can therefore allocate resources to grow faster and pioneer oft-disturbed landscapes more rapidly. It it these two generalized survival regimes that had me confused on a recent backpack into the Pasayten Wilderness where there is a conifer that has blazed a unique path for survival on the edge of the Washington State alpine tundra.
As Allison and I began to map our route through the Cascades for our summer vacation I proposed that we visit Mount Saint Helens. Allison quickly agreed but jokingly asked what conifers were there that I wanted to see–I relented that I wanted to familiarize myself with noble fir (Abies procera) outside of California and this was a place recommended by Chris Earle on his epic website. What we found in the Goat Marsh Research Natural Area was a juxtaposed landscape shaped by geological forces. We ambled through some of the most depauperate and some of the most productive forests we had ever seen. The resulting plants fostered in certain locations were there based solely on the substrate. The forests on the flows of ash, mud, and rock placed here by Mount Saint Helens allowed only the heartiest plants to survive. Other forests, hidden around the edge of protective mountains and out of reach from the mud and rock flows, grew on soils which had remained undisturbed and were thus less porous with higher nutrient contents–ultimately yielding some of the grandest forests on Earth.