Life On the Edge:

As is characteristic of any edge community changes can occur quite suddenly. No where is this change more obvious than in the overflow zone, the previous river beds on either side of the current stream position. Curious virtual deserts appear in these area of harsh conditions. Out of the reach of the rivers high flood mark grasses and flowering plans are abundant. This lush grassland is right at the tree-line of the surrounding Mixed Evergreen Forest where there is plenty of fresh humus. But suddenly, at the edge of the flood mark the ground falls away to a rocky riverbed in which very little can grow. The change is quite abrupt with only a few cautious clover's reaching out over the parched stones.

The transect I did demonstrates this principle beautifully. I recorded the soil type and abundance and type of plant life along my transect line extending south from the creeks edge and over my rock for fifty feet to the edge of the forest. I began at the forest and worked my way back towards the creek beginning at the 50' mark. Every three feet I stopped and documented everything within six inches of the line in either direction. The results can be summarized as follows: 50'-44' (wildflowers and grasses, sparse spring grass, thick pine/oak humus) 41' (thick bull clover, spare grasses, thick pine/oak humus), 38' (sparse bull clover, soil sandy with boulders), 35'-14' (occasional tiny plant, soil mostly boulders), 11' (moss on larger rocks, soil larger boulders) 7' (moss thicker joined by large bunch grasses, larger boulders) 4' (moss thick one my rock), 1' (rich clay with tree roots), -2' (lush mosses and bunch grasses in the water).

These dry wastelands are the result of a very interesting ecological process. They are the previous riverbed of Beachtel Creek and as such consist primarily of small stones. Nothing can grow here because the old river bed is neither-here-nor-there so to speak. Closer to the creek as the river bed gets higher and we approach the river itself life springs up again, flourishing between rocks and shrouding the river with trees and even ground plants. The reliability of water has brought sediments on which these trees and plants can grow and in turn create more humus. But the old river bed does not have a reliable water flow to attract Riparian plants that are designed for such a rocky environment. Why then has the river bed not returned to a grassland? Because though the water is not reliable it is present at flood stages and this periodic, rather than consistent flow of water strips the area of any building sediments and humus that might provide habitat for plants. These overflow zones are thus parched deserts supporting growth only where the rocks are large enough to accumulate debris from a seasonal flood and build up a small amount of soil. While the rest of the community cycles through its seasonal changes this are remains barren and desolate.