P.O. Box 7908
Berkeley, CA 94707
Phone: (510) 527-7500
Fax: (510) 527-2790
info@cazadero.org
Map
Home
Programs
Family Camp
Music Camp


Pictures
FAQ
Employment
Support Caz
Directions
Links
Contact Us

  Nature Elective


The Riparian Biozone
First posted February 1, 2004 Last updated November 15, 2011

Cazadero Performing Arts Camp lies along Austin Creek. If you walk along the creek, you will quicky see how different this area is from the areas around the dining hall, tents, and the Lutt Family Ampitheater. The ground is level and stony and bare, not at all like the redwood area, which is steep in many areas and covered with leaf litter. The creek area is often hot in the bright sunshine of the summer, while the redwoods are much cooler. The creek area always has water present, and water is the main determining force for all the plants and animals that you find along the creek. Water, along with the climate and soil conditions, defines a plant and animal community called the Riparian Biozone. Although it is just a few feet away from the redwoods, the riparian zone of Caz is very different from it. However, it is fairly similar to that of any other riparian biozone of any other biome in California, from northern border to southern border, and from mountain to shore.

Water

Water is what defines the riparian zone ("riparian" means "river".) The river in winter covers almost all of the riparian zone. Here is Austin Creek in the winter of 2004, just after the torrential rains of January. This is a view of the river, looking downstream from near the baseball backstop, with the campfire area just under the water's edge. The baseball diamond would be just off to the right. During the winter floods, the river scours the riverbottom with gravel and rocks, distributing them along the bed in new formations each year. The willows and berry bushes that we see in the creekbottom during the summer are entirely underwater and being battered to pieces by rocks carried by the force of the water. The force of the water is so great it can wash out even steel bridges!

This is the time of year that the salmon move upstream to spawn, and the other underwater river creatures simply try to hide from the "underwater tornado" of the floodwaters.

The water in summer is another defining force in the riparian zone. As you can see from the photograph at the top of the page, in summer the river flow is very slow, and in some places the river is entirely underground. The stones, washed clean of any lichens, mosses, or plants, lie strewn about the riverbed, silent testimony to the power of the winter's ravages. The trout and many aquatic insects are very stressed, as the water temperature rises, causing a fall in the dissolved oxygen in the stream. This is called a "climatic pessima", a time of the year that is the hardest on these aquatic lifeforms, killing many in very dry years.

If you are interested in the current or past river level, click here for the California Department of Water Resources online river level of the Russian River at Guerneville.

All of the plants growing in the riparian zone need to be adapted to both the water's excesses in winter and the scarcity in summer. The redwoods cannot tolerate having their roots stripped of soil or submerged under water, so none grow in the annual floodzone. The willows have deep roots that penetrate well between the rocks and prevent them from being pulled from the ground, and they need the water that flows during the summer deep under the riverbed. The willows, therefore, are only found in the riverbed. (Note: while willows are naturally found in many streambeds, these were planted by William Mason Holmes (trumpet, SF Opera and a PhD in forest ecology) at the request of Bob Lutt, the founder of the camp, in about 2000 to help stabilize the riverbed near the kitchen and the baseball diamond. He also installed the boulders found just upstream of the kitchen, at the baseball field, and just downstream of the field. If you examine them closely, you will see that they are cabled together so that they do not wash away at high water.)

Mountain Alder at river's edge,
below Family Camp

Examine the branches of the willows and you will see the effects of the force of the river, and whatever logs or rocks are swept along with it. Look closely and you will see twigs of trees from far upstream, lichens that floated down, and plastic trash swept from human carelessness into the trees. The berry bushes, wild grape, and wild pea usually invade from the sideline of the river, but cannot survive in the path of the river's fury.

Along the sides of the riverbed, you will see plants that need a lot of water but cannot grow in the riverbed itself. Mountain alder is the principle tree you see, with some big leaf maples sprinkled in.

Notice the redwoods are all a bit further back from the riverbed. The tallest of our redwoods, however, grow on the level ground that is the highwater mark of the centuries, or the streambed of the river from ages ago. Redwoods need a lot of water and they have very shallow roots. In addition, redwoods up the side of the canyon are subjected to higher wind forces in the winter. These natural forces trim out some of the redwoods. This is why the tallest (oldest) redwoods are away from the river, but not too far away.

The animals of the riparian zone are also adapted to the water, some to its winter maelstrom (the salmon), and some to its summer sleepiness. Ducks and merganzers swim along, looking for fish. Newts swim in the slower areas of the river, looking for aquatic insects. Toads abound along the dry gravel at river's edge, as most of the little boys of camp know. They were just hatched from tadpoles and are scrounging for spiders and very small insects. If they survive the herons and ducks, they will hide in the foliage and make their way to higher ground. Aquatic insects specialized in hiding under stones are found everywhere, but principally in areas with current. The rapid flow provides a higher oxygen content, essential when the heat decreases the amount of dissolved oxygen. If you turn over stones in the area where the river seems dry but between pools, you will discover insects and frogs. They live below the bottom of the stream, in the area called the hyporheic zone, an entire world of organisms we usually completely overlook. Turn over a few stones if you want to enter into an entirely new world at Caz!

Other Biozones:

Redwood Forest

Oak Woodland Biozone

Chaparral Biozone

Grasslands Biozone