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Treebeard's Stumper Answer
10 April 98

Pastures of Plenty

We've had near-record rainfall here in Central California this year, thanks to El Niño. The storms have been nicely spaced to keep the ground wet. This should be perfect for wildflowers, but I've noticed two puzzles as I drive to and from school along Highway 154. There's abundant grass, but this is not a great wildflower year, despite nice displays of Lupine and Tidy Tips. There are already patches of summer brown showing in the soggy grassland. Why are the plants already starting to turn brown and die even though the ground is still wet?

The soggy fields are starting to turn brown because the annual grasses are beginning to ripen their seeds and die. This is the brown of ripeness, not decay. Annual plants live just one season, unlike perennials that can live for many years. This is an example of programmed death that has nothing to do with environment. It is their time. This is an effective life strategy, since these mostly introduced annual grasses have almost completely replaced the native perennial grassland that originally occupied the Santa Ynez Valley.

Note: There's some concern that the annual grasses may actually re-seed this year and produce a second crop because the ground is still so wet. This could make a bad fire season even worse.

It's a mystery to me how introduced annual grasses like foxtail, cheat grass, and wild oats were able to so completely replace the native perennial grassland in California.

The benefit of programmed death may be that the very act of dying gives an extra resource to the annual. The dying plant is able to absorb every last bit of nutrient from its stems and leaves and devote them to the formation of seed. Life is harder for the perennial that must conserve resources to stay alive for next year. I've read that the annuals really got established during an extended drought during the mid-1800s. The perennials were struggling to survive and set no seed, but the European annuals were able to set a quick seed crop and extend their range. After a decade of this, only the annuals were left. Environmental change can be swift, and hard to undo!

It's interesting to think that the "golden rolling hills of California" may have originally been the dull green of perennial bunchgrass!

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Copyright © 1998 by Marc Kummel / mkummel@rain.org