The Color of Drought Is — Green?

2014 has brought one of the worst droughts in recorded California history. So, what do you expect to find on the local Southern California hillsides in the middle of August?  Swaths of green?

As sentinels of dry death, the tumbleweeds have arrived.

Usually, in a “normal” year, the horticultural cycle starts with native (and not so native) grasses in January.  As they reach maturity, around April, the (non-native) black mustard spreads out and plasters the hills with green.  By May or June, the mustard explodes in yellow.  By summer, all that vegetation has dried out and turned brown.

Not this year.  This year, driving through the hills, there was an eery green awakening in the middle of August.  Upon closer inspection, it was tumbleweed.  Without keying it out, the plants were likely Sarsola tragus, or Russian Thistle.  There are actually several species that “tumble.”  Strangely, tumbleweed thrives most during droughts, likely because there is no competition from other plants for space, air, and what little moisture there is in the soil.  As a result,  they may be an indicator of soil that is so dry that the vegetation palette is changing by the time the next rain arrives.  They may very well be sentinels of death, for some native species that are unable to compete with invasive species that beat them to the moisture.

Long associated with the American Old West, it is believed tumbleweeds (or at least the Russian Thistle) didn’t actually show up until the latter 1800’s, when the seeds were interspersed with crop seeds in South Dakota.  How quickly they spread, as they rolled across the western landscape, dispersing their seeds along the way.  See Wikipedia for more on the tumbleweed.

With the explosion of tumbleweeds, fire fighters are weary of what may happen this Fall as they dry out and become rolling ignition points moving closer to residences, rolling right over those “fuel modification zones” in a strong Santa Ana wind.

So indeed, in 2014 the color of drought can be green.  But, green can come in different shades of threat.  So, green may not be such a good thing after all.  Only a little rain can bring back the native vegetation with a better shade of green.

Let’s all pray for rain to “Stop the Tumbleweed!”

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