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by Charles A Raguse
on July 16, 2015 at 11:19 AM
Author Kat Kerlin's post is interesting, enlightening, and certainly timely.  
 
In the days when I was actively teaching a lecture/lab course in rangeland ecology in the (then)Agronomy Department at UC Davis I would routinely make field collections of native-annual clovers (Trifolium spp.), trefoils (Lotus spp.), and "burr clover" (Medicago sp.) from the wildlands of the 5,700-acre UC Sierra Field Station. In total, these collections would amount to about a dozen native-annual species.  
 
I would take a large aluminum ice chest (with ice!), along with paper towels and small plastic bags. A collected plant sample would be wrapped in wet paper towels and placed in a plastic bag. When returned to Hunt Hall and kept in a cold room, then later used in a lab session, they were as fresh as if collected only minutes ago. Along with the plants I had developed an identification key, which students used to sharpen their knowledge of plant morphology as well as visual characteristics of individual species.  
 
Over time (the late 1960s to the early 1980s)individual species dropped, one by one, from my collection list. In disturbed (aka "developed") areas of the Station, exotic invader annuals, e.g., "Medusahead", entered the mix, but the native species mentioned above had instead been collected along undisturbed roadsides along the long route from Hwy 20 to the Station, and from upper areas of the Station (the Koch & Lewis Fields)that had not experienced contemporary disturbances.  
 
The current-attention fixation on climate-change influences on surviving-species diversity notwithstanding, shifts in botanical composition diversity of Sierran foothill annual rangeland have been occurring for decades.  
 
To what extent these changes have resulted simply from climate change remains speculative, and the researchers should describe how they establish that a given plant species is "drought tolerant".  
 
Over several decades of grazed annual-rangeland pasture management research, cooperative with the UC Davis Department of Animal Science, I have become convinced that such changes are uni-directional. Should El Nino bring an end to drought, and the "atmospheric rivers" of the "Pineapple Express return for good, the vanished species will not return.
 
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