On 5 December on my way to our El Dorado County farm, I took an alternate route to the southwestern corner of El Dorado County where the low elevation oak savannah ecosystem transitions to the open grasslands of the southern Sacramento Valley. To reach this area, I had to drive through an area of dense urbanization, where 40 years ago a thriving grassland ecosystem once existed. As I drove southward the urbanization abruptly ended and the road narrowed on its continuing southward path through an open oak savannah.
I eventually arrived at a low hill, elevation 810 feet (247 meters), where the Deer Creek Hills could be seen off in the distance to the west. The Deer Creek Hills are one of the few semi-intact remnants of the open grassland and oak savannah ecosystems in Sacramento County. Here the low elevation perennial, Delphinium variegatum ssp. variegatum and brilliantly colored Calochortus luteus can still be found in some measure of abundance. Here many Brodiaea Family species, Themidaceae, can be found blooming from early spring to early summer.
Off in the distance to the southwest, the western border of Amador County extends into the Central Valley. Many rare and endemic plant species can be found growing on the ultramafic soils of this area. The Ione Manzanita, Acrtostaphylos myrifolia, is one example. A number of distinct ecotypes can also be found growing on these ultramafic soils. For example, a number of years ago I found a distinct population of Arctostaphylos viscida ssp. viscida growing in this area. This population has very distinct intensely glaucous-gray leaves and a much more compact habit of growth than the type species.
With the autumn rains many annual species have germinated and are starting to turn the landscape green. Remnants of last year’s growth are still intact; however making a positive identification of many of the species is difficult to impossible at this late stage. The dry remains of Medusa’s Head, Elymus caput-medusae (pictured), were one of the few easy to identify species at this time. Klammath Weed, Hypericum perforatum ssp. perforatum and Turkey-mullein, Croton setiger, were also easily identified. The dried remains of Avena species were still noticeable; yet making a clear determination between Wild Oats, A. fatua, or Sender Oat, Avena barbata, was not possible.
From the rise overlooking the Deer Creek Hills I drove northeastward through a number of plant habitats to arrive at our farm. Oak savannah was quite common. During this past summer and autumn of prolonged extreme heat, soil moisture levels became extremely low and have been slow to recover. After abundant precipitation in late November, the soil moisture content has recovered, however it is still only 80% of average to date. At lower soil levels, the soil is still extremely dry. The extreme temperatures and low soil moisture levels created conditions of great stress to the vegetation, especially on open southern exposures. In these locations many of the trees, Blue Oak, Quercus douglasii, in particular are showing signs of stress, however other plant species have been impacted as well.
Pictured, the distant hills are covered with chaparral vegetation. Our low elevation chaparral ecosystems are quite distinct. White-leaf Manzanita, Arctostaphylos viscida ssp. viscida and Chamise, Adenostoma fasciculatum var. fasciculatum, are two of the most common species associated with these low elevation chaparral ecosystems, however a large and very diverse set of plant species are associated with these ecosystems.
I was hoping to visit our local serpentine barrens on this occasion, however I had a malfunctioning data recorder at the farm that took considerable time to bring back to working order. Visiting the serpentine barrens will have to wait for another occasion.
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