California’s Flora: A Natural Solution for a Changing Climate By: Scot Pipkin, Director of Education and Engagement
O
n the southern flank of the Tehachapi Mountains, there is a ridge that overlooks the Antelope Valley. Like its neighbors, this ridge runs east to west, before turning and rising to the southernmost reaches of the Sierra Nevada. Unlike its neighbors, this particular ridge is home to a small plant community that might not exist anywhere else in the world. Here, one can find three iconic California species all growing within a few yards of each other: valley oak (Quercus lobata), blue oak (Quercus douglasii), and Joshua tree (Yucca brevifolia). While the two oaks can often be found growing alongside one another in the foothills that create a ring around California’s great central valley, mixing in the Joshua tree, one of the great ambassadors of the Mojave Desert, is pretty unique (figure 1). If one were to ascend this ridge, all the way to its crest, they would find themselves standing at the interface of a block of limestone — ancient marine sediments thrust upward to a height of 6,000 feet (1,828 meters) above today’s sea level — and the granitic rocks more typical of the Sierra Nevada. On
these out-of-place substrates, another curious plant community emerges. Here, plants specialized to live in much more specific conditions can be found, including pine green gentian (Frasera neglecta; figure 2), a plant endemic to Southern California’s Transverse Ranges and a small corner of the Sierra Nevada. These limestone roof pendants are also home to the Tehachapi buckwheat (Eriogonum callistum), a recently discovered species that is only known to occur in these limestone soils and nowhere else on Earth. In some ways, this ridge is just a tiny blip in the story of California’s flora. It’s a relatively small area that yields to more typical vegetation on all sides — rubber rabbit brush (Ericameria nauseosa) and saltbush (Atriplex spp.) in the lower elevations and white fir (Abies concolor), canyon live oak (Quercus chrysolepis), and great basin sagebrush (Artemisia tridentata) up higher. However, this spot, at the cusp of such geographic drama — the great Mojave Desert, the Sierra Nevada, the Central Valley, and even some influence from the Pacific Coast — is emblematic of
Figure 1: At the westernmost edge of their range, Joshua trees (Yucca brevifolia) grow alongside nondesert plants such as valley oaks (Quercus lobata) and blue oaks (Quercus douglasii). (Photo: Scot Pipkin)
6 Ironwood
