Relict Species: Tecate Cypress

Relict, n: a remnant or survivor.

Species, n: a distinct sort or kind

Tecate Cypress (Cupressus forbesii)

This rare cypress occupies only four cites in Southern California, three of which – Otay Mountain, Tecate Peak, and Guatay Mountain – are in San Diego County. The fourth grove, in Coal Canyon on the north end of the Santa Ana Mountains, was nearly decimated by a 2006 wildfire. This tree, along with its even rarer cousin, the Cuyamaca Cypress, is one of the rarest trees in the region.

This bushy tree grows to a maximum of about 35 feet. It has no main trunk, and therefore takes on a bushy appearance, consistent with the chaparral that comprises its normal habitat. The tree relies exclusively on fire for reproduction, as its soccer-ball shaped cones open only with heat. This tree is also distinguished by its peeling bark, which bears a superficial resemblance to eucalyptus.

Up to fifty years ago, this population was already fairly rare. At that time, wildfires would sweep through the southern San Diego County region with less frequency than they do now. Recently, wildfires have swept through the area on an average of 15 years, as opposed to the less frequent 40 years in the past. While the tree relies on fire for reproduction, it is also slow growing due to low precipitation. If wildfires occur too often, the species cannot sustain its population, and thus its range has diminished.

This cypress is closely related with a number of other cypresses throughout the southwest, including the Arizona Cypress in Arizona and the Guadalupe Cypress in Baja California. The widespread, but isolated distributions of these trees suggest that they came from a parent tree that once covered vast stretches of inland California, Arizona, and Mexico during a time when the area was cooler and wetter. As the climate changed, the range of the trees shrank, created islands of trees that began evolving into distinct species. This process is much like what occurred between the Redwoods and the Sequoias.

While the Tecate Cypress is unlikely to disappear due to its success as an ornamental species, frequent fires could eventually destroy the wild populations. It may seem a trivial thing to lose an obscure tree that only exists in a handful of isolated spots. However, it’s usually the vulnerable species that go first, so the Tecate Cypress is something of a canary in the coalmine of climate change.

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