The Cloud Forest

The cloud forest on Santa Rosa Island.

Santa Rosa Island

We passed five Orcas (Orcinus orca) on the passage to Santa Rosa Island

After a two hour boat ride from Ventura Harbor that included sightings of gray and killer whales, passengers disembarked onto a newly-built pier and subjacent white sand beaches. We had arrived. Once unloaded, the park ranger offered an orientation rejoicing in our good fortunes. The high winds and thick fog which had typified the previous few weeks had now subsided. The forecast for the coming days included sun, low winds, and perfect temperatures.

Fog and wind are omnipresent on Santa Rosa Island and play a major role in shaping the landscape. Any plants with a propensity for upward growth are restricted to canyons, particularly north sloping ones. Here they find refuge from the wind and often more available moisture provided by the meager 15-20 inches of annual rain. However near the highest island peaks–like Black Mountain at 1,300 feet plants have adapted to wind and fog in different ways.

Approaching the summit of Black Mountain. Notice the dense stands of oak in the foreground on the north slopes with Santa Cruz Island on the right and the mainland in the distance.

Cloud forests, also referred to as fog forests, are generally tropical or subtropical in location and characterized by persistent cloud cover. On Santa Rosa it is estimated that the fog drip collected by the leaves of plants, particularly the island oak, account for up to three times the moisture received from rain storms. So if the average precipitation in the surrounding grassland is 15 inches a year, the cloud forests collect 60 inches–the quintessential microclimate!

Notice the wet soil beneath the Q. tomentella seedling. This is moisture collected from fog by the leaves.


Island oak (Quercus tomentella)

The island oak was not always restricted to the Channel Islands as it is today. Based on fossil records, it is known to have once ranged across Southern California. This relative of the canyon live oak (Q. chrysolepis) now defines the cloud forests of the Channel Islands where it inhabits steep mountain ridges (both north and south slopes) and also creeps toward sea level in north-facing canyons.

The Quercus tomentella cloud forest on Black Mountain.

Under the Quercus tomentella canopy.

Quercus tomentella in the cloud forest

The green rush has begun on the islands as ancient island oaks are highlighted by moss beds springing to life.

A rich assemblage of lichens and bryophytes take advantage of the fog too, growing here on an ancient island oak.

Rehabilitating the cloud forest

In the early days of California’s history, Santa Rosa was home to the Air Force which included a civilized base on the south shores and a high point with communications towers–built in the heart of a cloud forest. Use and landscape modifications degraded the soil layer and, today, only a few island oaks remain. Kathryn McEachern And Ken Niessen started a project in 2015 to change that.

Ken Niessen next to the wattles and fog nets put in place to rebuild the cloud forest habitat.

Grant funding has allowed them the take a multi-step approach to rehabilitate both the soil and ultimately the forest. Ken and Kathryn admit this is a long-term project but the goal is to build soil and erosion control with perennial grasses and shrubs. They are using wattles for erosion control and fog nets just above for water collection. In between these two they are planting Stipa diegoensis, Baccharis pilularis, and Quercus pacifica to start the vegetation on the mineral soil. When Quercus tomentella produces an acorn crop (they are hoping this is the year) they will add these acorns into the mix.

Wattles, fog hats, erosion fences, and fog fences will slowly rebuild soils lost when this area saw heavy use by the Air Force.

The site of former Air Force operations is now a cloud forest rehabilitation project in action–seen from below, after the fog cleared!

Erosion fencing, in place for only one year, is already capturing detritus and keeping if from washing down the slope.

  • Read more about the work HERE

Bishop pine (Pinus muricata)

John Knapp with the Nature Conservancy warned me before the trip that the bishop pines of the Channel Islands were not doing well. I witnessed as much on the north slopes of the cloud forests. Mortality seemed to be around 50 percent, but recruitment was common and many saplings and seedlings were springing up at the edge of the desiccated groves. Mortality in mature trees is presumed to be from a combination of bark beetle infestations and xerification due to climate change. We can only hope that the seedlings continue to thrive.

Bishop pine grove on Santa Rosa Island.

Seedling recruitment was common in the groves I visited.


Other cloud forest chaparral species

Chaparral of the cloud forest in on calcareous outcrops.

Summer holly (Comarostaphylis diversifolia) mixed with island scrub oak (Q. pacifica) and island Monkey Flower (Mimulus flemingii).

Vaccinium ovatum.

Ceanothus arboreus.

California polypody (Polypodium californicum)

Santa Rosa Island manzanita (Arctostaphylos confertiflora) was common at all elevations.

Castilleja hololeuca

San Miguel as seen from Black Mountain.

6 thoughts on “The Cloud Forest

  1. Pingback: Santa Rosa Island - Plant Explorations

  2. Michael, Thanks for a very interesting report about plant adaptations on Santa Rosa. I enjoy reading your informative descriptions of ecological relationships encountered during your excursions around California.

  3. At the risk of repeating what I’m sure you’ve heard many times before, you are certainly a gifted educator and storyteller. You make complex ecology seemed almost simple and certainly interesting. And I loved the fog fences. All the photos are great.

Leave a Reply

Your email address will not be published. Required fields are marked *