California Coastal Pine Forest

Small occurrences of this system may be found in scattered locations along California's entire coastline and onto the Channel Islands. They are found on marine sedimentary, non-metamorphosed features, often with podsols on sterile sandstone. These forests and woodlands are limited to coastal areas with moderate maritime climate and likely receive more annual precipitation than nearby coastal chaparral. Highly localized endemic tree species include Hesperocyparis macrocarpa, Hesperocyparis goveniana, and Hesperocyparis abramsiana in scattered groves along coastal Mendocino, San Mateo, Santa Cruz, and Monterey counties. Pinus contorta var. contorta, Pinus contorta var. bolanderi, Pinus muricata, Pinus torreyana, and Pinus radiata are dominant or codominant in these and other occurrences. These occurrences can also include pygmy woodland expressions where nearly lateritic subsoil underlies acidic sands (ancient marine terraces). Stunted and twisted Pinus contorta var. contorta stands along the Oregon coast (often called pygmy forests) are also part of this system. Other associated plant species include Arctostaphylos nummularia, Ledum groenlandicum, Vaccinium ovatum, Gaultheria shallon, Rhododendron macrophyllum, and Morella californica. The lichen and moss component of this system is very diverse, includes Cladonia spp., and can be abundant in these communities.

Highly localized endemic tree species include Hesperocyparis macrocarpa (= Cupressus macrocarpa), Hesperocyparis goveniana (= Cupressus goveniana), and Hesperocyparis abramsiana (= Cupressus abramsiana) in scattered groves along coastal Mendocino, San Mateo, Santa Cruz, and Monterey counties. Pinus contorta var. contorta, Pinus contorta var. bolanderi, Pinus muricata, Pinus torreyana, and Pinus radiata are dominant or codominant in these and other occurrences. These occurrences can also include pygmy woodland expressions where nearly lateritic subsoil underlies acidic sands (ancient marine terraces). Stunted and twisted Pinus contorta var. contorta stands along the Oregon coast (often called pygmy forests) are also part of this system. Other associated plant species include Arctostaphylos nummularia, Ledum groenlandicum, Vaccinium ovatum, Gaultheria shallon, Rhododendron macrophyllum, and Morella californica (= Myrica californica). The lichen and moss component of this system is very diverse, includes Cladonia spp., and can be abundant in these communities.

These woodlands occur in fire-prone, seasonally dry and nutritionally poor locations, in areas with a Mediterranean climate (Barbour 2007). Found in scattered locations along California's entire coastline and onto the Channel Islands, as well as along the southern Oregon coast and on two small Islands off the coast of Baja California, Mexico. These forests and woodlands are limited to coastal areas with moderate maritime climate and likely receive more annual precipitation than nearby coastal chaparral; fog drip can be an important source of moisture in some stands. They are found on marine sedimentary, non-metamorphosed features, often with Podsols on sterile sandstone. These occurrences can also include pygmy woodland expressions where nearly lateritic subsoil underlies acidic sands (ancient marine terraces). The soils are excessively well-drained in most cases, but stands of Pinus contorta var. bolanderi occur on poorly drained Spodosols.

These woodlands typically are found in sharply demarcated localized groves with a single-aged and monospecific overstory (Barbour 2007). The dominant trees are mostly serotinous in fire response (Davis and Borchert 2006), requiring heat to open the closed cones. Degree of serotiny varies widely across these species, along a continuum of conditions, but all are serotinous to some degree (Keeley and Zedler 1998, Barbour 2007). Pinus torreyana is reported to shed seeds from third-year cones and continuously from those cones for several years (Lanner 1999). The seeds are wingless and large, suggesting they are animal dispersed and cached in the ground which protects them from fires. Most of the closed-cone conifers are killed in crown fires because they grow in or near highly flammable chaparral (Barbour 2007). Moreover, they self-prune poorly, typically retaining lower limbs to within a meter of the ground surface (Barbour 2007) so fire easily carries into the canopy. Because they often grow in dense thickets of small-stemmed individuals, they may burn intensely even in the absence of chaparral. Basically, the fire regime of many closed-cone conifers is the same as that of the surrounding shrublands and particularly characterizes Hesperocyparis sargentii, Hesperocyparis forbesii, Hesperocyparis stephensonii, Pinus coulteri, and Pinus attenuata (Landfire 2007a). The typical fire regime for most adjacent communities is known to have a return interval of less than 50 years (Barbour 2007).

Postfire regeneration of these species is closely linked to the frequency of fire relative to cone bank accumulation. For example, Hesperocyparis sargentii needs at least 20 years between fires to accumulate a cone bank sufficient to regenerate the stand. Pinus coulteri likely needs at least 25 years and preferably 30 years to develop an adequate cone bank. Fires that kill a stand before an adequate cone bank is in place will disappear (immaturity risk) as has been observed in Hesperocyparis forbesii and Hesperocyparis sargentii. Fire opens closed cones but not all stands necessarily burn in crown fires. Some may burn in ground and surface fires (Landfire 2007a). Severe drought can cause mortality of the trees without triggering seed dispersal; some Hesperocyparis species are susceptible to cypress canker, a fungus (Coryneum cardinale) (Barbour 2007).

Conversion of this type has commonly come from logging which has removed the trees entirely, development including urban and suburban expansion, road-building and mining, and stand-replacing fires with no seedling recruitment. Most of the dominant tree species in these woodlands are found in only a few localities each, making the occurrences particularly vulnerable to loss due to a variety of impacts (development, changes in fire regime, lack of cone bank before burning, drought, etc.). The two occurrences in Mexico are very small and one of them is being impacted by domestic goats which have removed all regeneration seedlings/saplings for decades. Fire suppression activities in adjacent fire-prone vegetation communities will continue to be a threat for the conifer stands. These already small and generally isolated stands are continuing to be fragmented and reduced in area by suburban development, mining (for clay, diatomaceous earth, and sand), and road-building (Barbour 2007), as well as development of oil fields and associated service roads. Fragmentation is significant in privately-owned areas with "ranchette" development and a dense road network. Firebreaks, disease and smog/air pollution are other threats that have recently increased due to proximity to large urban and suburban areas of California.

In the west central coast regions, regional climate models project mean annual temperature increases of 1.6-1.9°C by 2070. The projected impacts will be warmer winter temperatures, earlier warming in spring and increased summer temperatures. Regional models project a decrease in mean annual rainfall of 61-188 mm by 2070. While there is greater uncertainty about the precipitation projections than for temperature, some projections call for a slightly drier future climate relative to current conditions (PRBO Conservation Science 2011).

In many coastal regions, the interaction between oceanographic and terrestrial air masses may be ecologically important. Intensifying upwelling along the California coast under climate change may intensify fog development and onshore flows in summer months, leading to decreased temperatures and increased moisture flux over land (Snyder et al. 2003, Lebassi et al. 2009, as cited in PRBO Conservation Science 2011). Coastal terrestrial ecosystems could benefit from these changes. However, current trends in fog frequency along the Pacific coast from 1901-2008 have been negative (Johnstone and Dawson 2010, as cited in PRBO Conservation Science 2011), thus the effect of climate change on coastal fog remains uncertain (PRBO Conservation Science 2011).

This system is found in scattered locations along California's entire coastline and onto the Channel Islands and possibly just into southern Oregon in southern Coos and Curry counties.