Closed-cone pine forest

A forest of Monterey pines

Closed-cone pine forest is a plant community of coastal California and several offshore islands. The plant community is often mono-dominant and single-aged, but dense with ladders. Closed Cone forests grow in low nutrient and/or stressed soils, which can lead to slow growth. It consists of stands of bishop pines, Monterey pines, and others which rely on fire and shoot death to open their cones and release the seeds.

Closed-cone pines

The most widespread naturally of the closed-cone pines is bishop pine (Pinus muricata), which can be found along the coast from Humboldt County, California in the north to the northwestern corner of Baja California in the south. Knobcone pine (Pinus attenuata) forests can occur further inland, on dry, rocky soils. Monterey pine (Pinus radiata) was once limited to the Monterey Peninsula, two other sites in central California, and Guadalupe and Cedros Islands off the coast of Baja California, but has now been introduced elsewhere in California and around the world. Most of these trees have an average life-span of around 50–90 years ^[1]

Climate

The weather of these forests is quite mild in both winter and summer. Temperatures rarely go below freezing or grow uncomfortably warm. Closed-cone pine forests of California are located in cool-summer Mediterranean climate regions along the coast with cool wet winters and foggy, dry summers. Despite the fact that the summers are dry, the air is consistently humid due to frequent coastal fog brought in by interior heat. The fog also supplies irrigation when it passes through the conifer needles of the pines. The moisture is caught this way and drips to the forest floor. Thus, drought is avoided by up to 40%.^[2] In the autumn, fog is less frequent and it is during this season when occasional heat waves are possible. This is when fires are most likely. Precipitation ranges from 20 to 60 inches a year, depending on the locale.

Environmental Triggers

The conifers are serotinous, meaning they release seeds in response to an environmental trigger. Seed release in the forest relies on fire and shoot death. Shoot death is when death of a stem signals cones to release seeds. One example of serotiny due to shoot death is cupressaceae. Although shoot death can be caused by fire, there are other sources of stem death. Closed-cone forests rely on predictable, infrequent fires. The fires are stand-replacing crown fires. One example of serotiny due to fire is Pinacae releasing seed after the cone has undergone 200°C for five minutes. Sargent cypress, Gowan cypress, McNabb cypress, Monterrey Pine, and Torrey Pine are all California endemic serotinous conifer species. Serotiny offers benefits to plant species because after a fire, there is less competition for the seeds on the ground. Thus, the fire signals an advantageous time for trees to drop their seeds.

Other flora and fauna

Black-tailed deer

While the pines are, by far, the most common tree in these forests, coast live oaks often accompany them. Due to the relatively short lifespan of closed-cone pines, many dead trunks and snags are available and attract a whole host of wildlife ranging from woodpeckers, titmice, chickadees, warblers, squirrels, chipmunks, raccoons, mountain lions, deer and many others. The lush undergrowths, typical of the forests, are excellent habitat as well. Blackberries, wild roses, wood mints, California honeysuckle, currants, and others are common. The flora and fauna varies from area to areas, especially the southern and northern closed-cone pine regions. Soils have low nutrients and are stressed due to a lack of nitrogen. This promotes slow growth.

See also

• Fire ecology
• Conifer forest
• California montane chaparral and woodlands- (subecoregion')
• California interior chaparral and woodlands- (subecoregion)

References

California’s Changing Landscapes, by Barbour et al. Ch.3 (1997, California Native Plant Society)

External links

• Las Pilitas Native Plant Nursery: Info on Closed-cone Pine Forests