PLANT COMMUNITIES

by Rosemary Foster
California Native Plant Society & Point Lobos Docent

All photographs by Ranger Chuck Bancroft unless otherwise noted

monterey pine  |   monterey pine forest  |  monterey cypress  |  monterey cypress forest
northern coastal prarie  |  northern coastal scrub  |  coastal bluff |  intertidal

What Is a Plant Community?

Even a brief examination of the overall landscape of Point Lobos will show that the plant species occur in aggregations which are called plant communities. Standing at one bend on the Cypress Grove trail, one can look to the left and see the cypress forest; straight ahead, a small meadow area; and to the right, an area of dense shrub growth growing right up to the edge of the pine forest. Each of these groups of plants is a relatively distinct grouping of plant species. Each community exists where it does as a result of complex interactions among a number of factors: climate, soils, topography, biota, fire, man, and time.

A plant community can be defined as an assemblage of plant species which interact among themselves and with their environment within a time-space boundary. The spatial boundaries of plant communities, called ecotones, can be gradual or abrupt. These are biologically the most productive areas: animals may find shelter in one area and more abundant food in another. Plant communities are often named for the dominant species of the community. A species may be dominant either by its physical size, such as the Monterey Cypress forest, or by its numerical dominance. Not all communities have one species which is dominant; these are named for physical or generic characteristics, such as grasslands or scrub, or by habitat, such as coastal bluff communities.

A classic plant community structure can be best seen here in the Monterey pine forest: a tree species dominating the community by its sheer size, the quantity of nutrients its roots absorb, and by the needle or leaf litter dropped; a shrub layer of Ceanothus, coffeeberry, and poison oak, and an understory of low-growing plants such as the wood-mint and Douglas iris.

Poison Oak in Green and Red Stages

Not all plant communities follow this structure. The Northern Coastal Scrub community consists mainly of shrub species growing tightly together with a weakly developed understory. Grassland communities generally consist only of grasses and very low-growing herbaceous plants. A careful look at the soils, the fog patterns, exposure to salt spray, or slope characteristics can give a clue to the differences in the growing conditions in each location.

The Point Lobos Plant Communities:

Monterey Pine
Pinus radiata, the Monterey pine, is perhaps the most widely planted of all pine species. This pine has become the most widely planted species for timber usage in the Southern Hemisphere. However, its natural occurrences are restricted to four localities: Ano Nuevo Point in southern San Mateo and northern Santa Cruz counties, in Cambria in San Luis Obispo county, and the Monterey Peninsula from the Monterey Peninsula south to Malpaso Creek. A variant, Pinus radiata var. binata, occurs on Guadalupe Island off the coast of Baja California, Mexico.

The Monterey pine grows to a height of 25-35 meters, symetrical when young, with an irregular rounded crown with age (60-80 years). The needles grow in a fascicle of three, 8-15 cm long. When growing in the open, the Monterey pine is a very symmetrical tree; growth crowded by other pines can cause a more distorted shape.

Staminate (male) cones are yellow-brown, about 12 mm long, growing in clusters on the tips of branches. The female cones are 7-15 cm long, unevenly conical with little or no stalk, pointing downward. The inner side of the cone next to the branch is imperfectly developed. The lowermost cone scales on the side away from the branch form thickened rounded knobs; the upper scales are more diamond-shaped. These cones persist unopened on the trees for several years. Each year's growth can be measured on the branches by the cone clusters surrouinding the branch. At times, the growth of the trunk or branches wil cover the unopened cones.

The Monterey pine is one of the closed-cone pines: the cones do not open as soon as the seeds ripen. The cones open only in response to heat. Unlike the Bishop and Knobcone pines, the cones of the Monterey pine will open on a very warm day as well as opeing as a response to fire.

Monterey Pine Forest
Trails: Whalers Knoll, Lace Lichen, PIne Ridge, South Plateau

This community is dominated by the presence of the Monterey pine. The size of the trees and the density of the canopy limit the plants growing in association with the pines to those able to tolerate the deep shade.The soils in these areas are quite shallow and nutrient-poor, further limiting the species able to grow among the pines. Fire is an integral part of a healthy Monterey pine forest. Without periodic burns, whether started by lightning, Native Americans in the past, or rangers today, the pine forest becomes a thicket of spindly trees with very few other species able to survive. Too many nutrients are locked up in dead vegetative matter on the forest floor to support healthy plant growth.

The other tree species in this community is the coast live oak. The term "live" refers to the fact that this is an evergreen, not deciduous tree. When this tree grows in the open it can reach 50 to 70 feet in height; within the pine forest it remains smaller. Coast live oaks live longer than the pines, so without periodic fires to regenerate the growth of the pines, the oaks might in time replace the pines as the dominant tree species.

Frequently found growing in both the oaks and pines is the lace lichen, Ramalina menziesii. This lichen grows on the tree branches taking advantage of openings in the canopy to grow in the light. It is not parasitic on the trees. Also found growing on the pines is a parasite, the dwarf mistletoe. Its roots grow into the tree itself, tapping the tree's nutrient supply. When mature, the seeds explode out to increase the chances of landing on another branch where they may thrive.

Monterey Cypress
Visitors to Point Lobos are familiar with Cupressus macrocarpa, the Monterey cypress, perhaps the land-dwelling symbol of the Reserve. We see the cypress here and all around the Monterey Peninsula, so we often forget just how unique this tree is.

There are only two native stands of Monterey cypress, here at Point Lobos and in Pebble Beach (appropriately enough at Cypress Point). The occurrence of the Monterey cypress in just these two localities has led to its listing by the State of California as a Category 1 Rare and Endangered Species (rare and endangered due to restricted habitat and/or low numbers of plants per population or vulnerable habitat.)

Monterey cypress is widely planted as a landscape tree throughout the west coast. This widespread planting has led to the tree not being listed as a federally endangered species: the federal list does not distinguish between naturally occurring populations and planted specimens.

The cypresses within the Allan Memorial Grove are especially valuable because of their isolation from planted cypresses from other areas. As close as Cypress Point is to Point Lobos, there are genetic differences between the two populations and minor variations in cone structure. Because they are surrounded by a landscaped residential area, the cypresses in the Del Monte Forest are also more likely to hybridize with trees planted from Point Lobos seed stock or, indeed, with other species of cypress planted as landscape trees. The cypress family tree has existed for a long time. Fossil remnants have been found from sediments of the Late Triassic (200 million years ago); and fossils of direct precursors of the modern genus Cupressus have been found from the Cretaceous period, the time of the dinosaurs, long before broadleafed plants evolved to provide serious competition to conifers.

Monterey Cypress Forest
Trails: Cypress Grove and North Shore at Guillemot Island.

The harshness of the growing conditions on Cypress Point and the deep shade beneath the cypresses limit the number of plant species growing in the cypress forest. There are very few shrub size plants growing in this community, and the small understory plants must be adapted to the deep shade and shallow, nutrient-poor soil.

Lace lichen is often found growing on the cypresses: it is not parasitic and does not harm the trees. The surfaces of the trees closest to the direct salt spray are often covered with a bright orange growth. This is Trentepohlia aurea v. polycarpa, a green alga which is rich in beta carotene, giving it a bright orange color. It, too, is nonparasitic and can be found growing on rocks and downed wood along the trail. Both the alga and the lichen condense moisture from the fog and sea spray. Excess moisture drips down into the root zone of the trees and provides extra water during the dry season.

Northern Coastal Prairie
The meadow areas within the Reserve (Hudson Meadow, Carmelo Meadow, and Mound Meadow) are the southernmost examples of Northern Coastal Prairie, a grassland adapted to the climatic conditions of the northern California coast. Extensive grazing all along the coast has greatly degraded the native prairie. Many native grass species have been grazed to the point where the populations are no longer viable or they have been crowded out by introduced species.

Fire suppression has also played a part in the diminution of these meadows. The prescribed burns previously done in the meadow areas of the Reserve are an attempt to restore the meadows to their condition before the arrival of the Spanish settlers. The native grasses are perennial grasses, growing in deep-rooted clumps; most of the introduced grasses are shallowrooted annual grasses more susceptible to destruction by fire.

The Native Americans on the central coast frequently set fires to thin the tree and shrub cover in an attempt to improve forage for the deer, thus making hunting easier. The Native Americans also used the seed of the giant rye grass, Leymus condensatus, which grows around the perimeter of Mound Meadow, as an important food source. This grass is well adapted to fire: deep roots survive a slow-burning fire, resprouting vigorously, and the plants produce an abundance of seed in the years following the fire.

Northern Coastal Scrub
Trails: Cypress Grove, Sand Hill Cove, Sea Lion Point, Bird Island

This is a plant community found in a narrow coastal strip from southern Oregon to San Mateo County, and in Monterey County from Pacific Grove to Point Sur.

Northern coastal scrub commnities are characterized by evergreen shrub species 1-2 meters tall and usually have a well-developed understory of herbaceous species. Most of the coastal scrub within Point Lobos State Reserve is dominated by Baccharis pilularis v. consanguinea, coyote bush, or Lupinus arboreus, bush lupine.

The plant species in this community display various adaptations to the harsh conditions which they grow:

deciduous in dry weather -
California sagebrush, poison oak, bracken fern.

gray foliage to reflect sunlight -
California sagebrush, pearly everlasting.

waxy coating on leaves to minimize water loss -
coyote bush, ceanothus.

fine hairs on leaves to minimize water loss and reduce exposure to sun -
Lizard tail, pearly everlasting.

Most species also have relatively small leaf areas to minimize moisture loss. The dense growth of the coastal scrub also helps the whole community to conserve moisture and survive the dry summer. This dense growth also provides cover for many small animals which live within this area.

Coastal Bluff
Coastal bluff community at Bird Island Trail Coastal bluff is often considered as a sub-community of northern coastal scrub. The plants of this community must be adapted to extreme conditions: intense sun or dense fog, very shallow soils or bare rock, nearly vertical rock faces, direct salt spray, and wind. The adaptations of the plant species to this environment are a further refinement of the northern coastal scrub species' adaptations. Indeed, many of the species are the same, although the size of the individual plants may be greatly reduced.

Intertidal Community
In addition to the mechanical action of the waves, variations in salinity, and substrate (rock or sand), tidal action strongly affects the distribution of the intertidal marine vegetation. Two high and two low tides of unequal height occur along this coast every 25 hours. During extreme tides, minus tides may occur to -2 feet, plus tides to +7 feet, creating a 9 foot intertidal zone. Being covered and uncovered by salt water, then being exposed to the air for exteneded periods of time has a profound effect on the marine vegetation and the animals which live in it. The durations of inundation and exposure define the plant species which can survive in a given location.

The greatest diversity of marine life occurs on rocky substrate. Kelp, a brown alga, grows from a hold-fast on the rocks. This is not a root system, merely a support. The giant kelp and bull kelp break off during winter storms and regrow from the holdfast each year. Giant kelp can grow as rapidly as one foot per day during the summer months.

Plants found in Zone 1: Spray zone to wet at high tide:
Blue-green algae (Cyanoactria), Green film alga (Enteromorpha)

Plants found in Zone 11: Wet twice each day:
Nail-brush alga (Endociadia muricta), Rock weed (Fucus gardneri), Turkish Towel (Mastocarpus papillatus), Rock weed (Pelvetiopsis and Pelvetia silvetia), Ruffled purple rockwee (Porphyra perforata).