Mixed Evergreen in The Coastal Range

 

Overview

            The Coast Ranges run parallel to the Pacific coastline for nearly 550 miles. Stretching from the Klamath ranges in the north down to the Transverse ranges in the south, the Coast Ranges are a product of California’s unique position on the edge of the North American tectonic plate. California’s incomparable geologic landscape reflects the activity of this plate boundary, which has shaped California’s landscape for well over 100 million years. The boundary between the North American and Pacific plates is defined by a series of strike-slip faults that run north to south. These faults and folds have encouraged rivers to flow in a north or south direction where waterways terminate great distances from their source.

A Map of California. Red outline of the coastline with a red arrow on the oceanside pointing north and a red arrow on the continental side pointing south. This represents the the grinding of the oceanic plate against the North American plate.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig A: Movement of the Pacific Plate against the North American Plate has yielded the Coast Ranges that parallel California’s coastline.

            The collision between the North American and Pacific Plates has created a landscape with dynamic edaphic (soil) properties. The mosaic of soil types found throughout the Coast Ranges has selected for an assortment of plant communities. From Chaparral and coastal scrub to dense Coast Redwood forests, this mountain range supports a diverse collection of plants. North of the San Francisco Bay we find an eclectic mix of conifers (cone bearing plants; gymnosperms) and hardwood (flower bearing plants; angiosperms) trees in regions not dominated by strands of Coast Redwood, valley grasslands, or Chaparral. South of San Francisco Bay we find a similar mix of conifers and hardwoods that generally dominate moist, north facing slopes at higher elevations. This mix of trees, with varying reproductive strategies (cones/flowers), embodies the iconic Mixed Evergreen plant community commonly associated with the Coast Ranges.

A view of Cone Peak Forest. Several jagged hills which lead into the Pacific Ocean.

 

 

 

 

 

 

 

 

 

 

 

Fig B: Cone Peak displaying an iconic coastal California forest. Photo: Dennis Poulin

 

The Plant Kingdom

            Beginning in the days of Aristotle, the biological world had been broken into two classification schemes; Plant and Animal. Organisms, or forms of life that moved were animals. Everything that did not move was a plant. Included in this group were all fungi and red algae; two groups that contemporary biologists consider distinct from plants. The current definition of a plant is now highly refined and excludes any ambiguity.  This section will clear up one’s understanding of a plant and what members of the biological world belong to this group.

 

            Plants are eukaryotic organisms that have cellulose-based cell walls and light absorbing pigments within specialized organelles called chloroplasts. Most plants obtain their energy from the sun through the process of photosynthesis. In this process, chloroplasts convert light energy into chemical energy through complex biochemical reactions that are found nowhere else in the biological world. The mysticism associated with plants often stems from their unparalleled life cycle. Another characteristic of plants is the alternation of generations. The alternation of generations is a transition between a seed forming (gametophyte) stage and spore forming (sporophyte) stage that all plants go through in their lifecycle. The sporophyte is what we often associated with the “common plant.” Non-vascular plants like mosses, in contrast, are dominated by the gametophyte stage. Both the “common plant” and the moss express each stage of the life cycle. The difference lies in which stage their life cycle is dominated by.

 

            The plant kingdom contains over 300,000 species. Green algae appeared in the geologic record some 1.2 billion years ago; the earliest forms of land plants some 450 million years ago. The following is a list of extant groups of plants. Oldest lineages listed first, followed by the next oldest group.

 

Kingdom Plantae

Green algae

-Chlorphyta

-Charophyta

Land Plants (Emphyophytes)

Non Vascular Plants (Bryophytes)

-Merchantiophyta (liverworts)

-Anthocerophyta (Hornworts)

-Bryophyta (Mosses)

Vascular Plants (Tracheophytes)

-Lycopodiophyta (Lycophytes)

-Pteridophyta (Ferns)

Seed Plants

-*Coniferophyta (Conifers)

-*Cycadophyta (Cycads)

-*Ginkgophyta (Ginkgo)

-*Gnetophyta (Gnetae)

-**Magnoliophyta (Flower plants)

(* denotes Gymnosperm)

(** denotes Angiosperm)

 Fungi

            Fungi are a vastly misunderstood group of organisms whose ecological roles are just now beginning to be discovered. The thought of a mushroom often comes to mind when one thinks of fungi. Mushrooms are in fact just a reproductive stage of one of many groups of fungi. Therefore the microscopic world stretches far beyond the traditional understanding. Fungi are heterotrophic eukaryotic organisms that reproduce through the production of spores. As a frame of reference, plants are autotrophic (produce their own food; photosynthesis) and generally use seeds as their primary mode of reproduction. In this respect, fungi are opposite from plants. Fungi often rely on plants for energy and, in return, provide plants with a more efficient access to resources (mycorrhizae). In addition, fungi provide a means to decompose expired plant matter on the forest floor (saprotrophs), which recycles nutrients into the ecosystem. Not all fungi perform these symbiotic roles. Over 5000 species of fungi pose serious threats as pathogens that attack wild and cultivated plants. There are fungi, colloquially called mold, that are responsible for millions of dollars in damage to homes on a yearly basis. Some fungi produce mycotoxins causing health problems that have induced neural damage and even death among exposed individuals. Other mycotoxins, like penicillin, have been used to our advantage and have revolutionized modern medicine. We owe thanks to fungi for producing alcoholic beverages, allowing bread to rise, and even the production of soy sauce.

 

            As one can boundlessly expand on the significance of fungi and the role they play in our world, the focus of this text remains within three classifications; saprotrophic, mycorrhizal, and endophytic fungi. Common to all fungi, except yeast, are long filamentous structures called hyphae. The fungus itself is composed of hyphae and is collectively known as mycelium.

White Oyster Mushrooms growing in coffee grounds.

 

Fig C: The mycelium of Pleurotus ostreatus (Oyster mushroom) growing through coffgrounds

 

 

 

 

 

 

 

 

 

Saprotrophs: These, along with heterotrophic bacteria, are the primary decomposers on Earth. Through the secretion of powerful enzymes, they break down and consume expired organic matter as a source of energy. Decaying organic (from life; plant, animal, insect, protists, other dead fungi, etc.) matter contains valuable mineral nutrients that are recycled through these life forms. Decomposers facilitate nutrient cycles and make resources available for an ecosystem. There is a saying: “No one ever fertilized an old growth forest.”

 

Mycorrhizae: On the other end of the spectrum are fungi that associate with the roots of most plants. Mycorrhiza, which translates to “fungus-root,” is quite well named. It is believed that these associations aided in the colonization of land by plants. Mycorrhizae increases root surface area and improves water absorption. It facilitates the absorption of mineral nutrients, like phosphorus which is an especially difficult mineral for plants to absorb. And, it also defends the rhizosphere from invading pathogens that are harmful to the plant. In return for these wonderful contributions to the plant’s health, the host partitions photosynthates (energy) to the associated fungus in its root system. The following are the two main types of mycorrhizae known:

-Ectomycorrhizae: surrounds, but does not penetrate root cells of the host. The network of mycelium within the cortex of the root (inside the root, but not inside any cells!) is known as the Hartig net. Externally, at the soil root interface, the mantle branches out and facilitates water and nutrient absorption. Russulas, Boletes, Amanitas, and Chanterelles fall within this subgroup.

-Endomycorrhizae: actually penetrates the host’s root cells within the plasma membrane (not the protoplast!) forming arbuscules.

A cross section of a root tip showing how Mycorrhize grow inside roots in order to increase water and nurtrient  uptake.

 

 

 

 

 

 

 

 

 

 

 

 

Fig S: Arbuscules forming inside the root cortical cells of Linum sp.

 

Endophytic Fungi: Living within the plant itself, these microorganisms provide pathogen and predator defense for the host. In addition, endophytes act as abarrier for this host plant, providing increased protection against drought, cold temperatures, and pollution. Some defense compounds, once thought to be produced by the plant, have now been discovered as product of the endophyte. These compounds are often harmless to the host plant and offer many benefits that promote the plant’s success. Other endophytes may show a certain degree of parasitism, but increase the overall success of the plant in times of intense predation.

 

Glossary

-Alternation of generations: the life cycle unique to the plant kingdom.

-Chloroplast: organelle that harvests light and converts it to chemical energy.

-Coast ranges:  the set of mountain ranges on California’s immediate coastline

-Conifer: cone bearing plants that do not produce flowers

-Dioecious: plants with male and female flowers on separate plants

-Epiphyte: a plant that grows on another plant

-Eukaryote: organisms with eukaryotic cells; membrane bound nucleus, golgi apparatus, mitochondria, etc

-Gametophyte: gamete producing form of a plant

-Hardwood: woody plants that produce flowers

-Heterotroph: an organism that relies on outside source of energy. Unlike plants, that are autotrophs.

-Mycorrhizae: a mutualistic association between a plant and fungus

-Mycotoxin: toxic secondary metabolites produced by a fungus

-Parasitism: success of one organism at the other’s expense.

-Sporophyte: spore producing form of a plant

-Symbiotic: a relationship between two or more organism

 

Species on Display

Angelica tomentosa

Arctostaphylos columbiana

Asarum caudatum

Baccharis pilularis

Berberis pinnata

Blechnum spicant

Calamagrostis rubescens

Carex nudata

Carex praegracilis

Corylus cornuta

Eschscholzia californica

Festuca californica

Frageria chiloensis

Gaultheria shallon

Heuchera maxima

Holodiscus discolor

Iris longipetala

Iris macrosiphon

Melica torreyana

Mimulus aurantiacus

Monardella villosa

Oxalis oregana

Perideridia kelloggii

Physocarpus capitatus

Polypodium scouleri

Polystichum imbricans

Rhamnus crocea

Rosa nutkana

Sambucus racemosa

Scrophularia californica

Scuttelaria californica

Spiraea douglasii

Symphoricarpus albus

Vaccinium ovatum

Whipplea modesta

 

VIII. References

-Schoenherr, Allan. A Natural History of California. Berkeley: University of California Press, 1992. Print.

-Peter Raven, Ray Evert, and Susan Eichhorn. Biology of Plants. Sixth. New York: W.H. Freeman and Company, 1999. Print.

- Sloan, Doris. Geology of the San Francisco Bay Region. Berkeley, CA: University of California Press, 2006. Print.

-Calflora: Information on California plants for education, research and conservation.

[web application]. 2008. Berkeley, California: The Calflora Database [a non-profit organization].

Available: http://www.calflora.org/ (Accessed: Oct 20, 2008).

-All photographs: Creative Commons Attribution