Ecosystems Field Notes (2008)

jschmied©2008

 

Sucession and the Center .   The Center Demonstrates primary, secondary, and preclimax communities.

Ecological Succession - The process of gradual change from one community of organisms to another.

Primary succession‚ areas where rocks breaking down mix with organic material to make basic soil.

Three ways this occurs

Physical erosion - Two primary means

a. Freeze Thaw cycle - water gets into small cracks in the rocks, freezes, makes cracks larger, eventually breaks rocks.

b. Abrasion - Basically many ways this happens.

i. Rock rubbing on rocks, Glaciers rubbing rocks together, water rubbing rocks together.

ii. Also Wind with sand blasting on the surface of rocks.

Chemical erosion - Two ways

a. Acid rain / acid water - dissolving rocks into other chemical compounds

b. Lichen (Mutualistic association of Fungi and Algae. Fungi gets sugars from Algae due to photosynthesis, Algae gets a safe place to stay.

Biological Erosion - Plants roots get into cracks, grow and expand, breaking rocks.

Eventually  rocks break down into sand, plants and animals live/grow in sand, die and add nutrients. Eventually becomes soil over 1000 years

Pioneer community ‚ first community of organisms, plants and animals, to move into a new environment.

Secondary succession areas with soil developing from either primary successional area, or where plants removed (landslides, earthquakes, bulldozers) and they are now growing back.  Caused by nature and man

Examples: Pipeline, Edge Area, Wetland, edge of the trail.

All Pioneers have four key attributes.

1. Like sunlight

2. Grow fast

3. Can stand drought

4. Can live in poor soil

Four Pioneers in this area. Many secondary pioneer communities are nitrogen fixers.  Take atmospheric nitrogen in root nodules and break it down to usuable nitrogen. When die/decompose release valuable nutrients (Nitrogen, Carbon, Potassium, Phosphorus etc).

Having Nitrogen is key as it is a limiting factor - without nitrogen organisms can't make DNA, thus no growth!

a. Tree Red Alder - Primary tree in secondary succession areas in Pac NW

b. Fireweed,

c. Scot broom,

d. Lupine.

Other secondary plants, sword ferns, mosses, other types of lichen, himalayian blackberries, Grasses. 

 

Fungul interface: (Mychorrizal interface)

Example Hemlock and fungal mutualism - Basic situation

a. Soil fungus infects the roots of the tree.

b. Helps tree by giving tree water - as fungus is spread way out , increasing effective root surface. Tree grows much faster

c. Helps fungus as tree gives nutrients.

d. When tree dies fungus infects rest of tree with hyphae. (Hollow, extudes digestive juices, sucks in digested nutrients.)

e. As fungus grows, eventually creates a "fruiting body" to give off spores... these are call "Conks".

Old foresters used to cut down all the trees in a lot - "Clear cutting" and then burn the remains "Slash". This was becuase the foresters used to think this would help the new trees grow and decrease competition.

This method of forestry is called "Slash and Burn".In this method the heat killed off most of the fungus in the soil. However recently scientists discovered the benefit of fungul interfaces and modern foresters stopped this as it actually slows the growth of the trees! Now foresters actually infect their seedlings with fungus on purpose!

 

Final stage is Climax Community. We don't have this, but we have a Pre-climax community... .... Tiaga Dominated by various conifers and some big leaf maples which are deciduous (broad leaf) trees.

Example ...In the Center itself... Conifers range between 65 to 75 years old.

Key Characteristics of Tiaga Climax Community

a. As the trees grow, the nutrient balance moves up into the canopy. In other words, most of the nutrients are in the body of the forest.

b. The area gets more and more complexity, providing more habitat.

c. Decomposition accellerates and returns nutrients to the tress quickly.

d. The soil gets richer and thicker and retains more moisture. Acts as a sponge, decreasing flooding and increasing water for the dry times

e. The forest moderates the temperature, thus a climax community is cooler during the summer.

Thus the Forest moderates temperature (cooler) and keeps moisture level higher than outside. Area of growth and decomposition.

 

What we are doing at the edge of the Center to trying to:

provide understory to lessen windthrow,

increase complexity - create a more diverse environment

develop wetlands across the eastern edge to increase aquatic animals and bring in more birds.

 

Ecosystem              http://ecosys.cfl.scf.rncan.gc.ca/def_eco_e.htm

An ecosystem consists of a dynamic set of living organisms (plants, animals and microorganisms) all interacting among themselves and with the environment in which they live (soil, climate, water and light).

An ecosystem does not have precise boundaries - it can be as small as a pond or a dead tree, or as large as the Earth itself. An ecosystem can also be defined in terms of its vegetation, animal species or type of relief

The major ecosystems are generally described as:

Aquatic ecosystems ‚

Saltwater ex coral reef, kelp forest, etc or

Freshwater lake, pond, stream wetland etc);

Estuary ..mix of salt and fresh

Terrestrial ecosystems (biomes) ‚

tundra,

taiga,

forests (temperate deciduous + rainforest),

grasslands (temperate + savannah), deserts (orographic + 30û N/S)

Climate is caused by long term patterns of temperature and precipitation.

Puget Sound Climate is moderated by the effect of having the Sound and the Ocean nearby.

Puget Sound Climate is affected by geography .... Cascade and Olympic mountains

Puget Sound climate is dominated by cold, rainy winters and spring, followed by dry summers and fall.

Natural wind patterns affect the moisture level

 

Taiga - area we live in is on the southern edge of the Taiga ecosystem (biome), also called the Northern Coniferous Forest.

The Center is a Tiaga island with a constructed wetland

Surrounded on all sides by urban development.

It is influences its surroundings‚ and The Surroundings influence the Center.

 

Disturbances transform environmental conditions (release nutrients, change light and moisture conditions, etc.) in the ecosystem. A process of secondary succession, or changes in the composition of the stand, follows.

Natural disturbances giving rise to secondary successions vary in terms of frequency, severity and affected areas, as well as in the changes they produce in the ecosystem. In addition to large openings in the forest cover, disturbances can cause an accumulation of ground debris, changes in water quantity and quality, a loss of organic matter, etc. All these factors influence regeneration and the species that will make up the new stand.

By studying natural disturbances, we gain a better understanding of the impact that human activities have on forest ecosystems. The impact of some human disturbances, such as forest cutting, is similar to that caused by natural disturbances.

Influence and the the Center

            Wind Mostly SW during winter/spring  NW summer/fall.  Windthrow.

            Temperature Sun on East, South, West sides

Rainfall development helps & hinders.  Some houses channel rain onto NW Loop

Development - Dries out soil on East & South Sides

- causes windthrow on the edges of the forest.

Edge area bare low growing grass allows wind to hit most vulnerable part of tree directly.Over time trees and shrubs on edge will moderate this.

Retention pond and wetland area keep moisture near, cool / warm Center, attracts wildlife, birds, amphibians, mammals etc

The Soil Dynamic interaction between vegetation and the soil is so strong, it's not clear which is dominant.

Soil helps secure and renew the forest, Plants help secure and renew the soil.

Soil provides a place for plants to anchor in (stability), useable nutrients, water, and oxygen.

Forest covers and protects soil from temperature extremes.  Slows erosion from wind, water, and gravity (slumps & landslides), adds organic material, seeds to the soil.

 

Soil is Alive - Healthy soil is a living body, made up of inorganic material, decaying organic matter, water, air, and billions of the healthy organisms.

Soil and Trees are Interdependent

Organisms in soil, fungi, form partnerships with tree roots and help the tree extract nutrients and water from the soil.

Other fungi break down organic material, recycle nutrients for next generation.

http://ecosys.cfl.scf.rncan.gc.ca/disturb/diseases_e.asp\

Soil Formation ... Begins with the parent material‚ Solid ROCK of the Earth's Crust

Formed by Natural processes, but can be made.

Physical Processes - Freeze Thaw‚ Glaciers‚ Earthquakes,

Water is a major influence in erosion.

Chemical Processes - CO2 makes weak acid, lichen,

Biological Processes - roots of plants expand, break rocks, decompose organic material

Eventually organic material is added via death and decomposition of plants and animals

Takes a long time to make soil. ex  200 to1000 years to form an inch of topsoil

Most nutrients cycle in the top 2 feet of topsoil via microbes (bacteria, fungi, algae, protists) in climax communities

Soil Horizons

 

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