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Wetlands &

Organic Soils

Bellevue & Issaquah

Soils and Land Use

ESRM 311- SEFS 507

Organic and Wetland Soils

Today?

• Definitions• How wetlands work• Types of wetlands• Distribution of organic soils in US• Uses of organic soils• Construction of wetlands?

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Wetlands

• Areas where water covers the soil, or is present

• either at or near the surface of the soil

– all year or

– for varying periods of time during the year,including during the growing season. (US EPA)

http://water.epa.gov/type/wetlands/what.cfm

Wetland facts• productive and diverse waters that stand between upland

and open water.

• important to water quality, flood storage, and biodiversity

• economists estimate that one acre of wetlands provides about $10,000 worth of ecosystem services which include:

• filtering and recharging drinking water,

• preventing flooding,

• protecting our coasts from hurricanes and storms, and

• providing habitat for diverse wildlife populations.

http://www.nwf.org/What-We-Do/Protect-Habitat/Waters/Wetlands-and-Watersheds.aspx 4

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How wetlands work!!

Delineating Wetlands using:

1) Hydrology2) Hydrophytic vegetation3) Hydric soils

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Marshtype of wetland ecosystem characterized by poorly drained mineral soils and by plant life dominated by grasses

Swamp

wetland ecosystem characterized by mineral soils with poor drainage and by plant life dominated by trees

Bog

type of wetland ecosystem characterized by wet, spongy, poorly drained peaty soil with trees, shrubs, mosses, acidic soils, precipitation dominated for water source

Fen

similar to bogs but with less acidic soil, due to more ground and surface water inputs. Low shrubs prevail, with some orchids and insect-eating plants.

Definitions of some Wetlands

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Marsh

poorly drained mineral soils dominated by grasses 8

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Swamps

mineral soils dominated by trees

Peat bog

http://www.borsheim.info/Sphagnum.htm

2200 yr in Danish peat bog

peaty soil with trees, shrubs, mosses, acidic soils, precipitation dominated for water source

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Fen Wetland

Ground and surface water inputs, less acidic peaty soils

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Walnut tip-over in wetlands

• Shallow soils• High water table = shallow rooting 14

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Organic soils can be fun too!!!

16Histosols

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A soil association common in the Puget Sound area showing soil type relative to different glacial deposits

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Histosol (organic soils)

peat and mucks

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Land Uses for Wetlands?

• Natural, wildlife refuges, aesthetics, recreation

• Building on wetlands–Drain – what happens?

• Mineral – oxidizes

• Organic – decomposes

• Agriculture

Horizon NameDecomposition

stage

OiLitter

(fibric)Low

OePeat

(hemic)Medium

OaMuck

(sapric)High

Characterization of Organic Horizons

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Seattle Soil Series

Oap 0 to 11 inches; Oe 11 to 17 inches; Oa1 17 to 21 inches; Oa2 21 to 35 inches; O'e 35 to 60 inches;

Agriculture on wetlands

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23http://en.wikipedia.org/wiki/File:Verschiedene Typen von Pflanzenkl%C3%A4ranlagen.jpg

Surface flow

Subsurface flow

Vertical flow

Constructed Wetlands

Shoreline Overlay DistrictsFig SM.1

The Watershed Co_2008

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Minimum Shoreline Jurisdiction

The Watershed Co_2008

The Watershed Co_2008

Minimum Shoreline JurisdictionMercer Slough

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The Watershed Co_2008

Minimum Shoreline JurisdictionLarsen and Phantom Lakes

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