Module 2

Wetland soils are often

Acidic due to the reduction of SO4 2- to H2S (hydrogen sulfide) by anaerobic bacteria, producing the characteristic rotten egg odor of certain wetlands (part of the sulfur cycle)

Denitrification

Anaerobic bacteria convert ammonia (NH3) to N2O and N2 N2 (inorganic) back to atmosphere, Nis lost to Wetland

Percipitation

Any form of water, such as rain, snow, sleet, hail or mist, that falls from the atmosphere and reaches the ground

Examples of Reduced soils (4)

Gray coloration soil appears wet iron reduction mottles in soil sample

Oxidation

Occurs during oxygen uptake by soils, or when they are rich in oxygen

Saturation

Occurs when the soil pores are holding the max amount of water and plants cannot uptake any more water either (Note: these conditions occur along a gradient of increasing soil moisture.)

Wetland water budget

Provide a basis for understanding these hydrologic process of a wetland

Wetland soils show signs of

Reduction

Si

Second, surface water flows into the wetland -Surface water in flow might come from an adjacent river for example

Go

Sixth, similarly water may leave a wetland by moving into ground water supplies

Cation Exchange Capacity

Some nutrients and heavy metals (pollutants)exist as cations (+), and absorb to negatively charged places (-) on clay particles

Saturated (non tidal Wetlands)

Substrate saturated for extended during growing season

Tidal Wetlands

Subtidal permanently flooded with tidal water

Ground Water

Supplies are also linked to wetlands -Wetlands are most commonly groundwater discharge areas, however recharge can also occur

Anaerobic Conditions

THe complete lack of oxygen in the soil because pores are saturated with water -causes stress to plants since roots need oxygen to function (i.e. prevents respiration) -Characterized by lack of oxygen lead to different chemical processes in the soil

Change in Volume/Change in Time

THe water budget measures changes in the volume of water in a wetland over time

Gi

Third, groundwater flows into the Wetland

Compacted soils

Those that have been driven over by tractors/ farm machinery, have reduced pore spaces

Main categories based of Tides

Tidal and Non-tidal

Muck Soils

are characteristics of some wetland types, displaying black color from large quantities of organic matter

The Cation Exchange Capacity Process causes Wetlands to

become a sink for nutrients, pollutants and sediments which become attached to the clay particles

Hydric Soil

is a soil that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part

Reduction

occurs when soils are releasing oxygen, or when they are deficient in oxygen

Humus

organic matter that decays -Wetlands often have an abundance of this in the A horizon

Wetland soils are often high in

organic matter; anaerobic conditions show decomposition , so wetland soils often have a thick layer of organic litter

Hydric soils have important (8)

physical geochemical properties high quantities of organic matter and humus saturated soil anaerobic conditions reduced soils Acidic pH Texture: often high in silt and clay, although wetlands sometimes occurs in sandy soils.

Water is necessary in soil for...(5)

plants chemical reactions mixing soil particles for decomposition of organic matter dissolving nutrients (However, when soils become completely saturated, their properties change)

3 Important conditions of soil moisture

saturation field capacit permanent wilting

Surface water

supplied to wetlands through normal stream flow, flooding from lakes and rivers overland flow, ground water discharge, and tides (Surface water amy be permanently, seasonally, or temporarily present in a Wetland

Wetland soils are acidic due to

the decomposition of built up organic materials

Hydroperiod

the seasonal patter of water level in a wetland how deep? How often does it flood? What is the duration of flooding? Termed a Wetland's hydrological signature

Permanent Wilting point

the water content of soil when most plants (corn, wheat and sunflower) growing in the soil wilt and fail to recover in their turer upon rewilting

Irregularly Exposed (Tidal Wetlands)

-Surface exposed by tides less often than daily

What are the hydrological impacts on a Wetland's character? (4)

1. A wetland's particular hydrologic regime leads to a unique vegetation assemblage (remember, plant species vary their ability to tolerate flooded conditions. The amount, frequency and the duration of flooding controls the types of vegetation that will grow. 2. Primary productivity and other ecosystem functions are oftenenhanced by flowing conditions and a pulsing hydroperiod; often stagnated by unvarying conditions. 3. Accumulation of organic material in a wetland is controlled by hydrology through its influence on primary productivity, decomposition and the import/export of organic matter 4. Nutrient cycling and availability are significantly influenced by a wetland's hydrology

Soils have a number of properties (6)

1. Composition 2. Texture 3.Porosity describes the number, size, and connectedness of soil pores (air spaces) 4. Soil moisture potential measure of water 5. Soil Color 6. Soil Horizons

Wetland's 3 basic Characteristics

1. Presence of Shallow water or inundated ground surface 2. Hydric soils 3.Hydrophytes (The hydrology of a wetland directly controls whether hydric soils will form or whether hydrophytes will be present

Wetlands 3 basic characteristics

1. Shallow water or inundated ground surface 2. Hydric soils 3. Hydrophytes

Hydrological functions of a Wetland in a landscape (4)

1. Water storage 2. Improve water quality 3. Recharge surface and ground water supplies 4. the unique hydrology of wetlands can support a diversity of animals

R Horizon (Bed Rock)

Bedrock, such as sandstorm, limestone, or granite

H2CO3 Carbonic acid

Build up of carbon dioxide, when dissolved in water, creates carbonic acid -created when an excess of carbon dioxide is dissolved in water

Tides

Can also influence waterflow in wetland -although tides are typically only an influence in coastal areas where they occur

Permanently flooded (Non-tidal Wetlands)

Flooded throughout the year

Intermittently flooded (Non-Tidal Wetlands)

Flooded throughout year, except in extreme drought

Hydrology

Consist of water level, flow frequency directly effects a wetland's biota and physiochemical environment

Nitrogen Fixation

Converts inorganic N2 to Organic forms Requires presence of oxygen Fixed by lightning bacteria, blue-green algae

Evapotranspiration

Describes the loss of water to the atmosphere (evaporation) and the loss due to transpiration by plants -Solar radiation, windspeed, turbulance relative humidity, available soil moisture and vegetation type and density effect the rate of evapotranspiration

Porosity

Determined in part by texture w/ larger particle sizes generally leading to more porous soils

ET

Fourth, some of the water in the Wetland is loss through ET (Evaporation and Transpiration)

How is a Wetland's physical environment controlled by?

Geomorphology, climate and hydrology

So

Fifth, additional water may be lost due to surface water out flow -For example, a wetland draining into a river

T

Finally, tides (where relevant) bring water in and out of a wetland

Pn

First precipitation (P) inputs water. Net precipitation (Pn) describes the amount that actually reaches the wetland -For example, some water is intercepted by plants before reaching the Wetland

Irregularly Flooded (Tidal Wetlands)

Flooded less often than daily

Classes of Hydroperiods

Hydroperiods are used to classify wetlands into different hydrological types or water regimes

Soil Color

Measure hue, chroma, and value; indicator of different properties as it is influenced by organic matter, minerals and water content -measured using the munsell chart

C Horizon (Parent Material)

Mineral soil, little affected from soil process (no accumulations of minerals or materials from upper layers)

Anaerobic conditions also effect the

Nitrogen cycle

Soil Texture

Texture classes defined using the textural triangle

Field Capacity

The amount of water remaining in the soil a few days after having been wetted and after free drainage has ceased. By definition, it is the amount of water available, stored, or released between field capacity and the permanent wilting point water content.

Wetland Hydrology

The formation, size, persistence and function of a wetland are all directly controlled by hydrological process.

B Horizon (Zone of accumulation)

The subsoil layer, predominantly mineral and accumulations from upper layers

A Horizon (Top Soil)

The top soil laye, mineral soil mized w/ some organic matter

What does Physiochemical environment impacts?

The wetland biota and indirectly impact hydrology.

Hydrograph

Water Levels in a wetland can be measured periodically in the field , often using a staff guage -depicts changes in a wetland's depth overtime (Used for studying and classifying wetlands)

Wetland soils often have high amounts of

clay and silt (although some have a sandy texture)

Regularly flooded (Tidal Wetlands)

flooded and exposed daily

Temporarily flooded (non tidal wetlands)

flooded for brief periods during growing season

Seasonally flooded (non tidal wetlands)

flooded for extended period of growing season, usually dry by the end of growing season

Semipermanently Flooded (non-tidal wetlands)

flooding during growing season of most years

Clay is important because it has a

high cation exchange capacity