Wetlands Exam 1

What is the definition of a Wetland?

What is the definition of a Wetland?

1. Water must be present at some point (inundation)

2. Soils inundated long enough to be anaerobic (hydride soil)

3. Biota adapted to saturated conditions (hydrophytic vegetation)

Hydroperiod?

is the balance between inflows and outflows of water; water budget

Hydrologic pathways

precipitation, surface runoff, groundwater, tides, river flow, evotranspiration

Hydrology Influences

species composition (diversity), primary productivity, organic accumulation, nutrient cycling

Hydrophyte

plant adapted to wet conditions

Halophyte

salt-tolerant plant

Hypoxia

waters (or soils) with dissolved oxygen less than 2mg/L

Anoxia

waters (or soils) with no dissolved oxygen

Soil is a combination of _______________________________

sand, silt, and clay aka soil matrix

Field capacity

water held by soil against gravity

Wilting point

level plants can not uptake water

Upland

ecosystems occur wherewater is far enough below the soil that only certain plants can thrive

Hydric soil

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

A.

Litter

B.

Peat

C.

Muck

D.

Gleyed mineral soil

Organic soils %

More than 18% OC if more than 60% clay; 12-18% if less than 60% clay (%Corg = %OM/2)

Mineral soils %

Less than 20-35% organic content

Organic soil

contains plant remains at various levels of decomposition

Humification

the breakdown of organic materials in soils and composts leading to the formation of humus

humus

dark organic matter in soil that is formed by the decomposition of plant and animal matter

Saprists (muck)

more than 2/3 decomposed; less than 1/3 plant fibers identifiable

*Fibrists (peat)

less than 1/3 decomposed; more than 2/3 plant fibers identifiable

Hemists

(mucky peat OR peaty muck)

Folists:

caused by excess moisture

Redoximorphic features formed by

reduction, translocation, and/or oxidation of iron and manganese oxides

Oxidized rhizosphere

Biogeochemical cycling

transport and transformation of chemicals

Terrestrial system Hydrology, Biochemical role, and Productivity?

Hydrology- Dry

Biochemical role- Source

Productivity- Low to Medium

Wetland Hydrology, Biochemical role, and Productivity?

Hydrology- Intermittently to permanently flooded

Biochemical role- Source, sink, or transformer

Productivity- Generally High

Deepwater aquatic system Hydrology, Biochemical role, and Productivity?

Hydrology- permanently flooded

Biochemical role- sink

Productivity- Generally low

Intrasystem

chemical cycling and transformations within the wetland

Intersystem

transport and exchange between adjacent systems

Oxidation reactions

is the loss of electrons

reduction reactions

is the gain of electrons

Reducing agents

are those that are oxidized

Oxidizing agents

are those that are reduced

Redox potential

Quantitative measure of the tendency of the soil to oxidize or reduce substances

Oxidized states still occur in

Oxidized rhizosphere • Oxidized soil surface

carbon cycle

Building block of life  Oxidation states range from -4 to +4

carbon cycle in Wetlands

Key Reactions in Wetlands carbon cycle

Oxygenic photosynthesis ◦ Major pathway ◦ CO2 reduced to organic compound

Anoyxgenic photosynthesis ◦ CO2 reduced to organic compound but no O2 ◦ In bacteria

• Oxic respiration ◦ Oxygen is the biological oxidation of organic matter

• Anaerobic respiration ◦ Biological oxidation of organic matter ◦ No oxygen

• Fermentation ◦ Carbohydrates broken down to dissolved organic carbon ◦ Provides substrate for other microbes

• Methanogenesis ◦ Methanogens use CO2 for the production of methane gas (CH4) ◦ Released into atmosphere

Oxygenic photosynthesis

Major pathway ◦ CO2 reduced to organic compound

Anoyxgenic photosynthesis

CO2 reduced to organic compound but no O2 ◦ In bacteria

Oxic respiration

Oxygen is the biological oxidation of organic matter

Anaerobic respiration

Biological oxidation of organic matter ◦ No oxygen

Fermentation

Carbohydrates broken down to dissolved organic carbon ◦ Provides substrate for other microbes

Methanogenesis

Methanogens use CO2 for the production of methane gas (CH4) ◦ Released into atmosphere

When is the wet season and when is the dry season?

Summer=wet

Winter=Dry

Nitrogen Cycle in Wetlands

Key reactions in Nitrogen Cycle in wetlands?

Fixation ◦ N fixing bacteria ◦ Nitrogenase inhibited by oxygen

• Mineralization ◦ Conversion of organic nitrogen into ammonium ◦ Ammonification

Nitrification ◦ Conversion of ammonium to nitrite to nitrate ◦ Biologically accessible ◦ Aerobic process •

Denitrification ◦ Conversion of nitrate to nitrite to nitric oxide to nitrous oxide to dinitrogen

Fixation

N fixing bacteria ◦ Nitrogenase inhibited by oxygen

Mineralization

Conversion of organic nitrogen into ammonium ◦ Ammonification

Nitrification

Conversion of ammonium to nitrite to nitrate ◦ Biologically accessible ◦ Aerobic process

Denitrification

Conversion of nitrate to nitrite to nitric oxide to nitrous oxide to dinitrogen

Phosphorus Cycle in wetlands

Key Reactions in Phosphorus Cycle in wetlands

Uptake

Sedimentation

Iron Transformation in wetlands

it is in reduced form –> ferrous

Manganese Transformation in wetlands

It is in reduced form –> manganous

Factors influencing nutrient budgets

Seasonality nutrient uptake •

Adjacent ecosystems •

Temporal and spatial variability •

Anthropogenic influence

Bog

A peat-accumulating wetland that has no significant inflows or outflows and supports acidophilic mosses, particularly Sphagnum

Fen

A peat-accumulating wetland that receives some drainage from surrounding mineral soil and usually supports marshlike vegetation

Marsh

A frequently or continually inundated wetland characterized by emergent herbaceous vegetation adapted to saturated soil conditions

Swamp

Wetland dominated by trees or shrubs

Five wetland indicator status categories

1) Upland (UPL)

2) Facultative Upland (FACU)

3) Facultative (FAC)

4) Facultative Wetland (FACW)

5) Obligate (OBL)

1) Upland (UPL)

Almost never occur in wetlands

2) Facultative Upland (FACU)

Usually occur in non-wetlands, but may occur in wetlands

3) Facultative (FAC)

Occur in wetlands and non-wetlands

4) Facultative Wetland (FACW)

Usually occur in wetlands, but may occur in nonwetlands

5) Obligate (OBL)

Almost always occur in wetlands

Submerged

= plants that conduct virtually all of their growth and reproductive activity under water

Free-floating

plants that most often grow with the leaves and other vegetative and reproductive organs floating on the water surface

Floating-leaved

plants that are rooted in sediment but also have leaves that float on the water surface

Emergent

herbaceous and woody plants that grow with their bases submerged and rooted in inundated sediment or seasonally saturated soil and their upper portions, including most of the vegetative and reproductive organs, growing above the water level

Hydrophytes

(plants adapted to wet conditions)

Aerenchyma tissue in roots and stem

helps with oxygen obsorbtion

Adventitious roots

helps with oxygen obsorbtion

Stem hypertrophy

makes bottom of trunks/stems thick (cypress) for added stability

Fluted trunks

thicker at truck for added stability

Shallow root systems/prop roots

providing a stable support system.

Lenticels

oxygen obsorbtion

Pneumatophores and cypress knees

oxygen obsorbtion

Physiological Adaptations

Pressurized gas flow

• Sulfide avoidance

• Anaerobic respiration

• Rhizospheric oxygenation

Decreased water uptake

• Salt excretion

• Altered nutrient absorption

Whole-Plant Strategies

Timing of seed production

Buoyant seeds and buoyant seedlings

Viviparous seedlings

• Persistent seed banks

• Resistant roots, tubers, and seeds

Succession

the process of directional change by which the species composition of a community changes over time

Proceeds through series of stages that remain relatively stable through (ecological) time

Pioneer species

the earliest species to arrive at a site

Climax community

The final seral stage in the process of succession

Wetland succession

Autogenic succession

Vegetation in communities

• Community changes through time by the biota

• Changes are linear and directed toward a mature, stable climax ecosystem

Allogenic succession

Influenced by environmental factors

• Create wetlands to transition

Structural (or Morphological) Adaptations

Adventitious roots

Stem hypertrophy

Fluted trunks

Rapid vertical growth / growth dormancy

Shallow root systems/prop roots

Lenticels

Pneumatophores and cypress knees

Sulfur reactions in wetlands

Sulfur oxidation

Sulfate reduction

Sulfate absorption and leaching

Iron sulfide production

Hydrogen sulfide emissions

Sulfur cycle in wetlands

a.

sink

b.

source

c.

transformer

What is probably the single most important determinant of the establishment and maintenance of specific types of wetlands and wetland processes?

Hydrology

Hydrology

water level, flow, frequency, etc.