wetlands ecology exam 1

List the three condition necessary for redox features to form in wetland soils.

-Sustained anaerobic conditions

-Sufficient soil temperature (> 5 degrees C)

-Organic matter (substrate for microbial activity)

Compare and contrast recharge and discharge wetlands. Remember, tell how the terms are similar and how they are distinct.

Recharge and discharge wetlands refer to the wetlands interaction with the water table (compare)

If the water table in an area is higher than the surface water level of the wetland then the wetland is called a 'discharge wetland' because the water table is discharging into the wetland

If the water table is below the surface water level of the wetland, then the wetland is called a recharge wetland because the surface water is recharging into the water table or the ground water (contrast)

Compare and contrast mineral soils and organic soils. Remember, tell how the terms are similar and how they are distinct.

Mineral soils and organic soils are both types of wetland soils. (compare)

Mineral soils contain <20% organic matter and water percolates through them very slowly due to their porosity. Mineral soils are typically found beneath organic soils and red/orange color

In contrast, organic soils can hold large quantities of water (low bulk density and porosity), and contain > 35% organic material. dark colored

Define environmental sieve. Give two examples of environmental sieves found in wetlands.

A set of conditions that determines/limits the type of species (plant or animal) that can inhabit the area

Two examples: the ability to withstand salinity and anaerobic conditions at times

How do natural disturbances, like fire and flooding, maintain wetland structure?

Fire removes medium to large canopy woody plants to maintain smaller herbaceous and graminoid (grass-like) species to persist. In the process, it increases species diversity and primary production, which leads to increased organic matter accumulation. Flooding can also be considered a disturbance that limits the species found there to only those that have adaptations specific for survival in saturated conditions. Furthermore, depending on the degree of hydrologic connectivity, flooding can also stimulate primary productivity by delivering nutrients.

What was the first noticeable indication that wetland area was diminishing in the United States, and what was done as a result?

Hunters first noticed that waterfowl populations were diminishing dramatically in the 1940's because loss of their breeding grounds and flyway. As a result, the duck stamp program became established to raise money for the protection and preservation of wetlands.

_______________ wetlands demonstrate the greatest variation between high and low water levels.

Riverine

________________ are a dominant feature of wetlands, which produce reduced conditions.

Anaerobic

____________ is the single most important determinate of the establishment and maintenance of specific types of wetlands and wetland processes.

hydrology

The rate of _________________ is affected by temperature and macrodetritivore activity.

decomposition

List three hydrologically-closed wetlands types.

-Vernal Pool

-Ombrotrophic bog

-Pocosin

-Prairie pothole

-Cypress dome

What three attributes must be present in order for an area to be considered a wetland?

1. Must have hydrology. The substrate must be covered for at least 5% of the growing season

2. Must have hydric soil

3. Must support hydrophytes

in short, must have wetland soils, water loving plants, and have water.

Describe why tides act as both a stress and a subsidy.

Tides are a stress because they bring salt into into coastal marshes/mangroves, and as a result of flooding, create saturated conditions (soil anaerobiosis).

They act as a subsidy because they remove excess salts and toxins from the marsh as well as bring in nutrients and sediments. Furthermore, incoming tides also help restore oxygenated (aerobic) condition to the area.

Please list the plant adaptions we discussed that directly influence oxygen availability in roots.

Lenticels

Aerenchyma

Pneumatophores

Adventitious roots

Shallow roots

Pressurized gas flow

To correctly answer this question, please follow these instructions. Looks at the terms before you and think of the relationships they share. You need to eliminate the term with the weakest relationship. Type that word first in your answer and place a period behind it. Then explain how the remaining terms are more closely related.

Buttressing. The remaining terms are related to mangroves. Lenticels (improve gas exchange with roots) are located on red mangrove prop roots and black mangrove pneumatophores.

How is it that crabs living in an intertidal area can continue to absorb oxygen when concentrations drop precariously low?

They have specialized blood pigments than enable them to continue to absorb oxygen even when other organisms cannot. If concentrations fall below that which they can absorb, they enter a state of dormancy. For example, fiddler crabs go completely inactive when oxygen concentrations drop low and can stay there for several tidal cycles

Hydrarch and Xerarch succession.

Both hydrarch and xerarch refer to classical succession theory (Clementian) in which communities progress in orderly and recognizable fashion to a climax community. They both display linear changes. (compare)

Hydrarch succession describes the linear change from open water or ocean to a forested climax community, while Xerarch succession describes linear change from bare rock to forested climax community. (contrast)

_____________ dictates the quantity of water flowing through both the Mississippi and the Achafalaya river systems.

Congress

Please give ten reasons why the current Mississippi River Delta no longer prograding.

-Subsidence/compaction of sediments

-Sea level rise

-Inability for the river to overflow banks

-Petroleum withdrawal

-Levees preventing lateral movement

-Dams restricting sediment flow downriver

-Current delta is losing sediments off continental shelf

-Interruption of delta cycle

-Canals/pipelines cut throughout coastal marshes

-Saltwater intrusion

-Hurricanes/storms

-Side-cast spoil materials preventing sediments from entering marshes

Why do wetland organisms exhibit adaptation not found in other ecosystems?

Because wetlands exhibit extreme conditions (stresses) not encountered in other habitats. The organisms that live in wetlands have to withstand conditions that most other organisms cannot deal with. These include low nutrient availability, fluctuating temperatures, anoxic conditions, high salinity and saturated soils.

Compare and contrast autogenic and allogenic succession in wetland development.

Both terms refer to theories of ecological succession in wetlands. Both are dependent on biota.

Autogenic succession is a Clemantian theory which suggests the development of distinct communities (aka: seres) that proceed in a linear fashion to a climax community. In this theory, all wetlands are in transition from open ocean to forest.

Allogenic succession, a Gleasonian theory, suggests that plant communities exist because they are adapted to those environmental conditions at that particular place and that particular time. Succession is a continuum in allogenic theory.

Why do wetlands tend to accumulate so much organic material? (two primary reasons)

1. They typically support unusually high levels of plant productivity

2. Decomposition of organic material is reduced under anaerobic conditions, and therefore accumulates.

Compare and contrast stress tolerators and regulators.

Both stress tolerators and stress regulators have mechanisms to survive in the face of environmental stresses. Stress tolerators either move out of the area or adapt to stresses while stress regulators expend energy in order to deal with the stress. Regulators actively expend energy to deal with stress!

what is a wetland?

transitional zone between water and land

why are wetlands important?

-take up 5-8% of Earth's surface on every continent besides Antarctica

-carbon sinks and help regulate climate

-stabilizes water supply

-controls flooding and filters polluted water

-forms the basis of food chains, supports rich biodiversity

why is protection of wetlands difficult?

people believe it is an infringement on property rights

history of wetland conservation

-prior to mid 70s, drainage and destruction of wetlands was encouraged

-first point of national concern was decline in waterfowl population, leading to Federal Duck Stamp Program (1934)

-Clean Water Act (1972) - keystone in wetland protection

-Food Security Act

bogs are __________

ombrotrophic - get water from precipitation

hydric soil

unique set of chemical reactions occur based on flooding/no oxygen

formed under saturation

hydroperiod

length of time area is flooded

measured by water depth, flow patterns,

hydrophyte

water plant

ecotone

transitional area between 2 habitat types

geromorphology

morphology of sediments beneath wetlands

single most important determinate of wetlands

hydrology

diurnal vs semidiurnal tides

diurnal - 1 high tide and 1 low tide per day

semidiurnal - 2 high tides and 2 low tides per day

how does vegetation impact hydrology?

-changes soil properties

-evapotranspiration

-increases flow resistance

-feedback loop: hydrology effects veg and veg effects hydrology

what explains wetland variation?

-water source

-geomorphic setting

-hydrodynamics

water wetland budget

balance of all inflows and outflows

what does decomposition require?

-electron donors

-moisture

-inorganic nutrients

-microorganisms

how to measure difference between organic and mineral soild?

bulk density

organic soils are classified as:

histols that can be:

-saprists (muck)

-fibrists (peat)

-hemists (mucky peat)

-folists

how does gleying happen?

when chemical species are reduced, become soluble in water, and removed from soil matrix (have not had oxygen in a long time)

only happens in low oxygen

oxidation vs. reduction

oxidation - chemical giving up an electron

reduction - gaining an electron

what is swamp gas?

when C is reduced to CH4 under highly deduced conditions

what is the most limiting nutrient in coastal ecosystems/wetlands?

nitrogen

then phosphorus

denitrification

carried out by facultative bacteria that converts N2 back to atmosphere

nitrogen mineralization/ammonification

organisms convert N to ammonium (NH4)

nitrogen fixation

first step of nitrogen cycle done with enzyme nitrogenase

carbon fermentation

also known as glycolysis, when organic matter is the terminal acceptor in anaerobic respiration

methanogenesis

when bacteria (methanogens) use CO2 as terminal acceptor for producing gaseous methane (CH4)

what can cause variability of concentrations of wetlands?

-climate

-human effects

-streamflow/ecosystem effects

-geographic effects

burial

where organisms are tied up and stored in areas unavailable to living organisms

sink vs. source

-sink - if net retention of a substance

-source - if net loss of a substance

obligate

able to exist or survive only in a particular environment or assuming a certain role (a restricted organism)

facultative

capable of functioning under varying environmental conditions

unicellular adaptations to anoxia

most are metabolic b/c cannot move

aerenchyma

structural plant adaptation to avoid root anoxia

stem hytrophy

buttressing caused by larger cells and lower density wood (not caused by aerenchyma)

adventitious roots

in hypoxic/anoxic conditions, ethylene stimulates formation of organs that assist plants in translocating oxygen to roots system

rapid stem elongation

when plants become established in submerged conditions or during rising water levels

shallow roots

helps vascular plant roots avoid anaerobic conditions

pneumatophores

air roots, structures that originate from roots of wetland plants and extend upwards protruding from ground

physiological plant adaptation

-pressurized gas flow

-rhizosphere oxygenation

-lower water uptake

-altered nutrient absorption

-avoiding sulfide

animal adaptations to control gas exchange

-special organs (gills/parapodia)

-improve o2 conditions

-respiratory pigments

-internal structural changes

fiddler crabs

-live in intertidal zones

-active at low tides and feed when marsh floor exposed

-when tides rise, retreat to burrows where oxygen concentrations can become low

simple marine organisms are ____ while complex organisms are ______

osmoconformers; osmoregulators

euryhaline vs stenohaline

-euryhaline - tolerant to varying salinities

-stenohaline - narrow osmotic limits

succession

-fundamental concept in ecology, predictable, and orderly changes in the composition or structure of an ecological community

seed banks

buried reserves of viable seeds that are important for wetland succession

pre-emption

role of chance plays larger role in the development of plant communities, especially in early stages

Functional Guild Model

group of functionally similar species in a community

Environmental Sieve Model

the presence and abundance of each species depends on its life history type and adaptation to the environment

the largest and most productive marsh ecosystem

Louisiana Delta

where does most of Mississippi River empty into?

Gulf of Mexico

delta progradation

the growth of a delta seaward, occurs by the accumulation of sediments in zones that shift seaward over time

sandy materials, silt, then clay

retrogradation

delta begins to disappear because the supply of sediment is not enough to offset sea level rise and dewatering of deposited sediment