UWA Wetlands Ecology (BY45912126SU2) Exam one

Define soil matrix

refers to the solid framework of the soil—the combination of mineral particles, organic matter, and the pore spaces between them that together create the physical structure in which water, air, and organisms exist.

Hydrophytes can exert_____ control on the hydrology and physicochemical environment

biotic

1. List two ways hydrophytes can affect hydrology

1. 1. evapotranspiration

2. 2. increases flow resistance

1. Compare and contrast: stress tolerators and stress regulators

Tolerators have functional modifications
that enable them to survive and often
function efficiently in the presence of
stress.
• In contrast, Regulators actively avoid
stress or modify it to minimize its effects.
• The mechanisms for either are many and
varied, but are related to the type of
organism. (bacteria vs. plants vs. animals,
etc)

Organisms attempting to withstand or avoid
stresses must expend energy to protects it’s
cells from external stresse

1. define: halophile

are organisms that survive high‑salt environments by keeping their internal osmotic concentration slightly higher than the surrounding medium. Because Na⁺ is toxic when accumulated, they avoid absorbing it and instead build up less harmful ions like K⁺ to balance osmotic pressure.

1. Define: Bulk density

Bulk density is the mass of dry soil per unit volume, including both the soil particles and the pore spaces. It reflects how compact or loose the soil matrix is.

1. The rate of _______ is affected by temperature and macro-detritivore activity

Decomposition

1. compare and contrast: fluting and butressing

• Fluting is primarily a surface modification of the trunk caused by water or erosion.

• Buttressing is a structural support adaptation that stabilizes the tree in unstable soils.

Both occur in wetland or saturated environments and reflect how trees adapt to hydrology and soil instability.

1. Wetlands occur most extensively in regions where ________ exceeds losses to evapotranspiration and runoff

Precipitation and rainfall

1. What two things have the most influence on wetland plant community types?

hydrology

soil physicochemical conditions

1. Denitrification converts _____ Amonimne _____ to N2O, and ultimately ______ nitrogen ____ gas, which escapes into the atmosphere

Denitrification converts nitrate (NO₃⁻) to N₂O, and ultimately dinitrogen (N₂) gas, which escapes into the atmosphere.

1. ________ is considered to be one of the most limiting nutrients in costal wetlands

Nitrogen

1. List the five major components that comprise a wetland water budget

1. 1. net precipitation

2. 2. surface inflows, including flooding streams

3. 3. groundwater inflow/groundwater outflow

4. 4. evapotranspiration

5. 5. surface outflows

1. Compare and contrast: Saprist and Fibrist Soils

Saprists (muck) 2/3rds of the material is
decomposed and less than 1/3rd of plant fibers
are identifiable

Fibrists (peat) Less than 1/3rd of the material is
decomposed, >2/3rds of fibers are indentifiable

Hemists (mucky peat or peaty muck) conditions
lie between saprist and fibrist

Compare and contrast: Euryhaline and stenohaline

Both terms describe salinity tolerance and how organisms regulate internal water and ion balance.

Key Contrast

• Euryhaline = broad salinity tolerance; thrive in fluctuating environments.

• Stenohaline = narrow salinity tolerance; restricted to stable environments.

1. Essay: looking for clear and coherent thought here! Using examples, describe the general structure of a food web in a tidal marsh, beginning with primary producers and ending with the ultimate fate of the materials/ energy produced. Include in your description the possible pathways energy can flow.

Soil exceed the aerobic and anaerobic levels, plants exceed at the cellular level, animals exceed at the organism/organ level. The soil brings in certain plants that feed off its higher oxygen rate which can handle large to large amounts of water and sometimes larger salt levels. Which then brings in other animals like fish and birds to eat off the plants and the surrounding stuff. The organic matter leftover thing gets decomposed back into the soil at the rate of how water fills the soil, the climate, participation.

1. All wetlands tend to recycle nutrients repeatedly

true

1. Define: bankfull discharge

When the river flow exceeds holding capacity
and enters a flood plain

1. Describe the origin of soils designated as folists

Organic soils created by excessive
moisture (precip>evap). Found in tropical and
boreal mountains. NOT classified as hydric

1. Eliminate and why: Ammonium, ammonia, nitrate, nitrite

Nitrogen can only be used in certain forms by
living organisms:
– NH 4 – Ammonium
– NO 2 – Nitrite
– NO 3 – Nitrate
• Forms such as N2 (dinitrogen) and NH3 (ammonia)
can not be assimilated by most living organisms.
• Since most Nitrogen exists as N2, a gas, it must be
converted before use

1. _________ wetlands are the most favorable for exporting materials, energy and biota to adjacent ecosystems

pulsed

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

Flooded soils, saturated soils, and anoxic conditions

1. Define: hydroperiod

is the seasonal pattern of water presence in a wetland — the timing, duration, frequency, and depth of flooding or soil saturation.

1. Methane released from wetlands is often called _______

swamp gas

compare and contrast: Oxidation and reduction

Oxidation occurs when a chemical gives up an
electron – either an O2 or an H+

Reduction is the opposite process that
releases O2 , gaining H or gaining an electron

Redox potential (oxidation/reduction potential)
is a measure of the electron availability in a
solution, and is often used to quantify the
degree of electrochemical reduction of wetland
soils.

1. Give two reasons why wetlands accumulate organic matter

1. 1. increased primary productivity

2. 2. decreased decomposition rates

3. 
   

1. Compare and contrast: primary and secondary succession

Succession that begins in areas where no soil is
initially present is called primary succession,
whereas succession that begins in areas where soil is
already present is called secondary succession

Succession may be initiated either by formation of
new unoccupied habitat (e g a lava flow or a severenew, unoccupied habitat (e.g., a lava flow or a severe
landslide) or by some form of disturbance (e.g. fire,
severe windthrow, logging) of an existing community.

1. What two strategies do vascular plants use to alleviate salt stress

Vascular plants reduce salt stress by (1) ion exclusion—blocking Na⁺/Cl⁻ uptake, and (2) ion sequestration—storing salts in vacuoles to prevent cytoplasmic toxicity

1. A lack of O2 prevents plants from carrying out aerobic root respiration, and strongly affects the availability of nutrients

true

1. What three factors affect wetland variation

1. 1. geomorphic setting(ex. floodplain, estuary fringe)

2. 2. water source

3. 3. hydrodynamics (ex. unidirectional flow, reversing flow)

1. What can influence the hydraulic conductivity of wetland soils?

How dense the soil is, how compacted it is with water, what nutrients are currently there

1. Consider a marsh. Please discuss, using specific examples from the community, the various feedback mechanisms operating on and between hydrology the physiochemical environment, and then biota ( plant the animals) that are found there

freshwater tides-(distribution and hydrology)-Widespread; seasonal to permanent flooding. (biota)- Grasses, sedges, frogs

Tidal salt and brackish marsh-(distribution and hydrology)-Intertidal zones; semidiurnal to fortnightly
flooding. (biota)- Salt-tolerant grasses and rushes, killifish, crabs, clams, snails

1. Ferrous iron can reach toxic concentrations in wetland soils, and ultimately prevent plants _______ uptake when oxidized around the roots

nutrient

1. _______ gives soils the red, brown-yellow and orange color when dry.

ferric iron

1. Deltas will continue to ______ grow _____ as long as sediment supply exceeds the rate of ______ decomposition ______.

deltas will continue to prograde as long as the
sediment supply exceeds the rate of relative sediment supply exceeds the rate of relative
sea level rise (or in the case of the modernsea level rise (or in the case of the modern
birdbird--foot, reach the continental shelf)foot, reach the continental shelf

1. Define alluvial valley

The edge of the recent
deposition areas (resulting from over bankdeposition areas (resulting from over bank
flows, etc.)flows, etc.)

1. Multicellular organisms often use reduced inorganic compounds as energy source

false

1. A wetland is a source for a specific substance if it shows net _____ profit ______ of the substance, and it is a sink if it shows net _____ loss _____ of the substance

retention

A wetland is a source if it shows net export (profit) of a substance, and it is a sink if it shows net retention (loss) of the substance.

1. Define: ecosystem engineer

is an organism that creates, modifies, or maintains habitats, thereby changing the availability of resources for other species.