NRS 423 Lecture Exam 1

3 important characteristics of a wetland

hydrology (inundation/saturation), hydric soils, biota

hydric soils

soils formed under saturated conditions

wetland definition

Wetlands are lands where saturation

with water is the dominant factor

determining the nature of soil

development and the types of plant

and animal communities living in the

soil and on its surface (Cowardin 1979).

legal wetland definition

Those areas that are inundated or

saturated by surface or groundwater at a

frequency and duration sufficient to support,

and that under normal circumstances do

support, a prevalence of vegetation

typically adapted for life in saturated soil

conditions. Wetlands generally include

swamps, marshes, bogs and similar areas.

(US ACOE 2012)

freshwater marshes

dominated by non-woody vegetation, emergent plants, mineral soils

freshwater swamps

dominated by woody vegetation, mineral to mucky soils

forested swamps

acidic to neutral water

shrub swamps

short + tall shrubs, dense vegetation

vernal pools

ephemeral (<12 months) hydroperiod

wet meadows

step in wetland succession, maintained by animals or land use practices

bogs

peat accumulation, acidic conditions, sphagnum, no significant inflow or outflow of water

fens

peat accumulation, acidic conditions, emergent vegetation, drainage from mineral soils

coastal salt ponds

periodic breaching, sandy shoreline

tidal salt marsh

tidal flow, impacted by humans

factors responsible for wetlands

hydrology, climate, biota, physiological environment, geomorphology, time

main drivers of wetland ecology

climate: monthly and annual precip

geomorphology: duration of water storage, where water forms on landscape, quality + quantity of habitat for biota. steep=fewer wetlands

hydrology importance

influences biochemistry of soils, most important factor controlling formation and maintenance of wetland types and processes

hydroperiod

portion of the year a wetland is inundated or saturated

wetland water budget

hydroperiod results from balance of water inputs and outputs, topography, subsurface soil, geology, groundwater

precip+ surface inflows + groundwater inflows - evapotranspiration - surface outflows - groundwater outflows +_ tides

wetlands most common

in areas where precip exceeds evapotranspiration rates

recharge

wetland has connection at some point in year with groundwater

when surface water of wetland is higher than water table

perched

wetland has no connection with groundwater

discharge

surface water of wetland is lower than water table

evapotranspiration

Water that evaporates from water/soil in

a wetland + moisture that is transpired

by vascular plants to atmosphere

hydrology impact on physiochemical environment

transport of sediments, nutrients, and toxins (in and out)

biotic controls on hydrology

plants: peat accretion, sediment storage, nutrient retention

animals: beavers, muskrats, geese, alligators

hydrophytic vegetation

plants that can survive and grow in wetlands

deficiency in soil oxygen

limited plant growth by respiration, water + mineral uptake, photosynthesis, unstable substrate for root attachment

morphological plant adaptations

buttressed stems, lenticels, hollow stems, shallow roots

buttressed stems

flared stems, improve gas exchange, mechanical support

hollow stems

increase aeration to roots

hypertrophied lenticels

enlarged lenticels, open pores that allow continuous gas exchange, improve gas exchange

pneumatophores

aeration organs on roots extend out of water, “knees”

shallow root systems

low oxygen levels and high water tables influence root growth, roots cannot survive in anoxic conditions

marine

open ocean over continental shelf

estuarine

deepwater tidal habitats and tidal wetlands

rivertine

wetlands contained within a channel unless dominated by vegetation or deepwater with higher salinity

lacustrine

wetlands in topographic depression with less than 30% vegetative cover, greater than 8 hectares in size

palustrine

non-tidal wetlands with greater than 30% vegetation, less than 8 hectares in size, tidal wetlands with low salinity

common wetlands in US

Palustrine (104,274), estuarine (24,333), lactustrine (16,859)

subtidal, intertidalm tidal

substrate exposure, water velocity

lower perennial, upper perennial, intermittent

water velocity and hydroperiod

limnetic and littoral

water depth

classes

describe general appearance of wetland focusing on dominant vegetation and substrate type

class based on

aerial cover

subclasses

further definition to a class

common waterfowl in wetlands

mallard, american black duck, wood duck, mute swans, canada geese

wood duck

near extinction late 1800s, 1918 wood duck box installments increased popualations, found in variety of wetlands

mute swan

invasive, use phragmites, increase pollution and contamination

turtles in RI

diamondback terrapin, snapping turtle, eastern musk turtle

frogs and toads

american bullfrog, green frog, wood frog, american toad

eastern spadefoot toad

breed in vernal pools (short hydroperiod), dont breen in unfavorable conditions, endangered

nitrogen and wetlands

N converts NH4 via mineralization in soils

in anaerobic soils NH4 consumed by plants/microbes, immobilized by negatively charged soil particles, or diffuses into aerobic layer

nitrogen in aerobic soils

nitrification converts NH4 to NO3 which is mobile and lost as runoff

NO3 can move to anaerobic soils and denitrify

denitrification

significant path of nitrogen loss in wetlands (not peatlands)

runoff and water quality

nitrogen in runoff leads to negative impacts on human health and ecosystem function

wetlands help reduce nutrient loading

nutrient overload

heavy nutrient loads cause eutrophication: animal die offs, contaminate drinking water

maganese

aerobic soils: mn is oxidized

anaerobic soils: nm is reduced

bog iron

iron carried into peatlands by groundwater, when oxidized it precipitates, smelted for tools and weapons

sulfur

hydrogen sulfide accumulates in hydric soils

high concentrations toxic to plants

carbon

fermentation in anaerobic soils vs aerobic respiration

methanogenesis: pecialized microbes (called methanogens) create methane gas as they break down nutrients

inundation/saturation effect on soil properties

extended periods of inundation affect pedogenesis

inundation fills pore spaces with water instead of air

existing oxygen consumed by microbes creating anaerobic conditions

anaerobic bacteria and prolonged inundation leads to hydric soils

redox ladder

soils definition

A natural body comprised of solids

(minerals and organic matter),

liquids, and gases that occurs on

the land surface, occupies space,

and is characterized by one or

more of the following: horizons, or

layers, that are distinguishable

from the initial material as a result

of additions, losses, transfers,

and transformations of energy or

the ability to support rooted

plant growth

hydric soil definition

Soils that formed under

conditions of saturation,

flooding or ponding long

enough during the growing

season to develop

anaerobic conditions in the

upper part.

hyrdric soil development factors

organisms, topography, parent material, time, climate, human activity

parent material

bedrock or transported material (glacial till + outwash in RI)

climate

humid climates = more water

are climate = less water

topography

depressions retain

slopes drain

time

soil formation ongoing

longer inundation, more frequent inundation

biota

microbes, plants, insects, beavers, muskrats, alligators encourage/impede development

human activities

changes in impervious surface

land clearing and dam building

agriculture

organic soil

dominated by plant material

greasy

stains fingers

porous and squishy

mineral soil

<20-25% organic matter

gritty

no stain

resists compression

O

organic layer, with lots of undecayed organic materials, not usable by plants in soil

A

topsoil: most important layer for plants because of decomposed organic material

E

leached layer, not in some soils

B

subsoil rich in minerals

C

deposited sediments from parent material

R

bedrock level

texture

classified by % sand, silt, clay

hue

dominant color family

value

lightness or darkness

chroma

strength of color