PSS Exam #2 QUESTIONS WITH CORRECT ANSWERS 100% SOLVED| GUARANTEED SUCCESS
*Intro to Soil Water* ...
Waterlogged soils -May include wetlands, seasonally wet depressions/flat areas, or
compacted soils
-Hydrophytes predominate (plants adapted to wet conditions)
-most other plants will suffer from oxygen deficiency in saturated soils
Affecting soil aeration -anything that affects macroporosity (ex. tillage, soil texture,
pedoturbation, soil structure)
-rates of respiration by microorganisms consuming oxygen (as affected by available food)
-rates of respiration by plants
-depth in profile
-seasons (soil temperature)
-vegetation effects on soil water content
-anaerobic & aerobic conditions can coexist
Effect of aeration on decomposition of organic materials -low oxygen levels slow aerobic
decomposition leading to a build-up of organic matter
-slower, anaerobic decomposition is favored, with alcohol or ethylene (toxic) gas end products
,Redox-dependent toxicity -arsenic most mobile & toxic in reduced state
-chromium most toxic in oxidized state
-ethylene gas production
-forms of soluble micronutrients (Fe2+ & Mn2+) can become toxic at higher levels
Wetlands -transition b/w air & water
-cover 14% of world's ice-free land; critically important natural resource
What is a wetland? -soils that are water-saturated near the surface for prolonged periods
when soil temps and other conditions are such that plants and microbes can grown and remove
the soil oxygen, thereby assuring anaerobic conditions
-considered a transition zone b/w terrestrial & aquatic ecosystems
-very easy to detect the wet boundary, but delineation of wetlands on the dry side is an entire
discipline
Types of wetlands -inland swamps & bogs
-riparian zones
-histosols
-salt marshes
-histels
,Wetland history... -Over half of wetlands that originally occurred in U.S. have been
destroyed by artificial drainage or filling
-for a long time, U.S. gov't encouraged & assisted drainage of wetlands, considering them
useless public health risks
-Today, USDA & other gov't agencies are responsible for protecting & restoring wetlands for
their benefits to society & environment
Roles & Benefits of wetlands in an ecosystem -Habitat: for rare wildlife, migrating birds,
spawning grounds for commercially-important fish
-Water filtration/purification: filter out sediments, nutrients and excess organic substances
before water reaches rivers, lakes groundwater
-Reduced flooding: slows runoff water & stores it, releasing it slowly to rivers
-Shoreline protection/erosion control: prevents shoreline & bank erosion by buffering the
energy of waves
-Natural products: cranberries, blueberries, fish
-Recreation: canoeing, bird-watching, fishing, hunting
-Groundwater recharge: allows for more infiltration of purified water to aquifers
, Wetland delineation -defining the boundaries of a wetland, from the wetter to drier end
-deciding what is and what's not a wetland has huge implications for....
*agriculture
*urban development
*watershed management
Ana area is designated a wetland if it possesses all 3 of the following characteristics during
some part of the growing season: -wetland hydrology or water regime
-hydric soils
-hydrophytic plants
Wetland Hydrology -Saturated soil conditions must be present for some part of the growing
season
-many wetlands are saturated for only short times during the growing season, depending on
their hydroperiod
Hydroperiod -the temporal pattern of change in the water table
Hydric soils 3 properties: 1. periods of saturation inhibit O2 diffusion
2. periods of reduced conditions
*Intro to Soil Water* ...
Waterlogged soils -May include wetlands, seasonally wet depressions/flat areas, or
compacted soils
-Hydrophytes predominate (plants adapted to wet conditions)
-most other plants will suffer from oxygen deficiency in saturated soils
Affecting soil aeration -anything that affects macroporosity (ex. tillage, soil texture,
pedoturbation, soil structure)
-rates of respiration by microorganisms consuming oxygen (as affected by available food)
-rates of respiration by plants
-depth in profile
-seasons (soil temperature)
-vegetation effects on soil water content
-anaerobic & aerobic conditions can coexist
Effect of aeration on decomposition of organic materials -low oxygen levels slow aerobic
decomposition leading to a build-up of organic matter
-slower, anaerobic decomposition is favored, with alcohol or ethylene (toxic) gas end products
,Redox-dependent toxicity -arsenic most mobile & toxic in reduced state
-chromium most toxic in oxidized state
-ethylene gas production
-forms of soluble micronutrients (Fe2+ & Mn2+) can become toxic at higher levels
Wetlands -transition b/w air & water
-cover 14% of world's ice-free land; critically important natural resource
What is a wetland? -soils that are water-saturated near the surface for prolonged periods
when soil temps and other conditions are such that plants and microbes can grown and remove
the soil oxygen, thereby assuring anaerobic conditions
-considered a transition zone b/w terrestrial & aquatic ecosystems
-very easy to detect the wet boundary, but delineation of wetlands on the dry side is an entire
discipline
Types of wetlands -inland swamps & bogs
-riparian zones
-histosols
-salt marshes
-histels
,Wetland history... -Over half of wetlands that originally occurred in U.S. have been
destroyed by artificial drainage or filling
-for a long time, U.S. gov't encouraged & assisted drainage of wetlands, considering them
useless public health risks
-Today, USDA & other gov't agencies are responsible for protecting & restoring wetlands for
their benefits to society & environment
Roles & Benefits of wetlands in an ecosystem -Habitat: for rare wildlife, migrating birds,
spawning grounds for commercially-important fish
-Water filtration/purification: filter out sediments, nutrients and excess organic substances
before water reaches rivers, lakes groundwater
-Reduced flooding: slows runoff water & stores it, releasing it slowly to rivers
-Shoreline protection/erosion control: prevents shoreline & bank erosion by buffering the
energy of waves
-Natural products: cranberries, blueberries, fish
-Recreation: canoeing, bird-watching, fishing, hunting
-Groundwater recharge: allows for more infiltration of purified water to aquifers
, Wetland delineation -defining the boundaries of a wetland, from the wetter to drier end
-deciding what is and what's not a wetland has huge implications for....
*agriculture
*urban development
*watershed management
Ana area is designated a wetland if it possesses all 3 of the following characteristics during
some part of the growing season: -wetland hydrology or water regime
-hydric soils
-hydrophytic plants
Wetland Hydrology -Saturated soil conditions must be present for some part of the growing
season
-many wetlands are saturated for only short times during the growing season, depending on
their hydroperiod
Hydroperiod -the temporal pattern of change in the water table
Hydric soils 3 properties: 1. periods of saturation inhibit O2 diffusion
2. periods of reduced conditions
