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Interim Functional Assessment Model for Lake Dakota Sand Plains


REVIEW DRAFT III - November 28, 1997

INTERIM FUNCTIONAL

ASSESSMENT MODEL FOR

LAKE DAKOTA SAND PLAINS

(Please note: due to table formatting issues, some of the Index numbers do not align properly with the Measurement or Condition in some of the tables)

FUNCTIONAL PROFILE

Tentative Subclass Name: Depressional, Endo-saturated, Highly Permeable Substrate, Temporary and Seasonal Wetlands.

Tentative Reference Domain: Lake Dakota Sand Plain of North and South Dakota.

Existing Classification:

NWI—PEMA, PEMB, PEMC

S & K -- Class II and Class IIICircular 39 -- Type 1 and 3

Climate: Cool Subhumid, Cold Winters and Hot Summers, Broad Seasonal Fluctuations in precipitation and temperature.

Geomorphic Setting: Closed Depressions

Geologic Materials: Sandy Glacial Outwash modified by wind. Drainage pattern not well defined, High Water Table, Undulating sands with low relief.

Soil Types: Wetland Soils—Hamar, Venlo, Fossum and Rosewood. The discharge wetland soil in this group is likely Rosewood and in a few cases maybe a Fossum soil. Venlo and Hamar are recharge wetlands. Fossum soil is most likely a flow-through wetland.

Associated Upland Soils—Hecla, Ulen, Alymer and Bantry soils.

Hydrology

Water sources: Principally ground water with precipitation.

Water losses: Evapotranspiration. Hydro period fluctuations with upward, downward and lateral movement of water.

Hydrodynamics: Mainly lateral with some vertical fluctuations within the wetland

Hydrologic Functions: Dominated by Moderating Groundwater Flow with Static and Dynamic Water Storage.

What are the most common alterations that may impact hydrology? Irrigation, land leveling, Tiling, filling, tillage, dugouts.

Vegetative communities(NWI or other classification schemes) Range Sites: Subirrigated, Wet Meadow, Wetland

Fully functional ecosystem characterized by: Tall warm mixed grass seasonal herbaceous vegetation on uplands with native herbaceous vegetation in wetlands.

Somewhat impaired ecosystem characterized by: Cool season introduced vegetation/ overgrazed eroding soils.

Critically impaired ecosystem characterized by: Potatoes, carrots, onions and watermelons.

Vegetative Red Flags (T&E): Orchids(western prairie fringe) on temporary wetland fringe.

Noxious plants/ invaders: Leafy Spurge, Canada Thistle

Existing vegetative classification other(not NWI): Low Prairie zone, Wet Meadow zoneHabitat: What kind of “critters” rely on this subclass for part or all of their life cycles
shore birds, waterfowl, salamanders etc., deer, fox, rabbits, sharptail grouse, prairie chicken and passerine birds.

Any T&E critters--

Live here: American Burying Beetle - South DakotaPass through: Bald eagle, Peregrine falcon, Whooping craneRely on: none

Does this subclass exist in a complex
with similar wetlands: YES
with other types of wetlands: YES Semi-permanent.

Is ecosystem fragmentation an issue: YES

Biogeochemical Functions: Removal of elements and compounds, nutrient cycling, particulate retention.

What common impacts might impair biogeochemical functions:

1. Lowering of groundwater level by irrigation

2. Tile drainage

3. Filling of low areas

4. Application of fertilizer

5. Removal of native vegetation from wetland and upland

6. Dugouts

7. Surface ditches

Existing literature about this subclass in addition to citations in Northern Prairie Model:

Water Resources #18 by ND State Water Commission

Ph.D. Thesis, David Hopkins

NDSU Oakes Test Area

Bureau of Reclamation

Schulze, Nagel, Van Scoyoc, Henderson, Baumgardner. 1993. Significance of Organic Matter in Determining Soil Colors. SSSA Special Publication no. 31 71-90

Current research this subject:

BMP study site SW of Oakes on Hecla, Hamar and Rosewood soils - NDSU (also Embden soils)

INTERIM FUNCTIONAL ASSESSMENT MODEL FOR TEMPORARY AND SEASONAL WETLANDS ON THE SANDY OUTWASH PLAINS OF GLACIAL LAKE DAKOTA

Notes: This Interim sandy outwash plain HGM Model is patterned after the Northern Prairie Pothole Model. Many of the definitions, logic, rationale, functions, and variables have been taken from the model, however, not all of the functions and variables have been included in this interim model.

1.0 MAINTAIN CHARACTERISTIC HYDROLOGY

DEFINITION: The capacity of the wetland to regulate the outflow and/or the inflow and the ability of the wetland to provide storage of water.

Effects On-Site: Contributes to the maintenance of characteristic soils, vegetation, invertebrate and vertebrate communities, and provides for water storage.

Effects Off-Site: Modifies off-site hydrology of wetland and riverine systems within the groundwater flow net.

Discussion of Function:

A combination of the geological material and the regional water balance in the sand prairie leads to moderation of ground water flow, and dynamic and static water storage within the depressions. The principal water sources for the sand prairie depressional wetlands are from groundwater and precipitation, and the principal water loss is through evapotranspiration. These hydrological elements produce an inter- and intra-annual cycle of ground water exposure and water storage above and below the edge of the temporary wetlands. This cycle supports the diverse plant and animal habitats as well as biogeochemical processes. These sand plain depressional wetlands sustain the hydrological cycle. The hydrological dynamics of the Prairie Pothole Region are addressed by Stewart and Kantrud (1972), Winter (1989) and Kantrud et al. (1989).

Discussion of Variables:

The variables associated with the performance of this function focus on land use and on the physical integrity of soil conditions. Human activities at nearby lower elevations and above or within the wetland affect the rate of ground water movement and quantity of surface and subsurface water entering and leaving the wetland. Vupuse, Vwetuse, and Vsource are used to describe potential alterations of water flow to the wetlands. Land use activities also affect erosion and sediment import into the wetlands by water and wind. An increased sediment load will decrease the wetland's capacity to expose water and trap water to be routed to the groundwater. The degree of sedimentation is captured by the Vsed variable. Undisturbed soil conditions within the wetland are closely related to ground water movement and water storage through the ability of the soil to transmit and hold water interstitially. This soil condition is described in the Vsorpt variable. Finally, the elevation of surface or subsurface outlet below the wetland temporary zone boundary inside and outside of the wetland boundary and fill placed in the wetland impacts surface water elevations and, therefore, the ability of the depression to capture and expose groundwater. The Vhydalt variable reflects this aspect of the function.

1.0 maintain characteristic hydrology
Model Variable Measurement or Condition Index
Vhydalt Hydrology Alterations

Definition: Presence of a constructed subsurface and/or surface outlet below the temporary zone. Depth of fill, changes in depth of the subsurface or surface drain and distance from the wetland impacts wetland groundwater surface elevation.

Logic: Surface outlet, subsurface drain or fill impacts ground water surface elevations

Surface outlet or subsurface drain has no effect on wetland. Surface outlet or subsurface drain is > 500 feet from the wetland edge and less than 5 feet below the wetland bottom elevation. If surface outlet is present, it is at or above the temporary zone in elevation. No fill in wetland.

Surface outlet or subsurface drain 150 to 500 feet from wetland edge and greater than 3 feet below wetland bottom elevation. Surface outlet invert lowered to remove some static storage. No subsurface drain present in wetland. Wetland filled to reduce some static storage.

Surface outlet or subsurface drain within 150 feet of wetland edge removing all static water and greater than 3 feet below wetland elevation bottom. If large wetland tile spacing greater than 300 feet and ineffectively removing saturated conditions. Site filled to the top of the temporary zone with some saturation remaining in wetland.

Surface outlet below bottom of wetland, and subsurface drain 3 feet below wetland bottom elevation with spacing less than 300 feet in all parts within the wetland. Wetland filled eliminating saturated conditions in the wetland.

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1.0 maintain characteristic hydrology
Model Variable Measurement or Condition Index
Vsource: Source Area of Flow Interception by Wetland

DEFINITION: The area surrounding a wetland that defines the catchment and groundwater flow area to the wetland.

LOGIC: Altering drainage patterns within wetland and ground water flow area will impact ground water elevation within basin.

No alteration of upland watershed source area through surface alterations (e.g., ditches, dugouts, roads, terraces) subsurface alterations (e.g., tile drains, ditches, terraces), or additions(e.g., irrigation).

Surface alterations of upland watershed source area which impacts overland flow into wetland((e.g., ditches, dugouts, roads, terraces), however , no subsurface alterations(e.g., tile drains), or additions e.g., irrigation).

Upland watershed source area is changed to alter the dominant surface and subsurface flow path of water to the wetland(e.g., draining or irrigation return). However alteration does not change the wetland subclass.

Upland watershed source area is changed to alter the dominant surface and subsurface flow path of water to the wetland(e.g., draining or irrigation return) -AND- Alteration does change the wetland subclass.

Upland watershed source area extremely altered such that almost all water flow to wetland eliminated (e.g., urbanization).

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1.0 maintain characteristic hydrology
Model Variable Measurement or Condition Index
Vupuse: Upland Land Use

Definition: Dominant land use or condition of the upland watershed that contributes to the wetland.

Logic: Upland land use impacts the evapo-transpiration process that influences the quantity and quality of groundwater flow to the wetland.

Managed native prairie which allows for adequate plant recovery time between vegetation removal.

 

Dominated by non-native species under some type of management -OR- Native species managed under season long grazing -OR- Idle grassland cover-OR-
Permanent Hayland

 

Native or non-native species heavily grazed, some bare ground, low plant vigor-OR-No-till small grain
-OR- Minimum till in a grass/legume rotation

 

Native or non-native species heavily grazed, high amounts of bare ground, low plant vigor, and evidence of soil erosion-OR- No-till row crop, minimum till small grain

 

Row crop or conventional tillage small grain

 

Urban, semi-pervious, or impervious surface.(this condition will result in maximum overland flow; a high rate of delivery to wetland) If best management practices employed, the impact may be somewhat less.

 

 

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1.0 maintain characteristic hydrology
Model Variable Measurement or Condition Index
Vsed: Sediment Delivered to Wetland

DEFINITION: Extent of sediment delivered to wetland from human disturbance sources, including agriculture.

LOGIC: Land use and erodibility characteristics of the soil affect the potential for sediment delivery to the wetland. The amount of sediment in the basin impacts the capacity of the wetland to moderate groundwater flow and store water.

No evidence of sediment delivery to wetland.

Representative sediment depth --
in temporary zone – <2 to <6 inches

in seasonal zone -- <2 inches

Representative sediment depth --
in temporary zone – 6 to <8 inches

in seasonal zone -- 2 to <7 inches

Representative sediment depth --
in temporary zone – 8 to <11 inches
in seasonal zone -- 7 to <12 inches

Representative sediment depth --
in temporary zone – =>11inches
in seasonal zone -- =>12 inches-OR- Wetland filled but some basin remains -OR-
A vegetation zone change(ie Shallow Marsh to Wet Meadow)

Basin filled and landscape depression is not evident from surface features.

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NOTE: For Vsed in the Sand Plain Model any surface A horizon thickness greater than 10 inches in the temporary zone is considered sediment if actual thickness of the sediment (or fill) can not be determined. This thickness is applicable to the Lake Dakota Sand Plain and adjacent sand plains in Central and Eastern North Dakota.

1.0 maintain characteristic hydrology
Model Variable Measurement or Condition Index
Vsorpt: Soil Sorptive Properties

DEFINITION: The physical ability of soils to hold and transmit elements and compounds in the upper 18 inches of the soil.

LOGIC: In sandy soils organic matter content and consistence affect groundwater movement and water storage.

The mineral soil in the upper 6 inches or A horizon has a – value of 2 or 3 and chroma of 0 or value of <2 and chroma of <1 -AND-Nearly all sand grains visible to naked eye are coated with organic matter in all parts of the A horizon within 6 inches of the surface. -AND/OR- Consistence is very friable within 18 inches of the surface. -OR- Organic Matter is >4.0%

The mineral soil in the upper 6 inches or A horizon has a – value of 2 to 3 and chroma of 1 or value of 2 and chroma of 2 -AND- Some individual grains of sand are not coated with organic matter—a salt and pepper effect is visible in the A horizon within 6 inches of the surface. -AND/OR- Consistence is friable within 18 inches of the surface. -OR- Organic Matter is 1.5 to =<4.0%

The mineral soil in the upper 6 inches or A horizon has a – value of >3 to 4and chroma of 1or 2 -AND- Most individual grains of sand are not coated with organic matter in the A horizon within 6 inches of the surface. -AND/OR- Consistence is firm or very firm within 18 inches and loose within 6 inches of the surface or all parts of the A horizon. -OR-Organic Matter is <1.5%

The substrate is a non-porous medium, i.e., asphalt, concrete, etc.

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1.0 maintain characteristic hydrology
Model Variable Measurement or Condition Index
Vwetuse: Wetland Land Use

DEFINITION: Dominant land use and condition of the wetland.

LOGIC: Land use in the wetland affects soil pore space and vegetation-/evapo-transpiration relationships that influences characteristic hydrology.

No evidence of tillage in the wetland. -OR- If previously tilled, outermost(temporary) wetland zone intact. -AND/OR- If some use in the wetland(haying, grazing), no evidence of compaction or rutting equipment or excessive trampling by livestock.

No evidence of tillage in zones wetter than the temporary(wet meadow) zone. -AND- Temporary zone minimally impacted by moderate grazing, haying, or tillage in portion of the temporary zone.

Temporary zone tilled or heavily grazed most years. -AND- Zones wetter than temporary zone are rarely tilled or are intact.

Temporary wetland zone tilled or heavily grazed most years. -AND- Zones wetter than temporary wetland zone receive minimal tillage or are intact.

Wetland receives conventional tillage in all zone(s) most years; if recently tilled, evidence of vegetation, clods in furrows, etc.

Wetland more severely disturbed than indicated above; (e.g., no vegetation , rutted, pig farm, feedlot, urban fill).

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1.0 INDEX OF FUNCTION: Maintain Characteristic Hydrology

=SQRT(Vhydalt * (((Vsource + Vupuse + Vsed)/3) + ((Vsorpt + Vwetuse)/2)/2))

=SQRT(_______ * (((_______ + ______ +_____)/3) + ((____ _+ _______)/2)/2))

2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS

DEFINITION: Short- and long-term cycling and removal of elements and compounds on site through the abiotic and biotic processes that convert elements from one form to another and nutrient cycling.

Effects On-Site: Net effects of retention, conversion and release are balanced between gains through import processes and losses through hydrologic export, efflux to the atmosphere, long term retention in persistent biomass and sediments, and cycling.

Effects Off-Site: Retention of elements and compounds and nutrient cycling on site decreases probability of export to aquatic ecosystems down-gradient and consequent nutrient loading.

Discussion of Function

The use of the term cycling refers to the annual turnover or release of mainly nutrients and retention refers to the relatively long term accumulation or loss through conversion or removal of elements and compounds from in coming water sources. Elements include macronutrients essential to plant growth(e.g., nitrogen, phosphorous, potassium etc.)n and other elements such as heavy metals (e.g., zinc, chromium, etc.) that can be toxic at high concentrations. Compounds include herbicides, pesticides, and other imported materials. Mechanisms of cycling, retention, conversion, release and removal include sorption, sedimentation, denitrification, burial, decomposition to inactive forms, decay, uptake and incorporation into short and long lived annual and perennial herbaceous biomass, and similar processes(Brinson et al. (1985).

Discussion of Variables

The variables within this function reflect land use, abiotic, and biotic components. Land use activities impact the magnitude of elements and compounds entering the system and the natural cycling and removal processes of the elements and compounds. Land use is reflected by upland land use, wetland land use, and sediment delivery variables. (Vupuse, Vwetuse, and Vsed respectively). In addition, the condition, continuity, and width of a buffer around the wetland influences the amount of sediment and soluble elements and compounds delivered to the wetland. The impact of a buffer is reflected by the (Vbcondition, Vbcontinuity, and Vbwidth) variables.

Biotic components of the wetland ecosystem cycle and retain elements and compounds through biomass accumulation and litter production. Elements and compounds are recycled annually through decay and decomposition and Neely and Baker (1989) report decay

rates for some emergent plants in the Prairie Pothole region to be greater than one year indicating retention. These decomposition rates facilitate both cycling on an annual basis and retention on a longer than one year basis within the wetland. Biotic components consist of the plant and detritus variables (Vpcover and Vdetritus,) respectively.

The abiotic components assist reduction and oxidation processes that biogeochemically cycle and retain elements and compounds. Abiotic components are represented by the soil integrity (Vsorpt), and amount/presence of water represented by the (Vhydalt and Vsource) variables.

2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index
Vsource: Source Area of Flow Interception by Wetland

DEFINITION: The area surrounding a wetland that defines the catchment and groundwater flow area to the wetland.

LOGIC: Altering drainage patterns within wetland and ground water flow area will impact ground water elevation within the basin.

No alteration of upland watershed source area through surface alterations (e.g., ditches, dugouts, roads, terraces) subsurface alterations (e.g., tile drains, ditches, terraces), or additions(e.g., irrigation).

Surface alterations of upland watershed source area which impacts overland flow into wetland((e.g., ditches, dugouts, roads, terraces), however , no subsurface alterations(e.g., tile drains), or additions e.g., irrigation).

Upland watershed source area is changed to alter the dominant surface and subsurface flow path of water to the wetland(e.g., draining or irrigation return). However alteration does not change the wetland subclass.

Upland watershed source area is changed to alter the dominant surface and subsurface flow path of water to the wetland(e.g., draining or irrigation return) -AND- Alteration does change the wetland subclass.

Upland watershed source area extremely altered such that almost all water flow to wetland eliminated (e.g., urbanization).

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2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index
Vhydalt Hydrology Alterations

Definition: Presence of a constructed subsurface and/or surface outlet below the temporary zone. Depth of fill, changes in depth of the subsurface or surface drain and distance from the wetland impacts wetland groundwater surface elevation.

Logic: Surface outlet, subsurface drain or fill impacts ground water surface elevations and maintenance of saturated anaerobic conditions throughout the wetland. Additionally, outlets provide vectors for the transport of elements and compounds to off-site aquatic systems.

Surface outlet or subsurface drain has no effect on wetland. Surface outlet or subsurface drain is > 500 feet from the wetland edge and less than 5 feet below the wetland bottom elevation. If surface outlet is present, it is at or above the temporary zone in elevation. No fill in wetland.

Surface outlet or subsurface drain 150 to 500 feet from wetland edge and greater than 3 feet below wetland bottom elevation. Surface outlet invert lowered to remove some static storage. No subsurface drain present in wetland. Wetland filled to reduce some static storage.

Surface outlet or subsurface drain within 150 feet of wetland edge removing all static water and greater than 3 feet below wetland elevation bottom. If large wetland tile spacing greater than 300 feet and ineffectively removing saturated conditions. Site filled to the top of the temporary zone with some saturation remaining in wetland.

Surface outlet below bottom of wetland, and subsurface drain 3 feet below wetland bottom elevation with spacing less than 300 feet in all parts within the wetland. Wetland filled eliminating saturated conditions in the wetland.

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2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index
Vupuse: Upland Land Use

Definition: Dominant land use or condition of the upland watershed that contributes to the wetland.

Logic: Upland land use impacts the evapo-transpiration process and the potential availability of elements and compounds that influences the quantity and quality of groundwater flow to the wetland.

Managed native prairie which allows for adequate plant recovery time between vegetation removal.

Dominated by non-native species under some type of management -OR- Native species managed under season long grazing -OR- Idle grassland cover -OR- Permanent Hayland

Native or non-native species heavily grazed, some bare ground, low plant vigor -OR- No-till small grain -OR- Minimum till in a grass/legume rotation

Native or non-native species heavily grazed, high amounts of bare ground, low plant vigor, and evidence of soil erosion -OR- No-till row crop, minimum till small grain

Row crop or conventional tillage small grain

Urban, semi-pervious, or impervious surface.(this condition will result in maximum overland flow; a high rate of delivery to wetland) If best management practices employed, the impact may be somewhat less.

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2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index
Vwetuse: Wetland Land Use

DEFINITION: Dominant land use and condition of the wetland.

LOGIC: Land use in the wetland affects soil organic matter content, vegetation, and detrital biomass that results in characteristic retention, conversion, and release of elements and compounds.

No evidence of tillage in the wetland. -OR- If previously tilled, outermost(temporary) wetland zone intact. -AND/OR- If some use in the wetland(haying, grazing), no evidence of compaction or rutting equipment or excessive trampling by livestock.

No evidence of tillage in zones wetter than the temporary(wet meadow) zone. -AND- Temporary zone minimally impacted by moderate grazing, haying, or tillage in portion of the temporary zone.

Temporary zone tilled or heavily grazed most years. -AND- Zones wetter than temporary zone are rarely tilled or are intact.

Temporary wetland zone tilled or heavily grazed most years. -AND- Zones wetter than temporary wetland zone receive minimal tillage or are intact.

Wetland receives conventional tillage in all zone(s) most years; if recently tilled, evidence of vegetation, clods in furrows, etc.

Wetland more severely disturbed than indicated above; (e.g., no vegetation , rutted, pig farm, feedlot, urban fill).

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2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index
Vsed: Sediment Delivered to Wetland

DEFINITION: Extent of sediment delivered to wetland from human disturbance sources, including agriculture.

LOGIC: The amount of sediment in the basin impacts the capacity of the wetland to maintain saturated anaerobic conditions throughout the wetland.

No evidence of sediment delivery to wetland.

Representative sediment depth --
in temporary zone – <2 to <6 inches
in seasonal zone -- <2 inches

Representative sediment depth --
in temporary zone – 6 to <8 inches

in seasonal zone -- 2 to <7 inches

Representative sediment depth --
in temporary zone – 8 to <11 inches
in seasonal zone -- 7 to <12 inches

Representative sediment depth --
in temporary zone – =>11 inches
in seasonal zone -- =>12 inches
-OR-

Wetland filled but some basin remains
-OR-

A vegetation zone change(ie Shallow Marsh to Wet Meadow)

Basin filled and landscape depression is not evident from surface features.

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NOTE: For Vsed in the Sand Plain Model any surface A horizon thickness greater than 10 inches in the temporary zone is considered sediment if actual thickness of the sediment (or fill) can not be determined. This thickness is applicable to the Lake Dakota Sand Plain and adjacent sand plains in Central and Eastern North Dakota.

2.0 RETENTION CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index
Vpcover: Vegetation Density

DEFINITION: The abundance of woody and herbaceous plants in all vegetation zones within the wetland.

LOGIC: Living plant biomass cycles nutrients through (1) soil and water nutrient uptake, (2) biomass accumulation, and (3) litter production.

Canopy coverage 75% to 125 % of reference standard.

Canopy coverage 25% to 75% or > 125% of reference standards.

Canopy coverage 1% to 25% of reference standard -OR- vegetation clods in furrows, etc.

Plants absent , no canopy coverage.

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2.0 RETENTION CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index
Vdetritus: Detritus

DEFINITION: The presence of litter in several stages of decomposition(e.g., litter)

LOGIC: Provides an energy source and increased surface area for microbial processing of nutrients.

75% to 125% of reference standard

50% to 75% or >125% of reference standard

25% to 75% of reference standard

Litter layer 10% to 25% of reference standard.

Litter layer >0% to 10% of reference standard.

Litter absent

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2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index
Vsorpt: Soil Sorptive Properties

DEFINITION: The physical ability of soils to hold and transmit elements and compounds in the upper 18 inches of the soil.

LOGIC: In sandy soils organic matter content and consistence affect the sorptive capacity of soils to hold elements and compounds for release, retention, and conversion.

The mineral soil in the upper 6 inches or A horizon has a – value of 2 or 3 and chroma of 0 or value of <2 and chroma of <1
-AND-
Nearly all sand grains visible to naked eye are coated with organic matter in all parts of the A horizon within 6 inches of the surface.
-AND/OR-

Consistence is very friable within 18 inches of the surface.
-OR-
Organic Matter is >4.0%

The mineral soil in the upper 6 inches or A horizon has a – value of 2 to 3 and chroma of 1 or value of 2 and chroma of 2 -AND- Some individual grains of sand are not coated with organic matter—a salt and pepper effect is visible in the A horizon within 6 inches of the surface. -AND/OR- Consistence is friable within 18 inches of the surface. -OR- Organic Matter is 1.5 to =<4.0%

The mineral soil in the upper 6 inches or A horizon has a – value of >3 to 4and chroma of 1or 2 -AND- Most individual grains of sand are not coated with organic matter in the A horizon within 6 inches of the surface. -AND/OR- Consistence is firm or very firm within 18 inches and loose within 6 inches of the surface or all parts of the A horizon. -OR- Organic Matter is <1.5%

The substrate is a non-porous medium, i.e., asphalt, concrete, etc.

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2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index

Vbcondition: Grassland Buffer Condition

DEFINITION: Dominant land use condition within 50 feet of the outermost edge of the wetland.

LOGIC: The condition of the buffer to spread surface and subsurface flow and increase water contact time in the buffer helps to limit direct inputs of particulate and dissolved elements and compounds.

No alteration

Tillage disrupts up to 50% of area to wetland -OR- VOR > 75% of reference standard

Tillage disrupts 50% or more of area to wetland -OR- No buffer and no till agriculture on area adjacent to wetland. -OR- VOR >50% to 75% of reference standard.

VOR >25% to < 50% of reference standard.

No buffer but Best Management Practices (BMP'S) are used in area adjacent to wetland. -OR- VOR >0% to 25% of reference standard.

No buffer and no BMP'S used in area adjacent to wetland.

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2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index

Vbcontinuity: Grassland Buffer Continuity

DEFINITION: Continuity of the grassland within 50 feet of the outermost edge of the wetland.

LOGIC: The continuity of the buffer when intact spreads surface and subsurface flow and increases water contact time which helps to limit direct inputs of particulate and dissolved elements and compounds.

Continuity is >75% to 100%.

Continuity is >50% to 75%.

Continuity is >25% to 50%.

Continuity is >0% to 25%.

No continuity, however there is potential for recovery.

No continuity, and no potential for recovery.

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2.0 RETENTION, CONVERSION AND RELEASE OF ELEMENTS AND COMPOUNDS
Model Variable Measurement or Condition Index

Vbwidth: Grassland Buffer Width

DEFINITION: Width of grassland buffer surrounding outermost wetland edge(<=50 feet from wetland edge).

LOGIC: The width of an intact buffer influences the spreading of surface and subsurface flow and increases water contact time in the buffer that helps limit direct inputs of particulate and dissolved elements and compounds.

Buffer is greater than 50 feet wide.

Buffer is between 37.5 and 50 feet wide.

Buffer is between 25 and 37.5 feet wide.

Buffer is between 12.5 and 25 feet wide.

Buffer is between 0 and 12.5 feet wide.

There is no buffer.

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2.0 INDEX OF FUNCTION: Retention, Conversion and Release of Elements and Compounds

= ((Vsource + Vhydalt)/2 + (Vupuse + Vwetuse + Vsed)/3 + (Vpcover + Vdetritus)/2 + Vsorpt + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/5)

= (( _______ + ______)/2 + (______ + _______ + _____)/3 + (_______ + _______ )/2 + _____ + ((_______ + _ _________ + ________)/3)/5)

3.0 RETENTION OF PARTICULATES

DEFINITION: Deposition and retention of inorganic and organic particulates (>.45 um) from the water column, primarily through physical processes.

Effects On-Site: Sediment deposition in Sand Plain Depressions is a natural geologic process that is maintained over thousands of years. Natural rates of accumulation are slow. The presence of sediments and the processes that follow result in characteristic soils, hydrology, and geochemistry.

Effects Off-Site: Reduces potential export of sediment to downstream wetland and aquatic ecosystems and groundwater systems.

Discussion of Function

Retention applies to particulates arising from both on-site and off-site sources, but excludes in situ production of peat. The retention of particulates function contrasts with the retention, conversion and release of element and compounds function because the emphasis is more dependent on the physical processes (e.g., sedimentation and particulate removal). For example, sediment retention occurs through burial and chemical precipitation (e.g., removal of phosphorous by Fe+++). Dissolved forms maybe transported as particles after under going sorption and chelation (i.e., heavy metals mobilized with humic and fulvic compounds). Imported sediment can undergo renewed pedogenesis on site, which potentially involves weathering and release of elements that were previously inaccessible to mineral cycling(Brinson 1995).

Discussion of Variables

The variables associated with the performance of this function focus primarily on components of the system that affect the physical processes of particulate removal and sedimentation. Particulate removal is dependent upon an undisturbed water column. The variable (Vhydalt) captures the presence/absence of an outlet and the extent of impact it has on the water level. The variable (Vwetuse) captures the extent of disturbance that may resuspend particulate matter within the water column. Sedimentation is represented by direct evidence (Vsed), or by indirect evidence of potential sources via land use activities (Vupuse). For example, Adomaitias et al. (1967) found that an aeolian mixture of snow and soil from surrounding fields without vegetation yielded nearly twice as much sediment as that deposited into native prairie. In addition, the condition, continuity, and width of a buffer around the wetland influences the amount of particulates delivered to the wetland. The impact of a buffer is reflected by the (Vbcondition, Vbcontinuity, and Vbwidth) variables.

3.0 RETENTION OF PARTICULATES
Model Variable Measurement or Condition Index
Vupuse: Upland Land Use

Definition: Dominant land use or condition of the upland watershed that contributes to the wetland.

Logic: None to moderate disturbance of the prairie yields the least particulates delivered to the wetland by water and/or wind.

Managed native prairie which allows for adequate plant recovery time between vegetation removal.

Dominated by non-native species under some type of management -OR- Native species managed under season long grazing -OR- Idle grassland cover -OR- Permanent Hayland

Native or non-native species heavily grazed, some bare ground, low plant vigor -OR- No-till small grain -OR- Minimum till in a grass/legume rotation

Native or non-native species heavily grazed, high amounts of bare ground, low plant vigor, and evidence of soil erosion -OR- No-till row crop, minimum till small grain

Row crop or conventional tillage small grain

Urban, semi-pervious, or impervious surface.(this condition will result in maximum overland flow; a high rate of delivery to wetland) If best management practices employed, the impact may be somewhat less.

1.0


0.75

 


0.5

 

0.25

 

0.1

0.0

 

3.0 RETENTION OF PARTICULATES
Model Variable Measurement or Condition Index
Vsed: Sediment Delivered to Wetland

DEFINITION: Extent of sediment delivered to wetland from human disturbance sources, including agriculture.

LOGIC: The amount of sediment in the basin affects the capacity of the wetland to retain particulates.

No evidence of sediment delivery to wetland.

Representative sediment depth --
in temporary zone – <2 to <6 inches
in seasonal zone -- <2 inches

Representative sediment depth --
in temporary zone – 6 to <8 inches
in seasonal zone -- 2 to <7 inches

Representative sediment depth --
in temporary zone – 8 to <11 inches
in seasonal zone -- 7 to <12 inches

Representative sediment depth --
in temporary zone – =>11 inches
in seasonal zone -- =>12 inches -OR- Wetland filled but some basin remains -OR-A vegetation zone change(ie Shallow Marsh to Wet Meadow)

Basin filled and landscape depression is not evident from surface features.

1.0

0.75

 

0.50

 

0.25

 

0.1

 

 

0.0

NOTE: For Vsed in the Sand Plain Model any surface A horizon thickness greater than 10 inches in the temporary zone is considered sediment if actual thickness of the sediment (or fill) can not be determined. This thickness is applicable to the Lake Dakota Sand Plain and adjacent sand plains in Central and Eastern North Dakota.

3.0 RETENTION OF PARTICULATES
Model Variable Measurement or Condition Index
Vhydalt Hydrology Alterations

Definition: Presence of a constructed subsurface and/or surface outlet below the temporary zone. Depth of fill, changes in depth of the subsurface or surface drain and distance from the wetland impacts wetland groundwater surface elevation.

Logic: If an outlet is present, changes in outlet elevation can affect the degree to which particulates will be retained or exported

Surface outlet or subsurface drain has no effect on wetland. Surface outlet or subsurface drain is > 500 feet from the wetland edge and less than 5 feet below the wetland bottom elevation. If surface outlet is present, it is at or above the temporary zone in elevation. No fill in wetland.

Surface outlet or subsurface drain 150 to 500 feet from wetland edge and greater than 3 feet below wetland bottom elevation. Surface outlet invert lowered to remove some static storage. No subsurface drain present in wetland. Wetland filled to reduce some static storage.

Surface outlet or subsurface drain within 150 feet of wetland edge removing all static water and greater than 3 feet below wetland elevation bottom. If large wetland tile spacing greater than 300 feet and ineffectively removing saturated conditions. Site filled to the top of the temporary zone with some saturation remaining in wetland.

Surface outlet below bottom of wetland, and subsurface drain 3 feet below wetland bottom elevation with spacing less than 300 feet in all parts within the wetland. Wetland filled eliminating saturated conditions in the wetland.

1.0

 

 


0.5

 

 


0.1

 

 

 

0.0

3.0 RETENTION OF PARTICULATES
Model Variable Measurement or Condition Index
Vwetuse: Wetland Land Use

DEFINITION: Dominant land use and condition of the wetland.

LOGIC: If and outlet is present, wetland land use determines the degree to which particulates are retained or exported due to roughness.

No evidence of tillage in the wetland. -OR- If previously tilled, outermost(temporary) wetland zone intact. -AND/OR- If some use in the wetland(haying, grazing), no evidence of compaction or rutting equipment or excessive trampling by livestock.

No evidence of tillage in zones wetter than the temporary(wet meadow) zone. -AND- Temporary zone minimally impacted by moderate grazing, haying, or tillage in portion of the temporary zone.

Temporary zone tilled or heavily grazed most years. -AND- Zones wetter than temporary zone are rarely tilled or are intact.

Temporary wetland zone tilled or heavily grazed most years. -AND- Zones wetter than temporary wetland zone receive minimal tillage or are intact.

Wetland receives conventional tillage in all zone(s) most years; if recently tilled, evidence of vegetation, clods in furrows, etc.

Wetland more severely disturbed than indicated above; (e.g., no vegetation , rutted, pig farm, feedlot, urban fill).

1.0

 

 


0.75

 

0.50

 

0.25

 

0.1

 

0.0

3.0 RETENTION OF PARTICULATES
Model Variable Measurement or Condition Index

Vbcondition: Grassland Buffer Condition

DEFINITION: Dominant land use condition within 50 feet of the outermost edge of the wetland.

LOGIC: The condition of the buffer to spread surface and subsurface flow and increase water contact time in the buffer limits direct inputs of particulates.

No alteration

Tillage disrupts up to 50% of area to wetland -OR- VOR > 75% of reference standard

Tillage disrupts 50% or more of area to wetland -OR- No buffer and no till agriculture on area adjacent to wetland. -OR- VOR >50% to 75% of reference standard.

VOR >25% to < 50% of reference standard.

No buffer but Best Management Practices (BMP'S) are used in area adjacent to wetland. -OR- VOR >0% to 25% of reference standard.

No buffer and no BMP'S used in area adjacent to wetland.

1.0

0.75


0.5

 

0.25

0.1

 

0.0

3.0 RETENTION OF PARTICULATES
Model Variable Measurement or Condition Index

Vbcontinuity: Grassland Buffer Continuity

DEFINITION: Continuity of the grassland within 50 feet of the outermost edge of the wetland.

LOGIC: The continuity of the buffer when intact spreads surface and subsurface flow and increases water contact time which limits direct inputs of particulates.

Continuity is >75% to 100%.

Continuity is >50% to 75%.

Continuity is >25% to 50%.

Continuity is >0% to 25%.

No continuity, however there is potential for recovery.

No continuity, and no potential for recovery.

1.0

0.75

0.5

0.25

0.1

0.0

3.0 RETENTION OF PARTICULATES
Model Variable Measurement or Condition Index

Vbwidth: Grassland Buffer Width

DEFINITION: Width of grassland buffer surrounding outermost wetland edge(<=50 feet from wetland edge).

LOGIC: The width of an intact buffer influences spreading surface and subsurface flow and increases water contact time in the buffer which helps to limit direct inputs of particulates.

Buffer is greater than 50 feet wide.

Buffer is between 37.5 and 50 feet wide.

Buffer is between 25 and 37.5 feet wide.

Buffer is between 12.5 and 25 feet wide.

Buffer is between 0 and 12.5 feet wide.

There is no buffer.

1.0

0.75

0.5

0.25

0.1

0.0

3.0 INDEX OF FUNCTION: Retention of Particulates

Vhydalt > 0.5 use:

= (Vupuse + Vsed) + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/3)

= (_______ + _____) + ((__________ + __________ + _______)/3)/3)

Vhydalt <= 0.5 use:

= (Vhydalt + Vwetuse + Vupuse + Vsed + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/5)

= (_______ + _______ + ______ + ____ + ((___________ + __________ + _______)/3)/5)

4.0 MAINTENANCE OF CHARACTERISTIC PLANT COMMUNITY

DEFINITION: Characteristic plant communities are not dominated by exotic or nuisance species. Vegetation is maintained by mechanisms such as seed dispersal , seed banks, and vegetative propagation which respond to variations in hydrology and disturbances such as fire and herbivores. The emphasis is on the temporal dynamics and structure of the plant community as revealed by species composition and abundance.

Effects On-Site: Creates microclimatic conditions that support the life histories of plants and animals. Converts solar radiation and carbon dioxide into complex organic carbon that provides energy to drive food webs . Provides habitat for feeding, and cover for nesting, resting refuge, escape, and breeding for resident and migratory animals.

Effects Off-Site: Provides a source of vegetative propagules for adjacent ecosystems which assists in revegetation following drought or disturbance and provides for gene flow between populations. Provides habitat for animals from adjacent ecosystems and for migrating birds (waterfowl, waders, etc.).

Discussion of Function:
Vegetation accounts for most of the biomass of prairie wetland systems. The physical characteristics of living and dead plants are closely related to eco-system functions associated with hydrology, nutrient cycling, and the abundance and diversity of animal species (Lillie and Evard 1994). Vegetation is not static, however, and species composition and physical characteristics can change in space and time in response to natural and anthropogenic influences (Weller 1987).

The vegetation in the prairie pothole temporary (wet meadows) and seasonal (shallow marshes) wetlands changes both inter- and intra-annually due to regional climatic cycles and its effect on local hydrological regime (Weller 1987, Kantrud 1989, et al. 1989). Variable precipitation and evapotranspiration commonly lead to years of extended drought or above normal moisture. Cyclic vegetation patterns arise from these climatic conditions (see Section III, Part 2). Much of the variability is explained by Stewart and Kantrud (1972).

Discussion of Variables:
The variables within this functional index address plant community characteristics and potential anthropogenic disturbance.

Plant community characteristics alter with various types of perturbation. The ratio of native to non-native plant species (Vpratio) indicates the health of a plant community. A healthy plant community is comprised of a high percentage of native non-invasive plants. As a system becomes perturbed, invasive native and non-native species out-compete sensitive native species. Plant abundance, as measured by percent cover (Vpcover), captures the ability of the system to remain self-sustaining. Detritus (Vdetritus) maintains thermal regulation of rhizomes and propagules, and is essential for nutrient cycling. In addition, the condition, continuity, and width of a buffer around the wetland increases water contact time in the buffer and limits direct inputs of particulate and dissolved elements and compounds from altering characteristic plant populations. The impact of a buffer is reflected by the (Vbcondition, Vbcontinuity, and Vbwidth) variables.

The elements of a healthy plant community may be compromised by anthropogenic activities. Land use within the wetland (Vsed, Vwetuse) directly impacts plant communities by burying or disrupting detritus, seed banks, rhizomes, etc. Finally, hydrophytic plants are directly affected by water level and soil moisture regime which may be affected by the presence of an outlet. The presence and degree of impact of an outlet is reflected in the (Vhydalt) variable.

4.0 maintain characteristic plant community
Model Variable Measurement or Condition Index
Vwetuse: Wetland Land Use

DEFINITION: Dominant land use and condition of the wetland.

LOGIC: Disturbance in the wetland can have an influence on the maintenance of native plant populations.

No evidence of tillage in the wetland. -OR- If previously tilled, outermost(temporary) wetland zone intact. -AND/OR- If some use in the wetland(haying, grazing), no evidence of compaction or rutting equipment or excessive trampling by livestock.

No evidence of tillage in zones wetter than the temporary(wet meadow) zone. -AND- Temporary zone minimally impacted by moderate grazing, haying, or tillage in portion of the temporary zone.

Temporary zone tilled or heavily grazed most years. -AND- Zones wetter than temporary zone are rarely tilled or are intact.

Temporary wetland zone tilled or heavily grazed most years. -AND- Zones wetter than temporary wetland zone receive minimal tillage or are intact.

Wetland receives conventional tillage in all zone(s) most years; if recently tilled, evidence of vegetation, clods in furrows, etc.

Wetland more severely disturbed than indicated above; (e.g., no vegetation , rutted, pig farm, feedlot, urban fill).

1.0

 

 

0.75

 


0.50

 

0.25

 

0.1

 

0.0

4.0 maintain characteristic plant community
Model Variable Measurement or Condition Index
Vsed: Sediment Delivered to Wetland

DEFINITION: Extent of sediment delivered to wetland from human disturbance sources, including agriculture.

LOGIC: Land use and erodibility characteristics of the soil affect the potential for sediment delivery to the wetland. The amount of sediment delivered to the basin impacts the capacity of the wetland to maintain native plant populations.

No evidence of sediment delivery to wetland.

Representative sediment depth --
in temporary zone – <2 to <6 inches
in seasonal zone -- <2 inches

Representative sediment depth --
in temporary zone – 6 to <8 inches
in seasonal zone -- 2 to <7 inches

Representative sediment depth --
in temporary zone – 8 to <11 inches
in seasonal zone -- 7 to <12 inches

Representative sediment depth --
in temporary zone – =>11 inches
in seasonal zone -- =>12 inches
-OR-
Wetland filled but some basin remains
-OR-
A vegetation zone change(ie Shallow Marsh to Wet Meadow)

Basin filled and landscape depression is not evident from surface features.

1.0

0.75

 

0.50

 

0.25

 

0.1

 

 


0.0

NOTE: For Vsed in the Sand Plain Model any surface A horizon thickness greater than 10 inches in the temporary zone is considered sediment if actual thickness of the sediment (or fill) can not be determined. This thickness is applicable to the Lake Dakota Sand Plain and adjacent sand plains in Central and Eastern North Dakota.

4.0 maintain characteristic plant community
Model Variable Measurement or Condition Index
Vhydalt Hydrology Alterations

Definition: Presence of a constructed subsurface and/or surface outlet below the temporary zone. Depth of fill, changes in depth of the subsurface or surface drain and distance from the wetland impacts wetland groundwater surface elevation.

Logic: Surface outlet, subsurface drain or fill impacts ground water surface elevations, and thereby controls the assemblage of aquatic-/nonaquatic vegetation.

Surface outlet or subsurface drain has no effect on wetland. Surface outlet or subsurface drain is > 500 feet from the wetland edge and less than 5 feet below the wetland bottom elevation. If surface outlet is present, it is at or above the temporary zone in elevation. No fill in wetland.

Surface outlet or subsurface drain 150 to 500 feet from wetland edge and greater than 3 feet below wetland bottom elevation. Surface outlet invert lowered to remove some static storage. No subsurface drain present in wetland. Wetland filled to reduce some static storage.

Surface outlet or subsurface drain within 150 feet of wetland edge removing all static water and greater than 3 feet below wetland elevation bottom. If large wetland tile spacing greater than 300 feet and ineffectively removing saturated conditions. Site filled to the top of the temporary zone with some saturation remaining in wetland.

Surface outlet below bottom of wetland, and subsurface drain 3 feet below wetland bottom elevation with spacing less than 300 feet in all parts within the wetland. Wetland filled eliminating saturated conditions in the wetland.

1.0

 

 


0.5

 

 


0.1

 

 

 


0.0

4.0 maintain characteristic plant community
Model Variable Measurement or Condition Index

Vpratio: Ratio of Native to Non-native Plant Species

DEFINITION: The ratio of native to non-native plant species present in wetland zones as indicated by the top 4 dominants or by a more extensive species survey.

LOGIC: The presence of a high ratio of non-invasive native to invasive native and non-native plant species indicates that disturbances which interrupt naturally occurring cycles and other vegetative dynamics are minimal.

100% of the species in the wetland are native species and no woody species are present.

Native species comprise 75% to <100% of the canopy in each zone.

Native species comprise 50% to <75% of the canopy in each zone

Native species comprise 25% to <50% of the canopy in each zone.

Native species comprise 0% to <25% of the canopy in each zone. -OR- If Lythrum salicaria (Purple Loosestrife) is among the dominant species. OR- A single dominant plant specie (native or non-native) comprise a monotypic invasive stand within any wetland zone(e.g., cattail, reed canary grass, etc.).

Wetland unvegetated

1.0


0.75


0.5


0.25


0.1

 

 



0.0

4.0 maintain characteristic plant community
Model Variable Measurement or Condition Index
Vpcover: Vegetation Density

DEFINITION: The abundance of woody and herbaceous plants in all vegetation zones within the wetland.

LOGIC: Characteristic plant densities of native prairies influence a suite of plant community components:

seed/rhizome source, nutrient cycling processes, microclimate conditions, etc.

Canopy coverage 75% to 125 % of reference standard.

Canopy coverage 25% to 75% or > 125% of reference standards.

Canopy coverage 1% to 25% of reference standard -OR- vegetation clods in furrows, etc.

Plants absent , no canopy coverage.

1.0


0.5


0.1


0.0

4.0 maintain characteristic plant community
Model Variable Measurement or Condition Index
Vdetritus: Detritus

DEFINITION: The presence of litter in several stages of decomposition(e.g., litter)

LOGIC: Detrital biomass impacts nutrient cycling processes and disturbance regime (e.g., fire) and thereby influences plant assemblages.

75% to 125% of reference standard

50% to 75% or >125% of reference standard

25% to 75% of reference standard

Litter layer 10% to 25% of reference standard.

Litter layer >0% to 10% of reference standard.

Litter absent

1.0

0.75

0.5

0.25

0.1

0.0

4.0 maintain characteristic plant community
Model Variable Measurement or Condition Index

Vbcondition: Grassland Buffer Condition

DEFINITION: Dominant land use condition within 50 feet of the outermost edge of the wetland.

LOGIC: The condition of the buffer to spread surface and subsurface flow and increase water contact time in the buffer limits direct inputs of particulate and dissolved elements and compounds from altering characteristic plant populations.

No alteration

Tillage disrupts up to 50% of area to wetland -OR- VOR > 75% of reference standard

Tillage disrupts 50% or more of area to wetland -OR- No buffer and no till agriculture on area adjacent to wetland. -OR- VOR >50% to 75% of reference standard.

VOR >25% to < 50% of reference standard.

No buffer but Best Management Practices (BMP'S) are used in area adjacent to wetland. -OR- VOR > 0% to 25% of reference standard.

No buffer and no BMP'S used in area adjacent to wetland.

1.0

0.75


0.5

 


0.25

0.1

 

0.0

4.0 maintain characteristic plant community
Model Variable Measurement or Condition Index

Vbcontinuity: Grassland Buffer Continuity

DEFINITION: Continuity of the grassland within 50 feet of the outermost edge of the wetland.

LOGIC: The continuity of the buffer when intact spreads surface and subsurface flow and increases water contact time which limits direct inputs of particulate and dissolved elements and compounds from altering characteristic plant populations.

Continuity is >75% to 100%.

Continuity is >50% to 75%.

Continuity is >25% to 50%.

Continuity is >0% to 25%.

No continuity, however there is potential for recovery.

No continuity, and no potential for recovery.

1.0

0.75

0.5

0.25

0.1

0.0

4.0 maintain characteristic plant community
Model Variable Measurement or Condition Index

Vbwidth: Grassland Buffer Width

DEFINITION: Width of grassland buffer surrounding outermost wetland edge(<=50 feet from wetland edge).

LOGIC: The width of an intact buffer influences spreading surface and subsurface flow and increases water contact time in the buffer which limits direct inputs of particulate and dissolved elements and compounds from altering characteristic plant populations.

Buffer is greater than 50 feet wide.

Buffer is between 37.5 and 50 feet wide.

Buffer is between 25 and 37.5 feet wide.

Buffer is between 12.5 and 25 feet wide.

Buffer is between 0 and 12.5 feet wide.

There is no buffer.

1.0

0.75

0.5

0.25

0.1

0.0

4.0 INDEX OF FUNCTION: Maintain Characteristic Plant Community

= (Vwetuse + Vsed + Vhydalt + Vpratio + Vpcover + Vdetritus + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/7)

=(_______) + (____) + (_____) + (_____) + (______) + (______) + ((_________) + (______ _____) + (______)/3)/7)

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND

DEFINITION: Soil, vegetation, and other aspects of the ecosystem structure within a wetland are required by animals for feeding cover, and reproduction.

Effects On-Site: Habitat provides potential feeding, cover, and reproductive sites for resident and migratory fauna.

Effects Off-Site: Provides feeding, cover, and reproductive sites for resident and migratory fauna.

Discussion of Function:

This function indicated the suitability of vegetation structure, microtopography, and hydrologic conditions for sustaining animal populations. Habitat components (1) provide potential feeding, resting, and nesting sites for vertebrates and invertebrates ; (2) regulate and moderate fluctuations in temperature; and (3) provide habitat heterogeneity to support a diverse assemblage of organisms. Since structure is an important habitat component for resident and nonresident animals, communities possessing a greater structural complexity often are more diverse and species rich. If intensive studies of wildlife and animal communities are needed and justified, the Habitat Evaluation Procedure (HEP) should be used (U.S. Fish and Wildlife Service 1980).

Discussion of Variables:

Faunal habitat requirements are areas for resting, nesting, feeding, and shelter from predication and thermal stress. The integrity of the system's vegetation components, which supply the bulk of the faunal habitat requirements, is captured by the following variables: (Vpratio, Vpcover, and Vdetritus). Land use reflects the ability of the wetland to sustain the habitat conditions and is captured by the (Vupuse, Vwetuse, Vsed, and Vhydalt) variables. Finally, many animals nest or feed in the buffer zone surrounding the wetland, therefore, buffer integrity is measured. Buffer integrity is reflected by the three buffer variables: buffer width, buffer continuity, and buffer condition (Vbwidth, Vbcontinuity, and Vbcondition) respectively).

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index
Vupuse: Upland Land Use

Definition: Dominant land use or condition of the upland watershed that contributes to the wetland.

Logic: Upland land use can affect how organisms move within and between wetlands.

Managed native prairie which allows for adequate plant recovery time between vegetation removal.

Dominated by non-native species under some type of management -OR- Native species managed under season long grazing -OR- Idle grassland cover -OR- Permanent Hayland

Native or non-native species heavily grazed, some bare ground, low plant vigor -OR- No-till small grain -OR- Minimum till in a grass/legume rotation

Native or non-native species heavily grazed, high amounts of bare ground, low plant vigor, and evidence of soil erosion -OR- No-till row crop, minimum till small grain

Row crop or conventional tillage small grain

Urban, semi-pervious, or impervious surface.(this condition will result in maximum overland flow; a high rate of delivery to wetland) If best management practices employed, the impact may be somewhat less.

1.0


0.75



0.5

 

0.25

 

0.1

0.0

 

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index
Vwetuse: Wetland Land Use

DEFINITION: Dominant land use and condition of the wetland.

LOGIC: Land uses in the wetland affect habitat features directly through alteration of vegetation composition, horizontal and vertical structure, and native plant and invertebrate populations.

No evidence of tillage in the wetland. -OR- If previously tilled, outermost(temporary) wetland zone intact. -AND/OR- If some use in the wetland(haying, grazing), no evidence of compaction or rutting equipment or excessive trampling by livestock.

No evidence of tillage in zones wetter than the temporary(wet meadow) zone. -AND- Temporary zone minimally impacted by moderate grazing, haying, or tillage in portion of the temporary zone.

Temporary zone tilled or heavily grazed most years. -AND- Zones wetter than temporary zone are rarely tilled or are intact.

Temporary wetland zone tilled or heavily grazed most years. -AND- Zones wetter than temporary wetland zone receive minimal tillage or are intact.

Wetland receives conventional tillage in all zone(s) most years; if recently tilled, evidence of vegetation, clods in furrows, etc.

Wetland more severely disturbed than indicated above; (e.g., no vegetation , rutted, pig farm, feedlot, urban fill).

1.0

 

 

0.75

 


0.50

 

0.25

 

0.1

 

0.0

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index
Vsed: Sediment Delivered to Wetland

DEFINITION: Extent of sediment delivered to wetland from human disturbance sources, including agriculture.

LOGIC: Sediment delivered to the wetland affects the capacity of the wetland to maintain native faunal populations.

No evidence of sediment delivery to wetland.

Representative sediment depth --
in temporary zone – <2 to <6 inches
in seasonal zone -- <2 inches

Representative sediment depth --
in temporary zone – 6 to <8 inches
in seasonal zone -- 2 to <7 inches

Representative sediment depth --
in temporary zone – 8 to <11 inches
in seasonal zone -- 7 to <12 inches

Representative sediment depth --
in temporary zone – =>11 inches
in seasonal zone -- =>12 inches
-OR-
Wetland filled but some basin remains
-OR-
A vegetation zone change(ie Shallow Marsh to Wet Meadow)

Basin filled and landscape depression is not evident from surface features.

1.0

0.75

 

0.50

 

0.25

 

0.1

 

 


0.0

NOTE: For Vsed in the Sand Plain Model any surface A horizon thickness greater than 10 inches in the temporary zone is considered sediment if actual thickness of the sediment (or fill) can not be determined. This thickness is applicable to the Lake Dakota Sand Plain and adjacent sand plains in Central and Eastern North Dakota.

 

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index

Vpratio: Ratio of Native to Non-native Plant Species

DEFINITION: The ratio of native to non-native plant species present in wetland zones as indicated by the top 4 dominants or by a more extensive species survey.

LOGIC: The presence of a high ratio of non-invasive native to invasive native and non-native plant species provides seasonally diverse plant community and, thereby, year round resting, nesting, and food supply for resident and nonresident fauna.

100% of the species in the wetland are native species and no woody species are present.

Native species comprise 75% to <100% of the canopy in each zone.

Native species comprise 50% to <75% of the canopy in each zone

Native species comprise 25% to <50% of the canopy in each zone.

Native species comprise 0% to <25% of the canopy in each zone. -OR- If Lythrum salicaria (Purple Loosestrife) is among the dominant species. OR- A single dominant plant specie (native or non-native) comprise a monotypic invasive stand within any wetland zone(e.g., cattail, reed canary grass, etc.).

Wetland unvegetated

1.0


0.75


0.5


0.25


0.1

 

 


0.0

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index
Vpcover: Vegetation Density

DEFINITION: The abundance of woody and herbaceous plants in all vegetation zones within the wetland.

LOGIC: Characteristic plant densities of native prairie influence habitat components (e.g., resting, nesting, and food supply) to support resident and nonresident fauna.

Canopy coverage 75% to 125 % of reference standard.

Canopy coverage 25% to 75% or > 125% of reference standards.

Canopy coverage 1% to 25% of reference standard -OR- vegetation clods in furrows, etc.

Plants absent , no canopy coverage.

1.0


0.5


0.1


0.0

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index
Vdetritus: Detritus

DEFINITION: The presence of litter in several stages of decomposition(e.g., litter)

LOGIC: Characteristic detrital biomass within the wetland offers year round habitat components (e.g., resting, nesting, and food supply) that support characteristic numbers of resident and nonresident fauna.

75% to 125% of reference standard

50% to 75% or >125% of reference standard

25% to 75% of reference standard

Litter layer 10% to 25% of reference standard.

Litter layer >0% to 10% of reference standard.

Litter absent

1.0

0.75

0.5

0.25


0.1


0.0

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index
Vhydalt Hydrology Alterations

Definition: Presence of a constructed subsurface and/or surface outlet below the temporary zone. Depth of fill, changes in depth of the subsurface or surface drain and distance from the wetland impacts wetland groundwater surface elevation.

Logic: Surface outlet, subsurface drain or fill impacts ground water surface elevations, thereby impacting the performance of water storage and maintenance of aquatic-habitat conditions throughout the wetland.

Surface outlet or subsurface drain has no effect on wetland. Surface outlet or subsurface drain is > 500 feet from the wetland edge and less than 5 feet below the wetland bottom elevation. If surface outlet is present, it is at or above the temporary zone in elevation. No fill in wetland.

Surface outlet or subsurface drain 150 to 500 feet from wetland edge and greater than 3 feet below wetland bottom elevation. Surface outlet invert lowered to remove some static storage. No subsurface drain present in wetland. Wetland filled to reduce some static storage.

Surface outlet or subsurface drain within 150 feet of wetland edge removing all static water and greater than 3 feet below wetland elevation bottom. If large wetland tile spacing greater than 300 feet and ineffectively removing saturated conditions. Site filled to the top of the temporary zone with some saturation remaining in wetland.

Surface outlet below bottom of wetland, and subsurface drain 3 feet below wetland bottom elevation with spacing less than 300 feet in all parts within the wetland. Wetland filled eliminating saturated conditions in the wetland.

1.0

 

 


0.5

 

 


0.1

 

 

 


0.0

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index

Vbcondition: Grassland Buffer Condition

DEFINITION: Dominant land use condition within 50 feet of the outermost edge of the wetland.

LOGIC: The condition of an intact wetland/upland ectone influences the availability of food sources for aquatic fauna (e.g., terrestrial invertebrates and upland seeds for water fowl).

No alteration

Tillage disrupts up to 50% of area to wetland -OR- VOR > 75% of reference standard

Tillage disrupts 50% or more of area to wetland -OR- No buffer and no till agriculture on area adjacent to wetland. -OR- VOR >50% to 75% of reference standard.

VOR >25% to < 50% of reference standard.

No buffer but Best Management Practices (BMP'S) are used in area adjacent to wetland. -OR- VOR > 0% to 25% of reference standard.

No buffer and no BMP'S used in area adjacent to wetland.

1.0

0.75


0.5

 


0.25

0.1

 

0.0

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index

Vbcontinuity: Grassland Buffer Continuity

DEFINITION: Continuity of the grassland within 50 feet of the outermost edge of the wetland.

LOGIC: The continuity of an intact wetland/upland ecotone influences the availability of food sources for aquatic fauna (e.g., terrestrial invertebrates and upland seeds for water fowl).

Continuity is >75% to 100%.

Continuity is >50% to 75%.

Continuity is >25% to 50%.

Continuity is >0% t0o 25%.

No continuity, however there is potential for recovery.

No continuity, and no potential for recovery.

1.0

0.75

0.5

0.25

0.1

0.0

5.0 MAINTENANCE OF HABITAT STRUCTURE WITHIN WETLAND
Model Variable Measurement or Condition Index

Vbwidth: Grassland Buffer Width

DEFINITION: Width of grassland buffer surrounding outermost wetland edge(<=50 feet from wetland edge).

LOGIC: The width of an intact wetland/upland ecotone influences the availability of food sources for aquatic fauna(e.g., terrestrial invertebrates and upland seeds for water fowl). Additionally, this wetland-/upland interface offers habitat for edge species (e.g., amphibians).

Buffer is greater than 50 feet wide.

Buffer is between 37.5 and 50 feet wide.

Buffer is between 25 and 37.5 feet wide.

Buffer is between 12.5 and 25 feet wide.

Buffer is between 0 and 12.5 feet wide.

There is no buffer.

1.0

0.75

0.5

0.25

0.1

0.0

5.0 INDEX OF FUNCTION: Maintenance of Habitat Structure Within the Weland

= ((Vupuse + Vwetuse + Vsed + (Vpratio + Vpcover)/2 + Vdetritus + Vhydalt + (Vbcondition + Vbcontinuity + Vbwidth/3)/7

((_______ + ______ + _____ + (______ + _______)/2 + ________ + _______ + (__________ +

__________ + ________)/3)/7

6.0 MAINTENANCE OF HABITAT INTERSPERSION AND CONNECTIVITY AMONG WETLANDS

DEFINITION: The spatial relationship of an individual wetland with respect to adjacent wetlands in the complex.

Effects On-Site: The assessed wetland contributes to habitat features of the wetland complex by virtue of its position in the landscape.

Effects Off-Site: Contributes to overall landscape diversity of habitat for aquatic and terrestrial organisms.

Discussion of Function:

Wetlands provide water and other life requirements for motile species that primarily exploit upland habitats. In addition, all vegetational strata in wetlands, from herbaceous layer to tree canopy, provide wildlife corridors(connections) between different wetland types, between uplands and wetlands, and between uplands(Sedell et al. 1990). Such connections between habitats were more isolated from one another (Brinson 1995).

Discussion of Variables:

Uninterrupted corridors are critical for movement of animals within and between wetlands. The integrity of these corridors may be disturbed through human-induced perturbations both within and around the assessment area. The extent of these perturbations is represented by the variables (Vupuse, Vwetuse, and Vhydalt). (Vupuse) represents the land use within the watershed above the wetland, (Vwetuse) represents land-use within the wetland, and (Vhydalt) represents the maintenance of water level within the wetland and alterations which impact this maintenance. The width, continuity, and condition of a buffer influences the cover and movement of organisms within and between wetlands. The buffer is represented by the (Vbcondition, Vbcontinuity, and Vbwidth) variables.

Wetland density and wetland area (Vwden, Vwarea, respectively) reflect the density, area, and pattern of different types of wetlands in the landscape, and their contribution to habitat. The frequency of distribution of wetland sizes within a radius of one mile relates to the animal guilds that use the wetlands.

Sand Plain depressional wetlands in the prairie pothole region are a dynamic, integrated system that provides habitat for migratory ducks and geese. If a wetland is accessible and provides a high quality food source, waterfowl will seek it out. Waterfowl dynamics as they are related to wetland types are explained in Gersib et al. (1989).

6.0 MAINTENANCE OF HABITAT INTERSPERSION AND CONNECTIVITY AMONG WETLANDS
Model Variable Measurement or Condition Index
Vupuse: Upland Land Use

Definition: Dominant land use or condition of the upland watershed that contributes to the wetland.

Logic: Upland land use can affect how organisms move within and between wetlands.

Managed native prairie which allows for adequate plant recovery time between vegetation removal.

Dominated by non-native species under some type of management -OR- Native species managed under season long grazing -OR- Idle grassland cover -OR- Permanent Hayland

Native or non-native species heavily grazed, some bare ground, low plant vigor -OR- No-till small grain -OR- Minimum till in a grass/legume rotation

Native or non-native species heavily grazed, high amounts of bare ground, low plant vigor, and evidence of soil erosion -OR- No-till row crop, minimum till small grain

Row crop or conventional tillage small grain

Urban, semi-pervious, or impervious surface.(this condition will result in maximum overland flow; a high rate of delivery to wetland) If best management practices employed, the impact may be somewhat less.

1.0


0.75

 

 

0.5

 

0.25


0.1

0.0

 

6.0 MAINTENANCE OF HABITAT INTERSPERSION AND CONNECTIVITY AMONG WETLANDS
Model Variable Measurement or Condition Index
Vwetuse: Wetland Land Use

DEFINITION: Dominant land use and condition of the wetland.

LOGIC: Land uses in the assessed wetland affect the capacity of the wetland complex to maintain native faunal populations.

No evidence of tillage in the wetland. -OR- If previously tilled, outermost(temporary) wetland zone intact. -AND/OR- If some use in the wetland(haying, grazing), no evidence of compaction or rutting equipment or excessive trampling by livestock.

No evidence of tillage in zones wetter than the temporary(wet meadow) zone. -AND- Temporary zone minimally impacted by moderate grazing, haying, or tillage in portion of the temporary zone.

Temporary zone tilled or heavily grazed most years. -AND- Zones wetter than temporary zone are rarely tilled or are intact.

Temporary wetland zone tilled or heavily grazed most years. -AND- Zones wetter than temporary wetland zone receive minimal tillage or are intact.

Wetland receives conventional tillage in all zone(s) most years; if recently tilled, evidence of vegetation, clods in furrows, etc.

Wetland more severely disturbed than indicated above; (e.g., no vegetation , rutted, pig farm, feedlot, urban fill).

1.0

 

 

 

0.75

 

 

0.50

 


0.25

 


0.1

 


0.0

6.0 MAINTENANCE OF HABITAT INTERSPERSION AND CONNECTIVITY AMONG WETLANDS
Model Variable Measurement or Condition Index
Vhydalt Hydrology Alterations

Definition: Presence of a constructed subsurface and/or surface outlet below the temporary zone. Depth of fill, changes in depth of the subsurface or surface drain and distance from the wetland impacts wetland groundwater surface elevation.

LOGIC: Changes in the water surface elevation can 1) alter the surface connections among wetlands, 2) change productivity and habitat structure, and 3) change hydro-period, and, therefore, wetland class.

Surface outlet or subsurface drain has no effect on wetland. Surface outlet or subsurface drain is > 500 feet from the wetland edge and less than 5 feet below the wetland bottom elevation. If surface outlet is present, it is at or above the temporary zone in elevation. No fill in wetland.

Surface outlet or subsurface drain 150 to 500 feet from wetland edge and greater than 3 feet below wetland bottom elevation. Surface outlet invert lowered to remove some static storage. No subsurface drain present in wetland. Wetland filled to reduce some static storage.

Surface outlet or subsurface drain within 150 feet of wetland edge removing all static water and greater than 3 feet below wetland elevation bottom. If large wetland tile spacing greater than 300 feet and ineffectively removing saturated conditions. Site filled to the top of the temporary zone with some saturation remaining in wetland.

Surface outlet below bottom of wetland, and subsurface drain 3 feet below wetland bottom elevation with spacing less than 300 feet in all parts within the wetland. Wetland filled eliminating saturated conditions in the wetland.

1.0

 

 

 


0.5

 

 

 


0.1

 

 

 

 

0.0

6.0 MAINTENANCE OF HABITAT INTERSPERSION AND CONNECTIVITY AMONG WETLANDS
Model Variable Measurement or Condition Index

Vbcondition: Grassland Buffer Condition

DEFINITION: Dominant land use condition within 50 feet of the outermost edge of the wetland.

LOGIC: The condition of an intact wetland/upland ectone influences the cover and movement of organisms within and between wetlands.

No alteration

Tillage disrupts up to 50% of area to wetland -OR- VOR > 75% of reference standard

Tillage disrupts 50% or more of area to wetland -OR- No buffer and no till agriculture on area adjacent to wetland. -OR- VOR > 50% to 75% of reference standard.

VOR >25% to < 50% of reference standard.

No buffer but Best Management Practices (BMP'S) are used in area adjacent to wetland. -OR- VOR >0% to 25% of reference standard.

No buffer and no BMP'S used in area adjacent to wetland.

1.0

0.75

 

0.5

 

 

0.25


0.1

 


0.0

6.0 MAINTENANCE OF HABITAT INTERSPERSION AND CONNECTIVITY AMONG WETLANDS
Model Variable Measurement or Condition Index

Vbcontinuity: Grassland Buffer Continuity

DEFINITION: Continuity of the grassland within 50 feet of the outermost edge of the wetland.

LOGIC: The continuity of an intact wetland/upland ecotone influences the cover and movement of organisms within and between wetlands.

Continuity is >75% to 100%.

Continuity is >50% to 75%.

Continuity is >25% to 50%.

Continuity is >0% to 25%.

No continuity, however there is potential for recovery.

No continuity, and no potential for recovery.

1.0

0.75

0.5

0.25

0.1


0.0

6.0 MAINTENANCE OF HABITAT INTERSPERSION AND CONNECTIVITY AMONG WETLANDS
Model Variable Measurement or Condition Index

Vbwidth: Grassland Buffer Width

DEFINITION: Width of grassland buffer surrounding outermost wetland edge(<=50 feet from wetland edge).

LOGIC: The width of an intact wetland/upland ecotone influences the cover and movement of organisms within and between wetlands.

Buffer is greater than 50 feet wide.

Buffer is between 37.5 and 50 feet wide.

Buffer is between 25 and 37.5 feet wide.

Buffer is between 12.5 and 25 feet wide.

Buffer is between 0 and 12.5 feet wide.

There is no buffer.

1.0

0.75

0.5

0.25

0.1

0.0

6.0 MAINTENANCE OF HABITAT INTERSPERSION AND CONNECTIVITY AMONG WETLANDS
Model Variable Measurement or Condition Index
Vwden: Density of water regime in the landscape

Definition: The absolute density of wetlands in a given water regime within a 1 mile radius from the center of the wetland.

Logic: Wetland landscapes often support many wetlands of different types (e.g., temporary, seasonal, semipermanent, and permanent). The density and pattern of different types of wetlands in the landscape is related to how animals use them and , hence, their contribution to habitat.

Density of wetlands within 1 mile radius from the center of the assessment wetland is > 75% of reference standard based on physiographic region (e.g., Glaciated Plains-vs- Missouri Coteau).

Density of wetlands within 1 mile radius from the center of the assessment wetland is 50%- 75% of reference standard based on physiographic region (e.g., Glaciated Plains-vs- Missouri Coteau).

Density of wetlands within 1 mile radius from the center of the assessment wetland is 25%- 50% of reference standard based on physiographic region (e.g., Glaciated Plains-vs- Missouri Coteau).

Density of wetlands within 1 mile radius from the center of the assessment wetland is 10%- 25% of reference standard based on physiographic region (e.g., Glaciated Plains-vs- Missouri Coteau).

Density of wetlands within 1 mile radius from the center of the assessment wetland is >0%- 10% of reference standard based on physiographic region (e.g., Glaciated Plains-vs- Missouri Coteau).

No other wetlands within a 1 mile radius.

1.0

 

 

0.75

 

 

0.50

 

 

0.25

 

 

0.10

 

 

0.0

6.0 MAINTENANCE OF HABITAT INTERSPERSION AND CONNECTIVITY AMONG WETLANDS
Model Variable Measurement or Condition Index
Vwarea: Wetland area in the landscape

Definition: The ratio of total area of temporary and seasonal wetlands to the total area of semi-permanent and permanent wetlands within a 1 mile radius of the assessment site.

Logic: Wetland landscapes often support wetlands of different sizes. The animal guilds that use them is related to the frequency distribution of sizes. One way to capture the size variable is to determine the ratio of the total area of drier wetlands (temporary and seasonal) and wetter (semi-permanent and permanent) wetlands within a one mile radius of the wetland being assessed. A radius of one mile is an appropriate scale for the range of dispersion and movement of most animal groups.

Ratio 75% to 125% of reference standards based on physiographic region (e.g., Glaciated Plains -vs- Missouri Coteau).

Ratio 50% to 75% of reference standards based on physiographic region (e.g., Glaciated Plains -vs- Missouri Coteau).

Ratio 25% to 50% of reference standards based on physiographic region (e.g., Glaciated Plains -vs- Missouri Coteau).

Ratio 10% to 25% of reference standards based on physiographic region (e.g., Glaciated Plains -vs- Missouri Coteau).

Ratio >0% to 10% of reference standards based on physiographic region (e.g., Glaciated Plains -vs- Missouri Coteau).

No other wetlands within a 1 mile radius (e.g., Glaciated Plains -vs- Missouri Coteau).

1.0

 

0.75

 

0.50

 

0.25

 

0.10

 

0.0

6.0 INDEX OF FUNCTION: Maintenance of Habitat Interspersion and Connectivity among Wetlands

=SQRT (((Vupuse + Vwetuse + Vhydalt + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/4) * (Vwden + Vwarea)/2)

=SQRT(((______ + ________ + ______ + ((__________ + ___________ + _______)/3)/4) * (_______ + _______)/2)

OR -- USE NUMBER OF BREEDING PAIRS OF DUCKS

1.0 INDEX OF FUNCTION: Maintain Characteristic Hydrology

=SQRT(Vhydalt * (((Vsource + Vupuse + Vsed)/3) + ((Vsorpt + Vwetuse)/2)/2))

=SQRT(_______ * (((_______ + ______ +_____)/3) + ((____ _+ _______)/2)/2))

2.0 INDEX OF FUNCTION: Retention, Conversion and Release of Elements and Compounds

= ((Vsource + Vhydalt)/2 + (Vupuse + Vwetuse + Vsed)/3 + (Vpcover + Vdetritus)/2 + Vsorpt + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/5)

= (( _______ + ______)/2 + (______ + _______ + _____)/3 + (_______ + _______ )/2 + _____ + ((_______ + _ _________ + ________)/3)/5)

3.0 INDEX OF FUNCTION: Retention of Particulates

Vhydalt > 0.5 use:

= (Vupuse + Vsed) + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/3)

= (_______ + _____) + ((__________ + __________ + _______)/3)/3)

Vhydalt <= 0.5 use:

= (Vhydalt + Vwetuse + Vupuse + Vsed + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/5)

= (_______ + _______ + ______ + ____ + ((___________ + __________ + _______)/3)/5)

4.0 INDEX OF FUNCTION: Maintain Characteristic Plant Community

= (Vwetuse + Vsed + Vhydalt + Vpratio + Vpcover + Vdetritus + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/7)

=(_______) + (____) + (_____) + (_____) + (______) + (______) + ((_________) + (______ _____) + (______)/3)/7)

5.0 INDEX OF FUNCTION: Maintenance of Habitat Structure Within the Wetland

= ((Vupuse + Vwetuse + Vsed + (Vpratio + Vpcover)/2 + Vdetritus + Vhydalt + (Vbcondition + Vbcontinuity + Vbwidth/3)/7

((_______ + ______ + _____ + (______ + _______)/2 + ________ + _______ + (__________ +

__________ + ________)/3)/7

6.0 INDEX OF FUNCTION: Maintenance of Habitat Interspersion and Connectivity among Wetlands

=SQRT (((Vupuse + Vwetuse + Vhydalt + ((Vbcondition + Vbcontinuity + Vbwidth)/3)/4) * (Vwden + Vwarea)/2)

=SQRT(((______ + ________ + ______ + ((__________ + ___________ + _______)/3)/4) * (_______ + _______)/2)

OR -- USE NUMBER OF BREEDING PAIRS OF DUCKS

VARIABLES

Vbcondition ____________
Vbcontinuity ____________
Vbwidth ____________
Vdetritus ____________
Vhydalt ____________
Vpcover ____________
Vsorpt ____________
Vpratio ____________
Vsed ____________
Vsource ____________
Vupuse ____________
Vwarea ____________
Vwden ____________
Vwetuse ____________

Comments on Variables

Vbcondition: Reference standards have not been collected for the Sand Plain Model.

Vdetritus: Reference standards have not been collected for the Sand Plain Model for this variable.

Vhydalt: All hydrology values have been incorporated into one variable Vhydalt. This variable could be split into 2 variables. One to cover surface outlet and filling of the wetland and the other to cover removal of the saturation by Vsubout adjusted to the proper spacing

Vsorpt: The Vsorpt variable is being developed for the Interim HGM Model on depressions in the Lake Dakota Sand Plains. Since this is an Interim Model, field testing has not been done and data will need to be gathered to further refine and develop this variable as it is used and tested. As defined this variable is applied to the A horizon or upper 6 inches of the soil except for the consistence indicator which applies to the upper 18 inches unless otherwise stated.

At this time the soils considered are the Rosewood, Venlo, Fossum and Hamar series that are hydric. Other states interested in using this Model are South Dakota, Nebraska, and Kansas. Colors, Organic Matter and Consistence levels will need to be checked and adapted as this is applied in the field.

The 1.0 index applies to soils that are least disturbed and if tilled minimally impacted and are able to sorb a high level of elements and compounds for cycling. The Organic Matter levels are high.

The 0.5 index soils are disturbed (annually tilled and cultivated or slightly eroded) and the Organic Matter has been reduced thus lowering the ability of the soils to cycle elements and compounds

The 0.1 index soils are frequently tilled, cultivated and eroded and much of the Organic Matter has been lost in the upper 6 inches.

pH is also an indicator of sorptive capacity of soils. May need to develop as a primary indicator, but probably is not easily enough done in a routine Functional Assessment.

Access to and the ability to query the North Dakota Laboratory Data computer database would add credibility and improve the refinement of this variable. Awaiting development of this ability at this time. Other states with Laboratory Data would be of help in adapting these indicators.

The uniformity or pureness of color as described by the salt and pepper effect for the sandy soils is a clue to the organic matter levels of these sandy soils and also to some degree in the loamy and silty textured soils as well. A change in pureness of color may not be described by color chip, but can be seen with the naked eye. This was noticed when comparing older(10+ years) no-till and grassland soils to annually tilled and cultivated cropland soils.

Ideally, a color index such as developed by Illinois would greatly facilitate the use of this variable in the field for sandy hydric soils.

Any comment or help is appreciated on this variable and its indicators.