Wetland Functions LACUSTRINE FRINGE COOS BAY, OR

Transcription

1 Wetland Functions LACUSTRINE FRINGE COOS BAY, OR

2 Introduction- This Module will: Introduce the terms Functions and Values Explain the need for Measurable Variables Explain how Variable ratings are combined to measure functions Show that different wetlands have different functions Make the case for a Functional Classification System Introduce Functional Assessments

3 What are Wetland Functions? Mathematical Equations? Ecosystem Services? Physical Processes? Societal Values? All of the Above? None of the Above?

4 Functions Are Processes That can be: Defined Measured Assessed Restored, Created, or Enhanced Defended in Front of: The Scientific Community The Public

5 Functions are not Values Values are: Aesthetic Subjective Based on Opinion Not Easily Quantified Can be Monetized

6 Measuring Wetland Values Which wetland has the greatest aesthetic value?

7 In Other Words: Justify why you care about this (particular) wetland? SLOPE WETLAND BOX ELDER CO., UT

8 Some Considerations: Different Wetlands Perform Different Functions Forcing an Increase in a Function Usually Results in a Decrease in Other Functions Functions Interact Functions are both On-site and Off-Site The List of Functions is Virtually Endless Functional Performance is Variable Temporally Spatially

9 Functions Can be put into Categories: Hydrologic Bio-Geochemical Wildlife Habitat Landscape

10 Hydrologic Functions: Hydrograph Attenuation Offsite Maintenance of Downstream Baseflow Offsite Surface Ponding for Habitat Onsite Soil Saturation for Plant Community Onsite Sediment Cycling Onsite and Offsite Aquifer Recharge On and Offsite Storm Surge Attenuation Offsite

11 Hydrograph Attenuation: Flashy Urban Hydrograph Highly Attenuated Western Snowmelt Hydrograph

12 Maintenance of Downstream Baseflows: Nebraska Sandhills: Water stored in these saturated wetlands is slowly released to maintain long term baseflow in these streams

13 Surface Ponding: Usually a Function Needed to Support Wildlife Habitat Little Hydrologic or Biogeochemical Benefit from Surface Water over Saturation Presence of Ponding measured as Frequency and Duration DEPRESSIONAL Carolina Bay, South Carolina

14 Soil Saturation: Most or all of the soil profile is saturated May be Saturated continuously down to the local water table OR may be Saturated on top of a perching layer Denitrification is much more effective in saturated/not ponded conditions Carbon Sequestration is much more efficient in saturated/not ponded conditions Measured as depth, duration and frequency of groundwater table

15 Sediment Cycling: Sediment moves from uplands and through watercourses to the ocean Movement is longitudinal and lateral Sediment is deposited by lateral and vertical accretion Sediment is removed by meander translation and scour This process is temporally and spatially variable This process depends on hydrologic disturbance. Need Channel Forming flows AND Flood Flows

16 Sediment Cycling (Cont.): Sediment moving through a watershed is not soil erosion, it is sediment transport Soil erosion is soil moving from it s source Wetlands exist in a state of equilibrium with sediment deposition and removal The hydrologic events of interest are more in the range of the 25-yr. and less in the 2-yr.

17 Sediment Cycling Case Study: RIVERINE North Central MO Wetland Restoration Project Sediment enters as with tailwater, not transported by headwater V latcon increased with levee breach

18 Biogeochemical Functions: Denitrification Phosphorous Cycling Sequestration of Organic Carbon Accumulation of Heavy Metals Carbon Export Most of These Require Anaerobic Conditions

19 Denitrification: Occurs when: Water with Dissolved Nitrates Discharge into Soil with Organic Carbon Energy Source. Under Anaerobic Conditions Direct Conversion to Nitrogen gas occurs as Anaerobic bacteria break nitrates down.

20 Phosphorous Cycling: Phosphorous is a Mineral Enters Wetlands attached to sediment OR in Dissolved form Taken up by plants Discharged in Dissolved form with outflow Removed by animals or humans as plant biomass Removed by animals or humans in animal carcasses

21 Sequestration of Organic Carbon: Carbon exists in wetland soils Soil Saturation promotes carbon accumulation because anaerobic conditions prevent oxidation Ranges from O horizons in Mineral Soils to True Organic Soils Accumulation is highest under conditions of near continuous saturation

22 Habitat Functions: Maintenance of Characteristic Plant Community Maintenance of Rare and Endangered Plant Community Maintenance of Waterfowl Habitat Essentially, the Abiotic Functions Interact to Create the Processes that Provide the Biotic Functions Key Points Hydrologic and Geochemical Functions are Driven by Soil Hydrodynamic Properties Wetlands that have the same Hydrologic and Geochemical Processes tend to have the same types of soils I. E. - The same soil Map Units tend to have the same processes

23 Landscape Functions: Interspersion and Connectivity for Wildlife Habitat to: Other wetlands (like and unlike) Other Habitats Provide Watershed Functions Appropriate to the Watershed Position of the Wetland Uplands Headwaters Low Order Streams Floodplains

24 Measurement: We can t Measure Functions Directly We Must Find Variables that Combine to Define Functions Variables Must be Truly Variable Variables Must be Measurable Factors necessary for functions to occur V1 VOAhor Condition of the O and/or A horizons in the soil profile V2 Vcompact Soil compaction V3 Vsoil Soil integrity within the WAA V4 Vdrain Anthropogenic drainage of the site V5 Vmicro Natural microtopography V6 Vlanduse Natural land cover within the surrounding watershed V7 Vrichness Richness of wet prairie associated plant species

25 Function Formulas: FCI is Functional Capacity Index Variable Scoring is From 0 to 1 Function Scores are From 0 to 1 Variable Weighting is Determined by Consensus the Interdisciplinary Team Vfeatures Vbwidth Vconnect Vcontig Habitat 1 FCI FCI = (( ) 4) x 0.68 FCI = (1.75 4) x 0.68 FCI = 0.44 x 0.68 FCI = 0.30

26 Hydrologic Variables: V latcon Lateral Connectivity Between the Stream Channel and it s Floodplain V subin Interception of Subsurface Inflow V subout - Subsurface Drainage Outflow V surfin Diversion of Surface Inflow V surfout Surface Outflow V drain Artificial Drainage V micro Microtopography V macro Macrotopography V watershed Hydrologic condition of contributing watershed

27 Lateral Connectivity (V latcon ): Degree of Connection Between a Real Stream and it s Floodplain Quantified by Frequency and Duration of Flooding

28 Microtopography (V micro ): Small, <6 or so in depth Hard to Build in restoration Temporally Dynamic Created by Water Created by Soil Created by Plant Community

29 Macrotopography (V macro ): Large Floodplain Features More Permament, but Still Temporally Variable Can Replicate in Restoration with Construction Equipment

30 Interception of Subsurface Inflow (V subin ): Interception Ditch Around Perimeter Of Large Discharge Wetland in Upstate NY GW Discharge

31 Biogeochemical Variables: Wetland Biogeochemical Processes Occur NOT because the soil is WET, but because the soil is ANAEROBIC! V poro Soil Porosity V SOM Soil Organic Matter V structure Soil Structure V ph Soil ph V compaction Soil Compaction V disturbance Soil Disturbance V soil health Soil Health

32 Landscape Variables: V contig Contiguous habitat between wetland and surrounding landscape V connect Habitat connections V proximity Wetland Proximity V buffer Native vegetation surrounding wetland V disturb Natural disturbance processes present

33 Landscape Variables: V proximity Aerial photography and ground reconnaissance Wetland Assessment Area Depressions Northern IL Proximity to Other Wetlands 2400 ft Measure Score < 300 ft ft ft ft 0.25 > 900 ft 0.10

34 Case Studies: Wyoming Headwater Reach Fed by Groundwater Discharge How Well can This Wetland Provide: Waterfowl Habitat? Hydrograph Attenuation? Downstream Baseflow Maintenance? Denitrification?

35 Case Studies: High Plains Playa TX Panhandle Fed by surface runoff How Well can This Wetland Provide: Waterfowl Habitat? Baseflow Maintenance? Aquifer Recharge? Denitrification? Photo: Dr. Loren Smith

36 Case Studies: Flatwoods KY Stream Terrace Fed by direct precipitation How Well can This Wetland Provide: Hydrograph Attenuation? Carbon Sequestration? Surface Ponding?

37 Case Studies: Floodplain Tennessee How Well can This Wetland Provide: Hydrograph Attenuation? Sediment Cycling? Surface Ponding?

38 So, how do we: Sort wetlands by function? Spatially define where a wetland type exists? Tell how our type operates? Assess how well our type is performing? Stay Tuned

39 Questions?