Status & Trends of Wetlands in Minnesota Vegetation Quality Baseline
Michael Bourdaghs MN’s Wetland Resource
– No net loss of the quantity, quality & biological diversity Omernik level II Ecoregions of MN’s wetlands – How do we know if we’re meeting no net loss? – Quantity Status &Trends • DNR estimates 10.6 million acres (+/- 364k) • Regional differences in quantity & predominant types • 2006-11: slight gain – Depressional Marsh Quality Status & Trends • Statewide: • 37% Good • 20% Fair • 42% Poor • Regional differences in depressional wetland quality • 674k acres (6.4% of extent) MWCA Survey Design
– MN Wetland Condition Assessment (MWCA) goal • Describe overall condition of MN’s wetlands – Vegetation condition is the primary indicator – Intensification of EPA’s National Wetland Condition Assessment (NWCA) – Target population • All non-cultivated wetlands with < 1m of surface water – Sample Frame — MN Status & Trends Quantity Survey • ~5,000 1 mi2 plots • Wetlands delineated via photo interpretation • Types (+/-) equivalent to Cowardin classes
Survey Design/Field Methods
–Target sample • 150 points statewide • 50 points/major ecoregion –Assessment Area (AA) • 0.5 ha/40m radius circle (standard) • Alternate layouts –Plant community mapping • Eggers & Reed types (n = 14) –Veg sampling (2011-12) • Meander through entire AA • Record all spp. & aerial cover/community Floristic Quality Assessment (FQA)
The Coefficient of Conservatism (C ) – Reflects the fidelity of a species to natural undisturbed habitats (0- 10) Primary metric – Weighted Coefficient of Conservatism (wC ) wC = ∑ pC
SciName % Cover Mid P C pC http://wisplants.uwsp.edu/ Carex stricta 50-75% 62.5 0.539 5 2.694 Calamagrostis canadensis 25-50% 37.5 0.323 4 1.293 Acer negundo Cypripedium candidum (Box elder) (Small white lady’s Phalaris arundinacea 5-25% 15 0.129 0 0 C = 1 slipper) Lysimachia thyrsiflora 0-1% 0.5 0.004 6 0.026 C = 10 Impatiens capensis 0-1% 0.5 0.004 2 0.009 Total Cover 116 wC 4.0 FQA Assessment Criteria
– 4 level wetland vegetation Biological Condition Gradient (BCG) – wC calibrated to BCG for each community – Data driven (n = 725)
Condition Categories Category Descriptions
Exceptional Composition/structure as they exist in the absence of measurable effects of stressors *When non-native Good 10th percentile taxa < 1% total
Similar to natural community, minor of group cover changes in composition/structure
Moderate changes in
FQA FQA Metric composition/structure. Abundance Fair distribution shifts towards tolerant taxa Large-extreme changes in 90th percentile Poor composition/structure including of group wholesale changes in composition
Pre- Minimally Severely settlement Impacted Impacted Human Disturbance Assessment
General Human Disturbance Assessment (HDA) • A categorical-BPJ based approach to rating the perceived human impacts occurring at a wetland • Incorporates 6 factors 1) Landscape Alteration (500 m buffer) 2) Immediate Upland Alteration (50 m buffer) 3) Within Wetland Physical Alteration 4) Hydrologic Alteration 5) Chemical Pollution 6) Invasive Species • Standard narrative guidance • Overall rating based on factor combinations • Completed for all AA’s Data Analysis
Community wC Vegetation Data & Calculation & AA Assessment Mapping Condition Assessment
Fresh Meadow Area = 0.19ha (39%) Weighted wC = 3.0 Average Category 0.39 * 3 = 1.17 Category = Fair (3) 0.61 * 4 = 2.44 Sum = 3.61 Shallow Marsh Overall Condition Area = 0.31ha (61%) Category wC = 1.1 Poor Category = Poor (4)
– Assessment results projected to ecoregion & statewide scales – ‘Post-stratification’ (i.e., subpopulation estimates) by major wetland type/communities – spsurvey package in R Statewide Wetland Veg Quality
– Surprisingly high proportion of high condition wetlands • Exceptional = pre- settlement condition • Roughly 2/3’s (67%) in Good-Exceptional condition • Only about 1/3 (35%) that are moderately- severely degraded • Poor = large changes in composition & structure Regional Wetland Veg Quality
Site locations w/condition category Veg Quality by Major Types Emergent Communities Human Impacts—Stressors Human Impacts—Stressors
Non-native invasive species... Relative Risk of stressors – Most prevalent poor condition @ high stress/poor condition @ low stress stressor by extent – There are big regional differences – Also the strongest stressor? – Response to stress or stressor? Cypripedium reginae Closing Messages (Showy lady’s slipper) Present in 5.5% of – Overall statewide wetland veg quality is good MN’s wetlands! • Driven by the large share of wetlands in the northern forest – Doesn’t mean there aren’t concerns • Veg condition outside of the northern forest has been largely degraded driven by non-native invasive spp. that often co-occur with human impacts/activities • Also consider... • About 50% of MN’s wetlands have been lost • Cultivated wetlands (Devoid-Deficient veg condition) not represented here – Making connections • Rapid FQA available for professionals w/moderate expertise • Same currency as the survey • Link project results to regional/type results • Refine decision making by situational context – Vegetation condition is just one measure of wetland ‘quality’ • More ways to measure condition • How does veg condition relate to function? – Are we meeting no-net loss? • High overall baseline of vegetation ‘quality’ and ‘biological diversity’ • Stay tuned Streamlined tree island within an extensive rich fen water track -Mulligan Lake Peatland SNA
[email protected] Human Impacts—Stressors
Which plant communities have been most affected by non-native invasives?
Shallow marsh with expected native composition (Polk Co.)
Shallow marsh dominated by narrow-leaved cattail (Marshall Co.) Human Impacts—Stressors
Which non-native invasive species are the most prevalent? Phalaris arundinacea Mixed Wood Plains Temperate Prairies (Reed canary grass) % wetland % wetland
>35% >35% Species Present Rel Cover Present Rel Cover Phalaris arundinacea 88.0 20.0 73.3 11.1 Cirsium arvense 42.0 62.2 Invasive Typha* 52.0 26.0 60.0 26.7 Cirsium arvense Phragmites australis+ 28.0 2.0 20.0 (Canada thistle) Rhamnus cathartica 38.0 28.9 Frangula alnus 16.0 Lythrum salicaria 12.0 *Data for Typha angustifolia and T. x glauca combined +Only the native genotype was observed during the survey Typha angustifolia / T. x glauca (Narrow leaved/hybrid cattail) Wetlands for water quality: Lessons learned from field and lab studies
Chris Lenhart, Dean Current, Nikol Ross, Brad Gordon and Ken Brooks University of Minnesota Outline
Background on wetland issues Review of wetland studies of sediment and nutrient removal in restored, created and natural wetlands Wetland mesocosm (100-gallon tank) studies Use of findings to develop a landscape-wide approach to wetlands (W. Mitsch)
Background
Wetland loss Need to store water and reduce nutrient loading to downstream river and lakes for CWA and TMDLs Wetland restoration and treatment wetlands: How well do they work? Which types work best in different landscape settings? Where in the landscape are the most effective
Wetland loss, >90%
Loss of hydrologic storage Loss of nutrient and sediment removal Loss of waterfowl habitat Seasonal wetlands (Types 1-2) greatest amount lost Deeper types restored and/or created for WQ treatment TMDL drives much of interest in WQ benefits WQ issues: need for water storage
Streamflow increase in Need to store water in Blue Earth River >1980 wetlands to reduce flow
Lenhart, C., Petersen, H. and Nieber, J. 2011. Watershed response to climate change in the upper Midwest: The importance of low and mean flow increases for agricultural watershed management. Watershed Science Bulletin, Spring 2011: 25-31. Wetland removal of sediment and nutrients
Sediment and turbidity Phosphorus Settling of sediment Much TP settles out Production of organic Plant uptake matter can add to turbidity Bio-available P key to eutrophication Nitrogen Release in anaerobic conditions Removal of nitrate via:
Primarily via denitrification by bacteria Dissolved Oxygen Plant uptake Wetlands often low in dO due to high BOD
Minnesota River basin setting
Prairie potholes in
POMME DE TRERRE southern to western RIVER 2,266 km2 MN (drained mostly)
CHIPPEWA RIVER UPPER 2 Floodplain wetlands MINNESOTA 5,397 km RIVER 1,971 km2 LAC QUI along main Minnesota PARLE RIVER 1,972 HAWK-YELLOW MEDICINE RIVER 2 River and larger tribs km 5,373 km2 LOWER MIDDLE MINNESOTA MR RIVER 2 (mostly intact) 3,490 4,714 km COTTONWOOD 2 RIVER km 2 REDWOOD 3,400 km RIVER Most of wet prairie 1,826 km2 WATONWAN RIVER LE SUEUR 2,273 km2 RIVER 2,881 eliminated km2 BLUE EARTH RIVER 4,015 km2 Types of wetlands discussed today
Prairie potholes Wet meadows to deep marshes; were common throughout southern & western Minnesota Oxbow wetlands Abandoned river channels; frequently flooded Typically wet meadows Treatment wetlands Constructed to remove pollutants, in this case from tile drainage Types of wetlands not often restored
Wet prairies Floodplain forest
Photo by Ryan P. O’Connor, Michigan DNR Wetland projects in Martin County
Treatment wetland
Lenhart, C., Brooks, K., Magner, J. and Suppes, B. 2010. Attenuating Excessive Sediment and Loss of Biotic Habitat in an Intensively Managed Midwestern Agricultural Watershed. Proceedings, 2010 Watershed Management Conference Proceedings. American Society of Civil Engineers: Madison, WI Minnesota River floodplain study
Soil borings to measure Minneapolis St. Paul rate of post-European sediment accumulation in Chaska Shakopee floodplain, including oxbows
Legend
Boring sites Minnesota River Cities Floodplain
Le Center DEM m St. Peter High : 396.864
Faribault Low : 207.944
Mankato 0 10 20 40 Kilometers Prairie pothole complex water level through the seasons Summer
Spring
Fall Kittleson Restoration Water sources to wetland
Surface runoff: flashy & Tile flow: most inflow by very intermittent volume Hydrologic benefits
Surface runoff – high in TSS, P Subsurface tile inflow is 75-90% of total water Outflow of wetland - reduced peak volume; high in nitrate
2005 Flood peak reduction by Ditch 73-2 1.6 Wetland at Site W5 1.4 1.2 120.0 1
0.8 tile
100.0 flow (cfs) 0.6
0.4 80.0 0.2
60.0 0
7/7/2005 8/4/2005 9/1/2005
40.0 6/9/2005
4/14/2005 4/28/2005 5/12/2005 5/26/2005 6/23/2005 7/21/2005 8/18/2005 9/15/2005 9/29/2005
10/13/2005 10/27/2005 11/10/2005 11/24/2005 Discharge (cfs) Discharge Date 20.0
0.0 Feb-05 Apr-05 May-05 Jul-05 Sep-05 Oct-05 Dec-05
WetlandDate outlet at W5 Surface inflow from W2 and W4 Nitrogen concentration benefits
Nitrogen inflow Nitrogen outflow
Nitrate-nitrogen concentration in tile flow 30 25 30 20 25 15
20 (mg/l)-N 3 10
15 N0 mg/l 5 10 0 5
0
6/9/2005 7/7/2005 8/4/2005 9/1/2005
5/12/2005 5/26/2005 6/23/2005 7/21/2005 8/18/2005 9/15/2005 9/29/2005
10/13/2005
7/7/2005 8/4/2005 9/1/2005
6/9/2005 Date
5/12/2005 5/26/2005 6/23/2005 7/21/2005 8/18/2005 9/15/2005 9/29/2005 10/13/2005 Date SHEEK wetland Kittleson wetland Seasonal Total P load 0.4
0.3 Crop Surface
Crop Tile
0.2 Yield Yield
(kg/hectare) Perennial Veg - 0.1 Wetland Complex
0 9/16/07 - 4/1/08 - 6/16/08 - 11/15/07 6/15/08 9/15/08
G. Fransen Summary: project benefits and issues
Highly successful at Very eutrophic removing sediment and Duck habitat value? nitrogen Phosphorus leakage? Reduced flood peak from Wind-driven resuspension farm runoff Recreational use Abundant waterfowl
Project #2 Multi-purpose riparian site (Mair land near Huntley, MN)
Treatment wetland
Lenhart, C., Brooks, K., Magner, J. and Suppes, B. 2010. Riparian corridor-channel restoration and management in Elm Creek, Minnesota. Ecological Restoration 28(3):240-242. Sediment and nutrient dynamics in floodplain – oxbow wetlands
Sediment and phosphorus But, absolute values may removal be high due to high Lower removal % compared sediment loads in river to pothole basins flow
33% TP, 20% TSS removal 25% N removal
Shields, D. et al. 2009. Management of an abandoned river channel wetland for mitigation of nonpoint source pollution. Stream valley wetlands and oxbows
Sediment deposition hot- MN River sample sites spots Minneapolis St. Paul Recent channel cutoffs have
high rate of deposition Chaska Shakopee
Legend
Boring sites Minnesota River Cities Floodplain
Le Center DEM m St. Peter High : 396.864
Faribault Low : 207.944
Mankato 0 10 20 40 Kilometers
Lenhart, C. F., M. L. Titov, J. S. Ulrich, J. L. Nieber, and B. J. Suppes. 2013. The role of hydrologic alteration and riparian vegetation dynamics in channel evolution along the lower Minnesota River. Transactions of the ASABE 56(2): (in press). Project Area: lower Elm Creek
Channelization in 1960s and entrenchment reduced connectivity of floodplain Reconnected at high flows Enhance sediment and P removal
Nate Campbell, M.S. thesis project Cross vane for directing flow into Cross vane for flow into oxbow wetland Sediment and nutrient removal
100s to 1500 tons Assumed phosphorus sediment per year removal with sediment deposited (estimated) Nitrate removal less? Increase sedimentation 2 Conditions for – 5 x pre-project denitrification not always present Cost $5000 (part of larger multi-purpose riparian project Wetland project #3
Treatment wetland Treatment wetland
Project origin: MDA grant for Clean Water Research in 2012 Landowner Darwin Roberts allowed land to be used for water quality benefits and research Project design and pre-project data collection 2012 Construction winter 2013 Monitoring 2013-2014
Treatment wetland design
Flow Routing Surface flow through Hydrologic benefits
Water outflow reduced by 82% due to infiltration Water slowly flows through subsurface clay loam
8000 7241.0
) 3 6000 4176.8 4000 2783.3
2000 Waer volume volume Waer (m 1313.6 0 Inlet AgriDrain#1 AgriDrain#2 Outlet Nitrate removal rates
Very low denitrification in surface water in year 1 (<10%) High removal in sub-surface (90%) Total load reduced by perhaps 50% Improved performance 2nd year (2014), denitrification in surface water more in range of 20-40% - Brad Gordon PhD work
Treatment wetland
Summary Issues Overall high removal of ET and denitrification peak nitrate by subsurface in mid summer but peak removal flow into wetlands in late Peak flow reduction spring Water volume reduction Fits in with existing slight agricultural systems but is costly relative to natural Phosphorus ?? wetlands
Wetland mesocosm studies
Purpose: to test different soil and plant types for their effect on denitrification rate Setup: Ten 100-gallon tanks with soils from wetlands of interest 5 Experiments run in 2013-2014 in the basement of BAE Hall Wetland mesocosms
Effects of plant type and Multi-species mix had species mixture higher denitrification rates Effect of soil type – Sarita than single species wetland vs. constructed Soil types 1: Sarita wetland wetland soils had higher rates of Effect of 3 wetland soil denitrification than types and plant type constructed wetland (cattail, reed canary & Current study- natural and sedge) restored soils > constructed wetland
Implications for management
It takes a few years for restored or created wetlands to develop soil & bacterial components Plant & soil ecology is important for function of wetlands Different types of wetlands needed to maximize removal of the “big three” pollutants: sediment, nitrate and phosphorus Summary Cost/benefit of all wetland projects
Prairie pothole basin – 30-40k for construction 70+ acres (not counting easements); hydrologic, WQ, recreation and wildlife benefits; land retired Oxbow wetland 5-10k for 1.3 acres, WQ benefits, economics: no land retired Treatment wetlands 20-30k for 0.3 acres, WQ and hydrologic benefits, economics: only 0.2 acres retired
Key variables effecting wetland performance
Physical Social - economic
Hydrologic storage & Landowner willingness loading rate Land values Watershed : wetland ratio Fit with existing agro- Nitrate loading is ecosystems proportional to flow volume; Phosphorus not
Landscape ecology-based wetland plan
Prairie potholes in Western MN
Water storage POMME DE TRERRE RIVER Waterfowl habitat 2,266 km2 CHIPPEWA UPPER RIVER Nitrate & phosphorus removal MINNESOTA 5,397 km2 RIVER 1,971 km2 LAC QUI Treatment wetlands and other PARLE HAWK-YELLOW RIVER MEDICINE RIVER 1,972 2 5,373 km LOWER km2 treatments for tile flow MIDDL MINNESOT E MR A COTTONWOOD3,490 RIVER RIVER km2 4,714 Edge of field nutrient removal in REDWOOD 3,400 km2 km2 RIVER 1,826 WATONWA LE 2 N km SUEUR intensive ag zones (Blue Earth) RIVER RIVER 2,273 2,881 2 km BLUE km2 Less load reduction for N & P EARTH RIVER 4,015 2 Floodplain reconnection in km channelized / leveed reaches Sediment and Phos. removal
Cost and management issues
High cost of farmland and corn prices have reduced enrollment of land in CRP & WRP; not easy to find landowners willing to enroll a 40-acre wetland Water storage vs. filtration ? Trade-offs between ecological restoration and water quality treatment (water level variation, reed canary grass, pollinator habitat) Ag water management is becoming more and more intensive; more like urban in that sense
Acknowledgements Funding support MN Dept. of Agriculture Clean Water Legacy Research for treatment wetland (2012) (Current & Lenhart) Univ. of Minnesota (2014) (BBE Dept. support for mesocosms), UROP grant MN Corn Growers - MN River work (Lenhart,Nieber) EPA 319 for riparian wetland (2007)(Brooks, Current) USDA - CSREES grant (2004) (Brooks, Current et al) Landowners: Richard Mair and Darwin Roberts Researcher collaborators and data help: Joe Magner, Greg Fransen, John Nieber, Kyle Donovan, Britta Suppes, Mike Kramer, Justin Fasching, Aileen Zebrowski Partners
Martin Soil and Water Conservation District Addressing the Nutrient Driver Paradigm for Dissolved Oxygen in Small, Low Gradient Streams
Jeff Strom - Wenck Associates, Inc.
Joe Bischoff - Wenck Associates, Inc.
Diane Sander – Crow River Organization of Water (CROW) Objectives
• Stream Dissolved Oxygen (DO) Paradigm
• Four DO impaired reach TMDL case studies • Methods • DO levels • Phosphorus levels • Response variables • Modeling Results • Restoration strategies
• Conclusions River/Stream DO Paradigm: High Nutrients (Phosphorus)
High Biochemical High Algae (Chl-a) Oxygen Demand (BOD)
High DO Flux Low & Stressed DO Conditions ** Large & Med. Rivers Four Crow River DO TMDL Case Studies Crow River DO TMDL Case Studies
Small tributary reaches Jewitts Creek Class 2B Grove Creek In-channel wetland Ditched wetland 4 - 10 river miles 18,000 – 32,000 acre watersheds
Agricultural watersheds 25-65% Row Crops 15-40% Pasture 5-20% Developed
Pioneer Creek Low Grade: <0.15% In-channel wetland Regal Creek Altered Headwater wetland/pond Ditched Straightened and/or over- widened
Wetland/lake interactions In-reach flow through wetlands (3) Headwater wetland (1) Upstream Lakes (3)
Dissolved Oxygen Balance
Sources Sinks
Reaeration Degassing Atmosphere
Respiration by aquatic plants Photosynthesis by aquatic plants Biochemical Oxygen Demand (BOD = CBOD + NBOD) Tributaries
Organic carbon to CO2 Water Column Water Organic nitrogen to NO3
Sediment Oxygen Demand
(SOD) Sediments DO TMDL Methodology
Historic Data
Synoptic Survey (Low-flow) Longitudinal DO surveys Continuous DO probes Longitudinal WQ survey: P and N series, Chl-a, BOD Dye study (travel time) Gauged flows Channel X-sections Elevation survey
Modeling: River and Stream Water Quality Model (QUAL2K) Steady state model Reaeration and gas exchange Algae and BOD Periphyton Daily DO flux (min & max) Sediment processes = sediment oxygen demand (SOD)
Dissolved Oxygen Conditions
25% - 65% violations
More violations during summer months (June-Aug)
Violations during all flow conditions
More violations downstream of wetlands
Phosphorus Conditions
80%-100% exceed nutrient criteria
Exceedances during all seasons and flow conditions
High ortho-P fraction
Spikes downstream of wetlands Chlorophyll-a (Algae) Conditions
Low during low-flow
Low downstream of flow- through wetlands
High chl-a during high-flows (Grove & Regal), lake/pond flushing Chlorophyll-a (Algae) Conditions: Headwaters
Grove Creek
Long Lake
Headwater Pond System
Regal Creek 5-Day BOD (BOD5) Conditions
High values (Regal Creek) correspond with high Chl-a
High values = lake/pond flushing during high flows DO Flux Conditions
0% - 72% days exceed nutrient criteria
Jewitts & Pioneer: wetland macrophytes & periphyton Crow River Case Studies:
High Nutrients (Phosphorus)
Algae (Chl-a) = Low
BOD = Low
DO Flux = Low
Low DO QUAL2K Model Results Wetland Model Sensitivity
1) Headwater conditions 2) SOD 3) Stream velocity
Wetland Model Scenarios
1) Headwaters must meet DO std. 2) SOD reductions (wetland reaches) 3) Increase velocity (altered reaches) - Increase Reaeration - Lower residence time Real Drivers of DO in Small, Low Gradient Streams 1) Headwater Conditions
Impaired Lakes
Ponds
Wetlands
2) Wetland SOD
3) Channel Form Conceptual Channel Cross Section
Ditched, straightened and over-widened Low velocity
Low reaeration
Reshape channels
Restoration Approaches
Kingston Wetland Lake TMDLs (Headwaters) Channel Reconstruction
Wetland Restorations
Aerators/Drop Structures
Channel alterations Conclusions
Traditional Nutrient DO Paradigm doesn’t fit in all cases
DO in small, low gradient agricultural streams
Headwater conditions
SOD
Channel form
Important to understand drivers – restoration activities
Phosphorus still a concern
High TP and Ortho-P
High DO flux in some reaches
Loading to downstream resources – Crow River, Miss. River, Lake Pepin
Questions ??