The Importance of Healthy Riparian Areas and their Current Status in Wisconsin

Tim Asplund, Buzz Sorge (WI DNR)

Advanced Lake Leaders – Green Lake

Sept. 26, 2013Courtesy of MN DNR

Lakeshore zoneShallow zone Complexity:

The degree to which both lakeshore and shallow zones are intact.

Complex habitats facilitate movement of food into and out of lakes, provide shelter and nesting areas for fish an wildlife, and buffer human impacts.

Disturbance:

Shorelands and Shallows

Shorelands and Shallows

Shorelands and Shallows

Shorelands and Shallows

SHORELINE DEVELOPMENT

Shoreland Assessments• Riparian Habitat

– Vegetation cover– Shoreline and bank– Trees and shrubs

• Littoral Habitat– Bottom substrate– Aquatic plants– Fish habitat

• Human Influences– Docks, piers, seawalls– Buildings, lawns, driveways

Data: U.W. BioComplexity project

logGrowthRate(mm/yr)

Woody Habitat (no./km)

High Development

Low Development

Undeveloped

High Development

Low Development

Undeveloped

From Schindler et al. 2000

Fish grow ~3X faster in lakes with lots of woody

habitat

FLOATING-LEAF VEGETATIONFLOATING-LEAF VEGETATION

20

25

30

35

40

45

50

2 4 6 8 10 12 14 16 18 20

Dwellings per km of shoreline

FQ

I Sc

ore

0

20

40

60

80

100

120

140

2 4 6 8 10 12 14 16 18 20

Dwelling per km of shoreline

Fre

quen

cy o

f oc

curr

ance

of

floa

ting

veg

etat

ion

10

15

20

25

30

35

40

45

50

2 4 6 8 10 12 14 16 18 20

Dwellings per km of shoreline

Num

ber

of p

lant

spe

cies

per

la

ke

Jennings et al 2003Jennings et al 2003

Shorelands and Shallows

Shorelands and Shallows

Shorelands and Shallows

2007 National Lake Assessment

Poor Biology is Three Times More Common when Lakeshore Habitat is Poor

Regional summary:• Northern Plains, Coastal

Plains and Xeric have highest proportion of lakes with poor habitat conditions

• While Northern Appalachian exhibits the highest proportion of lakes with high-quality habitat, > 25% of lakeshores are in poor condition

NLA Physical Habitat and Human Disturbance Indices

• Riparian (Lakeshore) Vegetation Cover Index

• Littoral Habitat Cover Index• Littoral Habitat and

Lakeshore Vegetation Complexity Index

• Riparian Disturbance Intensity and Extent Index

• Bottom substrate• Aquatic macrophytes• Fish cover

• Canopy• Understory• Ground cover• Shoreline substrate• Human influence

• Bank features• Invasive species

Littoral Zone

Riparian Zone

Both

Protocol

Condition of the Nation’s Lakes: Habitat

Stressors to the Nation’s Lakes:Extent, Relative Risk, and Attributable Risk

• #1 – Lakeshore vegetation: Poor biology is three times more common when lakeshore vegetation cover is in poor condition. This affects 36% of lakes.

• #2 – Nutrients: Poor biology is 2.5 times more common when nutrients are high. This affects about 20% of lakes.

Riparian Disturbance

pHab: Riparian Disturbance Index

0% 20% 40% 60% 80% 100%

Nation

Region

MN

WI

MI

NLA 2007 Weighted Percentage

High Mid Low Missing

pHab: Riparian Disturbance Index

Missing Low Mid High

Littoral Cover Index

pHab: Littoral Cover Index

0% 20% 40% 60% 80% 100%

Nation

Region

MN

WI

MI

NLA 2007 Weighted Percentage

High Mid Low Missing

pHab: Littoral Cover Index

Missing Low Mid High

Lakes sampled for shore habitat in 2012 and 2013

Goals of 2013 National Lake Assessment Lakeshore Sampling

1) expand the assessment of lakeshore habitat condition across Wisconsin

2) analyze lakeshore habitat condition in terms of lake area and surrounding land use

3) Compare macrophyte survey methods: point-intercept vs. transect

4) develop ecoregion-specific lakeshore habitat metrics for Wisconsin

5) Incorporate lakeshore habitat metrics into WisCALM and Citizen Lakes Monitoring

6) use lakeshore habitat metrics in addition to trophic status to assess lake health

• Restoring Complexity and Functional Values of Shorelands