eab in black ash wetlands: impacts and lessons from a simulated infestation

Adapting Forested Watersheds to Climate ChangeMarch15, 2017

EAB in Black Ash Wetlands:

Impacts and Lessons from a Simulated Infestation

Joseph Shannon ([email protected])Michigan Technological UniversitySchool of Forest Resources and Environmental Science

» Nicholas Bolton1

» Joshua Davis1

» Randall Kolka2

» Nam Jin Noh1

» Thomas Pypker3

» Joseph Shannon1

» Stephen Sebestyen2

» Matthew Van Grinsven4

» Joseph Wagenbrenner1, 5

Who we are

1 – Michigan Technological University, School of Forest Resources and Environmental Science

2 – USDA Forest Service Northern Research Station3 – Thompson Rivers University, Natural Resource Sciences 4 – Northern Michigan University, Earth, Environmental and Geographical

Sciences Department5 – USDA Forest Service Southwest and Pacific Research Station

Why black ash?

» Major canopy component in headwater wetlands, large wetland complexes, and intermittent and first-order streams

» Water quality» Timber» Carbon storage» Cultural significance

1 - Adapted from Kane, J., & Puentes, R. (2015). What the new clean water rule means for metro areas. Retrieved March 3, 2016, from http://www.brookings.edu/blogs/the-avenue/posts/2015/06/10-new-clean-water-rule-metro-areas-kane-puentes2 - By Uyvsdi (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons3 - James Solomon, USDA Forest Service, Bugwood.org. http://www.forestryimages.org/browse/detail.cfm?imgnum=3056007

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Percent of population that depends on drinking water from intermittent, ephemeral, or headwater streams by county

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Study Objectives

» Determine the impact of Emerald Ash Borer (EAB) on black ash wetlands

» Wetland water levels» Natural regeneration and suitable

replacement overstory species» Herbaceous community structure, and

remnant canopy and understory responses

» Carbon balance and nitrogen cycling

» Determine the potential for EAB impacts to propagate downstream

1 - Eric R. Day, Virginia Polytechnic Institute and State University, Bugwood.org. http://www.insectimages.org/browse/detail.cfm?imgnum=5382310

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Study Location and

Layout» Ottawa National Forest, western

Upper Peninsula of Michigan

» 14 isolated headwater wetlands

» 3 Treatments» Control» Girdle (Girdle ash stems ≥ 1” DBH) » Ash Cut (Cut and leave ash stems ≥ 1”

DBH)

» Timeline» Baseline conditions, 2011-2012» Treatments applied, Winter 2012-2013 » Monitoring and analysis, Continuing

Results

Where is the water coming

from?» Upland groundwater and annual

precipitation control maximum water levels in these wetlands» Wetlands are well connected to upland

groundwater» Duration of upland groundwater connection is

strongly controlled by annual precipitation

Figure adapted from Van Grinsven, 2015

What happens to water levels?

» Treated sites showed significantly higher water levels by the end of August when compared to pre-treatment levels

» Lost ash transpiration led to significantly reduced water level drawdown rates over the growing season


What happens to water levels?

» Treated sites showed significantly higher water levels by the end of August when compared to pre-treatment levels

» Lost ash transpiration led to significantly reduced water level drawdown rates over the growing season


» Ash responds much stronger to water table drawdown than red maple or yellow birch

» Changes to water level drawdown may be persistent

What does this mean for regeneration?

» Higher late-season water levels are not preventing natural regeneration

» Increased red maple seedlings and reduced black ash seedlings in treated sites

» American elm, basswood, silver maple, and northern white cedar are suitable options for species transition and retaining forested wetlands» Plantings should be focused on

natural hummocks within the wetlands

What species are suitable alternatives?

American elm

American basswood

N. white cedar

Burr oak

Black spruce

Tamarack

Yellow birch

Silver maple

Red maple

Balsam fir

Riparian Black Ash» Browse treatments

» Plantskydd» Fence» Control

» Microsite conditions» Constructed hummock» Natural flat area» Scarification of soil/ reduced

competition

Superior Municipal Forest

Herbaceous Cover» Herbaceous cover showed a

significant increase in percent cover lagging the treatment 2-3 growing seasons

Regeneration’s Competition

2012

2015

Is the herbaceous community changing?

» Sedge species showed the greatest increase in percent cover

» Obligate wetland and disturbance-adapted species commonly responded

L. Wallis, University of Michigan Herbarium

Northern water-plantainWater-parsnip

Are co-dominants and saplings released?

» No overall change in canopy growth rate or canopy and sapling basal areas

» Non-ash overstory mortality was significant in some sites

» Epicormic branching of black ash stems not quantified, but abundant across both treatment types

What does EAB mean for soil nutrients?

» Red maple and yellow birch return less nitrogen per litter mass than ash, and total litter mass of both species has not increased» Nitrogen returns have significantly deceased

post-treatment

» There is no difference in soil N-availability post-treatment but soil nitrates are increasing

What is happening to carbon?

» Significantly higher soil CO2 efflux in treatment sites indicate increased soil decomposition

» Direct decomposition rates are currently being studied

» CH4 soil efflux did not increase but CH4 efflux from black ash stems was unexpectedly high


Where will we see these effects?

» The paired watershed component is currently looking at how changes within the site will be manifested in the intermittent and first-order streams these sites feed

» Water yield, timing, and peak flow» Nitrogen and carbon exports» Quality of carbon exports» Stream temperature

How is this being used on the ground?

» Active pre-infestation transition» Planting silver maple, basswood, DED-

resistant American Elm and others on hummocks

» Reducing negative impacts of complete canopy loss

» Girdle in small gaps not to exceed 25% of canopy to reduce hydrologic and herbaceous response

Ottawa National Forest

Science and Management ofAsh Forests after Emerald Ash Borer

A workshop on the future of post-EAB ash forests

» July 25-27, 2017 in Duluth, MN» More info at ashworkshop.org» For more information contact

Nam Jin Noh, [email protected]