(It’s All Kyoko’s Fault) (Biocontrol of Aspen with EAB?) (It Started and Stopped Before I Started) Aspen Mortality in Northern Wisconsin – Legacy of FTC Defoliation

2008 Lincoln County

2008 Oneida County

2009 Langlade County

Aspen Decline Stand Characteristics Lost ft 2 /ac of basal area 2 years prior to survey (majority of losses may have happened prior to 2006) Averaged 39 ft 2 /ac of aspen (nearby unaffected stands averaged 69 ft 2 /ac) 28 – 40 years old 65% of soils are sandy loams; 20% are loamy sands No apparent site quality differences between declining and non-declining stands

80 ft 2 /ac aspen

40 ft 2 /ac aspen

What’s Killing the Aspens?

EAB IS KILLING OUR ASPENS!

Bronze Poplar Borers (Agrilus liragus) Are Contributing to Aspen Mortality

Armillaria & Hypoxylon Are Contributing to Aspen Mortality Roughly half of nearly-dead aspens estimated to be colonized by Armillaria

Armillaria & Hypoxylon Are Contributing to Aspen Mortality Roughly half of nearly-dead aspens estimated to be colonized by Armillaria The impact of hypoxylon canker is probably underestimated in decline surveys

Hypoxylon Canker

Hypoxylon was the main aspen killer 6 years after FTC defoliation in MN (Churchill et al. 1964) Strong evidence that Entoleuca (syn. Hypoxylon) can be a bark endophyte Low bark moisture promotes canker development Drought-stressed aspen are more susceptible to Hypoxylon canker Ostry & Anderson, Forest Ecology & Management 257, 2009

= Defoliation

JanFebMarchAprilMayJuneJulyAug.SeptOctNovDec 1998XXXXXX 1999\* 2000* 2001* 2002* 2003\\XX 2004X 2005\\\ 2006\ 2007XXX 2008\\\X \ = moderate drought X = severe drought XX = extreme drought * = forest tent caterpillar defoliation Drought and Forest Tent Caterpillar Defoliation in North Central Wisconsin

FTC Defoliation 2000

FTC Defoliation 2001

It’s All Kyoko’s Fault

Defoliation and Decline of Aspen, Unknown Cause(s), 2010, MN DNR Annual Report Problems with Aspen in MN Too scattered

2010 MN Aspen Decline Surveys MN DNR mapped less aspen decline this past year 2010 MI Aspen Decline Surveys Expansion of declining stands has stopped No new declining stands were detected

Aspen Decline Summary From 2006 – 2009, significant dieback and mortality was present in aspen stands in north central Wisconsin Majority of mortality in Wisconsin likely occurred between 2002 and 2006 The spatial distribution of mortality was not obvious

All areas with decline experienced FTC defoliation and drought in the last decade A similar aspen decline occurred after extreme drought in the UP in the late 70s In the 60s in MN, stands defoliated by FTC for 3 continuous yrs had % mortality in the 6 years after defoliation ended The rate of decline appears to have slowed in 2010 in the upper Great Lakes states The bronze poplar borer, Armillaria, & Entoleuca contributed to mortality Significant mortality should be expected after several years of consecutive defoliation Aspen Decline Summary

(Churchill et al., Ecology, 1964)

SAD (Sudden Aspen Decline) Is Not Occurring in Northern Wisconsin s.w. CO, s. UT, n. AZ (13% of aspen cover type in CO) Widespread, rapid, severe crown deterioration; lack of regen. after overstory death Predisposing factors: lower elevations; S and SW aspects Inciting factors: warm, dry conditions Contributing factors: Cytospora canker, poplar borer, bronze poplar borer, and two bark beetles By 2060, 76% of the sites now exhibiting sudden decline are projected to lie outside aspen’s climate profile

Kemp, USFS, from

Worrall, USFS, from

Predicted Suitable Habitat for Aspen in 2100 (USFS Tree Atlas 1999)

Predicted Suitable Habitat for Aspen in 2100 (USFS Tree Atlas 2007)

?s