Transitioning black ash wetlands to an EAB infested future

Transcription

1 Transitioning black ash wetlands to an EAB infested future The Context: millions of acres and billions of trees The Concern: threatened by EAB, etc The Need: adaptive strategies, including replacement trees species Brian Palik USDA Forest Service Northern Research Station Tony D Amato University of Vermont Robert Slesak Minnesota Forest Resources Council

2 Black Ash in the Lake States and Minnesota Black ash forests are a large proportion of Lake States landbase 440,000 ha ( 1.1 million ac) & 1 billion trees in Minnesota Glacial lake and outwash plains, muck soils, impeded drainage

3 -Timber -Habitat -Carbon storage -Cultural resource Why black ash forests matter

4 Why Minnesota in Unique Black ash can be the dominant species in wetland forests in the north 700 Overstory Species No. per ha Black ash Balsam fir Balsam poplar Paper birch American elm Green ash Quaking aspen Red maple White cedar Yellow birch Species Palik, Ostry, Venette, et al FEM 2011

5 What do we know about black ash age structure & disturbance? -Long-lived trees (300+ years) -Strongly uneven-aged; recruitment peaks reflective of drought and canopy disturbance -Overstory present during regeneration events; gap-based dynamics

6 But Black Ash Forests have Issues Including Emerald Ash Borer

7 Emerald Ash Borer is on the doorstep of the largest concentration of ash in the North America Very high mortality in trees over ~ 1 inch diameter

8 More bad news Climate projections for northern MN Projected habitat changes for co-occurring tree species in Fraxinus nigra wetlands: -Reduced habitat suitability 50% of spp. -Neutral: 25% -Increased: 25% EAB is cold sensitive; warmer winters > EAB survival No. per ha The few future adapted species occur only in low abundance in these forests Black ash Balsam fir Balsam poplar Paper birch American elm Green ash Quaking aspen Species Red maple White cedar Yellow birch

9 Even more bad news Sapling layer is mostly black ash and alder.. Not a lot of advance regeneration of other species Sapling Species Also, few trees in the regeneration layer: -speckled alder -hazel -mountain maple -dogwood No. per ha Wetland Upland No tree species poised to replace black ash.should something bad happen! Palik, Ostry, Venette, et al FEM Black ash American elm Balsam fir Balsam poplar Mountain maple Quaking aspen Speckled alder Sugar maple Willow Species

10 The Concern: Without Trees -Black ash wetlands get even wetter -Sedge/shrubs dominate -Tree establishment becomes difficult -Loss of ecosystem function, habitat

11 Loss of a Foundational Species Youngquist et al. Wetlands 2017 Landscape context Ash tree abundance Geomorphology Spatial scale Environmental stochasticity Precipitation Hydroperiod Emerald Ash Borer Invasion Plant Community Litter Quality Litter Quantity Canopy Cover * CPOM FPOM Algal Community Species traits Habitat preferences Life history strategies Landscape context Spatial scale Shredder Gatherer Predator Aquatic Community (amphibian and invertebrate) Scraper

12 There is a growing sense of urgency among regional organizations to find adaptation strategies to maintain trees in these ecosystems The Need: Adaptive strategies, that keep forests on the landscape Questions?

13 Evaluating the Ecological Impacts of Emerald Ash Borer in Black Ash Forests Large-scale manipulative experiment on Chippewa National Forest Brian Palik USDA Forest Service Northern Research Station Tony D Amato University of Vermont Robert Slesak Minnesota Forest Resources Council Kilometers -What are potential impacts of EAB and associated management actions on structure and function of black ash forests? -Are there adaptive strategies to build site-level resilience to EAB and climate change (i.e., maintain forested wetland condition)? 13

14 The Study: -Conceived by Gary Swanson (CNF) in Developed by Palik, D Amato, Slesak in Harvested winter Planted treatments 1. Unharvested control 2. Clearcutting 3. Group selection 4. EAB emulation -All treatments are 1.6 ha (4 ac); -8 replicates of each Northern Wet Ash Swamp (WFn55); Northern Very Wet Ash Swamp (WFn64)

15 Examining: -Hydrology: Jake Diamond, Dan McLaughlin; Virginia Tech -Native plant communities: Chris Looney, UMN -Natural regeneration: Chris Looney -Amphibian communities: Melissa Youngquist, UMN -Aquatic food webs: Melissa Youngquist; Sue Eggert, FS-NRS -Planted regeneration: Chris Looney -Small mammals: Alexis Grinde, NRRI-UMD -Birds: Alexis Grinde

16 Treatments Girdling Emulates EAB Group Selection Control Clearcut

17 Clearcut and Girdling Treatment: additional activities

18 Replacement Tree Species -12 tree species: planted F2011 &/or Sp2012 -Most present in regional ecosystem: Red Maple *, Yellow Birch *, Eastern Larch, Eastern Cottonwood *, Black Spruce, Balsam Poplar, Quaking Aspen, White Cedar, American Elm * -Two from the next southern climate zone: Hackberry *, Swamp White Oak * -One exotic: Manchurian Ash * Northeast Asia & Japan EAB-resistant * Future adapted: climate and EAB Questions?

19 Results Water table response (wet sites get wetter!) Slesak et al. (CJFR 2014 and ongoing) Jake Diamond, Dan McLaughlin Virginia Tech ** ** ** ** ** ** ** * ** Girdled and clearcut: -shallower depth to water -Group selection: tracks the preharvest forest -Regeneration is challenging in clearcut and girdle

20 Herbaceous plants Christopher Looney Dept. of Nat. Res., Univ. of Minnesota Clearcut treatment: -increase in herbaceous cover -sedges, grasses, cattails A challenging environment for tree regeneration Calamagrostis canadensis (bluejoint) Carex lacustris (hairy sedge) Carex spp. Looney et al. FEM. 2017

21 Results Planted seedling survival (5 years) 1. American elm (74) 2. Swamp white oak (69) 3. Manchurian ash (52) 4. Hackberry (43) 5. Balsam poplar (24) 6. Red maple (23) 7. Black spruce (11) Survival highest for non-native, pathologically-limited, or out-ofrange species Species with high survival are predicted climate change adapted Survival lowest for commonly occurring, native species Species with lowest survival are often climate change mal-adapted (predicted) 8. Tamarack (7) 9. White cedar (6) 10. Cottonwood (4) 11. Trembling aspen (3) 12. Yellow birch (3) Looney et al. CJFR 2015

22 Survival: Treatment x Species (5 th year) -Survival of futureadapted species was generally lower in the clearcut -Similar patterns of survival among control, group, girdle Mean Percent Survival (+/- 95% CI)

23 Survival: Species x Planting Season -Higher fall survival: swamp white oak, Manchurian ash, balsam poplar -Higher spring survival: black spruce, red maple -Generally not a large difference between planting seasons (overly wet microsites were avoided with spring planting)

24 Results Planted Seedling Growth (2013 to 2015) Looney et al. CJFR Both height and diameter (relative) growth increased from the control to the group selection to the girdle treatment, to the clearcut

25 Results Growth: Treatment x Species -Most species had highest growth in clearcut and girdle treatments, with group selection intermediate and control lowest -Replacement species growth: -Balsam poplar highest in all treatments; -Swamp white oak and American elm moderate in all treatments, -Manchurian ash and hackberry low in all treatments Relative Diameter Growth

26 Ecosystem Function Melissa Youngquist; Sue Eggert, FS-NRS Carbon/Nitrogen Ratios Leaf Litter Decomposition Rates Black ash has higher quality litter compared to sedge & swamp white oak Black ash litter decomposes faster than sedge & swamp white oak

27 Results Ecosystem Function Caddis Fly Survival -Best survival on black ash, speckled alder, swamp white oak -Lowest survival on balsam poplar, hairy sedge, American elm

28 Ranking replacement species: -Need to balance survival and growth -Consider shorter and longer-term perspectives -Factor in other ecosystem responses (food webs?) -Also, consider the best silvicultural approach Group Selection -consistent with ecology of the ecosystem (gap dynamics) -minimizes water table increase and limits herbaceous increase -regeneration survival is as good or better than other treatments -growth is moderate compared to clearcut and girdle

29 Ranking replacement species: Rank order of 5th year survival in group selection: 1. American elm (DED tolerant) 2. Swamp white oak 3. Manchurian ash 4. Hackberry 5. Balsam poplar 6. Red maple 7. Black spruce 8. Eastern larch 9. Northern white cedar 10. Eastern cottonwood 11. Yellow birch 12. Trembling aspen Rank order of 3 year diameter growth in group selection: 1. Balsam poplar 2. Eastern larch 3. Eastern cottonwood 4. Swamp white oak 5. Red maple 6. Black spruce 7. Northern white cedar 8. American elm (DED tolerant) 9. Hackberry 10. Manchurian ash 11.Yellow birch, trembling aspen(not enough to measure) Shorter term? Longer term?

30 Recommended replacement species In rank order for northern wet forests: Replacements should consider: -Site appropriateness, -EAB resistance -Future climate adaptation (swamp white oak?) 1. Tamarack 2. N. white cedar 3. American elm (DED tolerant) 4. Black spruce 5. Balsam poplar 6. Yellow birch 7. Balsam fir 8. Red maple 9. Trembling aspen 10.Ash 11. Silver maple?

31 Ongoing and Related Efforts Phase 1 (this study): regeneration, amphibians, small mammals, birds, hydrology, plant communities, food-webs Phase 2: Expanded range of sites across N. MN to look at natural regeneration, hydrology, amphibians, small mammal, birds

32 Summary and Conclusions Adaptation strategies for black ash wetlands need to consider replacement tree species, as well as the silvicultural approaches best suited to facilitate success Loss of trees from EAB or preemptive clearcutting, while increasing growth of some species, shift sites towards challenging hydrologic conditions and may limit longterm survival Group selection is consistent with the ecology of these systems (gap dynamics, uneven-aged) and has generally good seedling survival, including several future adapted species Balsam poplar and swamp white oak provide a good balance of growth and survival, particular with group selection Fall planting may be logistically easier, has higher survival for some species, and about the same survival as spring planting for most species Pre-emptive planting (before EAB) in uncut forest of tolerant, future-adapted species may be a viable strategy USDA Forest Service Northern Research Station