Managing for old growth characteristics in Wisconsin s northern hardwood forests Dustin Bronson -Wisconsin DNR

Transcription

1 Managing for old growth characteristics in Wisconsin s northern hardwood forests Dustin Bronson -Wisconsin DNR

2 Collaborators: Karl Martin (WDNR) Brian Palik (USFS) Tony Damato (Univ. Vermont) Tom Steele (UW Madison) Karin Fassnacht (WDNR) Tricia Knoot (WDNR) Acknowledgements: Colleen Matula (WDNR) Craig Lorimer (UW Madison) Mike Worland (WDNR) Teresa Pearson (WDNR) Brian Werner (WDNR)

3 Old-Growth Forest : A community dominated by biologically old trees (at or past life expectancy) and relatively undisturbed A high degree of compositional and structural heterogeneity.

4 Today s Northern Hardwoods Simplified Lack age- and size-class diversity Lack structural features Forest gaps, super canopy trees, snags and downed woody debris, tree cavities, and wind-throw mounds Homogenous Dominated by sugar maple Decrease in yellow birch (Betula allegheniensis), eastern hemlock (Tsuga canadensis), American basswood (Tilia americana), and white ash (Fraxinus americana) Frelich (1995); Mladenoff and Pastor (1993); Crow et al. (2002)

5 Northern Hardwood Management Historically, northern hardwood silviculture Focus on accelerating tree growth, increasing timber yield, improving log quality, and perpetuating northern hardwood covertype Evolving scope to include timber and non-timber attributes Resilience, adaptability, and intrinsic ecosystem processes (Messier et al. 2013)

6 Old Growth Characteristics Goodburn and Lorimer 1998

7 Old Growth Characteristics Goodburn and Lorimer 1998

8 Old Growth Characteristics Hanson and Lorimer 2007

9 Rx for Complexity & Diversity Complexity and diversity Enhance resiliency and adaptability to uncertain environmental conditions Experimental practices Enhance complexity and diversity, while maintaining timber production

10 Emerging Silvicultural Research Installing forest gaps (Kern et al. 2013) Moderate to heavy thinning (Choi et al. 2007) Retaining some large main canopy trees (Keeton 2006) Creating snags (Keeton 2006) Creating downed woody debris (Bolton and D Amato 2011)

11 Research Sites Flambeau River State Forest Northern Highland-American Legion State Forest Chequamegon- Nicolet National Forest

12 Choosing gap sizes 35ft 60/80ft 1-ac 35ft 60/80ft 1-ac 3-ac Hanson & Lorimer 2007

13 Schematic Representation of Treatments Woody Debris Treatment Canopy Treatment High Low 35 ft gaps Legend 35-ft gap 60-ft gap 80-ft gap 60 & 80 ft gaps shelterwoods, light-, and heavythin areas (multicohort) snag down wood thinned light thin heavy thin shelterwood

14 2007

15 2007

16 Control NHAL - Control ac 0 1/4 mi

17 Small Gap Treatment (35ft) 0 1/4 mi ac

18 Large Gap Treatment (60/80ft) 0 1/4 mi ac

19 Multi-cohort Treatment 0 1/4 mi ac

20 35 ft gaps

21 35 ft gaps

22 60/80 ft gaps

23 60/80 ft gaps

24 Multicohort Treatment

25 Artificial Snag Tree

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29 CWD/Snag Assessment

30 Seedling Assessment

31 Seedling Assessment

32 Deer Browse Exclosure

33 Deer Browse Exclosure

34 Deer Browse Exclosure

35 Single-tree Selection % Volume % Value 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Downed Trees & Snags Harvested Trees Residual Trees 3% 21% 19% 79% 78% Single Tree (Conv) Single Tree (Aug) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Downed Trees & Snags Harvested Trees Residual Trees 1% 18% 14% 82% 84% Single Tree (Conv) Single Tree (Aug) Steele et al., in prep

36 Group Selection 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Steele et al., in prep % Volume Downed Trees & Snags Harvested Trees Residual Trees 3% 26% 20% 74% 76% Group Selection (Conv) Group Selection (Aug) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% % Value Downed Trees & Snags Harvested Trees Residual Trees 1% 25% 20% 75% 78% Group Selection (Conv) Group Selection (Aug)

37 Irregular Multi-cohort 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Steele et al., in prep % Volume Downed Trees & Snags Harvested Trees Residual Trees 3% 25% 21% 75% 76% Irregular Multi-cohort (Conv) Irregular Multi-cohort (Aug) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% % Value Downed Trees & Snags Harvested Trees Residual Trees 1% 24% 18% 76% 81% Irregular Multi-cohort (Conv) Irregular Multi-cohort (Aug)

38 Characteristics of Downed & Snag Trees Characteristics: D&S Single-tree Group Multi-cohort Mean tree size (DBH, in) Mean stems per acre Mean % sawtimber trees with defect Types defects 70.0% 83.8% 85.9% Seam, hollow, Eutypella, maple borer, crook, broken top Mean value/tree $10.39 $11.96 $10.40 Steele et al., in prep

39 Summary Findings Cost of creating CWD Cost is consistently 3% volume and 1% of the original stand value Strategic marking of poor quality trees limited the opportunity cost Comparison across canopy treatments No significant difference in the harvest volume or stumpage revenue (as % of total volume and value) between irregular multi-cohort and traditional (ST and GS) Different pattern of removal across the landscape Steele et al., in prep

40 Implications Relatively small immediate opportunity costs associated with treatments for enhancing diversity and complexity. Each landowner must evaluate the ecologicaleconomic trade-off given their circumstances. Further understanding of long-term economic and ecological impacts of these novel treatments is needed. Steele et al., in prep

41 Questions Contact: Dustin Bronson Research Scientist, WDNR