1. jessica.smith@uqat.ca, Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec Canada SPRUCING UP EASTERN CANADIAN MIXEDWOODS: Do white spruce (Picea glauca) trees respond to partial cutting? Jessica Smith, candidate M.Sc. Biology B.Harvey PhD, A.Koubaa PhD, S.Brais PhD

2. INTRODUCTION Canadian Boreal Forest 90% of forested land in Canada British Columbia Newfoundland Quebec 1 (Baldwin et al., 2012)

3. Canadian Boreal Forest 90% of forested land in Canada Province of Québec Region: Abitibi–Témiscamingue 48°14'55.0"N 79°20'11.7"W Boreal Mixedwood Forest 2 INTRODUCTION

4. Boreal Mixedwood Forest Transitional phase of succession Shade intolerant broadleaf and shade tolerant conifers white birch (Betula papyrifera) trembling aspen (Populus tremuloides) white spruce (Picea glauca) black spruce (Picea mariana) balsam fir (Abies balsamea) shade intolerantshade tolerant Licher Stone Lane Gardens Tigner Fewless Maine Forest Service 3 (Bergeron and Harvey, 1997) INTRODUCTION

5. Boreal Mixedwood Forest Mature aspen: suitable for harvest Pre-mature white spruce: has not reached maximum growth potential white birch (Betula papyrifera) trembling aspen (Populus tremuloides) white spruce (Picea glauca) black spruce (Picea mariana) balsam fir (Abies balsamea) shade intolerantshade tolerant Licher Stone Lane Gardens Tigner Fewless Maine Forest Service 4 INTRODUCTION

6. Boreal Mixedwood Forest Mature aspen: suitable for harvest Pre-mature white spruce: has not reached maximum growth potential white birch (Betula papyrifera) trembling aspen (Populus tremuloides) white spruce (Picea glauca) black spruce (Picea mariana) balsam fir (Abies balsamea) shade intolerantshade tolerant Licher Stone Lane Gardens Tigner Fewless Maine Forest Service 4 INTRODUCTION

7. Why partial cutting? Ecosystem based management Diversify silvicultural strategies Emulate natural succession dynamics Maintain residual stand with complex structure and attributes Industry Residual trees show accelerated radial and volume growth rates following “release” Larger stems 5 (Youngblood, 1991; Yang, 1991; Man and Greenway, 2004; Grover et al. 2014) INTRODUCTION

8. Rouyn-Noranda, Abitibi–Témiscamingue, Québec, Canada Partial Cutting Treatments: 2002 Control 0% harvested 50% aspen BA harvested 65% aspen BA harvested 100% aspen BA harvested 3% balsam fir 1% black spruce 1% white birch 75% aspen 20% white spruce Pre-treatment species distribution by basal area Boreal Mixedwood Forest 6 STUDY SITE

9. Experimental Units 65% Control 42.65 46.91 40.32 50% 38.79 37.50 25.92 22.32 25.69 37.88 53% 52% 34.40 44.19 26.20 16.82 41.30 23.49 61% 74% 64% 100% 14.12 2 3 Initial BA (m 2 · ha -1 ) Residual BA Aspen removed (m 2 · ha -1 ) 51.08 93% 31.65 100% 11.44 58.04 99% 10.03 1 7 STUDY SITE

10. Evaluate radial and volume growth responses of residual white spruce trees, 10 years after the implementation of the partial cutting treatments 1. Post-treatment radial and volume growth rates will be higher in intermediate treatments (50% and 65%) than in the extreme treatment (100%) 2. Tree social status will influence post-treatment radial and volume growth rates, with dominant and co-dominant trees having superior growth rates to suppressed trees 8 OBJECTIVE HYPOTHESES

11. Experimental Design 3 3 3 3 1 1 1 1 2 2 2 2 65% 50% 0% 100% Scale 1:10,000 4 treatments 3 replications 12 Experimental Units 2002 2 trees 3 social status 6 Trees/ Experimental Unit 72 Trees 2012 9 METHODS

12. Sampling and Data Collection 1 (30 cm) 3 4 5 7 6 8 9 10 11 2 (130 cm) 10 (Chhin et al., 2010) METHODS

13. Annual Ring Width Measurements Win Dendro (Regent Instruments) annual radial growth rate (mm·year -1 ) 3 radii per disk 5 years pre-treatment 10 years post-treatment Stem Analysis Win Stem (Regent Instruments) annual volume growth rate (dm 3 ·year -1 ) 11 METHODS

14. Statistical Analysis Linear mixed effect model Response VariableExplanatory Variables 1. Annual Radial Growth at 1.3 m (mm·year -1 ) 2. Annual Volume Growth (dm 3 ·year -1 ) Fixed effects treatment intensity social status time time 2 mean growth rate 5 years pre-treatment treatment intensity : time treatment intensity : time 2 social status : time social status : time 2 Random effects experimental unit tree number 12 METHODS

15. Annual Radial Growth 1.3 m A) Suppressed B) Co-dominant C) Dominant 13 RESULTS

16. Annual Radial Growth 1.3 m In the 100% aspen removal treatment, average annual radial growth rates at 1.3m were: 23.5% higher for dominant trees 67.7% higher for co-dominant trees 154.3% higher for suppressed trees as compared to the control treatment over the 10 year post-treatment period A) Suppressed B) Co-dominant C) Dominant 13 RESULTS

17. Annual Radial Growth 1.3 m C) 65% Aspen BA removal D) 100% Aspen BA removal A) ControlB) 50% Aspen BA removal 14 RESULTS

18. Annual Volume Growth A) Suppressed B) Co-dominant C) Dominant 15 RESULTS

19. Annual Volume Growth In the 100% aspen removal treatment, average annual volume growth rates were: 7.2% higher for dominant trees 24.1% higher for co-dominant trees 65.6% higher for suppressed trees as compared to the control treatment over the 10 year post-treatment period A) Suppressed B) Co-dominant C) Dominant 15 RESULTS

20. Annual Volume Growth C) 65% Aspen BA removal D) 100% Aspen BA removal A) Control B) 50% Aspen BA removal 16 RESULTS

21. 1. Post-treatment radial and volume growth rates will be higher in intermediate treatments (50% and 65%) than in the extreme treatment (100%) 2. Tree social status will influence post-treatment radial and volume growth rates, with dominant and co-dominant trees having superior growth rates to suppressed trees Validating Hypotheses 17 RESULTS

22. 1. Post-treatment radial and volume growth rates will be higher in intermediate treatments (50% and 65%) than in the extreme treatment (100%) 2. Tree social status will influence post-treatment radial and volume growth rates, with dominant and co-dominant trees having superior growth rates to suppressed trees Validating Hypotheses 17 RESULTS

23. 2. Tree social status will influence post-treatment radial and volume growth rates, with dominant and co-dominant trees having superior growth rates to suppressed trees 1. Post-treatment radial and volume growth rates were higher in 100% aspen removal treatment Validating Hypotheses 17 RESULTS

24. 2. Tree social status will influence post-treatment radial and volume growth rates, with dominant and co-dominant trees having superior growth rates to suppressed trees 1. Post-treatment radial and volume growth rates were higher in 100% aspen removal treatment Validating Hypotheses √ 17 RESULTS

25. 1. Effect of partial cutting in 100% aspen removal treatment Annual Radial and Volume Growth 2. Treatment effect changes through time following a quadratic form Radial Growth: peaking 6 years post-treatment Volume Growth: plateau for suppressed and co-dominant trees, continuing linearly for dominant trees 4. Dominant and co-dominant trees superior to suppressed trees 3. Treatment effect across time is the same for all social statuses 18 5. Relative growth increases greatest for suppressed trees, least for dominant trees, and intermediary for co-dominant trees CONCLUSIONS

26. 2. Monitor regeneration and mortality 1.Remove high proportion of dominant, shade intolerant broadleaf species Savioja Schreiber 19 RECOMMENDATIONS

27. Fewless, Gary. http://www.uwgb.edu/biodiversity/herbarium/gymnosperms/picmar01.htm Licher, Max. http://swbiodiversity.org/seinet/taxa/index.php?taxon=3892 Maine Forest Service. https://www.maine.gov/dacf/mfs/archive/balsamfirtipblight.htm Savioja,Jouko.http://www.cbc.ca/news/canada/thunder-bay/appearance-of-dry-dead-trees-alarms-residents-1.1253376 Stone Lane Gardens. http://stonelanegardens.com/shop/betula-papyrifera-paper-birch-or-canoe-birch/ Tigner, Daniel. Canadian Forest Tree Essences. http://www.mnr.gov.on.ca/en/Business/ClimateChange/2 ColumnSubPage/267351.html Photos Arun Bose, Marc Mazerolle, Manuella Strukelj, Igor Drobyshev, Suzie Rollin, Fred Coulombe, Field Crew References Baldwin et al. Canadian Regional Team of the Circumboreal Vegetation Map Project. Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre (2012). Bergeron Y, Harvey B. Basing silviculture on natural ecosystem dynamics: an approach applied to the southern boreal mixedwood forest of Quebec. Forest Ecology and Management (1997) 92:235-242 Chhin S et al. Growth–climate relationships vary with height along the stem in lodgepole pine. Tree physiology (2010) 30:335-345 Grover et al. White spruce understory protection: From planning to growth and yield. The Forestry Chronicle (2014) 90:38-43. Man R, Greenway KJ. Meta-analysis of understory white spruce response to release from overstory aspen. The Forestry Chronicle (2004) 80:694-704. Yang R. Growth of white spruce following release from aspen competition: 35 year results. The Forestry Chronicle (1991) 67:706-711. Youngblood AP. Radial growth after a shelterwood seed cut in a mature stand of white spruce in interior Alaska. Canadian Journal of Forest Research (1991) 21:410-413 ACKNOWLEDGEMENTS