Competitive Interaction of Aspen – Lodgepole pine mixedwoods in the Sub boreal forest: Implication for reforestation policy and practices in British Columbia (BC) Christopher D.B. Hawkins and Amalesh Dhar Mixedwood Ecology and Management Program University of Northern British Columbia, BC 9/14/2018 1 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 1

Outline 1. Information about BC forest management 2. Objectives 3. Materials and Methods 4. Results 5. Conclusion 9/14/2018 2 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 2

Introduction Vegetation management in BC: historically BC reforestation policies and regulations are conifer-biased broadleaves species (birch, aspen) are routinely removed from plantations - maximize crop tree growth maintaining BC’s free-to-grow standard (BC Ministry of Forests 2000 ) “a stand of healthy trees of a commercially valuable species, the growth of which is not impeded by competition from plants, shrubs or other trees” stands may only be declared free to grow when 2/3 years have passed since chemical or manual brushing treatment applied all broadleaves vegetation treated as a competitor BC = forestry dependent province 44.5 million hectares of commercial forest land; Harvest = 70 million cubic meters 20% of Canadian total Plant more than 200 million seedlings annually Values of shipments = 24 billion CDN$; ~$14.6 billion Euro Accounts for 1/3 of Canada’s total forestry shipments Employs 270 k: Direct = 90k and 180 indirect 9/14/2018 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar

Vegetation management in BC: Introduction Vegetation management in BC: avoid administrative delays to get responsibility of the stand management broadleaf species must be less than 1000 sph practice has been consistently applied across much of Canada Few years earlier Province of Alberta has changed this rule and made free growing standard should be location specific. Depending on the site condition broadleaf density may vary. 9/14/2018 4 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 4

Objectives Objectives to examine the growth response of pine to varying levels of imposed aspen densities test the effectiveness of current BC free-growing criteria 9/14/2018 5 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 5

Materials and Methods 9/14/2018 6 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 6

Materials and Methods Location : Vama Vama Creek , Prince George, BC, Canada Zone: SBSwk1, wet and cool Latitude: 53°52’12” N Longitude: 122°09’46” W Elevation: 775 m asl Mean annual precipitation: 440-900 mm (25-50% falls as snow) Mean annual temperature: 1.7-5.2 °C Stand Age at plot establishment: 12 year-old stand Stand: predominantly lodgepole pine and aspen (lesser amounts of spruce and subalpine fir) USA Canada USA Canada 9/14/2018 7 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 7

Experimental design and data collection (Experiment 1) Materials and Methods Experimental design and data collection (Experiment 1) Design: completely randomized design Treatment: Six different aspen densities replicated three times - 0, 500, 1200, 2500, 5000 sph, and control Plot establishment year - 2000 (age of 12 years) - total 18, 50 m X 50 m treatment units - permanent plot (PSP) size - 5.64 m radius (100 m2) - broadleaf species other than aspen were cut within 1.5 m of pine - Plots were sampled at establishment and three times between ages 14 to 18 years To meet the treatment density the broadleaf species other than aspen were cut within 1.5 m of lodgepole pine for facilitating the pine aspen competition 8 9/14/2018 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 8

Materials and Methods Experimental design and data collection (Experiment 2) equal numbers of free growing (FTG) and not free growing (NFTG) pine selected and tagged -Pine with no aspen within the effective growing space (1 m radius cylinder centered on the pine) were classed as free growing Crown dimensions, height and DBH measured in 2000, 2001,2003 & 2006 Leaf area index (LAI) measured for both FTG and NFTG pine - midsummer of 2001 and re-measured in summer 2005 Light transmission measured by LiCor LAI-2000 (LiCor Inc., Lincoln NB) for FTG & NFTG - diffuse non-interceptance (DIFN) values are estimated of average growing season fractional transmittance (i.e., percent of open-sky light) - measurements at 1.3 m above the ground in midsummer 2005 - two readings from opposite directions were taken with 180° view restrictors The LiCor system requires open-sky, as well as understory, measurements in order to calculate DIFN. 9/14/2018 9 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 9

Results 9/14/2018 10 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 10

Results: Experiment -1 Mean pine and aspen diameter (± SEM) at plot establishment and pine MA diameter growth 2000-2006 5000 sph (stem ha-1) of aspen appears to be the critical density - diameter growth of the pine was significantly (p = 0.005) affected 2500 sph was the threshold density - diameter growth of the pine was not significantly (P = 0.168 ) affected 9/14/2018 11 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 11

Results: Experiment -1 Mean pine and aspen height (± SEM) at plot establishment and pine MA height growth 2000-2006 pine height growth showed insignificant relationship 9/14/2018 12 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 12

Results: FTG and NFTG (Exp. 2) Repeated measures ANOVA from 2000, 2001, 2003 and 2006 in comparing height, diameter and crown volume for FTG and NFTG pine Source SS DF MS F P Height 11052.49 1 0.237 0.628 Error 3732081.54 80 46651.02 DBH 108.91 0.069 0.794 127043.92 1588.05 Crown Vol. 51.51 0.083 0.774 49425.69 617.82 FTG and NFTG pine were not significant differ for DBH, height and crown volume 9/14/2018 13 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 13

Results: FTG and NFTG (Exp. 2) FTG and NFTG showed similar DBH growth response in 2002 to 2006 9/14/2018 14 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 14

Results: FTG and NFTG (Exp. 2) FTG and NFTG showed similar DBH growth response in 2002 to 2006 9/14/2018 15 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 15

Results: FTG and NFTG (Exp. 2) FTG and NFTG showed similar DBH growth response in 2002 to 2006 9/14/2018 16 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 16

Results: FTG and NFTG (Exp. 2) height of FTG pine was similar with NFTG pine 9/14/2018 17 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 17

Results: FTG and NFTG (Exp. 2) FTG or NFTG pine was not significantly differ for different densities LAI of pine increased with increased of aspen density 9/14/2018 18 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 18

Results: FTG and NFTG (Exp. 2) FTG and NFTG pine were not significantly differ for different density classes DIFN for pine decreased with increased of aspen density 9/14/2018 19 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 19

Results: FTG and NFTG (Exp. -1) pine DBH growth slightly increased with the increase of DIFN - response was not significant least DBH growth was observed at lower DIFN in NFTG pine 9/14/2018 20 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 20

Conclusion 9/14/2018 21 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 21

Conclusion Impact on overall pine growth pine DBH growth not impacted by up to 2500 sph aspen pine DBH growth significantly impacted with 5000 sph aspen Pine height growth not significantly differed by density treatment Impact on FTG and NFTG pine no significant differences between FTG & NFTG pine in height, DBH and crown volume rate of change of DFIN and LAI is similar up to 2500 sph but rate of change is high if densities greater than this 9/14/2018 22 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 22

Conclusion Current policy (1 m radius) Appropriateness of the free growing status at 1 m radius is conservative 2500 sph exceeds the current allowable free-growing maximum (1000 sph aspen) Spruce-birch mixedwood experiment also showed the threshold limit was 3000-4000sph Now its time to rethink about the BC free-growing guideline 9/14/2018 23 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 23

Conclusion Consequence of current policy Administrative vegetation control Unnecessary cost for density management Reduced diversity Potential productivity reduced Final recommendations Leave more broadleaf competition Reduced management cost Potential productivity increases Greater structural diversity Greater species diversity 9/14/2018 24 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 24

Acknowledgements Funding provided by Ministry of Forests and Range, British Columbia FRBC-Slocan Mixedwood Chair Carrier Lumber Technical support provided by Peter Fielder Phil Comeau Cindy Baker Nicole Balliet Jennifer Lange 9/14/2018 25 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 25

For further communication Prof. Dr. Christopher .D.B. Hawkins Yukon Research Centre Yukon College P.O. Box 2799 Whitehorse, YT, Canada Y1A 5K4 Phone: +1 867 456-8627 FAX: +1 867-456-8672 Email: chawkins@yukoncollege.yk.ca Dr. Amalesh Dhar Mixedwood Ecology and Management Program University of Northern British Columbia 3333 University Way, Prince George, BC, Canada V2N 4Z9 Phone: +1 250 960 5778 Fax: +1 250 960 5339 Email: dhar@unbc.ca 9/14/2018 26 Mixedwood Ecology and Management Program (UNBC) | Christopher D.B. Hawkins & Amalesh Dhar 26

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