Growth of young lodgepole pine stands after mountain pine beetle attack

Transcription

1 Growth of young lodgepole pine stands after mountain pine beetle attack Chris Hawkins and Kyle Runzer University of Northern British Columbia Prince George, BC, Canada October 26, 2007 SAF, Portland, OR

2 Outline Mountain pine beetle Background (context) Objectives Study Findings Conclusions Recommendations

3 Mountain pine beetle (MPB) MPB (Dendroctonus ponderosae) most severe insect pest adults attack (lay eggs) in summer larvae feed on phloem with fungi girdle and kill the tree From: CFS MPB historic role in stand dynamics periodic invasions fuels fire regeneration of lodgepole pine increased probability pine will reoccupy site

4 MPB endemic in BC 1910 Background 2.5 million ha (6.2) mature (>80 year old) pine million ha (19.8) mature pine 14.9 million ha of pine stands fire suppression (WW II) suitable host (lots) recent warm winters few days < -30 C warm summers poor access

5 Expansion of MPB Change in the landscape From: BCFS

6 Expansion of MPB Change in the landscape From: BCFS From CFS

7

8 1-3 % 4-20 % % % % >80 %

9 41-60% 61-80%

10 >80%

11 Background: MPB killed volume Gross Annual Gross, millions ~ AAC for BC Annual, millions Projected: 80% of mature killed by 2013

12 Background Several AAC assumptions for Prince George TSA Only mature stands affected (>60 years old) Stands > 80 years attack rates > 80% Stands years old 50% attack Unlogged regeneration delay of 15 years Shelf life of 15 years Saw logs 5 years Oldest attack is processed first

13 Background Several AAC assumptions for Prince George TSA Only mature stands affected (>60 years old) Stands > 80 years attack rates > 80% Stands years old 50% attack Unlogged regeneration delay of 15 years Shelf life of 15 years Saw logs 5 years Oldest attack is processed first No attack in stands < 61 years old (immature)

14 Background Several AAC assumptions for Prince George TSA Only mature stands affected (>60 years old) Stands > 80 years attack rates > 80% Stands years old 50% attack Unlogged regeneration delay of 15 years Shelf life of 15 years Saw logs 5 years Oldest attack is processed first No attack in stands < 61 years old (immature) Net result AAC falls to 75% of pre MPB level Downward pressure

15 Background: Timber Supply Impact Pre MPB

16 Background: Timber Supply Impact Pre MPB

17 Objectives for PG TSA study 1. Quantify MPB attack (immature) 2. Changes in stand structure and composition 3. Amount and quality of regeneration (secondary structure) 4. Model future growth 5. Management recommendations

18 Study Stands years old fire origin Age class 3 Stands < 41 years old plantation origin Age classes 1 (< 21 years old) and 2 (21 40 years old) 2005 west of Prince George (dry sub-zones) 92 pine leading stands 65 re-sampled in 2006

19 Study Stands years old fire origin Age class 3 Stands < 41 years old plantation origin Age classes 1 (< 21 years old) and 2 (21 40 years old) 2005 west of Prince George (dry sub-zones) 92 pine leading stands 65 re-sampled in east of Prince George (moist sub-zones) 90 pine leading stands

20 100 Km Study area

21 Study Trees 7.5 cm at dbh Plot radius 5.64 m 2 MPB attack, vigor, dbh, site index, danger tree Regeneration (secondary structure) < 7.5 cm at dbh Plot radius 3.99 m 2 Seedlings < 1.37 m tall Height, vigor, Saplings 1.37 m tall Height, dbh, vigor, (MPB attack)

22 Findings dbh when attacked 1. Generally less than 16 cm 2. Dry dbh gradually increased with age class 3. Moist dbh greatest age class 2 dbh, cm AC1 AC2 AC3 Moist06 Dry05 Photo by Ken Hodges BCFS

23 Findings dbh when attacked 1. Generally less than 16 cm 2. Dry dbh gradually increased with age class 3. Moist dbh greatest age class 2 very small trees attacked dbh, cm AC1 AC2 AC3 Moist06 Dry05 Photo by Ken Hodges BCFS

24 Findings MPB attack 1. Little attack in dry age class 1 2. Attack rates similar in age class 2 3. Attack rate greater in dry age class 3 4. Large standard deviation (stand to stand variation) Attack, % AC1 AC2 AC3 Moist06 Dry05 Dry06

25 Findings regeneration 1. Lots of regeneration in each age class AC 3 most 2. More in moist than dry 3. High variation: SD > mean Stocking, sph AC1 AC2 AC3 Moist Sap Moist Seed Dry Sap Dry Seed

26 Findings regeneration 1. Lots of regeneration in each age class AC 3 most 2. More in moist than dry 3. High variation: SD > mean Age class 1 3 Dry: Pl=, At<, Sx> Moist: Pl<, At, <, Sx<, Bl> Stocking, sph AC1 AC2 AC3 Moist Sap Moist Seed Dry Sap Dry Seed

27 Findings regeneration 1. Lots of regeneration in each age class AC 3 most 2. More in moist than dry 3. High variation: SD > mean 4. Manage on a stand by stand basis (secondary structure) Stocking, sph AC1 AC2 AC3 Moist Sap Moist Seed Dry Sap Dry Seed

28 Study SORTIE ND model scenarios No MPB attack (base case) No management after MPB attack Secondary structure grows Under plant after MPB attack (advance regeneration too) 300 spruce pine per ha in dry area (2005) 600 spruce per ha in moist area (2006) Clear stand and replant after MPB attack 800 spruce pine per ha

29 Findings age class 2 (dry) modeling Low attack rates (< 30%) Low moderate or high regeneration MPB case Little impact on yield at PRA (planned rotation age) Yield Years from 2006 LL32 LLB LM23 LMB LH37 LHB

30 Findings age class 2 (dry) modeling Attack rates ~ 60% Yield loss at PRA m 3 Yield loss proportional to MPB attack Yield Years from 2006 ML34 MLB MM30 MMB MH32 MHB

31 Findings age class 2 (dry) modeling Attack rates ~ 60% Yield loss at PRA m 3 Yield loss proportional to MPB attack Amount of regeneration not correlated to yield loss Yield M H Years from 2006 ML34 MLB MM30 MMB MH32 MHB

32 Findings age class 2 (dry) modeling Attack rates > 75% Yield loss m Yield Years from 2006 HL29 HLB HM28 HMB HH23 HHB

33 Findings age class 2 (dry) modeling Attack rates > 75% Yield loss m3 Yield positively related to attack and regeneration Yield H L M Years from 2006 HL29 HLB HM28 HMB HH23 HHB

34 Findings economic assumptions Age class 2 dry Stumpage Spruce $40, Pine $25, Sub alpine fir $25, Aspen $10 Stumpage inflation 1.4% Initial planting $900 per ha Clearing 2007 $1000 per ha Plant 2007 $1200 per ha Under plant 2007 $450 per ha Real interest rate 2, 3,, and 4% Photo by Ken Hodges BCFS

35 Findings NPV 60% attack Moderate regeneration Stand value reduced by ~$3000 per ha by MPB (3% interest) Under planting or starting new not best investment $50,000 $40,000 $30,000 P528 NPV $20,000 $10,000 $0 -$10, $20,000 Years from 2006 Base MPB MPB + UPlant Clear + Plant

36 Base MPB MPB + UPlant Clear + Plant Findings NPV > 75% attack Low regeneration Stand value reduced by ~$5000 per ha by MPB (3% interest) Under plant is a good investment $50,000 $40,000 $30,000 P235 NPV $20,000 $10,000 $0 -$10, $20,000 Years from 2006

37 Base MPB MPB + UPlant Clear + Plant Findings NPV > 75% attack Low regeneration Stand value reduced by ~$4000 per ha by MPB (2% interest) Under plant almost same value as base Clearing and planting may be viable $50,000 $40,000 $30,000 P235 NPV $20,000 $10,000 $0 -$10, $20,000 Years from 2006

38 Base MPB MPB + UPlant Clear + Plant Findings NPV > 75% attack Low regeneration Stand value reduced by ~$5000 per ha by MPB (4% interest) Under plant best option $50,000 $40,000 $30,000 P235 NPV $20,000 $10,000 $0 -$10, $20,000 Years from 2006

39 Base MPB MPB + UPlant Clear + Plant Findings NPV > 75% attack High regeneration Stand value reduced by ~$5000 per ha by MPB (3% interest) No management is best investment $50,000 $40,000 $30,000 P619 NPV $20,000 $10,000 $0 -$10, $20,000

40 Conclusions Attack in immature stands is not 0 % or low Negative pressure on mid-term timber supply Significant secondary structure (regen) at landscape level Highly variable at stand level

41 Conclusions Attack in immature stands is not 0 % or low Negative pressure on mid-term timber supply Significant secondary structure) (regen) at landscape level Highly variable at stand level Attack rates < 30% (low) no yield impact (AC 2) Attack rates 60% (moderate, high) yield losses No treatment best investment after attack (AC 2) Exception High attack low regeneration (secondary structure)» Under plant best investment

42 Recommendations Based on planned rotation age ~ 75 years old Age class 2 low and moderate attack ( ( 60%) Management not required Age class 2 high attack (>75%) Management required if little regeneration

43 Recommendations Based on planned rotation age ~ 75 years old Age class 2 low and moderate attack ( ( 60%) Management not required Age class 2 high attack (>75%) Management required if little regeneration Age class 1 No management likely needed Age class 3 Complicated (merchantability( merchantability) Still developing

44 Acknowledgements 1. Funded by BC Forest Science Program projects M and M and NRCan, CFS Mountain Pine Beetle Initiative projects 8.23 and Bruce Rogers, Deanna Danskin, Cindy Baker, Jenny Li, Nicole Balliet, Orrin Quinn, Shonna Smith, Yi-Ping Liang, Min Jun Lee and Cosmin Man are thanked for their contributions in the field.