Natural (and inexpensive) means of regeneration of white spruce in mixedwood boreal forests

Transcription

1 Natural (and inexpensive) means of regeneration of white spruce in mixedwood boreal forests Victor Lieffers Ellen Macdonald, Brigitte Grover, Kevin Solarik, Jonathan Martin-eMoor & Stefanie Gärtner epartment of Renewable Resources, niversity of Alberta

2 How do we manage spruce now?

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7 ontrol aspen Herbicide or Brush saw treatments 7/9/2012 7

8 8 year plantation

9 Tended juvenile spruce plantation few examples of this in nature

10 In many areas of Alberta this is mixedwood management

11 How did we get here? Regeneration policy, AA and yield expectations We have culture that good forestry is intensive.

12 Natural mixedwoods

13 Aspen-dominated mixedwood without leaves understory spruce

14 nderstory spruce (A spruce stand 40 years from now)

15 Why do we believe that natural regeneration is infeasible? Not completely predictable (stochastic) Viewed as unmanageable/unpredictable by silviculturists Martin-eMoor an. J. For Res. 40: Solarik, an. J. For. Res. 40: Gärtner Biological Reviews. 19:

16 Seed Source Masting- Seed crops (2-8 years apart)

17 Seed Trees within 100m

18 Mineral soil - good Seedbeds

19 Mineral soil (good but prone to frost heaving)

20 Feather mosses are poor seed beds

21 Feather mosses are terrible seedbeds after clearcutting

22 Shallow organic layers -best

23 Spruce recruits on rotten logs sheds leaf litter late recruitment

24 ompetition

25 alamagrostis with persistent litter kills spruce seedlings

26 Matted litter smothers small seedlings Once hardwood leaf area develops, the recruitment window is largely shut.

27 ense hardwoods slows spruce growth

28 Spring Flooding

29 Regeneration in aspen stands Jonathan Martin-eMoor 8-15 years after logging (no silviculture) Aspen stands Whitecourt/Edson AB 162 transects across 81 aspen cutover

30 Meters Forest Stands AW40 SW30 PB20 AW80 PB20 00 AW90 PB10 00 AW90 PB10 00 AW70 PB20 SW10 AW70 PB20 SW10 Study Blocks Transects Seedlings 1st cohort 2nd cohort Mature Spruce Advance Growth Residual Map/Photo 5m Buffer 10m Buffer 15m Buffer 30m Buffer 60m Buffer 100m Buffer

31 Stocking was a function of: ensity of seed trees Masting Season of logging limate moisture index ensity of grass ensity of tall shrub/hardwoods

32 Final Model variables retained in the final model a. Effect Num F en F F-value oefficient Std Error P Mast Year - Season of Harvest Treatments Mast Year - Summer Harvest <.0001 Mast Year - Winter Harvest <.0001 Non-mast Year - Summer Harvest <.0001 Non-mast Year - Winter Harvest <.0001 Seed Source ensity (5m-60m) (SS) <.0001 SS - Mast Year <.0001 SS - Non-mast Year <.0001 limate Moisture Index (Aug-July) <.0001 Grass (ense) Tall Shrub (ense)

33 ifferent scenario: Predicted Scenario Mast Season SS/ha MI Grass Shrub Stocking % best observed values Y S L L average values - mast year Y S L L 6.72 average values - non mast N S L L 3.74 season of harvest - winter Y W L L seed source density - high (dense) Y S L L seed source density - very low (sparse) Y S L L climate moisture index - low (dry) Y S L L climate moisture index - very high (wet) Y S L L grass - high Y S H L shrub - high Y S L H Martin-eMoor an. J. For Res. 40:

34 Emend project 10 year survey Kevin Solarik an. J. For. Res. 40:

35 Emend Experiment mast years 2 and 4 years after cutting ompartment Size: ~10 Ha Project Size: ~1000 Ha

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37 ompartment 932 Block H Seed Trees

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40 75%,100% n=432 0%, 10%,20%,50% Stocking Total Area seed< 45.5 seed>= n=144 10%,20%,50% 0% n= n= n= n= n= % variance explained,,m n= n=136

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42 Seed Trees ha -1 < 30 Seed Trees ha % n=576 Stocking Trails vs. Interiors Seed Trees ha -1 < 11 Seed Trees ha Interior orridor 14.1% n= % n= % n= % n=350 Error: V Error: SE: % 10%,20%,50% 75% 10%,20%,50% 13.8% n= % n= % n= % n= % 80.6% n=49 n=126

43 10% % Stocking hapman - Richards urve eciduous onifer Mixedwood eciduous ominated - onifer understory 20% 50% Seed Trees ha % Stocking % Seed Trees ha lear ut % Stocking

44 Frequency of stocking on the transects

45 Variable Retention/structure cuts Not just for biodiversity issues! Time for silviculturists to see its potential Seed trees, site preparation (season of logging), masting, MI, grass, shrubs/deciduous

46 Assuming masting within 2 years, random skidding Almost no seed trees - negligible potential Seed Tree Efficiency

47 Very low Seed-tree ensity No scarification Light scarification Frequency Strata-level Stocking (%)

48 Seed tree shortage low Regeneration Potential

49 Low-Moderate Seed-tree ensity No scarification Light scarification Frequency Strata-level Stocking (%)

50 Moderate seed trees

51 Moderate Seed-tree ensity No scarification Light scarification Frequency Strata-level Stocking (%)

52 High Regeneration Potential

53 High Regeneration Potential

54 High Regeneration Potential

55 High Seed-tree ensity No scarification Light scarification Frequency Strata-level Stocking (%)

56 Preparing seedbeds How can this be done inexpensively?

57 Summer harvest traffic

58 Planning/Assessments Masting limate moisture index Vegetation

59 How to implement Plan for natural regeneration except where stands are needed. Planners/regulators must use the distribution of outcomes (accept stochastic response) se regeneration surveys to gather data on strata

60 Natural regeneration is predictable Regeneration is predictable Silviculturists can influence it

61 Gärtner 2011 Biological Reviews. 19:

62 Acknowledgments Mixedwood Management Association Weyerhaeuser, Westfraser, MI, anfor NE-SFM NSER John Spence Jan Volney Andreas Hamann

63 Seedling ensity (seedlings / 10m 2 ) B B B B B B A Seedling ensity (seedlings / 10m 2 ) Maximum Seedling Height (cm) A A B AB B B B B Seedling Stocking (%) B B B AB A Seedling Stocking (%) A B AB B Overstory Retention Intensity (%) 0 u Mx Overstory anopy omposition

64 se of skidders on return trip into the block