Growth, Yield, and Productivity: Managing Site Resources Through Key Intensive Treatments

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Center for Intensive Planted-forest Silviculture Intensive Silviculture of Planted Douglas-fir Forests: Opportunities for Increased Productivity Growth, Yield, and

1 Center for Intensive Planted-forest Silviculture Intensive Silviculture of Planted Douglas-fir Forests: Opportunities for Increased Productivity Growth, Yield, and Productivity: Managing Site Resources Through Key Intensive Treatments Doug Maguire Center for Intensive Planted-forest Silviculture College of Forestry, Oregon State University

2 Basic growth and yield concepts Concepts/principles Current work Current relevance Inherent site controls on productivity (soils/climate) The factory (species/genotype) Effects of silvicultural activities on growth and yield patterns Genetic improvement Initial spacing Vegetation management Fertilization Thinning What does this mean for the practitioner?

3 Do foresters have principles? Do we have a science base? Do we have a strong science base?

4 Do foresters have principles? Definition and drivers of NPP/GPP Growth and yield as a fraction of NPP/GPP MAI/PAI Maximum size-density limit and recommended density range for timber production (-3/2 law of selfthinning) Eichhorn s rule Langsaeter s hypothesis Liebig s law of the minimum

5 Estimates of PNW Douglas-fir productivity Potential MAI Bulletin 201 (1930, Normal yield tables for Douglas-fir) Staebler (1955) adjustment for capture of mortality (gross increment) Current field trials 210 ft 3 /ac/yr (15 m 3 /ha/yr) 270 ft 3 /ac/yr (19 m 3 /ha/yr) 300 ft 3 /ac/yr (21 m 3 /ha/yr)

6 On 4.2 million ac of forestland owned by private industry on the Westside: Average growth 135 ft 3 /ac/yr Potential growth 160 ft 3 /ac/yr 25 ft 3 /ac/yr

Brazil: 4-fold increase in Eucalyptus productivity (MAI) over last 4 decades: 12 48 m 3 ha -1 yr -1 (172 686 ft 3 /ac/yr) Genetics (species-provenancehybrids-clones) Silviculture (site

7 Brazil: 4-fold increase in Eucalyptus productivity (MAI) over last 4 decades: m 3 ha -1 yr -1 ( ft 3 /ac/yr) Genetics (species-provenancehybrids-clones) Silviculture (site prep, fertilization, pest control,...) Veracel average and target mean annual increment m 3 ha -1 yr -1 ft 3 ac -1 yr -1 bf ac -1 yr , ,000 target ,500

8 Potential MAI Douglas-fir, PNW 300 ft 3 /ac/yr 21 m 3 /ha/yr Douglas-fir, New Zealand 428 ft 3 /ac/yr 30 m 3 /ha/yr Eucalypts, Brazil 800 ft 3 /ac/yr 56 m 3 /ha/yr What controls productivity? What limits Douglas-fir productivity in the PNW?

9 Short answer: Length of growing season Seasonal availability of water Vapor pressure deficits Management intensity (factors influenced by silviculture) Water availability Competing vegetation control Nutrient availability Fertilization Competing vegetation control Genetics (species, genotypes)

10 Determinants of productivity Soil Nutrients Water holding capacity Depth to water table Total soil depth Temperature Texture Climate Daytime temperature Nighttime temperature Rainfall (amount and timing) Humidity (vapor pressure deficit) Solar radiation Length of growing season RESPIRATION FOREST BIOMASS TREE BIOMASS STEM WOOD Extreme events (temperature, vapor pressure deficit,...) Soil micro-organisms, including bacteria and mycorrhizae NPP GPP

11 Determinants of productivity Ecophysiological growth models (Process models) (Mechanistic models) RESPIRATION Hybrid models (Empirical growth models + ecophysiological components) FOREST BIOMASS TREE BIOMASS NPP GPP Required resolution on stems, logs, products Key resource-driven mechanisms STEM WOOD

12 Estimates of regional site index from an ecophysiological growth model, 3PG Swenson and Waring (2005)

13 Climatic inputs, parent material, soil are fixed parameters (beyond silvicultural control) Annual precipitation cm

14 What DO we have some silvicultural control over? (within constraints of climatic drivers and inherited parent materials) Soil Nutrient availability Water availability Water holding capacity Micro- and macro-organisms Climate Distribution of solar radiation (via stand structure)

15 Two primary effects of silvicultural activities: Change in NPP (net primary production) Change in allocation of NPP trees vs. other vegetation crop trees vs. other trees aboveground vs. belowground stemwood vs. crown biomass

16 Do foresters have principles? Definition and drivers of NPP/GPP Growth and yield as a fraction of NPP/GPP MAI/PAI Maximum size-density limit Eichhorn s rule Langsaeter s hypothesis Liebig s law of the minimum RESPIRATION FOREST BIOMASS Trees TREE BIOMASS STEM WOOD

17 Working hypothesis Genetics Competing vegetation control GPP + ( +?) NPP + ( +?) NPP / GPP 0 0 Tree / other vegetation 0 + Crop tree / other trees 0 + Shoot / root + 0 Stem / crown + 0 Merchantable / non-merch + 0 Stem form + 0

18 Working hypothesis Fertilization Thinning GPP + NPP + NPP / GPP 0 0 Tree / other vegetation 0 Crop tree / other trees 0 + Shoot / root + 0 Stem / crown 0 Merchantable / non-merch 0 + Stem form

19 Do foresters have principles? Definition and drivers of NPP/GPP Growth and yield as a fraction of NPP/GPP MAI/PAI Maximum size-density limit (-3/2 law of self-thinning) Eichhorn s rule Langsaeter s hypothesis Liebig s law of the minimum

22 peak in CAI (PAI) Inflection point = point of most rapid growth

23 MAI = volume accumulated to age A A

25 This pattern in MAI and PAI is the engine that drives the economic performance of planted forests under alternative silvicultural regimes.

26 Simulated site effect on MAI and PAI curves (ORGANON simulations) PAI PAI SI 90 ft SI 140 ft MAI MAI 12-ft initial spacing (300 tpa)

27 SMC Lewisburg spacing trial

28 PAI variation Growth, Yield, and Productivity What do real MAI and PAI curves look like? (Marshall and Curtis Hoskins thinning plots) net MAI peak in controls delayed MAI peak under thinning mortality loss under no thinning

29 Thinning & Growth-growing stock

30 Trends in MERCHANTABLE CUBIC VOLUME PAI and MAI on Hoskins LOGS plots Cubic volume increment (CV6/ac/yr) Stand age (yr)

31 Douglas-fir Levels-of-Growing-Stock Study (Curtis 2006) CAIs CAIs well above MAIs Lower growing stock MAIs Treatment means of CAIs and MAIs in gross CVT in relation to age.

32 Do foresters have principles? Definition and drivers of NPP/GPP Growth and yield as a fraction of NPP/GPP MAI/PAI Maximum size-density limit (-3/2 law of self-thinning) Eichhorn s rule Langsaeter s hypothesis Liebig s law of the minimum

33 Carrying capacity is difficult to predict Maximum SDI for individual permanent plots: Douglas-fir Western hemlock Hann et al. 2004

34 Maximum size-density limit Density Management Diagram (Stand Density Index) Thinned stands in DF LOGS studies tend to remain between 30% and 60% maximum SDI Hoskins LOGS treatments Management zone 35-55%, for maximizing production & maintaining tree vigor Marshall and Curtis 2002

35 Maximum size-density limit Remaining challenge: maximum for specific site?

36 Do foresters have principles? Definition and drivers of NPP/GPP Growth and yield as a fraction of NPP/GPP MAI/PAI Maximum size-density limit (-3/2 law of self-thinning) Eichhorn s rule Langsaeter s hypothesis Liebig s law of the minimum

37 Do foresters have principles? Eichhorn s rule The total standing volume of a given tree species at a given stand height should be identical for all site classes. Stands of the same mean height have the same volume. Stands of a given species take longer to attain a specified height on sites of lower quality, but whenever they attain the same top height they will have accumulated the same total stem volume.

38 Do foresters have principles? Assmann s yield level theory (in contrast to Eichhorn s rule) Range in volume capacity for given top height Related to stockability issue in Pacific Northwest (particularly Eastside)

39 Douglas-fir Levels-of-Growing-Stock Study (Curtis 2006) Gross CVTS yield of controls in relation to top height, by installation. Hoskins Stampede Creek

40 Do foresters have principles? Definition and drivers of NPP/GPP Growth and yield as a fraction of NPP/GPP MAI/PAI Maximum size-density limit (-3/2 law of self-thinning) Eichhorn s rule Langsaeter s hypothesis (manipulation of stand density) Liebig s law of the minimum

41 Langsaeter hypothesis Growing stock range with equal productivity (not time!)

42 Langsaeter hypothesis Time since thinning? Growing stock range with equal productivity (not time!)

43 Growth growing stock relationship on Douglas-fir Hoskins LOGS plots over successive growth periods During specified thinning regime Decreasing slope, increasing conformity to Langsaeter hypothesis After end of thinning regime

44 Cubic volume increment (CV6/ac/yr) Trends in MERCHANTABLE CUBIC VOLUME PAI and MAI on Hoskins LOGS plots Diminishing level of postthinning site occupancy Stand age (yr)

45 Closed stand, high tpa Reduced leaf area Reduced site occupancy Thinning Growth

46 Langsaeter: Variation in basal area (or cambial surface area?) for a given maximum leaf area?

Leaf area X cambial surface area X basal area total age 35 yrs 55 yrs 55 yrs crown surface 304 M ft 2 319 M ft

47 Leaf area X cambial surface area X basal area total age 35 yrs 55 yrs 55 yrs crown surface 304 M ft M ft M ft 2 bole surface 17.7 M ft M ft M ft 2 basal area 112 ft ft Briegleb ft

48 Stand density measure accounting for crown size/surface area Net Gross Briegleb 1952

49 Douglas-fir Levels-of-Growing-Stock Study (Curtis 2006) Treatment means of cumulative gross CVTS yields in relation to top height. Average of controls across sites Increasing thinning intensity (cumulative loss of site occupancy or resources)

50 Fertilization and nutrient availability

51 Fertilization and nutrient availability Multi-nutrient trials ( Beyond N trials) Rob Harrison Regional Forest Nutrition Research Cooperative Nutrition Project of Stand Management Cooperative Long-term Site Productivity Lots of others

52 Liebig s Law of the Minimum Minimum N Ca P

53 Multi-nutrient trials ( Beyond N trials) Possible predisposing effect of nutrition on Swiss needle cast Known nitrogen limitations to Douglas-fir growth Possibility of local deficiencies in other nutrients Possibility of gradual depletion of other nutrients with harvest of multiple rotations

54 Treatment Treatments Reason for inclusion Control N Lime CaCl 2 P Kinsey Fenn Statistical reference for treatments Standard operating procedure Add Ca, but also elevates ph, reduces Al Add Ca without increasing ph Limiting in other regions; P-fixing soils Address multiple/successive limiting nutrients Address multiple/successive limiting nutrients 16 installations with 10 reps/trt

55 P-values without covariates: with covariates: Three-year volume growth response

56 Thinning + Fertilization Thinning causes at least a temporary reduction in site occupancy and resource capture by crop trees Rate of recapture of growing space and site resources depends on growth rate of trees

57 Thinning + Fertilization On many/most Douglas-fir sites, growth can be accelerated by nitrogen fertilization Short-term increase in N foliar concentration and photosynthetic efficiency Long-term increase in total foliage N and total foliar biomass

58 18 Aboveground biomass increment Annual biomass increment (kg/tree) Control Thin Fertilize Thin + Fertilize Direct + indirect effect Year from Brix (1983)

59 Growth rate corrected for initial size at start of each growing season (analogous to relative growth rate) 0.45 Biomass growth per unit initial mass (kg/kg) Direct effect Control Thin Fertilize Thin + Fertilize Year from Brix (1983)

60 Aboveground biomass increment per unit initial foliage mass Growth efficiency Direct effect + functional insight from Brix (1983)

61 Treatment effects on total foliage biomass (leaf area index) 10 8 Fertilized Thinned + Fertilized 6 Control 4 2 Leaf Area Index (projected) 0 Thinned YES NO Thinned? YES NO Fertilized? From Brix (1981)

62 Competing vegetation control

63 Vegetation Management Research Cooperative Concurrent monitoring of soil moisture, seedling water stress, and growth over six alternative regimes for controlling competing vegetation Increasing aggressive competing vegetation control Dinger and Rose 2009

64 Collaborations with VMRC cover (%) Competing vegetation cover T0000 TT000 TTT00 TTTT0 TTTTT 0TTTT 00TTT Sweet Home Seaside Summit Predictive models for competing vegetation dynamics water and other resource use by competing vegetation Competing vegetation cover (%) cover T0000 TT000 TTT00 TTTT0 TTTTT 0TTTT 00TTT Sweet Home Seaside Summit Plantation age (years) Plantation age (years)

65 Effects of competing vegetation control on tree growth VMRC Herb 1 Study Total vegetation control Tree volume (dm 3 ) NO vegetation 5 8 control 12 Years since planting VMRC - Rose et al. 2006

66 Effects of competing vegetation control on YIELD? Age shift? Slow convergence Fast convergence Reduced longterm potential Years since planting Tree volume (dm 3 )

67 Time and yield gains from competing vegetation control (Wagner et al. 2006) Time since treatment Douglas-fir Yield gain (%) Sites Author , Oregon Hanson (1997) , Oregon Hanson (1997) , WA & OR Harrington et al. (1995) , Oregon Stein (1995) , Oregon Monleon et al. (1999)

68 Age shift (time gain in VMRC Critical Period Threshold study) Reduction in time to get same yield as untreated check plots

69 What does this mean for the practitioner? Resources for tree growth are largely determined by the site s climate and soils Silvicultural treatments manipulate the proportion of resources captured by crop trees Genetic tree improvement achieves growth and yield increases by increased resource use efficiency and heritable differences in morphology and allocation Some activities like fertilization increase the total amount of available resources and NPP

70 What does this mean for the practitioner? (cont d) Continuous site occupancy by crop trees tends to ensure fullest capture of site resources Thinning is a compromise among several responses: Some reduction in stemwood productivity per unit area Recovery of volume that would be lost to mortality Increase in average tree diameter Enhancement of individual tree vigor Thinning + fertilization accelerates site occupancy and fuller capture of site resources

71 What does this mean for the practitioner? (cont d) Competing vegetation control is very effective for channeling resources to crop trees vs. other plant species Longevity of growth response to competing vegetation control is not well established Interactions among treatments implemented in the full sequence constituting a silvicultural regime are not well understood, but largely presumed additive

72 Thanks for your kind attention!

Measures of productivity

Measures of productivity Determinants of productivity Site index Guide curve method Stem analysis method Repeated measurement method One vs. two equation systems Determining site index Growth intercept Plant indicators Soil-site