Are Free-Growing Stands Meeting Expectations?

Alex Woods, Regional Pathologist, NIFR, MOFR

Wendy Bergerud, Senior Biometrician, Research Branch, MOFR

Funded by FREP, Effectiveness Evaluation Program

and the BCMOFR Forest Health Program

Overall Objective:

To test if the Free-Growing declaration point-in-time assessment is an accurate predictor of future stand productivity and if the assumptions of stand performance are valid.

Strathcona TSA (2006)

Lakes TSA (2005)

Okanagan TSA (2006)

“This photo illustrates a successful free-growing stand of trees” (Forest Practices Board 2003)

Sampling Design:

•Sample population consisted of all openings declared FG prior to 2002 in the Lakes, Okanagan and

Strathcona TSAs.

•60 stands randomly selected from each TSA,

•15, 3.99 m radius plots established in each stand,

•Height and dbh measured for all well spaced trees,

•Site Index determined using growth intercept method

•Strict adherence to Free-Growing damage criteria.

Questions:

(1) Do TIPSY projections of declaration attributes projected to the present differ from current measured attributes?

(2) Do TIPSY projections of harvest volumes at age 80 differ between runs based on declaration values and runs based on current stand attributes?

(3) Has the composition of leading species changed significantly since Free-Growing declaration?

Questions:

(4) Does Site Index differ between the Free-Growing declaration estimate and the current estimate based on the growth intercept method?

(5) Have stocking levels changed significantly since Free-Growing declaration?

(6) Have losses to forest pests increased since declaration?

What was I thinking???

I’m sure “Free-Growing” is fine…???

Miller Time?

Photo: Tim Ebata

18% of Free-growing stands in the Lakes TSA no longer contain the minimum 700 fgsph based on the LCL rule.

Results: Forest Health/Free Growing

Photo: Dave Weaver

•Stand (93F072-004), spaced and pruned, age class 2 lodgepole pine, now has 70-75% of the trees attacked by MPB (but no Free-Growing Damage Criteria for MPB)

Lakes TSA

Oh, to be a pine in the Lakes TSA…, sorry about your folks!

I wonder how the Okanagan looks?

Photo: Tim Ebata

A gem from the Okanagan TSA (2006)

•   “This block is SR and FG when root rot is not  taken into consideration.  There is a fair amount of DRA in this block and when the 3m rule is applied the WS drops to 767/ha with 544 FG/ha.  Since this area would be FG if not for the DRA and nothing can be done to alleviate the root rot problem, consider this block FG and roll over to the MoF."

Percent of sample stands by BEC zone and by Free-growing status within BEC zones, in 60 randomly

selected Free-Growing stands in the Okanagan TSA

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

ICH MS IDF ESSFBEC Zones

Perc

ent

% of Sample %NSR (mean)% NSR (LCL)

Comparison of the percentage of stands no longer Free-Growing based on means and the LCL rule, between stands created pre-1987 and those post-1987 based on 60 randomly selected Free-Growing

openings in the Okanagan TSA (2006)

31.4

22.2

30.0

58.8 58.355.6

0

10

20

30

40

50

60

70

Pre-'87 Post-'87 Total

Num

ber of

sta

nds an

d pe

rcen

tage

of s

tand

s

# ofstands

% NotFG

%NSR(LCL)

Forest pests are having a considerable influence on Free-growing density but how does

that affect Timber Supply projections?

Contrasts

Contrast Means

SE of Difference

p-value

Projected Volume at 80 yrs Declaration 2005

1) Early: 327 324 1.4 0.032 2) Late: 316 314 1.4 0.091

Early Late 3) Averaged over time 325 315 10.1 0.32

F-growing (stems/ha) (M) 1) Early: 1020.8 972.9 34.5 0.17 2) Late: 975.0 1010.7 34.5 0.31

Early Late

3) Averaged over survey time 996.9 992.8 27.8 0.89

TIPSY projected volumes and Free-growing density Lakes TSA

The degree of reliance that the Crown has placed on TASS/TIPSY mirrors the extent of trust placed on

Free-Growing policy.

However…

Contrasts

Contrast Means

SE of Difference

p-value

Two measures of Volume Measured* TIPSY 1) Early: 40.4 54.7 3.3 <0.0001 2) Late: 19.9 21.0 3.3 0.73 Average Quadratic Diameter Measured TIPSY 1) Early: 11.2 8.0 0.30 <0.0001 2) Late: 8.6 5.2 0.30 <0.0001 Max DBH Measured TIPSY 1) Early: 14.9 15.4 0.65 0.52 2) Late: 11.9 13.1 0.65 0.074

TIPSY vs current measured attributes, Lakes TSA

We need a standardized approach to field verifying TASS/TIPSY

projections mid-rotation.

If TASS/TIPSY was able to project the volume of the well-spaced trees

throughout a rotation, field verification of the model would be much easier.

How are Free-Growing, TASS/TIPSY and Timber Supply

Linked?

Analysis for vol_80: Projected Volume at 80 yearsDeclared FG=Late 95-01 Sample Time=2005

brush N Y

Proj

ecte

d Vo

lum

e at

80

yrs

180

200

220

240

260

280

300

320

340

360

380

400

FG 2005600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700

Declared 1995-2001 (Lakes TSA)

TASS/TIPSY volume projections are based on

Total Trees not Free-growing trees

How closely are Free-growing trees related to

Total trees?

It depends on how old the stand is…

Declared FG=Early 85-94 Sample Time=2005

FG 2

005

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

Total Trees (2005) >2m0 1000 2000 3000 4000 5000 6000 7000 8000

Declared 1987-1994 (Lakes TSA)

Over 10,000 tsph at Declaration, No

pests noted

Now <700 fgsph (LCL) and 39% hard pine rusts

Declared FG=Late 95-01 Sample Time=2005

FG 2

005

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

Total Trees (2005) >2m0 1000 2000 3000 4000 5000 6000 7000 8000

Declared 1995-2001 (Lakes TSA)

Is there a fundamental disconnect between our current results-based

goal of Free-Growing, and the Growth and Yield model that drives nearly all Timber Supply Reviews in

the Province, TASS/TIPSY?

It’s not clear that Free-growing stands are currently meeting our expectations given the disconnects we have highlighted.

How well will free-growing policy uphold the ministry’s stewardship mandate given the uncertainty associated with the direct and indirect impacts of climate change?

A free-growing designation pre-supposes that young trees will continue to grow and thrive in a relatively stable environment.

Closing Thoughts:

Acknowledgements:

• Silvicon Services (Brad Leroux)• JCH Forest Pest Management (Janice Hodge)• Nadina Forest District (Carolyn Stevens)• Okanagan Shuswap Forest District (Don Purdy)• Campbell River Forest District (Carolyn McLeod)• David Rusch• Westfor (Nigel Ross)• Erin Havard, NIFR• Stefan Zeglen, Coast Forest Region• Jim Goudie, Research Branch MOF• Peter Bradford, and Anthony Britneff MOF HQ