Patterns of Spruce Regeneration in the

Gunnison National Forest

Mike Battaglia, USFS RMRS Jason Sibold, CSU Tony Cheng, CSU/CFRI

Goals• Fill in critical

knowledge gaps:

• assist management/decrease uncertainty

• provide information for adaptive management

Specific Goals• Establish monitoring baselines to

understand ecological results of treatments

• Patterns of spruce regeneration in relation to:

• landscape position

• treatment location and implementation

• past treatments

• treatment locations, can treatments in green stands initiate a pulse of regeneration?

• microsite conditions

• post-treatment conditions

4

Current Research Topics

• Comparison of previously harvested stands and unharvested stands • Tree Mortality • Post-beetle stand structure • Tree regeneration

Previously Harvested Sites – plots installed 2015

Site Forest type Control PRE-TRT 2015

Salvaged

LaGarita Spruce 4 4 4 (Cut 2015)

Rambouillet

Spruce need 12 5 (Cut 2015)Spruce-fir need 1

Spruce-Aspen need 1

Roadside Spruce 3 3 3 (Cut 2015)West Pinos Spruce 3 3 (cut 2014)

Windy Point Spruce 5 5 (cut 14/15)

Unharvested Sites – plots installed 2015

Forest type Control

Spruce 41

Spruce-Aspen 7

Plot set-up and MeasurementsFull plot size: 0.05 Hectare (0.12 acres)

Tallied all seedlings

Tallied all seedlings

Coarse Wood Transects and Forest Floor depth

Trees > dbh On entire plot • Species • Diameter • Status (live/

dead) • Agent of death • Cone presence • Subset of ages

Seedlings (< dbh) On NE and SW quadrat of plot • Species • Height class • Age category (<5 yrs or >5 yrs) • Damage

Substrate subplot• Litter • Rock • Woody

material • Soil • Moss • Stump • Vegetation

Microsite for seedling establishment 15 Spruce seedlings per quadrat Same categories as substrate subplots Distance and identification of ‘nurse’ objects

7

Tree mortality in Spruce stands high

Spruce Beetle OutbreakBefore After

Tota

l Tre

es p

er a

cre

0

200

400

600

800

1000Unharvested Previous Harvest Salvage

• Pre-outbreak: Previously harvested stands were denser (Basal area and TPA) than unharvested stands

• Post-outbreak: 94-95% total BA mortality but only ~65% TPA mortality

• Post-outbreak: There was no difference in Total Basal Area

• Post-outbreak: Previously harvested stands had more TPA than salvaged areas, but similar TPA to unharvested stands. Unharvested stands slightly higher TPA to salvaged stands (p=0.06)

*

AB B

A

Spruce Beetle OutbreakBefore After

Tota

l Bas

al A

rea

(ft2 /a

c)

0

50

100

150

200

250Unharvested Previous Harvest Salvage

ns

*

94-95% mortality

65% mortality

Spruce stand diameter substantially reduced

Spruce Beetle OutbreakBefore After

Spru

ce Q

uadr

atic

mea

n di

amet

er (i

nche

s)

0

2

4

6

8

10Unharvested Previous Harvest Salvage

ns

ns

• Past management didn’t impact spruce diameter

• Post-outbreak spruce diameter similar across treatments

• Average spruce diameter: 1.7 inches

Diameter distribution change: Unharvested stands

Diameter distribution change: Previously harvested stands

Post-outbreak seedling density (less than DBH)

Spruce Beetle OutbreakSpruce Fir Aspen

Tree

s pe

r ac

re

0

500

1000

1500

2000

2500Unharvested Previous Harvest Salvage

AB

A

B

p=0.07

ns

• Past management didn’t negatively impact spruce seedling density

• More fir in previously harvested stands

• Spruce seedling densities exceed minimum stocking requirements

Seedling height class (inches)

U_4 to

8

H_4 to

8

U_8 to

20

H_ 8 to

20

U_20 t

o 54

H_20 t

o 54

Age

(Yea

rs)

0153045607590

105120135150165180195210225

Height Class (in)

Unharvested Median Age (Q1 and Q3)

Harvested Median Age (Q1 and Q3)

P-value

4 to 8 18 (14, 20.5)

17 (15,25)

NS

8 to 20 22 (18, 29)

33 (25, 48)

0.001

20 to 54

60 (40, 68)

70 (51, 103)

NS

It takes a long time for a spruce seedling to reach DBH

• Spruce seedlings between 8 and 20 inches tall are about 10 years younger in unharvested stands

Forest type conversion

Unharvested

Forest type

Spruce

Spruce

/fir

Spruce

/aspen

Spruce

/fir/A

spen Fir

Bristle

cone

Aspen

Nu

mb

er o

f p

lots

0

10

20

30

40

50Pre-outbreak Post-outbreak

Harvested

Forest type

Spruce

Spruce

/fir

Spruce

/aspen

Spruce

/fir/A

spen Fir

Bristle

cone

Aspen

Num

ber

of p

lots

0

10

20

30

40

50

Pre-outbreak Post_outbreak

Objectives• Are spruce

seedlings found in specific locations on the landscape?

• Is the spruce beetle outbreak creating opportunities for regeneration?

Methods

Field Sampling Sites (74)

Are older spruce (5 years old) seedlings in specific locations?

0.0 0.5 1.0 1.5 2.0

−0.5

0.0

0.5

trans_asp (22%)

fitte

d fu

nctio

n

0.0 0.2 0.4 0.6 0.8 1.0

−0.5

0.0

0.5

twi_norm (19.2%)fit

ted

func

tion

20 40 60 80

−0.5

0.0

0.5

LITTER (19%)

fitte

d fu

nctio

n

N Y

−0.5

0.0

0.5

PAST_TRT (9.4%)

fitte

d fu

nctio

n

0 10 20 30 40

−0.5

0.0

0.5

MOSS.LICHEN (7.5%)

fitte

d fu

nctio

n

2.4 2.8 3.2 3.6

−0.5

0.0

0.5

available.water.storage.0.25.cm.weight.avg (6.5%)

fitte

d fu

nctio

n

100 200 300 400 500

−0.5

0.0

0.5

age_no (5.3%)fit

ted

func

tion

3100 3300 3500

−0.5

0.0

0.5

ELEVATION (3.3%)

fitte

d fu

nctio

n

0 20 40 60 80

−0.5

0.0

0.5

herb_shrub_cover (3.2%)

fitte

d fu

nctio

n

N Y

−0.5

0.0

0.5

potr_PA (2.8%)

fitte

d fu

nctio

n

0 20 40 60 80

−0.5

0.0

0.5

percLDu2.5cm (1.9%)

fitte

d fu

nctio

n

Are older spruce (>5 years old) seedlings in specific locations?

0.0 0.5 1.0 1.5 2.0

−0.5

0.0

0.5

trans_asp (22%)

fitte

d fu

nctio

n

0.0 0.2 0.4 0.6 0.8 1.0

−0.5

0.0

0.5

twi_norm (19.2%)

fitte

d fu

nctio

n

20 40 60 80

−0.5

0.0

0.5

LITTER (19%)

fitte

d fu

nctio

n

N Y

−0.5

0.0

0.5

PAST_TRT (9.4%)

fitte

d fu

nctio

n

0 10 20 30 40

−0.5

0.0

0.5

MOSS.LICHEN (7.5%)

fitte

d fu

nctio

n

2.4 2.8 3.2 3.6

−0.5

0.0

0.5

available.water.storage.0.25.cm.weight.avg (6.5%)

fitte

d fu

nctio

n

100 200 300 400 500

−0.5

0.0

0.5

age_no (5.3%)

fitte

d fu

nctio

n

3100 3300 3500

−0.5

0.0

0.5

ELEVATION (3.3%)

fitte

d fu

nctio

n

0 20 40 60 80

−0.5

0.0

0.5

herb_shrub_cover (3.2%)

fitte

d fu

nctio

n

N Y

−0.5

0.0

0.5

potr_PA (2.8%)

fitte

d fu

nctio

n

0 20 40 60 80

−0.5

0.0

0.5

percLDu2.5cm (1.9%)

fitte

d fu

nctio

n

• 33% of distribution from BRT

• Moisture availability (north slopes, concave areas, higher elevations)

• Moisture retention (littler, moss)

• Past treatments

Are young spruce (<5 years) seedlings in specific locations?

7400 7800

−0.6

−0.2

0.2

0.6

solar_sum (30.4%)

fitte

d fu

nctio

n

2.4 2.8 3.2 3.6

−0.6

−0.2

0.2

0.6

available.water.storage.0.25.cm.weight.avg (17.7%)fit

ted

func

tion

20 40 60 80 100

−0.6

−0.2

0.2

0.6

sb_mort_stem_hi (15.3%)

fitte

d fu

nctio

n

0 10 20 30 40

−0.6

−0.2

0.2

0.6

MOSS.LICHEN (7.8%)

fitte

d fu

nctio

n

100 200 300 400 500

−0.6

−0.2

0.2

0.6

age_no (6.8%)

fitte

d fu

nctio

n

10 30 50 70

−0.6

−0.2

0.2

0.6

day (6.2%)

fitte

d fu

nctio

n

0 20 40 60 80

−0.6

−0.2

0.2

0.6

percLDu2.5cm (5%)fit

ted

func

tion

0 20 40 60 80

−0.6

−0.2

0.2

0.6

herb_shrub_cover (4.4%)

fitte

d fu

nctio

n

20 40 60 80

−0.6

−0.2

0.2

0.6

LITTER (3.8%)

fitte

d fu

nctio

n

3100 3300 3500

−0.6

−0.2

0.2

0.6

ELEVATION (2.6%)

fitte

d fu

nctio

n

Are young spruce (<5 years) seedlings in specific locations?

7400 7800

−0.6

−0.2

0.2

0.6

solar_sum (30.4%)

fitte

d fu

nctio

n

2.4 2.8 3.2 3.6

−0.6

−0.2

0.2

0.6

available.water.storage.0.25.cm.weight.avg (17.7%)

fitte

d fu

nctio

n

20 40 60 80 100

−0.6

−0.2

0.2

0.6

sb_mort_stem_hi (15.3%)

fitte

d fu

nctio

n

0 10 20 30 40

−0.6

−0.2

0.2

0.6

MOSS.LICHEN (7.8%)fit

ted

func

tion

100 200 300 400 500

−0.6

−0.2

0.2

0.6

age_no (6.8%)

fitte

d fu

nctio

n

10 30 50 70

−0.6

−0.2

0.2

0.6

day (6.2%)

fitte

d fu

nctio

n

0 20 40 60 80

−0.6

−0.2

0.2

0.6

percLDu2.5cm (5%)

fitte

d fu

nctio

n

0 20 40 60 80

−0.6

−0.2

0.2

0.6

herb_shrub_cover (4.4%)

fitte

d fu

nctio

n

20 40 60 80

−0.6

−0.2

0.2

0.6

LITTER (3.8%)

fitte

d fu

nctio

n

3100 3300 3500

−0.6

−0.2

0.2

0.6

ELEVATION (2.6%)

fitte

d fu

nctio

n

• 36% of variation from BRT

• Moisture availability (north slopes, higher elevations)

• Spruce beetle mortality

• Moisture retention (littler, moss)

• Negative with shrub cover

Take Homes• Are spruce seedlings

found in specific locations on the landscape? YES

• wetter topographic positions

• moisture retaining features (litter, moss)

• Is the spruce beetle outbreak creating opportunities for regeneration? YES

Caution and Next Steps• Bumper crop of spruce seedlings

in 2016!

• will they survive?

• Need a few more sites in specific topographic settings and forest types (spruce-aspen mix)

• are treatments an opportunity to shift species mix?

• Relating patterns to climate change projections

Summer 2016

• Revisit Summer 2015 plots • Seedling survival • Remeasure newly salvaged areas • Set up seed traps

• Install additional monitoring plots in Spruce-Aspen