8th north american forest ecology workshops, usa 2011

1Mixedwood Ecology and Management Program (UNBC) | Amalesh Dhar & Chris D.B. Hawkins04/09/13

Amalesh Dhar and Chris D. B. HawkinsMixedwood Ecology and Management Program

University of Northern British Columbia, BC

Chemical brushing for forest vegetation management in British Columbia: impact on species’ diversity,

growth and White pine weevil attack


Outline

1. Introduction

2. Objectives

3. Materials and Methods

4. Result

5. Conclusion


Introduction

Some points about BC Forest

• historically BC reforestation policies and regulations are conifer-biased

• broadleaves species (birch, aspen) are routinely removed from plantations

- for maximizing crop tree growth

• broadleaf species must be less than 1000 sph

• practice has been consistently applied across much of Canada


Introduction

Vegetation management in BC:

• to maintain BC free-to-grow standard (BC Ministry of Forests 2000 )

“a stand of healthy trees of a commercially valuable species, the growth of which

is not impeded by competition from plants, shrubs or other trees”

• stands may only be declared free to grow when 2/3 years have passed

since chemical or manual brushing treatments applied

• avoid administrative delays to get responsibility of the stand management


Objectives

• Determine the impacts of chemical brushing on:

i) crop or target tree growth

ii) competitor tree growth

iii) white pine weevil attack

• Long term impact on non tree vegetation dynamics

- species diversity of plant community

Objectives


Materials and Method


Location:

USA

USA

Canada

Untreated

Herbicide Treated



Location :

Sinclair Mills, Prince George, BC, Canada

Zone: SBSv1, wet and cool

Latitude: 54°01’60” N

Longitude: 121°38’20” W

Elevation: 710 m asl

Mean annual precipitation: 900 – 1635 mm (two-thirds falls as snow)

Mean annual temperature: 1.3 – 4 °C

Stand Age at plot establishment: 13 year-old stand



Site preparationTotal area 90 ha

- herbicide treated area – 25 ha

- herbicide untreated area – 65 ha


• Clear-cut – 1987/88

• Planted – 1989

•Glyphosate herbicide applied - 1996

- 6 L per ha

• Plot establishment - 2002

- total 38, 70 m X 70 m treatment units

- further 30 m X 30 m measurement units

installed in the center of the treatment plot

Untreated

Herbicide Treated


Survey : Overstory Vegetation

• survey year 2002 and 2003

• plot size - 5.64 m radius (100 m2)

• no. PSP for herbicide treated - 15

• no. PSP for herbicide untreated – 13

• DBH and height of all conifer and broadleaf trees within a PSP were

measured



White pine weevil (WPW) [Pissodes strobi (Peck)]





• by noting trees with the characteristic of Sheppard’s crook or major stem deformities

- kills the previous year's growth

terminal leaders




• survey- pre 2001- every fall from 2001 – 2005


Understory vegetation survey

• survey year from 2002 to 2006

• plot size - 1 m X 1m quadrates

- 5 m away at 45 degrees of each sky direction at each PSP

- plant species were identified according to MacKinnon et al. (1999) and Cranston et al. (1996)

- visual estimate of vegetation percent cover was recorded

- surveys were conducted by the same people in all five years



Understory vegetation survey

• species diversity assessment • species richness (S) • species-abundance curves• alpha diversity (Magurran 1988)

- shannon diversity (H’)- shannon evenness (J’)- simpson’s diversity (1/D)- simpson’s evenness (E1/D)

• beta diversity (between treatment diversity) (Magurran 2004)- sorensen’s quantitative index (CN) -modified version of the Morisita-Horn index (CMH)



Results


Results: Overstory Vegetation

0

1000

2000

3000

4000

5000

Treated Untreated

Treatment

Tre

e /h

a

Spruce Birch

Stocking in herbicide treated and untreated area in 2003

18Mixedwood Ecology and Management Program (UNBC) | Amalesh Dhar, Chris D.B. Hawkins04/09/13

0

2

4

6

8

10

Treat-birch Untreat-birch treat-spruce Untreat-spruce

Species and treatment

DBH

[ cm

]

2002 2003




02468

Treat-birch Untreat-birch Treat-spruce Untreat-spruce

Height [ m ]


2002 2003



0

0.003

0.006

0.009

0.012

0.015

Treat-birch Untreat-birch Treat-spruce Untreat-spruce

Volume [ m-3

]


2002 2003


0

40

80

120

160

200

Treat-birch Untreat-birch treat-spruce Untreat-spruce


HDR

2002 2003



0

20

40

60

80

Pre 2001 2001 2002 2003 2004 2005

Survey year

WP

W a

ttac

k [%

]

Herbicide Untreated


• significantly greater in herbicide treated area

White Pine Weevil Attack

• lower densities enable weevils to more easily locate terminal leaders

• overhead shading in untreated area (Taylor et al. 1996)

• females WPW select vigorously terminal leaders for brood (Alfaro 1995)


Results: Understory Vegetation

y = 11.497e-0.1069x

R2 = 0.9679

02468

1012

C.c

an

ade

nsis

H.u

mb

ela

tum

Bra

chy

sp.

Dic

ranu

m s

pp

Gra

ss s

pR

.par

viflo

rus

T.

offic

ina

leR

. id

aeus

E.

angu

stifo

liaG

. tr

iflo

rum

P.

cris

ta-

T.

trifo

liata

P. g

lau

ca x

V.c

anad

ens

isA

.mar

gar

itace

E. a

rven

seC

. arv

en

seG

. dry

op

teris

M.

nud

aR

. la

cust

reS

alix

sp

S. r

ace

mos

aA

. ru

bra

A. a

lnifo

liaA

.con

spic

uo

uA

.mod

est

us

A.f

ilix-

fem

ina

C.

ran

gife

ring

G.m

acr

op

hyll

T.h

ete

rop

hyll

Species

RA

[%

]

Herbicide treated 2002

Relative species abundance (%) of herbicide untreated and treated areas [black line is fitted curve and other one is real data]



y = 9.7478e-0.0935x

R2 = 0.9645

0

4

8

12C

.can

aden

siB

rach

y sp

.A

.filix

-fem

ina

R.p

arvi

floru

sE

.ang

ustif

olia

H.a

uran

tiacu

T.tr

ifolia

taG

.trifl

orum

Gra

ss s

pG

.dry

opte

risD

icra

num

Pla

giom

nium

T.o

ffici

nale

E.a

rven

seV

.can

aden

siA

.mod

estu

sC

.arv

ense

R.id

aeus

Sal

ix s

pS

.rose

usA

.dio

icus

G.m

acro

phyl

lO

.hor

ridus

P.c

rista

-S

.race

mos

aA

.mar

garit

acA

.nud

icau

lus

A.c

auda

tum

A.c

onsp

icuo

uD

.hoo

keri

H.u

mbe

latu

mM

.dila

tatu

mP

.tric

hoca

rpu

S.ra

cem

osa

S.a

mpl

exifo

li

Species

RA

[%]

Herbicide untreated 2002




Herbicide treated 2006

y = 7.1157e-0.0697x

R2 = 0.9509

0

2

46

8

10

1 6 11 16 21 26 31 36 41 46

In total, 133 species were recorded from 2002 to 2006 but 30 % of 2002’s species were not present in 2006




Herbicide untreated 2006

y = 5.857e-0.0612x

R2 = 0.9437

0

2

4

6

8

10

1 6 11 16 21 26 31 36 41 46 51 56

In total, 133 species were recorded from 2002 to 2006 but 30 % of 2002’s species were not present in 2006




0

10

20

30

40

50

60

2002 2003 2004 2005 2006

Survey Year

Spec

ies

Ric

hnes

s [S

']

Herbicide Untreated Herbicide treated



0

0.5

1

1.5

2

2.5

3

3.5

4

2002 2003 2004 2005 2006

Shannon [H']

Survey year

Treated Untreated

Summary of Shannon diversity (H’) from 2002 to 2006

Alpha diversity



Summary of Shannon evenness (J’) from 2002 to 2006

0

0.2

0.4

0.6

0.8

1

2002 2003 2004 2005 2006

Shannon [J']

Survey year

Treated Untreated

Alpha diversity



0

0.2

0.4

0.6

0.8

1

2002 2003 2004 2005 2006

Survey year

Sim

pson

[E1/

D]

Treated Untreated

Summary of Simpson‘s evenness (E1/D) from 2002 to 2006

Alpha diversity



0

5

10

15

20

25

30

2002 2003 2004 2005 2006

Simpson [1/D]

Survey year

Treated Untreated

Summary of Simpson's diversity (1/D) from 2002 to 2006

Alpha diversity


Sorensen Morisita-Horn Critical Value = 5.99, k = 3, d.f. = 2

2002 2003 2004 2005 2006 2002 2003 2004 2005 2006Kruskal-Wallis H 4.356 2.222 6.006 5.600 5.422 4.267 2.489 5.600 5.956 4.267

P- value 0.113 0.329 0.05 0.061 0.071 0.118 0.288 0.061 0.05 0.118

Summary of non-parametric analysis

Beta Diversity indices [β]

Survey year

2002 2003 2004 2005 2006

Sorensen 0.60 0.62 0.64 0.61 0.60

Morisita-Horn 0.73 0.81 0.80 0.84 0.61

Summary of beta diversity



Conclusion


Impact on Growth

No volume difference between treatments

No significant difference in DBH

spruce height difference was not significant but greater in untreated area

Not impacted by birch up to 4300 sph of birch

Impact of White Pine Weevil Attack

significant difference between treatment

greater number of stem defects in treated area

reduce wood quality

Conclusion


Impact on understory vegetation

Species’ richness and alpha diversity were similar between

treatments

- no significant difference in alpha diversity

• between treatments

• between years

Conclusion

Overall herbicide did not affect diversity indices

Beta diversity was relatively low indicating little treatment effect

Herbicide reduced structural diversity


Final Remark: Glyphosate application: - does not remove all birch

- showed minimal or no impact on herb and shrub layer

Conclusion

Final recommendations reduce broadcast use of herbicide

- spot vegetation control more appropriate - reduce financial investment- positive impact on diversity

identify the thresholds broadleaf density that has no impact on

conifer growth

finally the BC free to grow standard need to reconsider


• Funding provided byForest Renewal British ColumbiaFRBC-Slocan Mixedwood ChairForest Investment British Columbia

• Technical support provided byKim Menounos Anne ColeTracy Murray Cindy BakerTodd Bondaroff Chris Maundrell Nicole Balliet Kari BondaroffKatie Krc

Acknowledgements


Dr. Amalesh DharMixedwood Ecology and Management ProgramUniversity of Northern British Columbia3333 University Way, Prince George, BC, Canada V2N 4Z9Phone: +1 250 960 5778Fax: +1 250 960 5339Email: [email protected]

Prof. Dr. Christopher .D.B. HawkinsYukon Research CentreYukon CollegeP.O. Box 2799Whitehorse, YT, Canada Y1A 5K4Phone: +1 867 456-8627FAX: +1 867-456-8672Email: [email protected]

For further communication

mailto:[email protected]

mailto:[email protected]

8th north american forest ecology workshops, usa 2011

Education