Response of Response of Microstegium Microstegium vimineumvimineum and and Lonicera japonicaLonicera japonica to to

continuous cover forestry continuous cover forestry practicespractices

N. J. Loewenstein, E.F. Loewenstein, J. M. Lhotka and B.J. Ostrom

Microstegium vimineumMicrostegium vimineumNepalese browntop, Japanese stiltgrass, Mary’s grassNepalese browntop, Japanese stiltgrass, Mary’s grass

Annual CAnnual C44 grass grass Shade tolerantShade tolerant Shallow rootsShallow roots Mesic soilsMesic soils Most of eastern USMost of eastern US Class C noxious weed Class C noxious weed

in Alabamain Alabama

Lonicera japonicaLonicera japonica Japanese honeysuckleJapanese honeysuckle

Semievergreen to Semievergreen to evergreen woody vineevergreen woody vine

Shade tolerantShade tolerant Tolerates a wide range Tolerates a wide range

of site conditionsof site conditions Most of USMost of US Ornamental and deer Ornamental and deer

browsebrowse

BackgroundBackground

Silviculture study looking at forest management Silviculture study looking at forest management options for private landowners at the urban-rural options for private landowners at the urban-rural interfaceinterface

Continuous cover forest managementContinuous cover forest management Promote the continued establishment and Promote the continued establishment and

development of tree reproductiondevelopment of tree reproduction

Silviculture study objectivesSilviculture study objectives

Apply gradient of cutting regimes.Apply gradient of cutting regimes.

Quantify the relationship between residual Quantify the relationship between residual forest structure and understory microclimate forest structure and understory microclimate (especially light).(especially light).

Assess the relationship between the understory Assess the relationship between the understory environment and seedling growth response.environment and seedling growth response.

Quantifying Forest EnvironmentQuantifying Forest Environment Vertical and horizontal structureVertical and horizontal structure Understory microclimateUnderstory microclimate

Assessing Relationships Between:Assessing Relationships Between: Canopy structure and light transmittanceCanopy structure and light transmittance Canopy structure and development of planted Canopy structure and development of planted

cherrybark oak, yellow poplar, and water oak cherrybark oak, yellow poplar, and water oak seedlingsseedlings

Canopy structure, light transmittance and Canopy structure, light transmittance and growth of growth of MicrostegiumMicrostegium and and LoniceraLonicera

Fifty 0.05 ha plots in riparian hardwood Fifty 0.05 ha plots in riparian hardwood forestforest

Structural manipulations:Structural manipulations: Control: No trees cut Control: No trees cut Light cut: 1/3 of all midstory trees cut Light cut: 1/3 of all midstory trees cut Moderate cut: 1/2 of all midstory trees cut Moderate cut: 1/2 of all midstory trees cut Heavy cut: all midstory trees cutHeavy cut: all midstory trees cut

Uncut Heavy cut

Gradient in forest structureGradient in forest structure

Canopy cover (%)

0.40.50.60.70.80.91.0

% fu

ll lig

ht

0

5

10

15

20

25

30

35

Light regimes in four representative plotsLight regimes in four representative plots

Plot 28 - July 31, 2004

time

05:00:00 09:00:00 13:00:00 17:00:00

PA

R ( m

ol m

-2 s

-)

0

500

1000

1500

2000

2500

3000

clear cutplot 28

Plot 20 - 7/31/04

time

05:00:00 09:00:00 13:00:00 17:00:00

PA

R

0

500

1000

1500

2000

2500

3000

clear cutplot 20

Plot 36 - 7/31/04

time

05:00:00 09:00:00 13:00:00 17:00:00

PA

R

0

500

1000

1500

2000

2500

3000

clear cutplot 36

Plot 32 - 6/16/04

time

05:00:00 09:00:00 13:00:00 17:00:00

PA

R

0

500

1000

1500

2000

2500

3000

clearcutplot 32

MethodsMethods

BiomassBiomass Percent cover - 1 mPercent cover - 1 m22 plots (spring and late plots (spring and late

summer)summer) Clip plots (late summer) Clip plots (late summer)

PhotosynthesisPhotosynthesis Photosynthetic light curves Photosynthetic light curves

FecundityFecundity Clip plots (after seed set)Clip plots (after seed set)

Above-ground biomassAbove-ground biomass

Canopy closure (% )

0.40.50.60.70.80.91.0Tota

l dry

wt

(g)

0

2

4

6

8

10

12

14

16

18

20

Microstegium

Canopy closure (% )

0.40.50.60.70.80.91.0

Tota

l dry

wt

(g)

0

2

4

6

8

10

12

14

16

18

20

Lonicera

Canopy cover (% )D

ry w

eig

ht

(g)

0

1

2

3

4

5

6

7

8

9

10

11

Microstegium

Canopy cover (% )

Dry

weig

ht

(g)

0

1

2

3

4

5

6

7

8

9

10

11

stemsleavesstd err

Lonicera

PAR (mol m-2 s-1)

0 200 400 600 800 1000 1200 1400 1600Photo

synth

esi

s (

mol m

-2 s

-1)

-2

0

2

4

6

8

10

12

14

16

18

20

Microstegium

Photosynthetic Light CurvesPhotosynthetic Light Curves

PAR (mol m-2 s-1)

0 200 400 600 800 1000 1200 1400 1600

Photo

synth

esi

s (

mol m

-2 s

-1)

-2

0

2

4

6

8

10

12

14

16

18

20

Plot 32Plot 28Plot 23Plot 20Plot 30Plot 36

Lonicera

Chasmogamous flowersChasmogamous flowers - - flowers that open, flowers that open, exposing stamens and styles to the environment exposing stamens and styles to the environment allowing potential cross-pollinationallowing potential cross-pollination

Cleistogomous flowersCleistogomous flowers -- flowers that do not flowers that do not open and are self-pollinatedopen and are self-pollinated

Microstegium fecundityMicrostegium fecundity

Canopy cover (% )

0.40.50.60.70.80.91.0

Num

ber

of flow

ers

0

100

200

300

400

Canopy cover (% )

0.40.50.60.70.80.91.0R

ati

o c

h/c

l flow

ers

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

ConclusionsConclusions

MicrostegiumMicrostegium was more responsive than was more responsive than LoniceraLonicera to the moderate increase in light. to the moderate increase in light.

First year results may not fully reflect the First year results may not fully reflect the potential impact of potential impact of Lonicera.Lonicera.

Herbicide treatments may be required.Herbicide treatments may be required.

AcknowledgementsAcknowledgements

Field siteField site: Blanton Creek Wildlife Management : Blanton Creek Wildlife Management Area, Area, Georgia Power and Georgia DNRGeorgia Power and Georgia DNR

Field and lab assistanceField and lab assistance: Gayla Trouse: Gayla Trouse

FundingFunding: Center for Forest Sustainability, : Center for Forest Sustainability, Auburn UniversityAuburn University

Questions?Questions?