HABITAT SUSCEPTIBILITY TO INVASION BY

COGONGRASS ON CAMP SHELBY TRAINING SITE, MS

Lisa Y. Yager, The Nature ConservancyDeborah L. Miller, University of Florida

Jeanne Jones, Mississippi State University

Cogongrass

• Spread by wind-dispersed seeds, man-dispersed rhizomes, rhizomatous growth.

• Establishes in a wide variety of habitats including roadsides, firing points, upland pine forests, and wetlands

• Displaces Native Species

Why Do We Care?

•Poor Forage Quality

Why Do We Care?

•Degrades Gopher Tortoise Habitat

•Alters Fire Intensity and Frequency

Why Do We Care?

•More Flammable, Burns Hotter

Camp Shelby Training Site

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N

CSTS BoundaryRoadsImpact Area

# Cogongrass

5 0 5 10 Miles

Limited Resources

• Protect and prioritize areas of high conservation value –gopher tortoise habitat –longleaf pine/bluestem habitat

• Determine most effective use of resources for prevention and control

ObjectivesCompare

• Linear Vegetative Growth

• Seed Dispersal

In Different Habitats

Pine/Shrub

Pine/Bluestem

Mowed Herbaceous

Hardwood

Vegetative Growth- Methods

Patch Map

Arcview Cogongrass

2002

2003

Vegetative Growth 2003

0.6

1.09

0.560.85 0.92

2.72 2.57

3.22

2.53

1.89

0

0.5

1

1.5

2

2.5

3

3.5

4

Hardwood Pine/Bluestem

Pine/Shrub

Roadside Military Areas

Til

ler

Ext

ensi

on

(m

/yr) Mean Maximum

Vegetative Growth 2004

0.48 0.74 0.71 0.78 0.91

2.361.92

3.49

2.16

5.0

0

1

2

3

4

5

6

Hardwood Pine/Bluestem

Pine/Shrub

Roadside Military Areas

Til

ler

Ext

ensi

on

(m

/yr) Mean Maximum

Soil Disturbance

Military Training Areas

• Patches with > 7 m and > 10 m linear growth

• Reduced patch size for 2003 and 2004 for a patch which was “rehabilitated”- disked and planted with ryegrass

Seed Dispersal

• 3 Locations for Each Habitat

• 5 Releases of 50 Spikelets/ Habitat/ Location

• Flag and GPS Locations

Pine/Bluestem

Pine/Shrub

Mean Maximum Wind Speed

1.7 m/sec

0.7 m/sec

0

5

10

15

20

25

30

35

40D

isp

ersa

l Dis

tan

ce (

m)

Pine/BluestemPine/Shrub

0

5

10

15

20

25

30

35

40

Mean Distance

**Maximum Recordable Distance

Pine/BluestemPine/Shrub

Seed Dispersal

n = 15

0

5

10

15

20

25

30

> 5 m

Per

cen

tag

e o

f Sp

ikel

ets

0

5

10

15

20

25

30

> 5 m > 10 mDistance Dispersed

Pine/BluestemPine/ShrubPine/BluestemPine/Shrub

Seed Dispersal

Seedbed

% Spikelets Landing on Bare Ground or Litter

Pine/Bluestem Pine/Shrub

34 % 16 %

Conclusion

• Vegetative encroachment by cogongrass occurred in all habitat types

• Cogongrass vegetative growth rate was lowest into the hardwood habitat

Conclusion

• Soil disturbance can enhance rapid vegetative growth

• Cogongrass spikelets penetrated further into the pine/bluestem habitat type

• Cogongrass spikelets were more likely to land on bareground or litter in the pine/bluestem habitat

Conclusions

Priorities

• Pine/bluestem and Military Training Areas (Mowed Herbaceous Habitats)

• Treatment of cogongrass prior to activities which create soil disturbance or reduce canopy/shrub cover

Acknowledgements

MS Army National Guard USDA Forest Service

The Nature ConservancyBrian Mitchell, Robin Switzer,

CJ Sabette, Jeff Kaminski.