1. School of Forest Resources and Conservation
What Research Has Found about Cogongrass Spread and Control in the Longleaf Pine Ecosystem?
Shibu Jose
School of Forest Resources and Conservation
University of Florida

5. Can species rich longleaf pine ecosystem resist invasion by cogongrass?

6. Hypotheses
Diverse communities use resources more completely and are therefore more resistant to invasion
Diverse communities are more probable to have a species that can outcompete cogongrass or that can limit congongrass growth and spread

7. Study 1: Black water river state forest

8. Study 1: Black water river state forest
Selected four patches per site
Set up 20 2m x 1m plots
Used flags to mark edge
Remarked edge at each observation interval

9. Study 1: Black water river state forest
Once plots were established, conducted plant surveys
Group plant species into one of 5 functional groups: annual forbs, perennial forbs, grasses, shrubs and trees

10. Study 1: Species Richness or Functional Richness Didn’t Matter!!!
Collins et al. 2007, Biological Invasions

11. What does it mean for the longleaf pine ecosystem?
Reduction in species richness and diversity

12. Loss of Key Species?

13. Changes in soil Properties

14. Shifts in ecosystem N pools
(E.g. 1 year-old-stand with and without cogongrass understory)
Pine
Pine
Below
Above
Below
Above

15. Changes in Fire Regime and Species Composition:
Mortality of Longleaf pine Seedlings and Saplings
Lippincot, 1997

17. Cogongrass burns hotter !!!
Lippincot, 1997

20. Study 2. Are there any species out there that could outcompete cogongrass?

21. Study 2. Treatments
Daneshgar 2007

22. Gallberry (Ilex glabra)
Broomsedge (Andropogon virginicus)
Narrowleaf Silkgrass
(Pityopsis graminifolia)
Wiregrass (Aristida stricta)
Partridge Pea (Chamaecrista fasciculata)

23. Study 2. Cogongrass Introduction and Measurements
Mesocosm communities were established and allowed to grow for one year
Cogongrass was introduced as a single seedling in the center of the mesocosm in April
Allowed to grow until mid-August; % cover estimated biweekly; above and belowground biomass harvested and weighed

24. Daneshgar and Jose 2007, in review
Study 2. Again, species richness or functional richness didn’t matter!!
% cover of cogongrass
% cover of native species
Daneshgar and Jose 2007, in review

25. Study 2. Sampling effect was more pronounced than diversity effect!!
Control
Gallberry
wiregrass
Partridge pea
Broomsedge
Daneshgar and Jose 2007, in review

26. Study 2. How does A. virginicus resist the invasion by cogongrass?
Percent root mass at different soil depth by species
Daneshgar and Jose 2007, in review

27. How can we restore infested longleaf pine stands?
Depends on the degree of infestation
Young or sparse infestations - chemical control
Well-established dense infestations –
First line of attack - mechanical, including fire depending on stand conditions
Then chemical control
Ultimately revegetation with species or species mixes that can outcompete cogongrass

29. Successful Restoration: Which ladder do you take when it comes to cogongrass control?

30. THANK YOU