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

Can species rich longleaf pine ecosystem resist invasion by cogongrass?

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

Study 1: Black water river state forest

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

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

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

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

Loss of Key Species?

Changes in soil Properties

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

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

Cogongrass burns hotter !!! Lippincot, 1997

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

Study 2. Treatments Daneshgar 2007

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

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

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

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

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

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

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

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