WEED MANAGEMENT FORESTED WETLANDS

Weed Problems Early successional – let nature take its course Florida Institute of Phosphate Research Invasive, persistent exotics – nature needs some help

Primrose Willow and Cattail Florida Institute of Phosphate Research Considered as nuisance species by DEP Primrose willow a category I invasive according to FLEPPC

Reclaimed Forested Wetlands Florida Institute of Phosphate Research Primrose willow, cattail and elderberry effects on wetland trees Can trees shade-out primrose, etc.? Consequences: let nature take its course vs. herbicides, mowing, etc.

Primrose Willow

Primrose Willow Mowed

Resprouted

Weeds Removed

Trees grow in the presence of primrose willow and overtop it

Tree canopy shades out primrose willow

Bald Cypress, Red Maple, Popash Planted Nov. 1992, 2.1 m (7 ft) Spacing

Shade Tolerant Understory With Primrose willow

Primrose willow removed: sun-loving weeds

Weed Removal and Possible Tree Damage

Pond Cypress and Cattail

Bald Cypress and Cattail

Tree Canopy Shades-Out Cattail

Hummocks and Understory Colonization

Reclaimed Forested Wetlands Role of Primrose Willow and Elderberry Florida Institute of Phosphate Research Pioneer species (shaded out by trees) Organic matter and nutrient accumulation Early canopy closure (shade tolerant understory)

Forested Wetlands Dealing with Primrose Willow and Cattail Florida Institute of Phosphate Research Wetland trees grow in spite of these nuisance species Trees can shade them out Weed control efforts may damage trees Early canopy closure (trees + primrose willow) enhances understory

Trees Can Grow with and Shade-out Primrose Willow and Cattail Trees grow slower in ponded conditions Better growth if moist but well-drained –Seepage slope vs. flood plain vs. pond –Trees grow faster on primrose willow sites than cattail sites Need sufficient tree density Need time and patience

Wetland Trees and Weeds Timber vs. Natural System Restoration Popash & Red Maple growth better with primrose willow than without (triclopyr sprayed around bagged trees) Bald Cypress has some tolerance to triclopyr Tree growth better with elderberry than with primrose willow Organic matter accumulation less with weeds removed (soil elevation difference)

Richardson, S.G., and R.A. Kluson Managing nuisance plant species in forested wetlands on reclaimed phosphate mined lands in Florida, p In P.J. Cannizzaro (ed.). Proceedings of the 26th Annual Conference on Ecosystems Restoration and Creation. Hillsborough Community College, Tampa, Florida. May, Reference