Organic Sediment Tussock Management on Orange Lake Why

Organic Sediment & Tussock Management on Orange Lake

Why Manage Organic Sediment?

In a Word……SUCCESSION Definition: the gradual change in physical and biological characteristics of a water body that results from long term accumulation of organic material. i. e…. . dead plants and animals Slough Sawgrass Marsh Cypress & Willow Mixed Swamp Forest Hardwood Hammock A natural process that has been accelerated by human induced changes in the watershed.

Plants Produce Organic Material (Accretion) Excessive accumulation of organic material can change the physical and bio-chemical conditions of the soil substrate

Basin Morphology Shoreline Slope Plays a Crucial Role Shallowest Regions are Most Productive Higher Rates of Accumulation Minor Change in Depth Causes Major Change in Vegetation

Habitat Benefits • Shift species composition and community structure of fringing marsh (littoral zone). • Stimulate germination of underlying beneficial vegetation. • Reset micro-hydrology. • Consolidate substrate • Firm bottom provides good substrate for rooted aquatic plants. • May reduce potential for sediment resuspension. • Promotes beneficial conditions for fish spawning.

FWC Sediment Management Direct Methods Goal: Reduce, eliminate or consolidate organic sediments to set-back effects of accelerated succession. • Drawdown with scraping • Aeration and tilling • Dredging*

Drawdown - Scraping

Consolidation & Reduction

Dredging

FWC Sediment Management Indirect Methods (Managing Vegetation) Goal: Inhibit production and accumulation of new sediments by reducing the standing crop of aquatic/wetland vegetation. Mechanical • • Shredding Harvesting Roller Chopping Mowing Chemical • Herbicide

Mechanical and Chemical Vegetation Control

Harvesting

Mechanical Shredding

Roller Chopping

Fire Vegetation management under flooded conditions.

Biomass Production Plant Species Standing Crop Tons/acre Annual Production Rate Tons/acre/yr Productivity Multiplier Cattail 5. 8 15. 4 2. 7 Bidens 4. 5 6. 0 1. 3 Pickerelweed 3. 0 4. 0 1. 3 Pigweed 4. 3 6. 9 1. 6 Pennywort 4. 0 20. 0 5. 0 Duck Potato 1. 9 4. 8 2. 5 Water Hyacinth 9. 8 37. 8 3. 9

“Herbaceous plant species typically recycle the entire above-ground portion of the plant annually in temperate environments. ” & “…. most herbaceous species lose a fraction of living leaf and stem material as litter throughout the growing season, so there is a continuous rain of dead plant tissues throughout the year…” (Kadlec et al, 1995)

Theoretical Aquatic Plant Litter Accumulation 45 40 Tons (DW) per Acre 35 30 25 20 15 10 5 0 Year 1 Year 2 Un-managed Year 3 Year 4 Maintenance Control Year 5

http: //www. globalchange. umich. edu/globalchange 1/current/lectures/kling/energyflow. html Freshwater Marshes are One of the Worlds Most Productive Habitat Types

Questions?