Restoration Ecology - Week 6 & 7
Case Studies From Southern Florida
I. Scale
A. Small - e.g., Mangrove planting in South Dade Wetlands
B. Medium - e.g., Matheson Hammock, Snapper Creek Hammock, Hole-in-the Donut
C. Large - e.g., Kissimme River, Everglades
II. Mechanisms
A. Exotic Removal
B. Planting
C. Reintroduction of animals
D. Regrading
E. Hydrological alterrations
1. Water quantity
2. Water Quality
E. Fire Regime alterrations
III. Mangrove Planting in South Dade Wetlands
A. Problem - Roads constructed perpendicular to the shoreline extended into mangroves. Alterred water flow, allowed access, and were optimal sites for exotics.
B. Mechanisms
1. Remove road bed
2. Match pre-existing grade
3. Plant red mangrove seedlings
IV. Hole in the Donut
A. History
1. 4,000 hectares formerly farmed, beginning in the 1930s (???)
2. Early farming used only rudimentary soil preparation techniques
3. 2,000 hectares were rock-plowed in the 1950s
4. Changed anaerobic, low nutrient soils to aerobic, nutrient-rich soils. Also increased elevation by decreasing density of substrate.
5. Abandoned in the 1970s now dominated by Brazilian Pepper
B. Vegetation dynamics
1. Herbaceous vegetation establishes first, followed by Brazilia Pepper. Relatively low density of Brazilian pepper for the first 5 to 10 years
2. Extremely high densities of Brazilian pepper occur from year 10 to year 20
3. Density is lower, but stands persist after 20 years
C. Restoration Attempts
1. Planting
2. Mowing
3. Burning
4. Bull-dozing
5. Substrate removal
D. Methods of Pilot study (financed by mitigation money)
1. Removed exotic vegetation and substrate on 24.3 ha. (to limestone bedrock on 18.2 ha and half of substrate removed on 6.1 ha)
2. 3,437 dump truck loads (68,740 cubic meters) of substrate were removed by 13 June 1989.
3. Vegetation Analysis
a. 63 permanent 10m x 10m plots were established
b. Nested 1m x1m subplots were located in the se corner of each plot to count Brazilian pepper seedlings
c. Sampling occurred in August 1989 and February 1990.
E. Results
1. 101 species found in plots (54% were wetland specices)
a. 11% obligate wetland species
b. 39% facultative wetland species
c. 2% submerged species
d. 29% facultative upland speccies
e. 20% upland species
2. Brazilian Pepper
a. 6 of 63 1m x 1m plots contained Brazilian Pepperr seedlings
b. Two were in areas of complete substrate removal (0.08 seedlings/m2) and four were in areas of complete removal (0.93 seedlings/ m2)
F. Costs $640,000 or $26,337 per hectare
G. Full restoration
a. Estimated cost of $70 million dollars
b. Time 20 years
III. Everglades
A. Exotics - Melaleuca, Brazilian Pepper, Burma Reed, Lather leaf
B. Plantings ?
C. Regrading - Hole in the Donut
D. Hydrological Alterrations
E. Fire Regimes