Estero Bay Tributaries Riparian Vegetation Analysis

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Estero Bay Tributaries Riparian Vegetation
Analysis

• Edwin M. Everham III, David W. Ceilley, Brenda
  Thomas, Daniel Hamilton, E. Corrie Pieterson,
  Robert Leisure III, Brad Kolhoff, Jason Hahner,
• Jeff Key, and Mary Kay Cassani

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Objectives

• Investigate riparian vegetation change in
  response to changing freshwater flow in
  tributaries to Estero Bay
• Historical analysis of vegetative change
• Establishment of long-term study plots to track
  future changes
• Attempt to develop vegetative indicators of
  changes to freshwater flow

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Methods Historical Analysis

• Analyzed change in the five tributaries to Estero
  Bay Estero River, Hendry Creek, Imperial River,
  Mullock Creek, and Spring Creek
• Aerial photography from 1966, 1981, and 2002
• preliminary identification of vegetative
  communities in 2002, with ground-truthing
• Identified five broad vegetative communities
• mangrove
• mixed riparian
• mixed upland
• human landscapes
• agriculture
• GIS map of 100-meter zone on both sides of each
  tributary

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Summary of change by land use category for each
tributary 1966-1981 and 1982-2002
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Historical Analysis

• Development occurred at different times along
  different tributaries.
• Agriculture replaced by residential 1966-81
• Uplands lost to residential 1981-02
• Buffers lost early, protected later
• Mangroves did not appear to move
• Exotics may have increased over time

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Methods Transect Establishment

• Three transects were established at each
  tributary (upper-middle-lower)
• middle transect was placed at the estimated
  transition point between freshwater and estuarine
  systems, the upstream extent of tidal influence.
• two additional transects were placed
  approximately 0.5 1.0 km above and below this
  point.
• Each transect is 50 meters long, and 5 m wide to
  include emergent vegetation along the shore.
• The transects were sub-divided into 5m sections,
  providing a 5 m by 5 m sampling unit.

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Methods Field Data Collection

• Within each 25 m2 unit (each 5 m section of the 5
  m wide transect), we
• Estimated percent cover for 126 species found
• Measured mapped all woody stems 10 cm or larger
  in diameter at breast height (dbh)
• recorded canopy density, and
• measured the vertical structure of the
  vegetation. 

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Figure 4 - Cluster of all Taxa. Hierarchical
clustering of stream transects based on
Bray-Curtis similarity of plant community
structure (cumulative totals for species
coverage/transect). Similarity profile test
(SIMPROF) indicates that there are six
significantly different (Plt0.05) groupings
(labeled in black). Slice indicates 42
similarity level.
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Conclusions

• Riparian vegetation mapping was able to document
  trends in land use change the possible effects
  of regulations 1966-2002
• Exotics species appear to be good indicators of
  historical shoreline disturbance and human
  encroachment.
• cover by freshwater and saltwater plants may
  serve as tools for establishing minimum flows and
  levels (MFLs) on tidally influenced streams.
• Indicator groups may be better than whole
  community assessments for diagnostic purposes.
• Long-term study plots have been established for
  detecting changes to shoreline communities over
  time.