Native Habitat Inventory Final Report 2004 - St. Lucie County

process from the natural community totals derived from the GFC data to arrive at a
percent loss estimate.” This analysis showed that the rate of conversion of native habitats
varied dependent upon the type of habitat from less than one percent for mangrove
swamp to more than 40 percent for dry prairies and dome swamps.
The limitations to such a technique include:
1. The 1986 GFC habitat data is not an inventory but a modeled layer. The habitat
types were estimated from the spectral characteristics of the 1986 Landsat
Thematic Mapper satellite imagery. Only a small subset of the image pixels were
ground-truthed statewide, and this sample may or may not be representative of the
County. This can cause significant errors in habitat classification and subsequent
loss calculations.
2. The Landsat data is captured at a 30-meter resolution, which is too coarse to
visually identify any details on the ground.
3. KBN sampled only a portion of the entire county and extrapolated from that
sample to the entire county. This is a good technique if the sample is truly
representative of the entire county. However, if the sample is not representative
(e.g., skewed) this would result in errors in the habitat classifications and in the
subsequent loss calculations. There is insufficient information in the KBN report
to evaluate the evenness of this technique.
4. The small natural areas (of 1-2 acres) may not have been captured in such a
technique due to limitations of time and data resolution (of both the Landsat
imagery and the REDI maps). Thus the total amount of natural area is most likely
underestimated and the amount of loss less accurate.
For all of these reasons there are differences between the 1992 KBN report (Tables 6 and
7) and this report in the total number of acres of natural area and the habitat loss rates.
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