Middle St. Johns - Florida Department of Environmental Protection

30 Water Quality Assessment Report: Middle St. Johns
Land Cover and
Land Use Mapping
The land cover used to
identify natural communities
was mapped by the
FWC from LandSat imagery
taken from 1985 to 1989. In
contrast, the land use data
in this report were mapped
by the SJRWMD from color
infrared photography taken
between late 1993 and
1995. The total acreage and
percentage of different land
covers obtained from Land-
Sat imagery differs from
the values obtained for land
use interpreted from aerial
photography for a number
of reasons. Besides the difference
in dates of mapping,
different land cover classification
schemes were used,
and the LandSat imagery had
less resolution than the aerial
photography.
Xeric
Adapted to extremely dry
conditions.
The intensity and type of anthropogenic land uses vary by area of
the basin. Urban land use is concentrated around Orlando and along
the northeastern Interstate 4 corridor. Primary agricultural activities
are improved pasture and field crops, with some citrus. Ferneries are an
important horticultural activity in the basin. Leatherleaf fern is the most
common commercial fern grown for use in the floral industry. Reports
from the early 1990s indicated that there were 4,282 acres of commercially
grown leatherleaf fern in Volusia County, 832 acres in Putnam County,
and 438 acres in Lake County (Singleton, 1996). About half the acreage
for Lake and Putnam Counties is in other river basins.
Future growth is expected in and around DeLand, and continued
development pressure from the growth of Orlando may affect lands
along the Wekiva and Econlockhatchee Rivers and around Lake Jesup
(SJRWMD, 2000a). An increase in commercial and industrial development
is anticipated along the Interstate 4 corridor (SJRWMD, 2000a).
Publicly owned lands in the basin include state parks, preserves/
reserves, wildlife management areas, and state and national forests
(Figure 2.2). The larger and better known public lands include the Ocala
National Forest, Wekiwa Springs State Park, Rock Springs Run State
Reserve, Seminole State Forest, Blue Spring State Park, and Lake George
State Forest and Conservation Area.
Ecological Resources
Natural Communities
The Florida Fish and Wildlife Conservation Commission (FWC) used
land cover maps to identify major natural communities in the basin. The
maps identified 22 different land cover classifications: 17 classes of natural
vegetation, 1 aquatic class, and 4 classes of disturbed land. The mapping
is not intended to accurately portray current land use. Rather, it provides a
relative picture of the type and spatial importance of natural communities
in the Middle St. Johns Basin, and overall appears to have an accuracy of
80 to 90 percent (Cox et al., 1994).
Table 2.3 lists the estimated acreage and percentage of basin area occupied
by each natural community type. Table B.1 in Appendix B contains
more complete descriptions of each type. Table B.2 contains a summary
for each planning unit. Disturbed community types occupy the greatest
acreage, covering about 414,842 acres, or almost 32 percent, of the basin.
Of these, shrub and brushland (about 181,869 acres) occupy the greatest
acreage of disturbed land. This category includes lands that are disturbed
as part of the harvesting of commercial pine plantations. Pinelands occupy
13 percent of the basin. Commercial pine plantations (silviculture) are
included in pinelands acreage.
A number of different natural communities occupy the remaining
acres of the basin. Predominant upland types are sand pine scrub, dry
prairie, and hardwood hammock. Three xeric community types—sand
pine scrub, sandhill, and xeric oak scrub—combined occupy a little more
than 14 percent of the basin. All 3 of these communities occur on sandy
soils and are generally associated with areas of high to moderate aquifer