HABITATS OF LAKE WOODRUFF NATIONAL WILDLIFE REFUGE

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Lake Woodruff NWR comprises over 21,500 acres of a variety of habitats bordering the St. Johns River and 2200 acre Lake Woodruff.   The lake is accessible only by boat or extensive slogging through floodplain marsh.    The habitats below are arranged in the order that a visitor would encounter them, entering through the main gate on Mud Lake Road.

Xeric hammock

Immediately after you cross the railroad tracks and enter the refuge, you'll encounter a low-stature, dry forest dominated by various oaks (live oak, laurel oak) and saw palmetto.   Hammocks typically are not fire-tolerant habitats, so in areas where regular burns are conducted, the hammock tends to be replaced by pine forest.  Some of the xeric hammock just inside the refuge was formerly a fernery (left).  In some of the drier areas, extensive stretches of the ground are covered by Cladonia spp.,(reindeer moss, actually a lichen), that may take several years, or even a decade,  to reestablish after disturbance (right).

This habitat is one of the better places on the refuge to look for certain reptiles, including gopher tortoises and eastern diamondback rattlesnakes.  Pine snakes are found here as well, but incredibly hard to find as they spend most of their time underground.  Gopher tortoise burrows can be easily found by hiking south along the sand road paralleling the railroad tracks just before you enter the refuge.

Pinewoods

Some areas near the refuge entrance, and in other more distant parts of the refuge, are planted in slash pine, and are burned on a regular cycle to prevent invasion of hardwoods and succession to hammock. 

These pine communities are relatively low in biotic diversity compared with surrounding hammock.  Immediately after a burn, the herbaceous plant community can be surprisingly rich and colorful, though. In older stands that haven't recently burned, the understory can be dominated by saw palmetto (right).  Some breeding bird species that otherwise would not occur in the area are attracted to the pine woods, including the pine warbler.

Hydric hammock/ Hardwood swamp

The next community you will traverse as you drive into the refuge is often characterized by pools of standing water.  The canopy height is greater than in the upland communities, and the greater diversity of woody species gives it greater structural heterogeneity as well.

In lower areas where the water table is close to the surface, or may actually be above soil surface for significant periods of time, a variety of hardwood communities can be found, including species such as bald cypress, various bays, red maples, and other species adapted to the presence of standing water.  These habitats are a good place to look, or listen, for barred owls, though they will range over most of the refuge as well.

Mesic hammock

The distinction between different types of hammock is often subtle, and boundaries can be indistinct, as one community often intergrades into another.  However, as you approach the parking lot, there is a very slight increase in topography and some of the swamp hardwoods drop out, especially to the south of the parking lot.

Mesic hammocks are characterized by several oak species, including live and laurel oak, magnolia, and often contain stands of sabal palmetto (right).  Mesic hammocks also occur as isolated "islands" of habitat amid the floodplain marsh (center), varying in size from a couple of acres to several hundred acres.

Cordgrass/sawgrass marsh

As you leave the parking lot and continue to the west (towards Lake Woodruff), you will encounter one of the more abrupt habitat transitions on the refuge - that between hammock and marsh.  Floodplain marsh is the most extensive habitat type on the refuge, encompassing some 12,000 acres. These marshes are highly variable in water level, and fluctuate in response to rainfall and rises in the level of the St. Johns River.  Heavy rains in the upstream areas of the the St. Johns (actually to the south) will often cause water levels in the marsh to rise even if there has been no local rainfall.  The predominant species are cordgrass (Spartina bakeri) and sawgrass (Cladium jamaicensis), though a variety of other woody plants may invade along the edges, including various mallows, wax myrtle (Myrica cerifera) , and saltbush (Baccharis halimifolia).  You can see some of these invasive woody species in the left photo below (before a burn), and right (after a burn). 

The marshes are subjected to prescribed burns to counter invasion by the woody species and maintain dominance by the grasses. The marsh above left has not been burned for several years.   The effects of fire, which is usually applied in winter, are dramatic.  Recovery of the marsh grasses, which are often brilliant emerald green (right) for a couple of weeks, is rapid.   The marshes are a good place to listen for rails-  kings are breeding birds, and soras are common in winter. 

Levees, canals and impoundments

Three man-made impoundments are circled by about 8 miles of levee suitable for hiking or biking. The water level of these impoundments is controlled by refuge staff to optimize habitat suitability for specific wildlife species.

These pools are the best places to look for water birds such as ducks, moorhens and coots, wading birds such as egrets, herons and limpkins, and shorebirds, including black-necked stilts in spring and early summer.

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