Monday, February 22, 2016

The New Tram Ridge Trail at the Lower Suwannee National Wildlife Refuge

Staff of the Lower Suwannee National Wildlife Refuge have recently completed a new trail in the refuge headquarters area near Fowler's Bluff, Florida. It is an unusually appealing trail, and anyone completing the 2.8 mile loop can get a better understanding of the past, present, and desired future of the refuge.

Forking to the right at the beginning of the loop and going in a counterclockwise direction, visitors first pass through an area with widely spaced pine trees and extensive low vegetation.

Former Pine Plantation Undergoing Restoration
Once a tree farm densely planted with slash pines (Pinus elliotii), restoration efforts have included removal of many of the pines, opening the canopy and permitting light penetration to the ground to promote the growth of a diverse community of low-growing plants. Regular controlled burns prevent the invasion of hardwood trees. The natural vegetation of the area would have included widely-spaced longleaf pines (Pinus palustris), and management here has sought to functionally recreate this landscape--a savanna--that historically covered much of Florida and the southeastern coastal plain. Longleaf pines are being reestablished in parts of the refuge, but this restoration strategy is costly, laborious, and mostly undertaken on relatively small sites. Large scale thinning planted stands of slash pines is feasible and believed to be an efficient substitute.

Interspersed with the pine savanna are occasional wetlands dominated by pond cypress (Taxodium ascendens) and mesic hardwoods such as red maple (Acer rubrum).

Wetland
Slash pines like moist soil, but another species, loblolly pine (Pinus taeda) occurs on even wetter sites normally on the edges of wetlands.

Loblolly pine on the edge of a wetland.
Loblolly pines are relatively rare on the refuge. They can be distinguished from slash pines by shorter needles, smaller cones, darker bark with reddish, rather than brownish plates, and upward branching rather than dome-like crowns.

Even rarer are longleaf pines. Those in the photo below were found in a small patch where the trail comes close to County Road 347. Very long needles, large cones, bark that is scaly rather than broken into regular plates, and more open crowns distinguish these pines from the others. I saw no sign of reproduction of longleaf here, although these trees may not yet be old enough to produce fertile cones.


Longleaf pine.
Growth of pine trees is not the ultimate goal of habitat restoration. That goal instead is to promote the growth of the rich understory that is the repository of much of the region's biological diversity. Low woody vegetation, includes saw palmetto (Serenoa repens), gallberry (Ilex spp.), fetterbush and staggerbush (Lyonia spp), and other hardwood shrubs. These do not normally completely cover the ground, and are kept in check by fires. Resultant openings leave room for diverse grasses and forbs, and provide favored habitat for species like the gopher tortoise (Gopherus polyphemus) and the constellation of species that its presence promotes.

The trail crosses a small hardwood hammock and soon enters an area of scrub forest.

Scrub
This dry area is shaded by a thin canopy of scrub oaks, prominently
including sand live oak (Quercus geminata) and myrtle oak (Quercus myrifolia). This area is probably too dry for growth of pines, and its trees have little or no economic value. Loggers did put the ridge to use, however. It proved to be an ideal place to build a tram trail--a light railway used for getting lumber on its way to markets. As can be seen in the photo below, very little effort was needed to build a roadbed here.

Tram trail

A flat, straight trail could be constructed with little need to move significant quantities of earth. Unfortunately, the ridge gave out before its builders had achieved the desired distance, and as the landscape became wetter, it became necessary to construct a more substantial embankment.


Embankment

Not only did continuation of the tramway require more work, but it caused more serious and longer lasting damage to the environment. Acting like a dam, the half mile long embankment interrupted the normal flow of surface and ground water, making some places wetter, and others drier than before. In places ponds were formed where they would not otherwise have occurred.


Pond vegetation in a ditch created by construction of the tramway embankment

Changes caused by construction of logging roads are a problem throughout the refuge, and they are unlikely to be reversed, owing to the level of effort required and the difficulty of recreating drainage patterns that were disrupted long ago. The problem of hydrological change is particularly severe in the refuge's lowland swamps where ditches interrupt sheet flow of water. Some uplands have been further damaged by "windrowing," in which deep furrows were dug in order to create artificial "slashes" --depressions that would collect moisture and favor the growth of slash pines. 

Despite various habitat alterations, the Lower Suwannee National Wildlife Refuge is a rich repository of biological diversity. In the first mile of the Tram Ridge Trail one encounters a restored pine savanna, and large and small patches of different communities, including forested wetlands, palmettos and hardwood shrubs, grasslands, a hardwood hammock, and xeric scrub. Each of these habitats has its own assemblage of plant and animal species, and the mosaic they form accommodates a diverse mixture of species favoring not only each different habitat, but also those favoring their borders and the transition areas between them. 

By the end of the trail visitors will have gotten a better understanding of damages done to the natural environment by industrial timber production. These include more or less reversible damage being addressed by ongoing restoration activities, and the less reversible changes resulting for road construction and other landscape alterations. The restored pine plantations provide a glimpse of what the natural savanna vegetation of the region might have looked like. They also provide hope for the future in the eventual restoration of their diverse plant and animal communities.

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