Lake Dan Nature Preserve: A Mosaic of Florida Ecosystems

Lake Dan Nature Preserve, in combination with Lake Francis Nature Preserve, encompasses 2,700 acres in Northwest Hillsborough County. This expansive area showcases a diverse mosaic of ecosystems, from cypress domes to mesic flatwoods, presenting both ecological significance and management challenges.

Two deer stand alert in a misty wetland area of Lake Dan Nature Preserve, surrounded by cypress trees draped in Spanish moss. Photo by Sonja Pedersen.

Environmental Lands Management Specialist Ryan Cosbey paints a vivid picture of the preserve's unique landscape: "It takes you to another place. Once you leave the red trail, you enter these low, open areas, but all around you there are these cypress domes. They rise up like mountains, and you get the feeling like you're in a valley."

As we explore Lake Dan, we'll uncover how its history has shaped its current ecology, the ongoing efforts to restore native habitats, and its role in protecting Florida's unique biodiversity, including species like the threatened Southeastern American kestrel.

Aerial view of Lake Dan Nature Preserve's eastern portion, showing the intricate mosaic of mesic flatwoods (lighter areas) and cypress domes (darker circular patches).

For a look into the past, the eastern portion of Lake Dan Preserve remains largely intact, providing a model of the area's pre-settlement ecosystem. Here, mesic flatwoods intersperse with cypress domes. The landscape has experienced less ditching, and roads don't frequently abut the domed wetlands.

Cypress domes are wetland ecosystems characterized by a circular or oval shape, with taller cypress trees in the center that gradually decrease in height towards the edges, creating a dome-like appearance. These wetlands play crucial roles in water filtration, flood control, and providing habitat for numerous species.

Hillsborough County wildland firefighters conduct a prescribed burn in Lake Dan's mesic flatwoods, maintaining the open structure of pine forests and promoting native plant growth. Photo by Bill Carlisle.

Mesic flatwoods, on the other hand, are upland ecosystems typically dominated by pine trees. They are characterized by relatively flat topography and moderately moist soils. In Lake Dan, the pine density in these mesic flatwoods varies from medium to sparse, creating an open canopy structure. The undergrowth is composed largely of low palmetto, native grasses, and forbs.

This combination of cypress domes and mesic flatwoods creates a diverse landscape that supports a wide range of flora and fauna. The varying moisture levels and vegetation types provide niches for numerous species, from aquatic organisms in the cypress domes to terrestrial wildlife in the flatwoods.

An American Kestrel perches on a steel cable in Lake Dan Nature Preserve. These small falcons hunt in open areas created by the preserve's mix of habitats. Photo by Linda Wilson.

A 2009 survey documented the presence of the state-threatened Southeastern American kestrel (Falco sparverius paulus) in Lake Dan's improved pastures. This subspecies is non-migratory, nesting year-round in Florida, and requires high-quality habitat to thrive.

Kestrels prefer flatwoods and sandhill environments. These habitats provide widely spaced, tall pines for hunting perches and open areas for improved visibility of prey. The mosaic of cypress domes and mesic flatwoods in the more intact portions of Lake Dan Nature Preserve creates ideal hunting grounds. As insects move between aquatic and terrestrial environments, they often pass through areas where kestrels can easily spot and catch them.

A Black-and-White Warbler searches for insects on a tree trunk in Lake Dan Nature Preserve. This migratory species relies on Florida's preserved habitats during its annual journey. Photo by Linda Wilson.

However, much of what we see today at Lake Dan Nature Preserve diverges from this model. Agriculture required drier conditions than those naturally occurring in mesic flatwoods, which are adapted to seasonal soil saturation.

To accommodate these agricultural requirements, historic landowners extensively modified the area through a combination of actions:

• Grading: Lower mesic areas were raised to create drier conditions.
• Ditching and canaling: A system was implemented to redirect water flow.
• Logging: Much of the flatwoods was cleared for timber and to create pastureland.

Satellite image of Lake Dan Nature Preserve showing the conversion of natural flatwoods and cypress stands to pastureland, with remnant wetlands visible as darker patches.

These modifications effectively maximized usable pastureland by concentrating water into existing wetland areas. However, they also dramatically altered the landscape's structure. The once-gradual transitions between ecosystems (ecotones) became narrow and abrupt, often marked by roads, fences, and ditches. This restructuring of the environment, coupled with the conversion to low-quality pastureland, resulted in decreased animal movement. Consequently, the remaining cypress domes became more isolated, impacting species like the kestrel that depend on a steady supply of prey across diverse habitats.

An American alligator rests in a shallow wetland at Lake Dan Nature Preserve, these large predators thrive along the ecotones between fresh water habitat and terrestrial habitat. Photo by Linda Wilson.

Despite these habitat alterations, kestrels have managed to persist in Lake Dan. However, the balance of species has shifted. Today, most kestrels observed in Lake Dan are migratory sub-species (Falco sparverius sparverius), possibly due to the loss of year-round nesting sites for the resident Southeastern American kestrel.

Kestrels are cavity-nesting birds, relying on woodpeckers for nest construction. The ideal nest for a kestrel in Lake Dan would be a cavity excavated by a Pileated Woodpecker (Dryocopus pileatus) in a pine tree. These woodpeckers prefer to work on dead or dying trees (snags) found in mature forest stands. While cypress domes and swamps provide suitable habitat for woodpeckers, the lack of established longleaf pines in former pastureland limits opportunities for woodpeckers to excavate nests in locations favored by kestrels. This restricts kestrel nesting sites to the more intact portions of the preserve.

A Pileated Woodpecker drills into a tree in Lake Dan Nature Preserve, looking for prey. These birds create nesting cavities that are later used by other species, including kestrels. Photo by Linda Wilson.

The most severely impacted portions of the preserve, now pastureland, face unique challenges for land managers. The area's extensive ditching has significantly altered natural water flow patterns. Full recontouring of the land isn't feasible due to potential impacts on nearby developed areas, requiring land managers to work within these constraints.

Recent changes have opened new opportunities for restoration. The last cattle leases have ended, removing grazing pressure and allowing for more focused habitat improvement efforts. Land managers are now implementing a strategy of pastureland enhancement, installing clusters of native vegetation throughout the former grazing areas. These "oases" serve dual purposes: providing habitat for local wildlife and encouraging animal movement across the landscape.

A Sabatia grandiflora (largeflower rosegentian or marsh-pink) blooms in Lake Dan Nature Preserve, many indigenous plant species depend on Hillsborough County ELAPP Nature Preserves for survival. Photo by Bill Carlisle.

The cluster planting approach offers an additional benefit by minimizing disturbance to existing ecosystems. Some restoration areas harbor hundreds of gopher tortoise burrows, a keystone species in Florida. (To learn more about them and their incredible engineering skills, check out our recent article on the subject.) By adjusting the size and placement of vegetation clusters, which typically consist of 50% grass with the remainder being forbs and shrubs, managers can work around these important habitat features.

Innovative use of existing structures also plays a role in the enhancements. Rather than removing all the old powerline poles on the property, land managers have strategically retained some, spaced appropriately for raptor use. Plans are underway to augment these with kestrel nesting boxes, osprey platforms, and wood duck platforms, enhancing habitat opportunities for a variety of bird species, including the year-round resident Southeastern American kestrel.

Starry night sky over Lake Dan Nature Preserve, with a moss covered tree silhouetted against the horizon. The preserve's dark skies and open spaces offer opportunities for nocturnal wildlife. Photo by Julie Wernicki.

Looking to the future, the preserve's long-term vision includes gradually reestablishing a more natural landscape. Plans call for planting widely spaced pine trees, which over decades will mature to provide sustainable habitats for many native species. This approach not only aids wildlife but also supports effective land management. Native plant communities make prescribed fire management safer and more viable, helping to mitigate wildfire risks associated with exotic plants and inappropriate vegetation.

For visitors, Lake Dan Nature Preserve provides a window into Florida's natural history and its potential future. Whether you're a bird enthusiast hoping to spot a kestrel, a nature lover exploring the cypress domes, or just looking for some good fishing on the Lake, the preserve offers something to discover. There is so much more to cover on Lake Dan Nature Preserve, so keep an eye out for more features in the coming winter and spring seasons!