Claypan Basin Flatwoods

Description

These open woodland reference sites were strongly influenced by fire. Herbivory by native (now expatriated) ungulates, such as bison and elk, also played a role. Consequently, drought and fire-tolerant post oak and black oak stand over a ground flora of tallgrass prairie grasses, sedges and wildflowers. There are two phases associated with this reference state.

Community Phase 1.1
The overstory in this phase is dominated by post oak and black oak, with scattered blackjack oak and black hickory. This open woodland community typically has a two-tiered structure, with canopy height of 35 to 50 feet and 50 to 70 percent closure. The abundant herbaceous layer is dominated by little bluestem and sedges. Fire frequency was likely every 1 to 5 years. This continued fire and natural native grazing would have maintained the open canopy and profusion of ground flora species.

Community Phase 1.2
The overstory in this phase is dominated by post oak and black oak, with scattered blackjack oak and black hickory. This brushy woodland community typically has a three-tiered structure, with 60 to 80 percent closure. It is characterized by a thick understory of oak saplings, and shrubs. The herbaceous layer is dominated by little bluestem. Fire-free intervals likely ranged from 5 to 10 years.

Submodel

Description

Most current areas of Claypan Basin Flatwoods have experienced fire exclusion for decades. In the absence of fire, ongoing recruitment of trees into the canopy develops a closed canopy, shading out the rich herbaceous ground flora. Black oak and mid-story species increase. Herbaceous cover and diversity greatly diminishes, leaf litter builds up, and more shade-tolerant woodland species persist, such as elmleaf goldenrod, panicgrass and spreading aster. The understory also develops with oak and hickory saplings along with sassafras and some black cherry.

Submodel

Description

Many sites have been heavily grazed by domestic livestock at some point in their history. Grazing decreases the cover and abundance of saplings, shrubs and herbaceous ground flora, opening up the understory. Weedy native shrubs and vines, such as coralberry, gooseberry, poison ivy and Virginia creeper, often flourish after grazing, and exotic species like tall fescue and sericea lespedeza increase in abundance.

Poorly managed grazing can cause compaction and denudation of the soil surface, allowing mats of lichens and mosses to flourish. Soil compaction may also further limit height growth of trees. With poorly managed grazing, this can result in an increase in weedy natives such as broom sedge, and exotics such as sericea lespedeza if they are present. Single-tree timber harvesting also occurred, resulting in a high grading of the canopy structure, creating many stands with poorly formed trees.

Submodel

Description

Claypan Basin Flatwoods are often converted into wide, open tall fescue grasslands, adjacent to densely overgrown and grazed woodlots. A return from this condition to a flatwoods state requires enormous cost and management inputs.

Submodel