Quantified approach for habitat assessment to improve prescribed fire in longleaf pine and related restoration efforts for gopher tortoises

Background/Question/Methods

Ecological restoration spans a wide range of activities from planting dominant plant species on prepared ground to improving degraded sites that support residual ecological values.  No matter where a site falls along that continuum, assessment and establishment of goals to guide restoration activities are important initial steps.  Recovery of moderately degraded sites may provide critical habitat for vertebrate species of conservation concern much sooner than areas in need of traditional and extensive restoration.  However such sites are not always targeted for restoration, perhaps because it is assumed that they fall within the range of natural variability and/or there is a lack of knowledge to determine what action is needed when a site is close to the desired ecological condition.  This may be the case for many second-growth stands of longleaf pine (Pinus palustris), a frequent-fire maintained ecosystem.  However there is concern that small differences in habitat quality may be detrimental to a declining species, the gopher tortoise (Gopherus polyphemus).  We assessed vegetation attributes over the landscape of five areas as well sampled embedded plots around resident tortoise burrows to determine if conditions around these targeted points could provide insight into what restoration might be required to improve the habitat.

Results/Conclusions

Although it is known that gopher tortoises require habitat characterized by open canopy with an understory dominated by herbaceous plants only recently have quantified guidelines been proposed.  Although useful, these guidelines have rarely been evaluated.  Our data set provides one of the first efforts to compare field conditions to quantified guidelines for this species.  We also documented the need to add additional variables to those already proposed to better guide restoration activities.  Principle components analyses supported expected positive relationships between burrow placement and lower canopy cover plus higher herbaceous cover.  In addition we determined that there was a negative relationship between burrow placement and number of understory woody stems (mean of 252.8/ha versus 482.2/ha) as well as the percent cover of woody plants in the groundcover (12.1% versus 18.0%). These results suggest that if fire was used more effectively it would improve habitat quality for gopher tortoises and perhaps increase the amount of area available for use by the species.  Our approach of comparing variables related to habitat structure at a landscape level compared to specific areas used by the species of conservation interest is likely to provide useful guidance for restoration efforts in many types of ecosystems.