Mapping habitats helps tortoise species


 

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Posted: 3/12/2009

 

Intensive commercial forestry and urban development are threatening natural habitats and have put the gopher tortoise on the federally threatened species list for Alabama, Mississippi and southeastern Louisiana.

"The gopher tortoise lives in natural longleaf pine forests of the coastal plains," said Jeanne Jones, wildlife and fisheries associate professor at Mississippi State University. "Loss of well-drained burrows and sandy soil habitats of these forests poses a serious threat to the tortoise’s and more than 360 other species’ survival."

Better methods to inventory and manage gopher tortoise habitats are essential for monitoring this species and bringing about its recovery. Scientists in MSU’s Forest and Wildlife Research Center, in cooperation with the U.S. Army Construction Engineering Research Laboratory, are studying the management requirements for longleaf pine forests to sustain tortoise populations.

Some of the largest populations of gopher tortoises in Mississippi occur on Camp Shelby’s training site and DeSoto National Forest. Camp Shelby, one of the largest Army National Guard training sites, serves as training grounds for more than 100,000 troops each year.

"The land bases offer an excellent place to conduct research on tortoises," Jones said. "To accomplish this work, we count burrow openings and measure plant and soil conditions around burrows. The tortoises are typically shy and difficult to observe."

Gopher tortoises spend much of their time in burrows, as deep as 6 feet. They feed and bask near their burrows during daylight hours in the spring, summer and early fall. In the winter, they are fairly inactive, taking cover in their underground burrows. Occasionally, some will come aboveground to bask on warm winter days in some areas of their range, Jones said.

Scientists are using remote-sensing technologies coupled with ground-based field surveys to understand the tortoises’ location preferences. These techniques help scientists determine what tortoises need to survive.

The first phase of the study involved ground-based surveys documenting habitat characteristics of current or previously inhabited sites. These locations are compared with areas that are not used by gopher tortoises.

"Using remote-sensing data, we can assess and identify habitat characteristics in an effort to model those most critical to tortoise survival," said David Evans, MSU forestry professor.

Evans explained that the primary data used for the remote-sensing assessment is LiDAR, or light detection and ranging, which uses pulses of laser-light energy emitted from an airplane to map the structural features of the Earth’s surface.

"The techniques we are using to determine gopher tortoise habitats were developed in a similar study of red-cockaded woodpecker habitat near Fort Bragg, N.C.," Evans noted.

The red-cockaded woodpecker also is considered an endangered species throughout its range and prefers longleaf pine forest habitat like the gopher tortoise.

"Once complete, the study will provide managers with a set of new tools to identify and manage areas that provide suitable habitat for the gopher tortoise, the red-cockaded woodpecker and perhaps other threatened or endangered species," Evans said.


Forestry