Invasive species in Split Oak Forest

This post kicks off National Invasive Species Awareness Week 2018! Split Oak Forest has been incredibly well-managed by Florida Fish and Wildlife Conservation Commission (FWC) for over 20 years. They’ve kept a tight burn rotation as well as aggressively controlled the few invasive species that were onsite when Split Oak Forest was acquired by the two counties.

Wild hogs (Sus scrofa) are the most destructive invasive animal species in Split Oak. They are difficult to control even when trapped and hunted extensively. They dig on the sides of paths and firebreaks and anywhere they can find grubs, fungi, and easily-accessible roots.

Natal grass (Melinis repens) is scattered throughout Split Oak Forest, but appears to be restricted near the main entrance, disturbed areas (like our spoil sandhills by Lake 1 and Lake 2), and along firebreaks.

Natal grass in Hyderabad, Andhra Pradesh by J.M. Garg via Wikimedia Commons

Caesar weed (Urena lobata) is restricted to the oak hammock called Eagles Nest Hammock. There is little groundcover there to compete with it, save a few saw palmettos (Sabal palmetto) and beautyberry (Callicarpa americana).

Caesarweed in Osceola County by Osceola CISMA

Split Oak is lucky to be not afflicted with cogongrass (Imperata cylindrica), which ifs very expensive and difficult to control.

Cogongrass in Osceola County by Osceola CISMA

Similarly, no old world climbing fern (Lygodium microphyllum) is found in Split Oak, but I have found it along the Swamp Trail in Moss Park just 100′ from Split Oak’s boundary.  We (and Orange EPD and FWC) should keep an eye on it and preferably treat it soon.

Old world climbing fern in Osceola County by Osceola CISMA

Split Oak Forest Burn History and Fire Management

In light of an incorrect statement by an elected official about Split Oak Forest’s burn history, I have decided to describe Split Oak’s fire management and why it’s critical to the integrity of the park.

I requested Split Oak Forest’s burn history from the managers of the site, Florida Fish and Wildlife Conservation Commission (FWC), and was given this Burn History Map 2017 -2018. I created a heat map of the whole site using this data.

To summarize, every burn unit in Split Oak Forest has been burned with a prescribed fire in the last thirteen years. FWC has conducted 125 separate controlled burns on Split Oak since they’ve been managing it.

216 acres (+/-12%) of Split Oak was burned in the past year. Four burns were conducted last fall.

There are two places within Split Oak Forest that have never burned under FWC’s management. The first is Lake Hart, which is a body of water, so would only burn if it’s water levels dropped several feet for an extended period of time so that the bottom could dry out and be flammable. This would not occur because SFWMD controls Lake Hart’s level via S62. You can view S62’s real-time status here.

The second is the Lake Mary Jane Marsh. ‘Slough marshes’ such as this one used to burn more frequently in the past but are rarely burned by public agencies on purpose these days because the muck will smoulder for weeks and sometimes months. A good example of this were the muck fires last spring that caused road closures in Lake County, covered by WFTV.

Newly emerging saw palmetto fronds indicate a less-than-week-old fire in Unit 13. Photo taken August 2017.

Burned sticks of oak sprouts and gallberry bushes as well as the fire-scarred longleaf pine in the foreground and a completely torched longleaf in the background are evidence of the July burn in Unit 7.

A burn-scarred slash pine tree from the April 2016 burn in Unit 16A as of January 2018, looking over Lake Two.

Split Oak Forest must be managed according to a management plan that honors the original intent of establishing Split Oak Forest (page 15):

“The principle management emphasis at Split Oak Forest will be the protection and enhancement of habitat that is important to state and federally listed wildlife populations.”

Based on the condition of Split Oak prior to acquisition by the two counties, only improved fire management were anticipated as necessary to meet that goal (page 4):

“Only fire management is needed in most of the upland portion of the site.”

Prescribed fire is a major theme in Split Oak Forest’s current management plan.