Tag: invasive species

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Controlling invasives with biology at CREW

By Allison Vincent

Lygodium Microphyllum

Have you ever been out on the trail, any trail, and that friend that knows a thing or two about invasive species points out a few for you? He or she discusses the threat they pose to the native ecosystem that they’re encroaching on and you wonder, what can we do about it?

One highly successful way of managing invasive species is to employ a biological control agent, using other living organisms to help control invasive and non-native species. It’s a way of reacquainting invasive pests – such as Old World Climbing Fern or Lygodium microphyllum – with their natural enemies to provide natural and sustained population reduction. In the case of Lygodium, the enemy is the brown Lygodium moth (Neomusotima conspurcatalis) which has been successfully used in Florida since 2008.

It’s time-consuming and difficult to get official approval to use biological control agents, but it’s worth the wait. Some agents have proven to be very successful and without unintended consequences. Biological treatment studies often extend for decades before hitting the ground, assuring that there are no negative impacts beyond their intended use.

You may have noticed technicians at the CREW Bird Rookery Swamp trails lately distributing state-approved biological control agents near pockets of a certain species. They hope to limit the expansion of Lygodium from the area – a tall order, as it is one of the worst invasive species, crowding out many native plants and habitats for wildlife. Management of this invasive plant using traditional strategies, such as mechanical and chemical treatments, has proved difficult and expensive, with limited long-term success. Enter biological control agents.

Without natural competition, invasive plants like Lygodium will inevitably wreak havoc on an area not ready for its intense growing cycle. Each fertile leaflet has 133 sori – or the frilly bits on the fern – and each sori has 215 spores! Multiply those numbers to find that each fertile-female leaflet may spread 28,500 spores into the surrounding area (Volin et. al, 2004). It doesn’t stretch the imagination to picture the fern-filled scene should the invasion go untreated. Every invasive plant spreads through different means and in the case of Lygodium, the female portion of the plant with her fertile spores does the work. Other common invasive plants, like Caesar weed, spread by other vectors, such as wildlife and humans. Caesar weed has a particularly sticky bur containing lots of seeds, so be sure to trash those burs that make it home with you after a hike.

Trail camera photo of Florida black bear covered in caesar weed “burs”

But how do the land managers, the South Florida Water Management District (SFWMD) in the case of CREW, go about treating such a powerful invasive plant? Well, they fight fire with fire, sometimes literally, as prescribed fires, after other biological and chemical treatments, have been known to increase the successful die-back – or sustained control of plant spread – both above and below the ground. Many times land management uses a combination of mechanical, chemical and biological control to yield the best results.

In the case of Lygodium, the biggest observable impact in the long-term comes primarily from biological control and, in particular, those brown Lygodium moths. While other species have been introduced and had some success in destroying Lygodium, the brown Lygodium moth has unleashed the biggest disaster for this invasive plant.

Neomusotima conspurcatalis, the brown lygodium moth

It all starts with little caterpillars, who feed on fern leaflets causing browning of leaves and breakdown of entire Lygodium plants. Female moths lay an average of 136 eggs during her short life span – the life cycle of the moth from egg, through caterpillar and pupa to adult, is only about 30 days. Researchers observing the impact of testing sites over 4-6 months found that moth populations increased, and noticeable caterpillar feeding damage in the form of browned-out patches of Lygodium became apparent. Good for us, bad for Lygodium.

Throughout the history of CREW, biological control agents have been used as one element of a three-part approach to treat the invasive Melaleuca quinquenervia tree on the CREW lands. You can still see the process in action in the “Melaleuca graveyard” on the Red trail of CREW Flint Pen Strand where large stands of trees were treated with a combination of mechanical and chemical treatment. Later, biological control agents were added for long-term success – if you look closely you can still see weevils and psyllids, the Melaleuca-loving biological control agent.

We all benefit from the long-term research studies on biological control agents. Through partnerships with leading wildlife agencies and the SFWMD, land managers for the CREW lands hope to see similar results, like the sustained success on throughout the state. There will always be a need for invasive treatment, but with each step we take toward restoring our natural Florida environment, everyone benefits.

CREW Flint Pen Strand lands under preservation for future generations to enjoy!
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What’s so invasive about that plant?

by Allison Vincent

Urena lobata, Caesar’s Weed

When you visit the CREW lands you’ll come across invasive plant species, and whether you’re aware of them or not, they’re there! Some invasive species are beautiful, like the caesar weed, and you might find yourself wondering why the land managers have it out for them. What could a few plants possibly do to impact the broader ecosystem? 

Let’s begin with a few definitions, because invasive species are best understood by discussing the meaning of native and non-native and their interactions with humans. The scientific community agrees that native species wandered into an area naturally and long ago – some time during or after the mid 16th century at the time of European contact with the unexplored land across the Atlantic – either by wind, sea, birds, animals or other natural factors. As species expand or contract their native territory, they go through a process called “range change”. The native species then go about the process of adapting to the changed ecosystem, which in geographic terms was a feat considering that much of Florida was once the bottom of the ocean. 

Invasive australian pines (left) kill all the understory plants, whereas native mesic flatwoods (right) host a diverse ecosystem.

Non-native species, on the other hand, are introduced to a new environment either intentionally or by accident. The distinction in defining invasive takes non-native issues one step further because invasive species, in addition to being introduced by humans, often pose an environmental or economic threat and may cause harm to humans.

Still, what exactly is so negative about the impact of these invasive plant species, given they all make oxygen and absorb carbon dioxide? These tough questions are outlined by land management professionals who rely on current science to categorize the level of impact invasive species have on lands they manage, like the CREW lands. For instance, some invasive species, like the Melaleuca tree, will overtake wetlands and absorb an inordinate amount of water if not treated, which is exactly why they were brought to southwest Florida – to drain the  swamps. 

Melaleuca tree at CREW Flint Pen Strand

In turn, land managers use mechanical, chemical and biological control efforts to manage the spread of invasives, because without naturally occurring factors that limit their impact – like weather, diseases or insect pests – invasive species can disrupt the balance of the ecosystem they’ve supplanted, often out-competing and displacing the native species. The reduction in biodiversity can adversely impact wildlife and alter natural processes such as fire and water flow, all of which directly affect the human population which relies on those same resources.

Let’s talk more about the unintended impact that invasive species have on human populations, specifically in south Florida. Primarily, invasives threaten remaining wetland environments that provide a freshwater recharge of our drinking water sources in the underground aquifers. Native species have had time to adjust to the particular conditions of the Florida environment, so when the wetland composition goes from a natural state to a place overrun with counterproductive species, some of our basic needs – like water and safe shelter – are drastically affected. 

Before and after hydrologic restoration at CREW Flint Pen Strand

Protecting these wetland areas provides habitat for wildlife that in turn generates billions of dollars a year in expenditures by wildlife enthusiasts, hunters and anglers. The financial benefits of preserving the complicated ecosystems of south Florida are well documented and worthwhile. Without the wetland environment to slow the flow of rainwater so that it can be absorbed into the ground and replenish the drinking water supply in the aquifers, Florida would not be able to sustain its current significant population, much less what we expect to see in the future. 

The CREW Project began watershed preservation in the late 80s and the CREW lands will continue to be preserved in perpetuity. Several large scale projects, like the hydrologic restoration project completed at CREW Flint Pen Strand and the ongoing CREW Marsh trails restoration focused on carolina willow, provide visible examples of the land management process you can witness in person on the trails over time. The 60,000 acres of CREW preserve land for water retention, wildlife and all the other ways these important resources overlap. To protect this land and the water it stores for the next generation we all must partner to fund this preservation, to protect it, and to educate everyone about it.

Youth hiking CREW Flint Pen Strand through hydrologic restoration area.
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How to Report a Python Sighting at CREW

…or a boa, or any other non-native, invasive snake.

You’ve seen the news reports. You know they are here. But have you ever actually seen a python while out hiking in southwest Florida? And what should you do if you see one at CREW?

BurmesePython
Python photo from FFWCC

The first known sighting of a python in CREW occurred in Bird Rookery Swamp in 2005. Since then, no other sightings have been reported in the watershed – until this year. In June 2013, a 10-foot python was seen near the CREW field office off Corkscrew Road in Lee County. Last week, a 9-foot common boa was found by exotic plant treatment contractors in Flint Pen Strand off Bonita Beach Road.

These two recent sightings confirm that these large non-native snakes are moving into the CREW watershed, so we want you to know what to do if you see one while out hiking on the CREW trails.

  • First – do not approach the snake, but do confirm its identity, and if you can, take a photo and mark the GPS coordinates of the snake’s location.
  • Second – if the python or boa is still in your view and staying put, call the FWC Exotic Species Hotline number 888-IVE-GOT1 (888- 483-4681) to report the location.
  • If the snake is moving away and out of your sight, report it using the IVEGOT1 smartphone app for iPhone or Android or the website form at IVEGOT1.org (register ahead of time, so you don’t have to do that part in the field)
  • Do not attempt to remove the snake. Only permitted, trained individuals may remove pythons or boas (also known as conditional species) and even then only from certain Wildlife Management Areas and other public lands with permits/permission from both FWC and the landowner.

And if you want to get more involved, you can complete this online training course from the University of Florida that will help you recognize and report large invasive reptiles. (REDDY – Reptile Early Detection and Documentation training)

REDDY Training

Additional info: http://ufwildlife.ifas.ufl.edu/REDDy/alreadyreddy.shtml

Quick Reference guides: http://ufwildlife.ifas.ufl.edu/REDDy/resources.shtml

Reporting your sighting helps FWC, the SFWMD, and other agencies manage these invasive exotic species and determine their distribution and range. Burmese pythons and boas  are non-native snakes introduced in Florida by accidental and intentional releases by pet owners. They can be found in or near freshwater aquatic habitats like marshes and swamps and can grow up to 20 feet in length. They eat alligators, birds, mice, rabbits, raccoons, deer, and other small mammals. To learn more, visit the Python pages on the FWC website.

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