It was introduced and widely cultivated in Florida for coastal landscaping but has fallen into disfavor in the past 20 years because of its invasive growth habit and aggressive choking of indigenous vegetation (Barrett 1956). Once established, may inhibit the growth of native species. In 1980, Casuarinas numbered in the hundreds and thousands on several Florida Bay keys and on beaches from Cape Sable to the Ten Thousand Islands. Now one can expect to find pioneers on any sandy area above the high tide mark (Morton 1980). It is concluded from observation by experts that Casuarinas' inhibition of any undergrowth is the result of an aggressive and dense colonization habit and possibly to the production of phytotoxic exudations (Klukas 1969, Digiamberardino 1986, Okuda et al. 1982). In an experiment by Fernald and Barnett (1988), seedlings of indigenous species planted beneath a Casuarina canopy on spoil islands in the Indian River near Vero Beach, Fl. had a 54% survival rate. This implies that deterrents Casuarina presents to pioneers, whether physical, mechanical, or chemical, may be overcome or circumvented by introducing plants at the seedling stage. If phytotoxins are produced by Casuarina, they may only be inhibitory to germination. Even when Casuarina is planted along the highway there are rarely more than a dozen plant species growing below the canopy and the majority of these are other exotics (Austin 1978). A monotypic stand is a sterile system that harbors few native plants or animals (ELEMENT STEWARDSHIP ABSTRACT for Casuarina equisetifolia Australian Pine). Dense thickets of Australian pine displace native dune and beach vegetation, including mangroves and many other resident, beach-adapted species. Because its roots are capable of producing nitrogen through microbial associations, Australian pine can colonize nutrient-poor soils. Once established, it radically alters the light, temperature, and soil chemistry regimes of beach habitats, as it outcompetes and displaces native plant species and destroys habitat for native insects and other wildlife. Chemicals in the leaves of Australian pine may inhibit the growth of other plants underneath it (Fact Sheet: Australian Pine).

Australian pine is very sensitive to fire, and may be killed by even a light burn (Floridata). May wildfire killed 60 to 70 percent of sheoak in Florida [10]. A smoldering controlled burn in Florida killed 90 percent of the sheoaks on the study plot [14]. A second attempt in the same area killed all the sheoaks; trunk diameters were between 5 and 8 inches (13-20 cm). Another tree, with a d.b.h. of 2 feet (0.66 m), was killed after charcoal was left to smolder at its base [14]. Trees less than 3 inches (8 cm) in diameter may sprout following fire.Trees larger than this usually die. Periodic fires coupled with the use of herbicides may be an effective method of controlling sheoak. However, too frequent, intense fires that kill overstory native pines may actually encourage Casuarina species to establish. Morton warns that burning Australian pine in peat soils may be hazardous. Elfer suggests that fire may be an effective control method for trees greater than 3 inches (8 cm) in diameter and in dense stands. Burning could be potentially harmful if the soil pH is changed such that native species cannot establish (USFS). An exhaustive Google/Google Scholar search did not reveal any additional evidence and this defaults to a “no” answer at this time.

While cattle readily eat the sprouts in Australia, they are recognized as high in tannin, astringent, and constipating, and are used for hardship fare only. It is now known that tannin interferes with digestive system utilization of protein, results in weight deficits, and is carcinogenic. Apart from the hazards that Casuarina presents to its habitat and to other plants and animals, it also poses a problem to humans because it is a source of respiratory irritation. Casuarina pollen can cause allergic reactions symptomized by eye irritation, runny-nose, and hoarseness or sore throat (Morton 1980) (ELEMENT STEWARDSHIP ABSTRACT for Casuarina equisetifolia Australian Pine). The pollen is plentifully airborne from December to April and has been definitely linked to respiratory complaints during these months (The Australian pine or beefwood (Casuarina equisetifolia L.) an invasive ‘‘weed’’tree in Florida). Australian pine tree’s dense shallow root system interferes with the ability of the endangered American crocodiles and sea turtles to construct coastal nests (Weed alert Australian pine (Casuarina species)). The alterations to ecosystems, direct and indirect negative impacts to wildlife, and substantial allergens to humans warrant a "yes".

Casuarina monocultures are usually flat without dune-swale topography and lack diversity in understory vegetation. The shallow root systems of the trees makes them susceptible to toppling during storms (Digiamberardino 1986). Reproduces prodigiously via coppicing to produce close, impenetrable stands. A monotypic stand is a sterile system that harbors few native plants or animals (ELEMENT STEWARDSHIP ABSTRACT for Casuarina equisetifolia Australian Pine). Dense thickets of Australian pine displace native dune and beach vegetation, including mangroves and many other resident, beach-adapted species. Because its roots are capable of producing nitrogen through microbial associations, Australian pine can colonize nutrient-poor soils. Once established, it radically alters the light, temperature, and soil chemistry regimes of beach habitats, as it outcompetes and displaces native plant species and destroys habitat for native insects and other wildlife. Chemicals in the leaves of Australian pine may inhibit the growth of other plants underneath it (Fact Sheet: Australian Pine).