Invasion Ecology and Response to Fire of the Nonnative Fern Lygodium microphyllum in the South Florida Everglades

Authors

Nicole Sebesta, Florida International UniversityFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

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First Advisor's Name

Jennifer Richards

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Suzanne Koptur

Second Advisor's Committee Title

Committee Member

Third Advisor's Name

Michael Ross

Third Advisor's Committee Title

Committee Member

Fourth Advisor's Name

Daniel Gann

Fourth Advisor's Committee Title

Committee Member

Fifth Advisor's Name

Diego Salazar Amoretti

Keywords

invasive plants, old world climbing fern, ecology, management, prescribed fire, foliar nectar, salinity tolerance, Lygodium microphyllum, biological control agents, biocontrols, integrated pest management

Date of Defense

4-30-2021

Abstract

Lygodium microphyllum (Old World Climbing Fern (OWCF)) is a climbing fern native to tropical and subtropical regions of Australia, Asia, and Africa. First introduced to Florida as an ornamental in the 1960s, the fern has become a serious invasive in numerous Florida habitats, severely degrading native herbaceous and woody vegetation and altering fire behavior. One area with the greatest increase in OWCF cover is the sawgrass marsh of southern Everglades National Park (ENP), where prescribed fire is used for both maintenance of sawgrass marshes and management of OWCF infestations. However, the efficacy of OWCF control using fire in this habitat is uncertain. This dissertation investigated the response of individual OWCF plants in coastal sawgrass marshes over two years following a prescribed burn. As some OWCF occurs in brackish conditions, salinity tolerance of the fern was assessed under greenhouse conditions. Additionally, nectar production, which can influence biological control agent success, was examined in OWCF and related species.

Following the prescribed burn, surviving OWCF recovered to pre-burn sizes between 6 and 15 months after burning, depending on the burn season. Mortality was size-dependent, with smaller plants suffering highest mortality rates. Sexual reproduction and biocontrol mite presence were both reduced for approximately 9 months post-burn. Saline conditions of 10 ppt reduced growth rates of greenhouse-grown OWCF within 6 weeks and resulted in significantly reduced biomass after 3 months as compared to plants in both 0 and 5 ppt. Spores had reduced and delayed germination in saline conditions compared to 0 ppt, and were completely prevented from germinating in 15 ppt. Foliar nectar production, previously discovered on OWCF, was documented on three additional species, including the other major Florida invasive, Lygodium japonicum.

The findings of the dissertation suggest that fire is an effective management strategy for OWCF and may be improved in certain habitats by combination with biocontrol releases. Although OWCF is found in mildly brackish habitats, higher salinity hinders its survival, suggesting limited invasion potential in more saline areas. Finally, if foliar nectar production occurs in the field, further study of its effects on biocontrol agent success is warranted.

Identifier

FIDC010247

ORCID

0000-0002-0976-3560

Recommended Citation

Sebesta, Nicole, "Invasion Ecology and Response to Fire of the Nonnative Fern Lygodium microphyllum in the South Florida Everglades" (2021). FIU Electronic Theses and Dissertations. 4820.
https://digitalcommons.fiu.edu/etd/4820