Archive: 2022 PRWG webinars

Holistic Conservation of the Pine Rocklands
Frank Ridgley DVM, Zoo Miami, Frank.Ridgley@miamidade.gov

In a relatively short amount of time, we have drastically altered the pine rockland ecosystem and their complex webs of species interactions. For many decades we have collectively been studying the rare flora that occupy the remaining fragments but the fauna remains relatively understudied. We all know individual species’ ecology do not exist in a vacuum. Appreciating, evaluating, and measuring what has been lost from the lands that we manage can aid us in being better land managers, biologists, researchers, and conservationists. With this knowledge, we may find ways to reintroduce these absent faunal influences to improve the overall health of the remaining pine rocklands.

Effects of Number and Density of Limestone Cavities on the Nesting Behavior of the Bahama Parrots (Amzona leucocephala bahamensis) on Abaco Island
By Dr. Caroline Stahala, Shorebird Program Manager, Audubon Florida, caroline.stahala@audubon.org

Abaco Parrots nest exclusively in limestone solution cavities on Great Abaco Island, The Bahamas. Limestone solution holes are ubiquitous on the island and come in various shapes, sizes, and depths. This population provides an opportunity to investigate nest site selection relatively free of the resource limitations usually affecting cavity nesting birds. Systematic transects were conducted throughout the parrot nesting area of South Abaco to document suitable nesting cavities. These cavities were overlaid with known nest cavities used by parrots. The total number and density of suitable nesting cavities was not found to be a limiting factor to nesting by Abaco Parrots. Results also show a selective behavior by parrots for nesting in aggregations rather than distribution with respect to cavity availability. Parrots also showed a preference for cavities with vegetation farther from cavity entrance, underscoring the importance of vegetation management in the parrot nesting area.

Pine Rockland Birds: Lifting the veil on what we lost
Noah Frade, Project Botanist, Fairchild Tropical Botanic Garden. nfrade@fairchildgarden.org

The birds which inhabit and once inhabited the pine rockland habitat of South Florida remain an understudied and underappreciated aspect of the region's biodiversity. Current breeding bird diversity in pine rockland fragments beyond Everglades National Park is extremely low; however, this was not always the case. Instead of exotic parrots, pigeons, and starlings, this ecoregion once hosted a unique combination of native bird species typical of pine savannahs across the southeastern U.S., as well as Caribbean species which reach the northern limit of their breeding range at the tip of the Florida peninsula. Using current data from intact habitat within Long Pine Key in Everglades National Park, Big Pine Key, and the Bahamas, we can attempt to paint a picture of the bird life that existed across much of metropolitan Miami over 100 years ago. This discussion will explore current and historical pine rockland bird assemblages in addition to sharing a new field guide created in collaboration with a local student and bird enthusiast.

Trends in plant community dynamics in urban pine rockland fragments
Lauren Trotta, Zachary Siders, and Ben Baiser, University of Florida; Jennifer Possley, Fairchild Tropical Botanic Garden; and Steven Woodmansee, Pro Native Consulting, lbtrotta@ufl.edu

An essential component to the success of ecological habitat management is periodic monitoring to determine whether management goals are being met. In 2018, we resampled vegetation plots across 16 of Miami’s urban pine rockland fragments for the fourth time since the plots were established in 1994. This long-term monitoring program captures changes in the highest quality pine rockland plant communities within these urban fragments, most of which have been actively managed for pine rockland habitat. Using these data, we explored trends in species richness and percent cover in pine rockland ground cover, midstory, and canopy plots over time. We also divided species recorded in plots into groups of management interest (i.e., native, rare, threatened, or endangered, non-native, and invasive species), and growth forms (i.e., tree, shrub, palm, graminoid, vine, and forb). With these species groups we can begin to evaluate habitat management goals such as promoting native species, reducing non-native and invasive species, and maintaining open pine rocklands vegetation structure. Finally, we dig into the data to reveal which species have contributed most strongly to each trend in Miami’s urban pine rocklands.

By assessing these best available long-term pine rockland plant community data, we find that species richness has increased across all levels of habitat structure: at the ground level, in the midstory, and in the canopy. Further, we show that management priorities like invasive species removal, hardwood species reduction, and the protection of rare, threatened, and endangered species have been successful. We also find signals that while diversity of native species has been increasing, the vegetation structure in these pine rockland plots has been shifting to encompass greater canopy cover, increased palm and tree cover in the midstory, and reduced graminoid richness and cover and herb cover at the ground level.

The Pine Rockland and Florida bonneted bats: a study case in an anthropogenic landscape
Melquisedec Gamba-Rios¹, Stephanie Brinez¹ and Frank Ridgley², ¹Endangered Species Interventions, Bat Conservation International. ²Conservation and Research Department, Zoo Miami, mgambarios@batcon.org

The Florida bonneted bat (Eumops floridanus) is a federally endangered species endemic to southern Florida. In the Southeast of the distribution, one of the main threats for the species is the irreversible loss of the Pine Rockland habitat. These forests provided the Florida bonneted bat's natural roosting habitats and food resources. Human population growth in Florida, leading to the development and land-use change increases, has been decreasing this critical habitat. Roosts play a crucial role in the longevity and stability of bat populations as they provide shelter for them to sleep, give birth, raise their young, and provide protection from predators and extreme weather events. Additionally, foraging habitats are vital to the survival of any bat population. For the past three years, Bat Conservation International and Zoo Miami have been working on an initiative to recover and conserve the Florida bonneted bat in the urban settings in which it is found. During this time, we identify the species' historical and contemporary roost use to better understand roost selection in urban environments. Also, we create an acoustic monitoring grid to identify foraging areas across Miami-Dade County. Our goal is to provide relevant data that supports the protection and enhances the recovery of the Florida bonneted bat in urban environments.

Link to Miami-Dade EEL video (sound all the way up) with Florida bonneted bat call

Pine rocklands in South Florida continue to be lost to urban development and habitat degradation.
Alex Seasholtz, Ecological Restoration Management Team Leader with The Institute for Regional Conservation, aseasholtz@regionalconservation.org

One of IRC’s missions of the Pine Rockland Initiative is to “ expand the footprint“ and begin to reclaim area once thought lost. Through the employment of restoration mowing and direct seeding we are better understanding the metrics of restoring ecological function to degraded pine rocklands.

Ecology and Conservation of Gopher Tortoises in Miami-Dade's Pine Rockland Preserves
Dr. Steven Whitfield, Conservation Scientist, Zoo Miami, steven.whitfield@miamidade.gov

The Gopher Tortoise (Gopherus polyphemus) is a resident of the southeastern coastal plain of the United States, including components of the pine rocklands ecosystem. Gopher Tortoise populations are declining range-wide, including in south Florida. Gopher Tortoises are both ecosystem engineers and keystone species: the burrows they create are used as refugia by hundreds of other animal species, and tortoises serve as important seed dispersers for pine rockland plants. While historically they were more widespread in Miami-Dade County, today only three small populations of gopher tortoises remain in Miami's pine rocklands, and these populations are at the forefront of impacts from urbanization and climatic warming. Here, I will review research led by Zoo Miami over the past several years focused on population ecology, thermal ecology, spatial ecology, disease ecology, reproductive biology, and ecosystem role as seed dispersers. I will review conservation actions led by Zoo Miami focusing on reducing human-wildlife conflict, rehabilitation of sick and injured gopher tortoises at the Zoo Miami veterinary hospital, and supplementation of depleted populations with tortoises illegally displaced by human in partnership with Miami-Dade County's Environmentally Endangered Lands program. I will review the current understanding of gopher tortoise conservation in the pine rocklands, and discuss conservation and management scenarios for long-lived ecosystem engineers in small natural areas of critically imperiled pine rockland.

Gopher Tortoises are Frugivores? Seasonal Shifts toward Frugivory by Gopherus polyphemus in the Pine Rockland Ecosystem
Adrian Figueroa¹, Alyssa Herrera², Lydia Cuni³, and Dr. Steven Whitfield⁴. ¹Florida International University, Department of Earth and Environment, ²Florida International University, Institute of Environment, ³ Fairchild Tropical Botanic Garden, ⁴Zoo Miami, Conservation and Research Department and Florida International University, School of Environment, Arts, Society. afigu083@fiu.edu

Frugivory is an important foraging behavior often leading to seed dispersal for fleshy fruited plants. Thus, most animal-mediated seed dispersal literature has focused on traditional frugivores due to the prevalence of fleshy fruits in their diet. This approach has led to research biases that imply traditional frugivores are primarily important for maintaining this ecological process over other animals that diverge in their foraging behavior. Previous research has unveiled that scats from diverse faunae contain seeds of plants with disparate dispersal syndromes aside from fleshy fruits. Herbivorous gopher tortoises (Gopherus polyphemus) – a candidate species for listing under the Endangered Species Act – currently inhabit the expanse of pine rockland habitat at The Richmond Tract in Miami, FL. These tortoises have been previously documented to ingest seeds of various plants at this site but surprisingly lacked seeds of many fleshy fruited species. However, this observation was due to sampling biases focusing on dry season scat collection. These same individual tortoises have now been tracked for over a year with weekly scat collections unveiling their diet and seed consumption across the wet and dry seasons. Through this research, clear patterns have emerged that depict dietary shifts that reflect the fruiting phenology of fleshy fruited pine rockland plant species. In this talk, I will discuss results from scat dissections as part of my dissertation research and share the implications of this frugivorous behavior by gopher tortoises for the conservation of pine rockland plant species.

Fragmentation disrupts microbial effects on native plant community productivity
Kasey N. Kiesewetter, Leydiana Otano, Michelle E. Afkhami, University of Miami, Department of Biology, Coral Gables, knk31@miami.edu

Habitat fragmentation – the breaking up of natural landscapes – is a pervasive threat to biodiversity that introduces novel, non-natural matrix habitat into landscapes worldwide. Despite the importance of the matrix, we have limited knowledge of how it influences microbiomes on remnant habitats and even less on how matrix-driven changes to microbiomes scale up to influence plant community productivity. Using field collections, microbiome sequencing, and manipulative mesocosms in the imperiled Pine Rockland fragments within Miami-Dade County, we (1) investigated how microbial diversity and composition differed between 15 native rocklands fragments and adjacent urban matrix, (2) compared how the strength of fragmentation and matrix features explained variation within these two habitat types, and (3) tested whether urbanization-driven changes in microbiomes affected plant community productivity and composition.

Microbial diversity and composition significantly differed between native habitat and urban matrix, including an ~80% increase in symbiotrophs in native habitats and a >300% pathotroph increase in urban matrix. Further, habitat fragmentation metrics explained variation in microbial diversity of native, pine rockland fragments but not of the adjacent urban matrix habitats. Importantly, native habitat microbiomes increased overall plant community productivity by ~300%, while urban microbiomes did not affect productivity, indicating that native plant communities showed diminished reliance on urban microbiomes. Our study not only documented matrix-driven changes in microbial diversity and composition, but also demonstrated native microbiomes persisting in fragmented landscapes are imperative to plant community productivity, highlighting preservation of native microbiomes as critical for native plants in remnant fragments.

Windthrow in South Florida pine rocklands: pit-and-mound features and plant microhabitat associations following a hurricane
Michael S. Ross^1,2, Susana Stoffella², John F. Meeder², Jay P. Sah², Pablo L. Ruiz³;¹Department of Earth & Environment, Florida International University, Miami, FL; ²Institute of Environment, Florida International University, Miami, FL; ³National Park Service, South Florida Natural Resource Center, Homestead, FL; rossm@fiu.edu.

Biotic legacies from natural disturbances can create topographic heterogeneity that affects plant composition and diversity across scales from centimeters to kilometers. In this continuing study of the effects of Hurricane Andrew (August 1992), we examined the immediate (3 years post-hurricane) and long-term (28 years post-hurricane) effects of pit-and-mound landforms created by uprooted trees on the pine forest understory in Everglades National Park. We found that trees uprooted from the limestone bedrock created deep pits that partially infilled over time but left a lasting mark on the landscape. Soon after the storm, the plant assemblages in the pits were about twice as species-rich as those on the mounds, and communities in both environments were distinct from control plots that represented background vegetation. By 2020, when the plots were resampled, several significant species-environment associations remained, though the strong initial differences in composition between pit, mound, and control had decreased substantially. Spatial analyses along transects also indicated that while old tipup features were sometimes associated with distinct compositional units, they were not the primary agent responsible for variation in community composition. Together, these results suggest that the uprooting of pine trees during periodic hurricanes creates ecologically significant substrate variation for early plant establishment on the rockland surface, and while succession and subsequent sedimentary processes erase some of this early vegetation patterning, the uprooting of trees contributes in an important way to the diversity of understory rockland assemblages.