Hardwood Hammocks Research Articles

Comparing Ant Activity and Plants Bearing Extrafloral Nectaries in Rockland Habitats of the Florida Keys with Those of the Everglades and the Bahamas

Rocklands are present in South Florida, both on the peninsula and in the Keys. Previous work has shown that extrafloral nectaries on pine rockland plants in the Florida Everglades and surrounding areas play a role in attracting ant protectors. Species with nectaries are more abundant and ant activity greater in more recently burned pine rockland habitats compared with longer undisturbed rockland hammock forest. The floristic composition and prevailing climate of Keys rocklands differs substantially from those on the mainland, so we sought to investigate ant activity and the abundance of plants with extrafloral nectaries in Big Pine Key rockland habitats. Standard baiting methods were used to assess ant abundance and potential predation activity in hardwood hammock, shrubby pine rockland, and open pine rockland sites. Ant activity was the lowest in open pine rockland, greatest in hardwood hammock, and intermediate in shrubby pine rockland, the opposite of what has been observed in previous studies in southern peninsular Florida and on Andros, Bahamas. Sampling vegetation at these same sites revealed a larger proportion of plant species with extrafloral nectaries in the pine rocklands than the hammock, as observed previously in Everglades habitats. Possible reasons for differences in ant activity in Keys rockland habitats are discussed.

Simulated extreme climate event alters a plant-frugivore mutualism

Anthropogenic climate change is contributing to an increase in the frequency of extreme weather events. These extreme events may affect interactions in mutualisms that provide key ecosystem functions, especially when the event is rare for a given system and participants are differentially affected. The tropical hardwood hammocks of Key Largo, Florida, USA are inhabited by a highly specialized endangered rodent, the Key Largo woodrat (Neotoma floridana smalli), which may be an important seed disperser of many native fleshy-fruited plant species. Other potential mammalian dispersers are generalist omnivores, northern raccoons (Procyon lotor) and Virginia opossums (Didelphis virginiana), that are less selective. We sought to demonstrate that extreme climate events could alter seed dispersal mutualisms by differentially affecting fruit preference of potential dispersers. We designed a replicated cafeteria-style experiment across the entire range of the Key Largo woodrat with fruit from sixteen native plant species and simulated an extreme climate event by exposing half of the fruits to sub-freezing temperatures. Freezing temperatures are rare in this tropical environment, but increased frequencies of these types of extreme events are predicted with climate change. Using camera traps, we monitored the removal of fruit and seeds by woodrats and the generalist consumers, predicting that changes in fruit quality resulting from exposure to sub-freezing temperatures would reduce preference by the more specialized woodrat relative to its generalist consumers. Indeed, exposure to subfreezing temperatures decreased the probability of fruit and seed removal by woodrats while generalist consumers preferentially removed more of the fruits and seeds exposed to sub-freezing temperatures. These data provide evidence that extreme climate events may affect species preferences for food asymmetrically, which may shift the dynamics of seed dispersal mutualisms. Over time, increasing frequencies of extreme weather events could indirectly affect communities and ecosystem services by shifting interactions between organisms.

At a fine scale, hardwood patches support wildlife diversity in longleaf pine woodlands

AbstractRestoring and maintaining biodiversity in a changing world is increasingly challenging due to the competing needs of species for suitable space and resources. One ecosystem that has seen considerable anthropogenic changes in extent and structure is the longleaf pine (Pinus palustris) ecosystem. Understanding how wildlife responds to restoration is important to informing forest restoration and conservation. We monitored game birds and mid‐large‐sized mammal occupancy in and around hardwood patches embedded within a longleaf pine woodland at The Jones Center at Ichauway in Newton, GA. We found that 11 species use the transition zone between the longleaf pine and hardwood hammocks. Gray squirrels (Sciurus carolinensis), Virginia opossums (Didelphis virginiana), and nine‐banded armadillos (Dasypus novemcinctus) occupancy increased along the gradient while fox squirrel (Sciurus niger) declined. Our results suggest that oak patches and transitional zones are important to maintaining biodiversity within the longleaf pine ecosystem.

Home Range and Habitat Use of Florida Box Turtles (Terrapene bauri) in the Ten Thousand Islands, Florida

For taxa with dispersal limitations, such as freshwater turtles, an understanding of their habitat and spatial needs can elucidate their risk to expected environmental and climatic changes. Florida Box Turtles (Terrapene bauri), a species of greatest conservation need, occurs in a diverse range of subtropical habitats on the Florida peninsula, including low-lying coastal areas subject to threats from climate change and sea level rise. We used radiotelemetry to assess the home range size and habitat use of Florida Box Turtles on a 37-ha anthropogenic, shell work island in southwestern Florida at the margin of its climatic niche. Home range calculated as 100% minimum convex polygons ranged from 0.29–1.52 ha with an average of 0.81 ha, which is consistent with, but smaller than, other parts of their range, and annual survivorship was estimated to be 0.875 (95% confidence interval = 0.67–1). Florida Box Turtles were most commonly located in tropical hardwood hammock forests (50.9%); other habitat use included shrub-scrub-cactus (29.6%), mangrove forest (13.4%) and shell barren (6.0%). Additional information on reproductive output, growth, temporal variation in survival, and response to disturbance such as hurricanes, storm overwash, and sea level rise is necessary to assess the long-term persistence of this population in the face of anticipated transitions of Florida's habitats because of global climate change.

Seasonal Dynamics of Mosquito-Borne Viruses in the Southwestern Florida Everglades, 2016, 2017.

Mosquitoes were collected for 12 consecutive months beginning June 2016, from 11 locations in the Florida Everglades, Collier County, and tested for viruses by isolation in Vero cells and subsequent identification. One species complex and 31 species of mosquitoes were identified from 668,809 specimens. Ochlerotatus taeniorhynchus comprised 72.2% of the collection. Other notable species were Anopheles crucians complex, Culex nigripalpus, Cx. erraticus, and Cx. cedecei. Seven species of virus were identified from 110 isolations: Everglades, Gumbo Limbo, Mahogany Hammock, Pahayokee, Shark River, Tensaw, and West Nile viruses. Everglades, West Nile, Tensaw, and Mahogany Hammock viruses were most frequently isolated. Largest numbers of viruses were identified from Cx. cedecei, Cx. nigripalpus, and An. crucians complex. Five species of virus were isolated from Cx. cedecei. Viruses were isolated from mangrove, cypress swamp, hardwood hammock, and sawgrass habitats. West Nile virus was isolated August through October when Cx. nigripalpus was most abundant. Everglades virus was the most frequently isolated virus from nine species of mosquitoes collected from June through August. Tensaw virus was isolated primarily from Anopheles species. Isolations were made in July, August, January, February, and April, suggesting that this virus may be present in host-seeking mosquitoes throughout the year. Mahogany Hammock, Shark River, Gumbo Limbo, and Pahayokee viruses were isolated primarily from Cx. cedecei from June through December. Shotgun metagenomic sequencing was used to document that seven pools of Cx. cedecei were infected with two arboviruses. As communities expand into the Everglades, more humans will become exposed to arboviruses.

Spiders (Araneae) of the Everglades National Park, Florida, USA

The spider fauna of the Everglades National Park in southern Florida was surveyed over 2 widely separated time periods: 1966 to 1967 and 2008 to 2009. Samples were made in 4 of the typical Everglades habitats: sawgrass prairie, willowhead marsh, pineland, and tropical hardwood hammock, as well as several “disturbed” areas. A total of 201 spider species was identified. Twenty-three additional taxa were identified only to genus and included for general Everglades information. One species was documented as new and undescribed, and several others possibly may be new. The Everglades National Park is located at the northern border of the Neotropical ecozone and the southern border of the Nearctic ecozone. Forty-seven percent of the species were Nearctic, 37% Nearctic/Neotropical, 12% Cosmopolitan, and 3% Neotropical. The greatest number of species was collected in the hardwood hammock habitat. Life cycles of 10 common species are provided.

Simulated hurricane-induced changes in light and nutrient regimes change seedling performance in Everglades forest-dominant species.

Wind damage from cyclones can devastate the forest canopy, altering environmental conditions in the understory that affect seedling growth and plant community regeneration. To investigate the impact of hurricane‐induced increases in light and soil nutrients as a result of canopy defoliation, we conducted a two‐way factorial light and nutrient manipulation in a shadehouse experiment. We measured seedling growth of the dominant canopy species in the four Everglades forest communities: pine rocklands (Pinus elliottii var densa), cypress domes (Taxodium distichum), hardwood hammocks, and tree islands (Quercus virginiana and Bursera simaruba). Light levels were full sun and 50% shade, and nutrient levels coupled with an additional set of individuals that were subjected to a treatment mimicking the sudden effects of canopy opening from hurricane‐induced defoliation and the corresponding nutrient pulse. Seedlings were measured weekly for height growth and photosynthesis, with seedlings being harvested after 16 weeks for biomass, leaf area, and leaf tissue N and 13C isotope ratio. Growth rates and biomass accumulation responded more to differences in soil nutrients than differences in light availability, with largest individuals being in the high nutrient treatments. For B. simaruba and P. elliottii, the highest photosynthetic rates occurred in the high light, high nutrient treatment, while T. distichum and Q. virginiana photosynthetic rates were highest in low light, high nutrient treatment. Tissue biomass allocation patterns remained similar across treatments, except for Q. virginiana, which altered above‐ and belowground biomass allocation to increase capture of limiting soil and light resources. In response to the hurricane simulation treatment, height growth increased rapidly for Q. virginiana and B. simaruba, with nonsignificant increases for the other two species. We show here that ultimately, hurricane‐adapted, tropical species may be more likely to recolonize the forest canopy following a large‐scale hurricane disturbance.

Emergence potential of mosquito-borne arboviruses from the Florida Everglades.

The Greater Everglades Region of South Florida is one of the largest natural wetlands and the only subtropical ecosystem found in the continental United States. Mosquitoes are seasonally abundant in the Everglades where several potentially pathogenic mosquito-borne arboviruses are maintained in natural transmission cycles involving vector-competent mosquitoes and reservoir-competent vertebrate hosts. The fragile nature of this ecosystem is vulnerable to many sources of environmental change, including a wetlands restoration project, climate change, invasive species and residential development. In this study, we obtained baseline data on the distribution and abundance of both mosquitos and arboviruses occurring in the southern Everglades region during the summer months of 2013, when water levels were high, and in 2014, when water levels were low. A total of 367,060 mosquitoes were collected with CO2-baited CDC light traps at 105 collection sites stratified among the major landscape features found in Everglades National Park, Big Cypress National Preserve, Fakahatchee State Park Preserve and Picayune State Forest, an area already undergoing restoration. A total of 2,010 pools of taxonomically identified mosquitoes were cultured for arbovirus isolation and identification. Seven vertebrate arboviruses were isolated: Everglades virus, Tensaw virus, Shark River virus, Gumbo Limbo virus, Mahogany Hammock virus, Keystone virus, and St. Louis encephalitis virus. Except for Tensaw virus, which was absent in 2013, the remaining viruses were found to be most prevalent in hardwood hammocks and in Fakahatchee, less prevalent in mangroves and pinelands, and absent in cypress and sawgrass. In contrast, in the summer of 2014 when water levels were lower, these arboviruses were far less prevalent and only found in hardwood hammocks, but Tensaw virus was present in cypress, sawgrass, pinelands, and a recently burned site. Major environmental changes are anticipated in the Everglades, many of which will result in increased water levels. How these might lead to the emergence of arboviruses potentially pathogenic to both humans and wildlife is discussed.

Mosquito Culex cedecei Stone and Hair (Insecta: Diptera: Culicidae)

The Featured Creatures collection provides in-depth profiles of insects, nematodes, arachnids and other organisms relevant to Florida. These profiles are intended for the use of interested laypersons with some knowledge of biology as well as academic audiences. Culex cedecei is a mosquito endemic to Florida, and a member of the Spissipes section of the subgenus Melanoconion of Culex. Several members of the Spissipes section are important vectors of enzootic subtypes of Venezuelan equine encephalitis virus (VEEV). Everglades virus (EVEV) is subtype II of VEEV in Florida, for which Culex cedecei is the primary enzootic vector. Culex cedecei is typically found in forested wetlands of southern Florida, ranging from mangrove swamps to hardwood hammocks and lowland pine ecosystems (Hoyer et al., 2019). Larvae of Culex cedecei develop in limestone solution holes, and abandoned crab burrows in a variety of habitats. Although Culex cedecei is not generally considered a pest of humans, it feeds primarily on muroid rodents (rats and mice), which are important hosts of EVEV in Florida. Culex cedecei is therefore considered a vector of a zoonotic pathogen that can affect human health.

Evidence for trait‐based community assembly patterns in hardwood hammock forests

AbstractThe hardwood forests of south Florida, commonly referred to as hammocks, persist as well‐drained patches of broadleaf forest, embedded in a matrix of brackish water swamp, freshwater marsh, or pineland. Little is known about the patterns of community assembly of these subtropical forest communities in the landscape mosaic of south Florida. We used a functional trait approach to understand the composition of these communities and their responses to environmental variation across four areas of south Florida: the pine rocklands and freshwater marshes in Everglades National Park, and the lower and upper Florida Keys, where the hammocks are surrounded by halophytic swamp communities. These sites represent an environmental gradient from less‐productive, more xeric sites in the lower Florida Keys, to more‐productive, wetter sites in the Everglades marshes. We examined the patterns of trait variation at three levels (individual, population, and community) to examine the underlying processes driving assembly in these hammock communities. To understand processes governing community composition in each site, we used methods that partition variance in six traits (maximum tree height, specific leaf area, wood specific gravity, leaf nitrogen, leaf phosphorus, and leaf stable carbon isotope ratios) into internal and external filtering components. Community‐weighted mean trait values for three traits (specific leaf area, height, and leaf phosphorus) increased significantly from dry, less‐productive coastal sites in the Florida Keys to the moist, more‐productive areas on the mainland, while wood specific gravity and leaf δ13C showed the opposite pattern. For one or more traits per site, standardized effect sizes differed significantly from null expectation. Processes such as competition for resources (e.g., water, nutrients, light) and species sorting across microhabitats (i.e., within site) operate to increase local functional trait variation within communities and among species across sites. External filtering on individuals for height and leaf phosphorus differed significantly from null expectations across sites, while external filtering on species was only observed for specific leaf area, maximum tree height, and leaf phosphorus. These results are consistent with strong environmental filtering across the region, among local communities differing in freshwater accessibility or that occupy different positions along strong edaphic gradients. Our results confirm the importance of intraspecific variation among species and reflect a high degree of trait plasticity across the environmental gradient.

National Audubon Society’s Corkscrew Swamp Sanctuary: A Wetland of Distinction

I n February 2019, the Society of Wetland Scientists recognized National Audubon Society’s Corkscrew Swamp Sanctuary (Naples, Florida, USA) as its newest Wetland of Distinction. The honor comes to a site that is an increasingly-rare remnant of Old Florida, one whose rich biodiversity and dynamic sub-tropical wetland ecology are preserved as a result of a conservation effort that has spanned over a century. Today, Corkscrew’s old-growth bald cypress (Figure 1), hardwood hammock (Figure 2), marsh (Figure 3), wet prairie (Figure 4), and pine flatwoods (Figure 5), are increasingly at risk from factors outside the sanctuary’s boundary, such as a lowered water table, regional wildfire suppression practices, and invasive species. Despite these challenges, Corkscrew remains an ideal site for experiencing and studying the ecology of a mature cypress swamp.

Comparison of TanDEM-X DEM with LiDAR Data for Accuracy Assessment in a Coastal Urban Area

The TanDEM-X (TDX) mission launched by the German Aerospace Center delivers unprecedented global coverage of a high-quality digital elevation model (DEM) with a pixel spacing of 12 m. To examine the relationships of terrain, vegetation, and building elevations with hydrologic, geologic, geomorphologic, or ecologic factors, quantification of TDX DEM errors at a local scale is necessary. We estimated the errors of TDX data for open ground, forested, and built areas in a coastal urban environment by comparing the TDX DEM with LiDAR data for the same areas, using a series of error measures including root mean square error (RMSE) and absolute deviation at the 90% quantile (LE90). RMSE and LE90 values were 0.49 m and 0.79 m, respectively, for open ground. These values, which are much lower than the 10 m LE90 specified for the TDX DEM, highlight the promise of TDX DEM data for mapping hydrologic and geomorphic features in coastal areas. The RMSE/LE90 values for mangrove forest, tropical hardwood hammock forest, pine forest, dense residential, sparse residential, and downtown areas were 1.15/1.75, 2.28/3.37, 3.16/5.00, 1.89/2.90, 2.62/4.29 and 35.70/51.67 m, respectively. Regression analysis indicated that variation in canopy height of densely forested mangrove and hardwood hammock was well represented by the TDX DEM. Thus, TDX DEM data can be used to estimate tree height in densely vegetated forest on nearly flat topography next to the shoreline. TDX DEM errors for pine forest and residential areas were larger because of multiple reflection and shadow effects. Furthermore, the TDX DEM failed to capture the many high-rise buildings in downtown, resulting in the lowest accuracy among the different land cover types. Therefore, caution should be exercised in using TDX DEM data to reconstruct building models in a highly developed metropolitan area with many tall buildings separated by narrow open spaces.

Effects of salinity on saplings of coastal hammock trees of the Everglades National Park, Florida, USA1

Coastal Everglades are experiencing a steady increase in soil and groundwater salinity due to sea level rise. Increase in soil salinity threatens plant assemblages in coastal upland forests of Everglades National Park (ENP). Here we test the effects of increase in soil salinity on saplings of tropical woody species common to the coastal hammocks (forests) of ENP, FL. Saplings were subject to salinity levels ranging from control (freshwater) to 30 parts per thousand (ppt). Significant mortality was observed among species of hardwood hammocks such as Piscidia piscipula (L.) Sarg., which displayed 7%, 20%, and 30% mortality in salinity levels of 5, 15, and 30 ppt, respectively. The canopy-forming Conocarpus erectus L. (buttonwood) and Cynophalla flexuosa (L.) J.Presl, an understory shrub of buttonwood hammocks, exhibited 100% survival across salinity treatments. Stomatal conductance and final shoot biomass were significantly higher in control than 30 ppt for all species except C. flexuosa. Our results suggest that the species of coastal hardwood hammocks show greater vulnerability to increase in soil salinity than the species of buttonwood hammocks. Increase in soil salinity will lead to decline in species diversity, biomass, and canopy height of coastal upland communities.

Hurricane‐Induced Changes in the Everglades National Park Mangrove Forest: Landsat Observations Between 1985 and 2017

AbstractThe Everglades National Park (ENP) has one of the largest mangrove forests in the United States, yet due to lack of data and methods, there has been no multidecadal record of detailed changes in its mangrove forests, not to mention their response to periodic hurricanes. Here, based on remote sensing spectroscopy, multisensor cross calibration, spectral normalization, and pixel unmixing, we develop a stepwise method to map distributions and changes of the ENP mangrove forests and other major wetlands cover types (marshes and hardwood hammocks) over the last three decades. The time series of Landsat‐based results indicate statistically significant increasing trend from 1985 to 2017 in the total ENP mangrove coverage with a cumulative increase of 10.2%, which has increased in the inner coastline area but decreased in the outer coastline area. The mangrove coverage also decreased considerably in certain hurricane years (1992, 2005, and 2017), with the largest decrease of 644.9 km2 (46.5% of the mean mangrove area in normal years) occurring in 1993 after Hurricane Andrew. Yet, these large mangrove die‐off areas gradually recovered to prehurricane levels 3–4 years after the passage of major hurricanes. Results also indicate that while the mangrove forests were always damaged by hurricanes, the extent of the damage depended on wind speed, direction, and distance from maximum wind. The findings here could serve as baseline information for future restoration efforts of the ENP ecosystem, and the study also provides a method extendable to other coastal wetland regions.

MANTRA-O18: An Extended Version of SUTRA Modified to Simulate Salt and δ18O Transport amid Water Uptake by Plants

Sea level rise and the increasing landward intrusion of storm surges pose the threat of replacement of salinity-intolerant vegetation of important coastal habitats by salinity-tolerant vegetation. Therefore, a means is needed to better understand the processes that influence this vegetation shift and to aid in the management of coastal resources. For this purpose, a hydrology–salinity–vegetation model known as MANTRA was developed by coupling a spatially explicit model (MANHAM) for simulation of vegetation community dynamics along coastal salinity gradients with SUTRA, a USGS groundwater flow and transport model. MANTRA has been used to project possible future changes in Coot Bay Hammock in southern Florida under conditions of gradually rising sea level and storm surges. The simulation study concluded that feasibility exists of a regime shift from hardwood hammocks to mangroves subject to a few conditions, namely severe damage to the existing hammock after a storm surge and a sufficiently persistent high salinity condition and high input of mangrove seedlings. Early detection of salinity stress in vegetation may facilitate sustainable conservation measures being applied. It has been shown that the δ18O value of water in the xylem of trees can be used as a surrogate for salinity in the rooting zone of plants, which is difficult to measure directly. Hence, the model MANTRA is revised into MANTRA-O18 by including the δ18O of the tree xylem dynamics. A simulation study by MANTRA-O18 shows that effects of increasing salinization can be detected many years before the salinity-intolerant trees are threatened with replacement.

The lichens of Dagny Johnson Key Largo Hammock Botanical State Park, Key Largo, Florida, USA

In January, 2015, we conducted a lichen inventory of Dagny Johnson Key Largo Hammock Botanical State Park in Key Largo, Florida. The site was divided into four ecologically different zones which included two coastal hardwood hammocks of different maturities, a disturbed exposed site once probably dominated by pines long extirpated and a fully exposed dwarf mangrove zone interspersed with other non-mangrove species. The mature coastal hammock yielded 172 species dominated by the family Graphidaceae, especially the subfamily Fissurinoideae and the tribe Thelotremateae. The most exposed mangrove site produced only 73 species dominated by the families Arthoniaceae, Physciaceae and Lecanoraceae. The park is also compared to two nearby South Florida preserves, Everglades National Park and Fakahatchee Strand Preserve State Park both of which have had recent lichen inventories. A surprisingly high number of species were found to be unique to each preserve suggesting at least some lichens have difficulty in dispersing themselves sexually or asexually over even moderate distances. Foray participants recovered 323 species including 315 lichenized and 8 lichenicolous fungi. Eighteen lichen species and one lichenicolous fungi are described as new to science: Acanthothecis floridensis F. Seavey and J. Seave sp. nov. Arthonia pseudostromatica F. Seavey and J. Seavey sp. nov., Coenogonium maritimum F. Seavey and J. Seavey sp. nov., Cryptothecia calusarum F. Seavey and J. Seavey sp. nov., Cryptothecia randallii F. Seavey and J. Seavey sp. nov., Cryptothecia submacrocephala F. Seavey and J. Seavey sp. nov., Enterographa johnsoniae F. Seavey and J. Seavey sp. nov., Enterographa keylargoensis F. Seavey and J. Seavey sp. nov., Fissurina albolabiata F. Seavey and J. Seavey sp. nov., Fissurina incisura F. Seavey and J. Seavey sp. nov., Graphis ferrugineodisca F. Seavey and J. Seavey sp. nov., Graphis koltermaniae F. Seavey and J. Seavey sp. nov., Leiorreuma erodens F. Seavey and J. Seavey sp. nov., Phaeographis pseudostromatica F. Seavey and J. Seavey sp. nov., Phaeographis radiata F. Seavey and J. Seavey sp. nov., Platygramme elegantula F. Seavey and J. Seavey sp. nov., Ramalina ramificans F. Seavey and J. Seavey sp. nov., Stirtonia divaricatica F. Seavey and J. Seavey sp. nov. The lichenicolous fungus Enterographa bagliettoae F. Seavey and J. Seavey sp. nov. is also described as new to science. Furthermore, the following 25 lichens are new to the North American lichen checklist: Arthonia microsperma Nyl., Arthonia hypochniza Nyl., Bacidiopsora orizabana (Vain.) Kalb, Baculifera micromera (Vain.) Marbach, Chapsa boninensis (Tat. Matsumoto) Rivas Plata and Mangold, Chapsa paralbida (Riddle) Rivas Plata and Lücking, Chapsa phlyctidioides (Müll. Arg.) Mangold, Coenogonium pyrophthalmum (Mont.) Lücking, Aptroot and Sipman, Graphis bungartzii Barcenas-Peña, Lücking, Herrera-Campos and R. Miranda, Graphis elongata Zenker, Graphis perstriatula Nyl., Graphis pseudoserpens Chaves, Lücking and Umaña, Leucodecton compunctum (Ach.) A. Massal., Leucodecton fissurinum (Hale) A. Frisch, Malmidea cineracea Bruess and Lücking, Mazosia viridescens (Fèe) Aptroot and M. Cáceres, Monoblastia palmicola Riddle, Mycomicrothelia apposita (Nyl.) D. Hawksw., Pertusaia rigida Müll. Arg., Pertusaria subrigida Müll. Arg., Phaeographis dividens (Nyl.) Kr. P. Singh and Swarnalatha, Phaeographis quadrifera (Nyl.) Staiger, Phyllopsora glaucescens (Nyl.) Gotth. Schneider, Stigmatochroma gerontoides (Stirton) Marbach, Stirtonia alba Makhija and Patw., as well as the lichenicolous fungus Arthonia tavaresii Grube and Hafellner. The following keys are provided: updated key to Florida Graphis; North American key to Phaeographis; corrected Neotropical key to Stirtonia, and a world key to Platygramme. In the updated Graphis key Graphis chlorotica A. Massal. is replaced by G. subtenella Müll. Arg. based upon a review of G. chlorotica type material in a recently published manuscript. Therefore, we recommend replacing G. chlorotica with G. subtenella on the North American lichen checklist.

Evaluating nest supplementation as a recovery strategy for the endangered rodents of the Florida Keys

The Key Largo woodrat (Neotoma floridana smalli) and Key Largo cotton mouse (Peromyscus gossypinus allapaticola) are federally endangered subspecies endemic to the tropical hardwood hammocks of Key Largo, Florida. Woodrats are considered generalists in habitat and diet, yet a steady decline in natural stick nests and capture rates over the past several decades suggests that they are limited by the availability of nesting habitat due to habitat loss and fragmentation. The more specialized Key Largo cotton mouse appears to rely on old growth hammock, a habitat type that is rare following past land clearing. In 2004, the U.S. Fish and Wildlife Service started building supplemental nest structures to restore habitat quality and connectivity for these endangered rodents, but nest use requires evaluation. We used camera traps and occupancy models to evaluate the factors influencing woodrat and cotton mouse use of the supplemental nests. We detected woodrats at 65 and cotton mice at 175 of 284 sampled nest structures, with co‐occurrence at 38 nests. Woodrat nest use followed a gradient from low nest use in the north to high nest use in the south, which might relate to the proximity of free‐ranging domestic cat (Felis catus) colonies in residential developments. Cotton mouse nest use, however, was related positively to mature hammock and related negatively to disturbed areas (e.g. scarified lands). The two species occurred independently of each other. Stick‐stacking behavior was observed at supplemental nests and, although it was correlated with detection of woodrats, it was not a strong predictor of their occurrence. We suggest that nest supplementation can be an important tool for species recovery as habitat quality continues to improve with succession.

Conserving rare plants in locally-protected urban forest fragments: A case study from Miami-Dade County, Florida

We consider Miami-Dade County’s Environmentally Endangered Lands (EEL) network of preserves as a means to conserve rare plant species in urban and suburban forest fragments. In this rapidly urbanizing landscape, upland forests are at particularly high risk of development. We examined the number of rare plant species present in preserves based on the site area, ecosystem type and management practices using the EEL database maintained by the county and a database of plant species inventories collected by the Institute for Regional Conservation. About 99% of the area of the EEL system is located in southern Miami-Dade. Pine rockland forests are primarily in the outer suburbs of the county where fire can be used most effectively for management. Hardwood hammock forests are distributed throughout the county including within the urban core. All 56 EEL forested sites under study contained at least one rare plant species. Small sites often contained high numbers of rare species per unit area, but presumably at lower population sizes. The type of upland forest was not related to the mean richness of rare or state-listed plant species. Public access was not related to the mean richness of rare plants, but was negatively associated with the richness of state-listed plant species.

Inferring implications of climate change in south Florida hardwood hammocks through analysis of metacommunity structure

AbstractAimIn order to explore how variation in regional biogeography would affect forest responses to climate change, we analysed metacommunity structure of trees in natural forest fragments across a boundary between tropical and sub‐tropical temperature regimes. We wished to determine whether species assemblages were constrained by periodic cold temperatures, dispersal limitation and/or local processes associated with fragment size, and consider how these influences might affect future species migration and community reassembly.LocationSoutheastern Florida, USA.MethodsWe collected complete tree species lists for 144 forest fragments, from our own surveys supplemented by publicly available sources. The resulting species‐by‐site data matrix was re‐ordered based on an ordination that identified the latent environmental axis most responsible for variation in composition, and metacommunity structure was analysed for coherence, turnover and range boundary clumping. Matrix structure was tested for associations with site variables, and with community‐aggregated functional traits related to cold tolerance, dispersal limitation and fragment size.ResultsForest patch size was the strongest single correlate with composition and species richness, but mean January temperature and a neighbourhood index denoting degree of isolation from other patches contributed significantly to regression models. The species‐by‐site matrix was highly nested, with trees common to small upland fragments in the Everglades interior representing a distinct subset of the richer assemblages found in sites closer to the coast. Interior forests were smaller, more isolated, and subject to cooler minimum temperatures than more coastal forests, and were comprised primarily of early‐successional, animal dispersed species.Main conclusionsWhile warming winter temperatures may relax some constraints on the northward migration of tropical species through the region, sea level rise will raise ground water levels, decreasing the size and number of suitable mesic patches, and increasing their isolation. The result will be a loss in tree species diversity, especially among late‐successional, edge‐sensitive species.

Box Turtles (Terrapene carolina bauri) on Ancient, Anthropogenic Shell Work Islands in the Ten Thousand Islands Mangrove Estuary, Florida, USA

Abstract We investigated the ecology, distribution, and density of Florida Box Turtle (Terrapene carolina bauri Taylor, 1895) populations in the Ten Thousand Islands (TTI), an estuarine mangrove ecosystem in southwestern Florida. The distribution and ecology of Box Turtles in this region and this habitat type have not been previously investigated. The study area encompassed 18 islands and included five natural islands, 13 man-made shell islands, and adjacent mangrove environments. Two hundred and twenty-nine live Box Turtles and 95 Box Turtle shells were detected a total of 409 times on seven of the 18 islands. The seven islands where Box Turtles were detected ranged in size from 7.3 to 31.0 ha and were ancient shell work sites, apparently constructed by the Calusa or other Prehistoric Indians approximately 1,900 to 900 years before present (ybp). Box Turtles were not detected on natural islands. We detected Box Turtles primarily in subtropical hardwood hammock forests, but we detected 10% of turtles in m...