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There is an increasing need for effective biomonitoring tools that quantify patterns of habitat occupancy by reptile species. Environmental DNA (eDNA) has been regarded as an emerging tool to detect specific target species; however, the dynamics of accumulation and degradation of eDNA in terrestrial environments are poorly understood. This study determines the time required for terrestrial snakes to leave enough eDNA behind to become detectable (accumulation time) as well as its persistence (degradation time). By targeting mitochondrial cytochrome oxidase subunit I and 12S rRNA genes of Red Cornsnakes (Pantherophis guttatus) in a controlled laboratory setting, we found that eDNA can be detected 3.5 h after the snakes had contact with soil and for up to 6 d after their removal. Estimated accumulation rate of Pantherophis guttatus eDNA per gram of snake biomass per hour was 12.6 μg. We also evaluated the applicability of eDNA detection under field conditions by targeting the mitochondrial cytochrome b gene of a cryptic invasive species in South Florida, Burmese Pythons (Python bivittatus). Soil samples were derived from two groups of field sites: telemetry-monitored refugia (i.e., radiotelemetry evidence of python presence) and telemetry-absent refugia (i.e., no telemetry evidence, but monitored with a burrow camera at time of sample collection). We were able to detect the presence of python eDNA in 66.7% of the telemetry-monitored sites that fit within our laboratory-defined residence and degradation time window. Additionally, at the telemetry-absent sites, no eDNA from Burmese Pythons was detected and burrow cameras did not detect their presence. We concluded that eDNA technology using soil can be an effective detection tool for terrestrial snakes, particularly when used with other traditional tracking and sampling methods.

This study examined a population of ghost orchids (Dendrophylax lindenii) in Fakahatchee Strand Preserve State Park in Collier County, Florida, to determine if they exhibit host species preference, vertical stratification, substrate diameter stratification, or a distribution pattern similar to their host plants. Twenty-five ghost orchids were found on three host plant species: 20 (80%) were on pop ash (Fraxinus caroliniana), four (16%) on arthritis vine (Hippocratea volubilis), and one (4%) on pond apple (Annona glabra). Our analysis indicated a statistically significant occurrence of ghost orchids on pop ash relative to other woody plant species in the study area. Although most orchids were found below 3 m from the forest floor, this was not statistically significant when compared to orchids above 3 m. A weak trend (p=0.06) for increasing occurrence was observed in the next to largest (14.1 cm to 17.2 cm diameter at breast height) size class among the five size classes of pop ash in this study. The spatial analyses indicated that both the stems of pop ash and ghost orchids demonstrate non-random clumping on the landscape. In addition, the presence of an individual orchid increases the probability of multiple ghost orchids on a stem. These results further emphasize the importance of pop ash as a host species in Florida’s ghost orchid populations and add to the list of hosts (arthritis vine) in the literature. Continuing to study the vertical position of ghost orchids will be important as climate change has the potential to alter humidity patterns and the occurrence of both low temperature events and hurricanes. Improved understanding of host plant preference, microhabitat requirements, spatial distribution, and continued long-term monitoring of population dynamics are critical for the conservation of the ghost orchid.

Herpetofaunal declines have been documented globally, and southern Florida, USA, is an especially vulnerable region because of high impacts from hydrological perturbations and nonindigenous species. To assess the extent of recent change in herpetofauna community composition, we established a baseline inventory during 1995-97 at a managed preserve in a habitat rich area of southwest Florida, and repeated our sampling methods fifteen years later (2010-11). Nine drift fence arrays were placed in four habitat types: mesic flatwood, mesic hammock, depression marsh, and wet prairie. Trapping occurred daily for one week during 7-8 sampling runs in each period (57 and 49 total sampling days, respectively). Species richness was maintained in mesic hammock habitats but varied in the others. Catch rates of several native species (Anaxyrus terrestris, Lithobates grylio, Anolis carolinensis, Nerodia fasciata) declined significantly. Other native species (Lithobates sphenocephalus, Siren lacertian, and Notophthalmus viridescens piaropicola) that were abundant in 1995-97 declined by greater than 50%. Catch rate of only two species (the nonindigenous Anolis sagrei and the native Diadophis punctatus) increased significantly. Hierarchical cluster analysis indicated similarity within habitat types but significant dissimilarity between sampling periods, confirming shifts in community composition. Analysis of individual species' contributions to overall similarity across habitats shows a shift from dominance of native species in the 1990s to increased importance of nonindigenous species in 2010-11. Although natural population fluctuations may have influenced differences between the two sampling periods, our results suggest considerable recent change in the structure and composition of this southwest Florida herpetofaunal community. The causes are unknown, but hydrological shifts and ecological impacts of nonindigenous species may have contributed.

A very detailed water budget analysis was conducted on Lake Trafford in South Florida. The inflow was dominated by surface water influx via five canals (61%), with groundwater influx constituting 12% and direct rainfall constituting 27%. Lake discharge was dominated by sheet flow (69%) and evapotranspiration (30.5%), with groundwater recharge of the hydraulically connected unconfined aquifer accounting for only 0.5%. The removal of 30 M tons (4.4 × 106 m3) of organic sediment impacted the groundwater influx, causing enhanced groundwater flow into the deeper parts of the lake and mixed flow along the banks, creating a rather unusual pattern. The large number of groundwater seepage meters used during this investigation led to a very reliable set of measurements with occasional failure of only a few meters. A distinctive relationship was found between the wet-season lake stage, heavy rainfall events, and pulses of exiting sheet flow from the lake. Estimation of the evapotranspiration loss using data collected from a weather station on the lake allowed the use of three different models, which, when averaged, produced results comparable to Lake Okeechobee (South Florida). A limitation of this investigation was the inability to directly measure sheet-flow discharges, which had to be estimated as a residual within the calculated water budget.

The effects of historical land use on tropical forest must be examined to understand present forest characteristics and to plan conservation strategies. We compared the effects of past land use, topography, soil type, and other environmental variables on tree species composition in a subtropical wet forest in the Luquillo Mountains, Puerto Rico. The study involved stems ≥10 cm diameter measured at 130 cm above the ground, within the 16-ha Luquillo Forest Dynamics Plot (LFDP), and represents the forest at the time Hurricane Hugo struck in 1989. Topography in the plot is rugged, and soils are variable. Historical documents and local residents described past land uses such as clear-felling and selective logging followed by farming, fruit and coffee production, and timber stand improvement in the forest area that now includes the LFDP. These uses ceased 40-60 yr before the study, but their impacts could be differentiated by percent canopy cover seen in aerial photographs from 1936. Using these photographs, we defined four historic cover classes within the LFDP. These ranged from cover class 1, the least tree-covered area in 1936, to cover class 4, with the least intensive historic land use (selective logging and timber stand improvement). In 1989, cover class 1 had the lowest stem density and proportion of large stems, whereas cover class 4 had the highest basal area, species richness, and number of rare and endemic species. Ordination of tree species composition (89 species, 13 167 stems) produced arrays that primarily corresponded to the four cover classes (i.e., historic land uses). The ordination arrays corresponded secondarily to soil characteristics and topography. Natural disturbances (hurricanes, landslides, and local treefalls) affected tree composition, but these effects did not correlate with the major patterns of species distributions on the plot. Thus, it appears that forest development and natural disturbance have not masked the effects of historical land use in this tropical forest, and that past land use was the major influence on the patterns of tree composition in the plot in 1989. The least disturbed stand harbors more rare and endemic species, and such stands should be protected.

The literature on the effects of catastrophic wind disturbance (windstorms, gales, cyclones, hurricanes, tornadoes) on forest vegetation is reviewed to examine factors controlling the severity of damage and the dynamics of recovery. Wind damage has been quantified in a variety of ways that lead to differing conclusions regarding severity of disturbance. Measuring damage as structural loss (percent stems damaged) and as compositional loss (percent stems dead) is suggested as a standard for quantifying severity. Catastrophic wind produces a range of gaps from the size caused by individual treefalls to much larger areas. The spatial pattern of damage is influenced by both biotic and abiotic factors. Biotic factors that influence severity of damage include stem size, species, stand conditions (canopy structure, density), and the presence of pathogens. Abiotic factors that influence severity of damage include the intensity of the wind, previous disturbance, topography, and soil characteristics. Recovery from catastrophic wind disturbance follows one of four paths: regrowth, recruitment, release, or repression. The path of recovery for a given site is controlled both by the severity of disturbance and by environmental gradients of resources. Recovery is influenced also by frequency of wind disturbance, which varies across geographical regions. To develop robust theories regarding catastrophic wind disturbance, the relative roles of different abiotic and biotic factors in controlling the patterns of severity of damage must be determined. These patterns of severity and environmental gradients must then be tied to long-term dynamics of recovery. /// La literatura sobre los efectos de disturbios catastróficos del viento (tormentas, ventarrones, ciclones, huracánes, tornados) sobre la vegetación de bosque es revisada para examinar los factores que controlan la severidad del daño y la dinámica de recuperación. El daño del viento puede ser cuantificado en varias formas, lo cual conlleva a diferir en las conclusiones en cuanto a la severidad del disturbio. Medir daños como la pérdida estructural (por ciento de tallos dañados) y la pérdida composicional (porcentaje de tallos muertos) son normas sugeridas para cuantificar la severidad. Los vientos catastróficos producen una extensión de aperturas de gran tamaño causados por árboles caídos sobre muchas otras áreas mayores. El patrón espacial de daño es influenciado por factores abióticos y bióticos. Factores bióticos que influyen severamente al daño pueden ser tamaño del tallo, especie, condición de tolerancia (estructura del dosel, densidad), y la presencia de patogénos. Factores abióticos que influyen severamente sobre el daño incluyen la intensidad del viento, disturbios anteriores, topografía, y las características del suelo. La recuperación de las catástrofes causados por el viento siguen uno de cuatro patrones: crecimiento, reclutaje, liberar o reprimir. La trayectoria de recuperación para un lugar es controlado por ambos: por lo severo del disturbio y por los gradientes ambientales del recurso. La recuperación es influenciada también por la frecuencia del disturbio por viento, el cual varia sobre el globo. Para desarrollar una fuerte teoría en cuanto a disturbios catastróficos por viento, los roles relativos de los factores abióticos y bióticos en el control de modelos de severidad de daño tienen que ser determinados. Estos modelos de severidad y gradientes ambientales tienen que ser enlazados para una dinámica de recobro a largo plazo. /// Обзор литературы о воздействии катастрофических ветров (штормов, циклонов, ураганов, смерчей) на лесную растительность с целью выявления факторов, влияющих на величину ущерба и на динамику рекомпенсации. Ущерб от ветра оценивается различными методами, приводящими к разным выбодам. Измерение ущерба как структурного воздействия (процент поврежденных стволов) и как композиционного воздействия (процент погибших стволов) предложено в качестве стандарта. Катастрофический ветер образует серию проплешин, размер которых колеблется в широком диапазоне. Пространственная конфигурация ущерба находится под воздействием как биотических, так и абиотических факторов. Биотические факторы величины ущерба включают: размер ствола, особенности особи, условия древостоя (структура и плотность листвы) и присутствие патогенов. Абиотические факторы величины ущерба включают интенсивность ветра, предшествующие атмосферные возмущения, топографию и характеристики почвы. Рекомпенсация после катастрофического ветрового воздействия следует по одному из четырех путей: спонтанное возобновление, спонтанное замещение дпугими древесными особями, подавление нижних ярусов древостоя (нуждающееся в их \"высвобождении\" от листвы верхнего яруса), нашествие сорняковой растительности. Какой из путей рекомпенсации возобладает, зависит от масштаба атмосферного возмущения и от целого ряда средовых градиентов. Рекомпенсация также зависит от глобально изменчивой частоты ветровых возмущений. Для создания продуктивных теорий измерения ветрового ущерба необходима оценка различных биотических и абиотических факторов, влияющих на величину и конфигурацию ущерба. Последняя, а также средовые градиенты должны быть увязаны с долгосрочной динамикой рекомпенсации.

1 The effect of a category 4 hurricane (Hurricane Hugo, 18 September 1989) on subtropical wet forest in Puerto Rico was examined at stand and species levels with respect to the frequency of tree damage, mortality, and resprouting. Data were collected from a 16-ha plot of secondary forest consisting of approximately 13 000 trees > 10 cm DBH representing 88 species. 2 Roughly one-quarter of the trees suffered some type of damage involving the main stem, and mortality due to the hurricane was 9%. Mortality among trees was primarily due to uprooting and broken stems. Many surviving trees sprouted new branches following the hurricane, indicating that this was an important component of stand recovery following hurricane damage. 3 Patterns of species-specific damage and recovery (investigated using 26 common species) appeared to form two distinct groups. One group (`pioneers'), represented by three species, suffered a high frequency of stem breakage and mortality during the hurricane and had a low capacity to sprout new branches after being damaged. The remaining species (`nonpioneers') lost many branches during the hurricane, thereby suffering low to moderate stem damage and mortality, and sprouted many new branches following the hurricane. Stem breakage and related species-specific characteristics were significantly correlated with wood density and shade tolerance. 4 Species exhibited few significant size-specific relationships (using DBH) with respect to hurricane damage, mortality, or resprouting, with the exception of branch damage, which often increased as a function of tree size. 5 The study revealed significant differences among tree species in the degree and type of damage suffered during a hurricane and in the ability to recover from damage and resume a position in the forest canopy. Nonpioneers dominate early in recovery because of the ability to survive a storm and sprout new branches following the storm, while the immediate impact of a hurricane on the abundance of pioneer species is strongly negative.

Lake Trafford, a 600-ha subtropical lake in southwestern Florida, has suffered from over 50 years of cultural eutrophication, resulting in the invasion of Hydrilla verticillata and organic sediment accumulation due to herbicide treatments. This study aimed to assess the effects of dredging on nutrient dynamics. A pre-dredging nutrient budget, developed using land use models and climatic data, estimated nutrient loads of 190 kg d−1 for total nitrogen (TN) and 18.6 kg d−1 for total phosphorus (TP), with total maximum daily loads (TMDLs) of 70.4 kg d−1 for TN and 4.15 kg d−1 for TP. Post-dredging analysis, using detailed spatiotemporal data, showed higher nutrient loads of 274.3 kg d−1 for TN and 24.2 kg d−1 for TP. While dredging reduced legacy nutrient accumulation, it led to increased nutrient influx from groundwater, caused by the exposure of organic sediment, as evidenced by increased lake water electrical conductivity. These findings demonstrate the importance of conducting thorough pre-dredging assessments to mitigate unintended consequences, offering practical insights for managing nutrient loads and improving restoration strategies in eutrophic lakes.

The control of invasive exotic plants is often deemed important for managing native wildlife, but surprisingly little research exists that evaluates benefits to wildlife, including species of conservation concern. Melaleuca quinquenervia (Melaleuca) is an invasive, non-native, broad-leaved tree that aggressively displaces native plant communities in south Florida. We used land-cover maps to document changes in plant communities and radio-telemetry data to compare habitat selection and mean home-range size of the endangered Puma concolor coryi (Florida Panther) within Big Cypress National Preserve (BCNP) during a Melaleuca removal project's removal phase (1991–1997) and the ensuing maintenance and habitat recovery phase (1998–2006). During the removal phase, Panthers incorporated areas infested by Melaleuca as components of their home range. Following >99.9% removal of Melaleuca, we documented pronounced increases in total cover of native upland forest (227%), wetland forest (211%), and prairie (54%) communities. During the habitat recovery phase, Panther habitat selection in the study area included significantly more upland forest within home-range core areas, and mean home-range size contracted by 16%. However, similar reductions in mean home-range size were not observed during the same time period for the regional population of radio-collared Panthers occupying contiguous conservation lands in south Florida. Although our findings are correlational and do not demonstrate cause and effect, the increase in native plant community cover, the increased use of native plant communities by Panthers, and the reduction in mean home-range size following the removal of Melaleuca are consistent with what would be expected if improvements in habitat quality reduced Panther home-range size requirements. Restoration of native plant communities and particularly native forest types, therefore, may have improved habitat quality for the Florida Panther and resulted in smaller home-range sizes and a potential increase in carrying capacity within BCNP.

Field experiments were conducted to investigate the effects of light, moisture, temperature, and litter on the regeneration of two early-, one mid-, and two late-successional tropical tree species. High light and litter seem to be universally good cues for regeneration, increasing seed/seedling survival for all species except for Cecropia (an early-successional species) whose small seeds may not be able to penetrate the litter layer. In addition, the high temperature environment in both artificially shaded and nonshaded areas of a natural gap exhibits less seed loss, an increase in the percent and rate of germination, and an increase in seedling survival for Dacryodes (a late-successional species), than the lower temperature environment under an intact canopy. Low soil water is also a good cue for Dacryodes germination as it is for Prestoea and Cecropia. Finally, the lower temperature environment found under the forest canopy (compared to the natural gap) leads to less seed loss and more germination for Guarea (a mid-successional species). Our results suggest that a good patch for regeneration of many species in this forest, early- as well as late-successional species, would have high light and a litter layer that moderates temperature and moisture extremes. The substantial variation in suitability among regeneration filters and species could: (1) contribute to low establishment success, i.e., most dispersed propagules do not become trees, (2) make it difficult to group species into germination strategies, and (3) make it hard to generalize about a net effect of any specific environmental variable on establishment. We suggest that tropical disturbances should be viewed in terms of their impact on a variety of environmental cues, which may signal germination and impact subsequent growth and survival