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Fire-adaptive traits in plants of tropical and subtropical grassy ecosystems have been the subject of considerable global research, but only recently studied in pyrogenic Florida subtropical grasslands. Plant growth forms, belowground organs, and post-fire recovery strategies were studied for 198 grassland specialists in peninsular Florida. Community types (dry-mesic, mesic, wet-mesic, and wet) were sampled with 1m2 plots along the edaphic-hydrologic gradient and the association between these variables and fire-related plant traits was tested using fourth-corner analysis. Caulescent herbs (43), cespitose graminoids (27), and rosette herbs (31) are the most common growth forms among species sampled. Plants with epigeogenous and hypogeogenous rhizomes dominate the sample plots, including matrix graminoids, shrub geoxyles, and an acaulescent rhizomatous fire-resilient palm (Serenoa repens). Most species (163; 82%) exhibit resprouting, including 30 facultative resprouters and 133 obligate resprouters. All woody rhizomatous species are obligate resprouters, and 35 ephemeral herbaceous species are obligate reseeders. Community type was a better predictor of species abundances than hydrology, however, hydrology was significantly associated with species traits measured, particularly rhizome texture, with woody rhizomes prevalent in all but the wet sites. Belowground organs (xylopodia, geoxylic suffructices) and growth form were associated with frequent fire and phylogeny, suggesting fire regime as a driver of community phylogenetic diversity. Persistence, rapid resilience and co-occurrence of geoxyles align Florida subtropical grasslands with other global geoxyle grasslands. The old-growth, pyrogenic grassy ecosystems of peninsular Florida are the center of geoxyle diversification on the southeastern US coastal plain. [ABSTRACT FROM AUTHOR]

Examination of the lectotype and isotype material of Physalis macrophysa Rydb. show its compatibility with P. longifolia, having nearly glabrous, ovate-lanceolate to broadly lanceolate leaves, and the presence of short, simple antrorse hairs on the petioles and pedicels. Other than its large inflated fruiting calyces (3.0-4.0 cm × 2.5-3.0 cm), it has little in common morphologically with another large inflated calyced Physalis macrosperma which is endemic to deep sands from a portion of the West Gulf Coastal Plain of the United States. Instead, P. longifolia has stems and pedicles that are either nearly glabrous or with antrorse, appressed, non-glandular hair and ovate-lanceolate leaves versus short glandular and non-glandular, spreading, upright hair and cordate to truncate leaves in the aforementioned Physalis macrosperma. We agree with previous authors that P. macrophysa Rydb., if meriting taxonomic status, should be treated as P. longifolia var. subglabrata (Mack. & Bush) Cronquist forma macrophysa (Rydb.) Steyermark or, alternatively, it may simply represent variation within P. longifolia not deserving of any taxonomic status. [ABSTRACT FROM AUTHOR]

A new species of Physalinae (Solanaceae) is described and illustrated that is endemic to the West Gulf Coastal Plain of the southeastern United States, a global biodiversity hotspot. Physalis macrosperma sp. nov. is distinguished by its large obpyramidal fruiting calyx (35-70 mm in length), its large seeds [3.2-4.2(4.8) mm in length and 2.5-3.5(3.9) mm in width], and its coarsely pitted seed testa. The ecological and geographical setting of P. macrosperma and its morphological relationships with similar taxa are presented. Physalis macrosperma is an herbaceous perennial psammophyte inhabiting open sand barrens within pyrogenic savanna-woodlands of xeric sandhills. It occurs on droughty undulating Eocene-age quartzipsamments within south-central and east-central Texas and on younger xeric sands embedded within the fire-maintained pinelands of southwestern Arkansas, western Louisiana, and southeastern Texas. [ABSTRACT FROM AUTHOR]

Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature). We used nonparametric cluster analyses of a 17-year (1993–2009) data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture) to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires) over a 13-year period with fire records (1997–2009). Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with timing of natural lightning ignitions should be useful as a basis for ecological fire management of humid savanna-grassland landscapes worldwide. [ABSTRACT FROM AUTHOR]

As part of ongoing work on the Flora of the Southeastern United States (Weakley & Southeastern Flora Team 2023) and related projects, as well as for general floristic, conservation, and scientific work in eastern North America, it is essential to document taxonomic and nomenclatural changes and significant distribution records. Here, we propose six new species of graminoids (two Rhynchospora, three Dichanthelium, and one Anatherum)--five from fire-maintained pine savannas and embedded wetlands of the southeastern Coastal Plain and one from the floristically and ecologically related fire-maintained pine savannas of North Andros Island in The Bahamas. We provide rationale and documentation for the "taxonomic resurrection" of Vaccinium ashei, an economically important member of Vaccinium sect. Cyanococcus, based on morphology, estimation of ploidy level with flow cytometry, and phylogenomic analysis based on high-throughput DNA sequencing. We make four new combinations in Convolvulus to accommodate the inclusion of Calystegia in Convolvulus to resolve paraphyly. We also make six new combinations necessary to recognize sect. Leptopogon of Andropogon at generic rank, as Anatherum, based on the phylogenetic work of other researchers and the previously incomplete transfer of recognized species to Anatherum, providing the needed names to recognize this group of species in genus Anatherum in North American floristic treatments. We document the surprising discovery of Carex lutea, previously believed to be endemic to two counties in eastern North Carolina, in two counties in the panhandle of Florida, and a county in eastern South Carolina--discoveries aided by iNaturalist and Facebook. We document new states as being within the distribution ranges of additional species: Quercus similis (Florida), Juncus brachycephalus (Arkansas and Missouri), Rhexia mariana var. mariana (Ohio), Asarum acuminatum and Elionurus tripsacoides (Alabama), and Mecardonia procumbens (Georgia). Other important distributional records, many representing rediscoveries of conservationally significant, extant populations of plants previously considered of only historical occurrence in a state, are also reported: Alabama (Arnica acaulis, Asclepias connivens, Berberis canadensis, Bulbostylis warei, Ctenodon viscidulus, Parnassia grandifolia, and Pinguicula pumila) and Georgia and Florida (Lobelia boykinii). [ABSTRACT FROM AUTHOR]

As part of ongoing work on the Flora of the Southeastern United States (Weakley & Southeastern Flora Team 2022a) and related projects, as well as for general floristic, conservation, and scientific work in eastern North America, it is essential to document taxonomic and nomenclatural changes and significant distribution records. Here we describe three new species (in Rhynchospora, Sabulina, and Solidago), describe a new section (in Trichostema), make new combinations to treat taxa at appropriate ranks in appropriate genera and with appropriate nomenclatural application based on types (in Lycopodioides, Moeroris, Morella, Nellica, Tamala, and Trichostema), and propose the lumping of two species, resulting in a change in name and nativity status (in Sisyrinchium). These new combinations (rank changes, or generic transfers to apply newly accepted generic concepts to taxa that do not have corresponding available names at the appropriate rank) are needed to accurately reflect current taxonomic understanding of the regional flora. In the course of doing so, we discuss and address various nomenclatural issues, including typifications, and clarify characters and identification of difficult groups (providing new keys) in the regional flora. We also report significant new distribution and naturalization records in many genera, in New Jersey (taxa in the genera Anthriscus, Calibrachoa, Chaenomeles, Dichanthelium, Diplotaxis, Ditrichia, Dysphania, Erigeron, Eucommia, Eupatorium, Lepidium, Malus, Montia, Nepeta, Persicaria, Picea, Psammophiliella, Pulmonaria, Quercus, Silphium, Verbascum, Verbena, Vicia), in the Coastal Plain of Alabama and Mississippi (taxa in the genera Baptisia, Clematis, Coreopsis, Galium, Matelea, Mirabilis, Poterium, Rhynchospora, Silphium, and Symphyotrichum), in southern Indiana (taxa in the genera Andropogon, Brunnichia, Echinacea, Landoltia, Montia, Persicaria, and Solidago), and in North Carolina, Virginia, and likely other states (Euphorbia). [ABSTRACT FROM AUTHOR]

Seasonality drives ecological processes through networks of forcings, and the resultant complexity requires creative approaches for modeling to be successful. Recently ecologists and climatologists have developed sophisticated methods for fully describing seasons. However, to date the relationships among the variables produced by these methods have not been analyzed as networks, but rather with simple univariate statistics. In this manuscript we used structural equation modeling (SEM) to analyze a proposed causal network describing seasonality of rainfall for a site in south-central Florida. We also described how this network was influenced by the El Niño-Southern Oscillation (ENSO), and how the network in turn affected the site’s wildfire regime. Our models indicated that wet and dry seasons starting later in the year (or ending earlier) were shorter and had less rainfall. El Niño conditions increased dry season rainfall, and via this effect decreased the consistency of that season’s drying trend. El Niño conditions also negatively influenced how consistent the moistening trend was during the wet season, but in this case the effect was direct and did not route through rainfall. In modeling wildfires, our models showed that area burned was indirectly influenced by ENSO via its effect on dry season rainfall. Area burned was also indirectly reduced when the wet season had consistent rainfall, as such wet seasons allowed fewer wildfires in subsequent fire seasons. Overall area burned at the study site was estimated with high accuracy (R2 score = 0.63). In summary, we found that by using SEMs, we were able to clearly describe causal patterns involving seasonal climate, ENSO and wildfire. We propose that similar approaches could be effectively applied to other sites where seasonality exerts strong and complex forcings on ecological processes. [ABSTRACT FROM AUTHOR]

As part of ongoing efforts to understand, document, and conserve the flora of southeastern North America, we propose a number of taxonomic changes, nomenclatural changes, interpretations of nativity, and distributional accounts. Regarding the Asaroideae (Aristolochiaceae), we support continued recognition of Hexastylis (and other segregates of a very broad Asarum s.l.) at generic rank and make the necessary combinations to continue the use of Hexastylis in southeastern North America floras. In Conoclinium (Asteraceae), we present morphological and distributional evidence corroborating the recent suggestion (based on molecular evidence) that Chapman's 1878 C. dichotomum is distinct, warrants recognition, and is present as a second Conoclinium in the southeastern North American flora. An analysis of historical accounts of Gaillardia pulchella (Asteraceae) strongly suggests that its modern occurrence east of Texas is adventive, rather than native. Two rare southeastern United States skullcaps, Scutellaria mellichampii and S. ocmulgee (Lamiaceae), have been persistently confused with one another and other species; we present a reassessment of the taxonomic distinction between them, best ways to distinguish them and similar species, and their known distributions. A reassessment of the taxonomy, distribution, and ecology of Linum carteri (Linaceae), a rare southern Florida endemic, confirms that two species should be recognized by modern species concepts; we make the necessary new combination to effect the recognition of two narrowly endemic species. In Andropogon (Poaceae), we propose that A. virginicus var. decipiens warrants recognition as distinct at species rank from other entities in the Andropogon virginicus complex. We also present more comprehensive information on the distributions of four species of "bushy bluestems" (Andropogon glomeratus s.l.), their ecology, and their practical recognition. In the Violaceae, modern reassessment of the taxonomy of many species (especially in the genus Viola) by H.E. Ballard, Jr. and collaborators have been vexed by uncertain application of many "old" names; we here provide a first installment of typifications and nomenclatural interpretations needed to move forward with a modern treatment of the genus in our region. In Xyris (Xyridaceae), we re-establish the generally ignored X. elliottii var. stenotera based on careful and extensive study of its morphology and ecology in comparison to X. elliottii var. elliottii, including a transplant study. English naturalist Mark Catesby (1683-1749) has been honored by having a genus and fifteen species of plants named for him, but most of these honorific names have been cons tructed in manners contrary to the Shenzhen Code; as these are "errors to be corrected," we therefore propose to correct and standardize these honorifics by restoring his name "catesby-" as the root of the names. Similarly, in seven names (variably formed) employed by W.W Ashe to honor his cousin and (later) wife Margaret Haywood Henry (Wilcox) (Ashe), we also standardize and correct the root of the names to be accurately based on her name, "margaret-," in conformance with the Shenzhen Code. [ABSTRACT FROM AUTHOR]

In the USA, the United States Department of Agriculture (USDA) Natural Resource Conservation Service (NRCS) has restored millions of acres of wetlands through its Wetland Reserve Easement (WRE) programs. However, few quantitative studies have explored whether WREs have enhanced wetland hydrology and wetland plant communities. Additionally, USDA Compatible Use Permits for cattle grazing and other management practices are sometimes issued for WREs, but little is known about potential benefits/detriments of such practice on the success of wetland restoration. In this study, we tested if hydrological restoration of previously drained species poor pastures increased water depth and hydroperiod. Restoration involved plugging key ditches, adding water control structures and a berm. We also tested if hydrological restoration increased plant diversity (alpha and beta), floristic quality (using coefficient of conservatism) and increased the cover of wetland species (using species wetland status). Finally, we tested if cattle grazing had an effect on the success of restoration by comparing grazed plots to fenced plots. We studied two conservation easements (a total of 748 acres) located on semi-native pastures in central Florida, USA. We monitored vegetation using permanent transects stratified by vegetation type before (2004–2005) and after (2012) the restoration (2008). We assessed wetland hydroperiod using groundwater wells set up in 2003 and located within and outside the boundaries of these two easements. We used linear mixed models and multivariate analyses to compare vegetation and hydroperiods pre- and post-restoration. Number of flooded days increased following restoration in one of the easements, but we did not detect significant changes in hydrology in the other easement. Floristic quality, beta diversity and cover of obligate wetland species increased in both conservation easements and in most vegetation types. These vegetation changes were likely due to restoration activities since annual rainfall was not significantly different pre- and post-restoration. Cattle grazing did not have a negative or positive effect on the success of restoration, nor did we detect any positive effect of grazing on the success of restoration. Overall, our study shows that hydrological restoration can enhance wetland hydroperiod, water depth and wetland vegetation, but more resources should be allocated to short- and long-term monitoring of the restoration success. [ABSTRACT FROM AUTHOR]

As part of ongoing efforts to understand and document the flora of the southeastern United States, a number of taxonomic changes at generic, specific, and infraspecific rank are made. We also discuss and clarify the recommended taxonomy for other taxa (not requiring nomenclatural acts) and present a point of view about the practical and philosophic basis for making taxonomic changes in an allegedly well-understood flora. The genera (and families) affected are Endodeca (Aristolochiaceae), Erigeron, Pityopsis, and Solidago (Asteraceae), Tillandsia (Bromeliaceae), Carex (Cyperaceae), Baptisia and Indigofera (Fabaceae), Salvia and Scutellaria (Lamiaceae), Stenanthium (Melanthiaceae), Epidendrum (Orchidaceae), and Andropogon, Coleataenia, Dichanthelium, Digitaria, and Panicum (Poaceae). [ABSTRACT FROM AUTHOR]

As part of ongoing efforts to understand and document the flora of the southeastern United States, a number of taxonomic changes at generic, specific, and infraspecific rank are made. We also discuss and clarify the recommended taxonomy for other taxa (not requiring nomenclatural acts) and present a point of view about the practical and philosophic basis for making taxonomic changes in an allegedly well-understood flora. The genera (and families) affected are Allium (Alliaceae), Erigeron, Liatris, and Trilisa (Asteraceae), Calycanthus (Calycanthaceae), Gaylussacia (Ericaceae), Dalea and Mimosa (Fabaceae), Hydrophyllum (Hydrophyllaceae), Didymoglossum (Hymenophyllaceae), Monarda (Lamiaceae), Kosteletzkya and Sida (Malvaceae), Narthecium (Nartheciaceae), Agalinis, Melampyrum, and Orobanche/Aphyllon/Myzorrhiza (Orobanchaceae), Dichanthelium and Elymus (Poaceae), Clematis (Ranunculaceae), and Maianthemum (Ruscaceae). [ABSTRACT FROM AUTHOR]

Wildfires are often governed by rapid changes in seasonal rainfall. Therefore, measuring seasonal rainfall on a temporally finescale should facilitate the prediction of wildfire regimes. To explore this hypothesis, daily rainfall data over a 58-yr period (1950--2007) in south-central Florida were transformed into cumulative rainfall anomalies (CRAs). This transformation allowed precise estimation of onset dates and durations of the dry and wet seasons, as well as a number of other variables characterizing seasonal rainfall. These variables were compared with parameters that describe ENSO and a wildfire regime in the region (at the Avon Park Air Force Range). Onset dates and durations were found to be highly variable among years, with standard deviations ranging from 27 to 41 days. Rainfall during the two seasons was distinctive, with the dry season having half as much as the wet season despite being nearly 2 times as long. The precise quantification of seasonal rainfall led to strong statistical models describing linkages between climate and wildfires: a multiple-regression technique relating the area burned with the seasonal rainfall characteristics had an of 0.61, and a similar analysis examining the number of wildfires had an of 0.56. Moreover, the CRA approach was effective in outlining how seasonal rainfall was associated with ENSO, particularly during the strongest and most unusual events (e.g., El Niño of 1997/98). Overall, the results presented here show that using CRAs helped to define the linkages among seasonality, ENSO, and wildfires in south-central Florida, and they suggest that this approach can be used in other fire-prone ecosystems. [ABSTRACT FROM AUTHOR]

Theory predicts that wildfires will encounter spatial thresholds where different drivers may become the dominant influence on continued fire spread. Studying these thresholds, however, is limited by a lack of sufficiently detailed data sets. To address this problem, we searched for scale thresholds in data describing wildfire size at the Avon Park Air Force Range, south-central Florida. We used power-law statistics to describe the “heavy-tail” of the fire size distribution, and quantile regression to determine how the edges of data distributions of fire size were related to climate. Power-law statistics revealed a heavy-tail, a pattern consistent with scale threshold theory, which predicts that large fires will be rare because only fires that cross all thresholds will become large. Results from quantile regression suggested that different climate conditions served as critical thresholds, influencing wildfire size at different spatial scales. Modeling at higher quantiles (≥75th) implicated drought as driving the spread of larger fires, whereas modeling at lower quantiles (≤25th) implicated that wind governed the spread of smaller fires. Fires of intermediate size were negatively associated with relative humidity. Our results are consistent with the idea that fire spread involves scale thresholds, with the small-scale drivers allowing fires to spread after ignition, but with further spread only being possible when large-scale drivers are favorable. These results suggest that other data sets that have heavy-tailed distributions may contain patterns generated by scale thresholds, and that these patterns may be revealed using quantile regression. [ABSTRACT FROM AUTHOR]