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USGS1917

The physical conditions indicated by the flora of the Calvert formation

The object of the present paper is to give a summary of the small flora preserved in the Miocene diatomaceous beds of the Calvert formation in the District of Columbia and Virginia, and more especially to discuss its bearing on the physical conditions of the Calvert epoch. Subsequent to the middle Eocene the next abundant marine fauna preserved along the middle Atlantic coast is that of the Calvert formation of the Chesapeake group. Although Miocene faunas so low in the stratigraphic column are known south of Virginia only in the vicinity of Porters Landing, Savannah River, closely related but younger Miocene faunas extend southward at least as far as Florida, where the containing formation rests unconformably on beds in which occur the warmer-water faunas of the Apalachicola group.

District of Columbia, Virginia↗

USGS1974

Seasonal variation of the upper digestive tract yeast flora of feral pigeons

Feral pigeons were sampled over a 16-month period to determine whether their normal yeast flora varied according to season. Candida albicans and Saccharomyces telluris occurred during the entire sampling period, with C. albicans reaching its highest levels between August and January and S. telluris peaking from March through May. Candida krusei was present for 10 months but exhibited no predictable variation in density. Candida tropicalis , C. guilliermondii and Geotrichum were isolated on several occasions while C. lusitaniae , C. pseudotropicalis and Torulopsis glabrata were each isolated once. The high levels of infection and frequency of occurrence of some yeast species make the feral pigeon highly suspect as a carrier and disseminator of potentially pathogenic yeast.

Journal of Wildlife Diseases↗

USGS1972

Normal yeast flora of the upper digestive tract of some wild columbids

Seven species of pigeons and doves were cultured for yeasts in the upper digestive tract. The following list gives the isolation rate for each columbid species and the yeasts cultured from them: feral pigeon Colwnha livia (Gmelin) 95% — Candida albicans (Robin) Berkhout, C. tropicalis (Castellani) Berkhout, C. krusei (Cast.) Berkhout, C. guilliermondii (Cast.) Langeron et Guerra, Torulopsis glabrata (Anderson) Lodder et De Vries, Saccharomyces telluris Van der Walt, and Geotrichum sp.; white-crowned pigeon ( C. leucocephala Linnaeus) 56% — S. telluris ; mourning dove ( Zenaidura macroura Linnaeus) 24% — C. albicans , C. tropicalis , C. guilliermondii , and Geotrichum sp.; passerine ground dove ( Collumbigallina passerina Linnaeus) 20% — C. parapsilosis (Ashford) Langeron et Talice, Kloeckera apiculata (Reess Emend. Klocker) Janke; zenaida dove ( Zenaida auritu Temminck) 16% — C. albicans , C. guilliermondii , and T. glabrata ; one moustasche dove ( Geotrygon mystacea Gosse) — C. guilliermondii ; ringed turtle dove ( Streptopelia rizoria Linnaeus) 14% — C. albicans and Geotrichum sp. No signs of disease could be seen in the 139 birds that were examined, and it was concluded that these yeasts comprise a part of the columbid's normal microbial flora.

Journal of Wildlife Diseases↗

USGS2014

Preliminary analysis of the role of lake basin morphology on the modern diatom flora in the Ruby Mountains and East Humboldt Range, Nevada, USA

As paleolimnologists, we often look at the world through a 5-cm-diameter hole in the bottom of a lake, and although a number of studies have shown that a single core in the deepest part of a lake does not necessarily reflect the entire diatom flora, time and money often limit our ability to collect more than one core from a given site. This preliminary study is part of a multidisciplinary research project to understand Holocene climate variability in alpine regions of the Great Basin, and ultimately, to compare these high elevation records to the better studied pluvial records from adjacent valleys, in this case, the Ruby Valley.

Nevada↗

USGS2013

Vascular flora of saline lakes in the southern high plains of Texas and eastern New Mexico

Saline lakes and freshwater playas form the principal surface hydrological feature of the High Plains of the Southern Great Plains. Saline lakes number less than 50 and historically functioned as discharge wetlands with relatively consistent water availability due to the presence of one or more springs. Currently, less than ten saline lakes contain functional springs. A survey of vascular plants at six saline lakes in the Southern High Plains of northwest Texas and one in eastern New Mexico during May and September 2009 resulted in a checklist of 49 species representing 16 families and 40 genera. The four families with the most species were Asteraceae (12), Amaranthaceae (8), Cyperaceae (5), and Poaceae (12). Non-native species (Bromus catharticus, Poa compressa, Polypogon monspeliensis, Sonchus oleraceus, Kochia scoparia, and Tamarix ramosissima) accounted for 10% of the total species recorded. Whereas nearly 350 species of vascular plants have been identified in playas in the Southern High Plains, saline lakes contain a fraction of this species richness. The Southern High Plains saline lake flora is regionally unique, containing taxa not found in playas, with species composition that is more similar to temperate desert wetlands of the Intermountain Region and Gulf Coastal Plain of North America.

New Mexico, Texas↗

USGS2022

Diverse native island flora shows rapid initial passive recovery after exotic herbivore removal on Santa Rosa Island, California

Removing exotic vertebrates from islands is an increasingly common and potentially effective strategy for protecting biodiversity. Yet, surprisingly few studies evaluate large-scale effects of island removals on native plants. We surveyed 431 hectares of habitat in 7 canyons on Santa Rosa Island just after exotic herbivore control began (1994–1996), and again after two herbivore species had been eradicated and ~ 90% of herbivores removed (2010–2012). We searched for 68 endemic and/or rare native plant taxa, mapping and recording abundances for the 39 found. Initially most of these 39 species were absent from most canyons (79.9% species-canyon combinations). Nearly 35% of absences changed to presences by 2010–2012, while only 5.5% of presences changed to absences. Thirty-six of these 39 species increased in total area, and 38 increased in total abundance. Graminoids increased more and shrubs less than other life histories, for both apparent colonizations and abundances. Beta diversity and species turnover between canyons was high at both surveys. Although a diversity of the 39 located taxa showed substantial gains, nearly half remained uncommon in 2010–2012. These results reinforce the devastating effects of exotic vertebrate herbivores on island native plants, particularly long-lived, slow-growing species. They also demonstrate significant potential benefits of exotic herbivore removal even without other active restoration, not only for vegetative cover but for a number of rare taxa. Our surveys were more spatially extensive than most post-removal studies; high spatial turnover in these data suggests that larger-scale monitoring may be critical to capture full effects of exotic animal removal.

California↗

USGS1971

Tertiary climatic fluctuations and methods of analysis of tertiary floras

On theoretical grounds, an analysis of the physiognomy of a Tertiary leaf assemblage is more direct and reliable than a circuitous floristic analysis in assigning thermal regimes to fossil assemblages. Using primarily foliar physiognomy and secondarily floristic composition, it can be shown that: ( 1 ) some middle latitude Tertiary assemblages probably lived under meteoroligically tropical climates; ( 2 ) a major and rapid climatic deterioration occurred in the Oligocene; and ( 3 ) a major climatic fluctuation probably occurred in the Late Eocene. These analyses thus substantiate the conclusions of several other paleobotanists regarding climatic fluctuations. Recent criticisms of these analyses are shown to be invalid and to be based largely on misinterpretations.

Palaeogeography, Palaeoclimatology, Palaeoecology↗

USGS2002

Lead distribution throughout soil, flora, and an invertebrate at a wetland skeet range

Lead pellets from a skeet range impart Pb to the local soil, plants, and animals. Concentrations and distributions of Pb in the various media were studied at the now-abandoned skeet range bordering a cordgrass marsh at the Naval Weapons Station Seal Beach in Southern California. The concentrations of Pb in soil (maximum = 16,200 ppm, dry mass) are significantly correlated to the shot pellet densities. Lead concentrations in plants vary according to species' abilities to inhibit Pb uptake from soil. Horn snails had a mean Pb concentration (1987 ppm, dry mass) over 100 times greater than the leaves of the plant species with the highest mean concentration (18.1 ppm, dry mass) at the same site. Avian predators of gastropods may receive minimum exposure to Pb due to calcium in the shells, but incidental ingestion of soil in addition to direct ingestion of shot pellets may provide significant exposure to birds. Because shotgun pellets may persist in wetland soil for 300 yr, reduction of wildlife exposure to Pb in such cases requires deliberate action.

Journal of Toxicology and Environmental Health, Pa↗

USGS2005

Palynology in coal systems analysis-The key to floras, climate, and stratigraphy of coal-forming environments

Palynology can be effectively used in coal systems analysis to understand the nature of ancient coal-forming peat mires. Pollen and spores preserved in coal effectively reveal the floristic composition of mires, which differed substantially through geologic time, and contribute to determination of depositional environment and paleo- climate. Such applications are most effective when integrated with paleobotanical and coal-petrographic data. Examples of previous studies of Miocene, Carboniferous, and Paleogene coal beds illustrate the methods and results. Palynological age determinations and correlations of deposits are also important in coal systems analysis to establish stratigraphic setting. Application to studies of coalbed methane generation shows potential because certain kinds of pollen are associated with gas-prone lithotypes. ??2005 Geological Society of America.

Special Paper of the Geological Society of America↗

USGS2016

Mediterranean biomes: Evolution of their vegetation, floras and climate

Mediterranean-type ecosystems (MTEs) possess the highest levels of plant species richness in the world outside of the wet tropics. Sclerophyll vegetation similar to today’s mediterranean-type shrublands was already present on oligotrophic soils in the wet and humid climate of the Cretaceous, with fire-adapted Paleogene lineages in southwestern Australia and the Cape Region. The novel MTC seasonality present since the mid-Miocene has allowed colonization of MTEs from a regional species pool with associated diversification. Fire persistence has been a primary driving factor for speciation in four of the five regions. Understanding the regional patterns of plant species diversity among the MTEs involves complex interactions of geologic and climatic histories for each region as well as ecological factors that have promoted diversification in the Neogene and Quaternary. A critical element of species richness for many MTE lineages has been their ability to speciate and persist at fine spatial scales, with low rates of extinction.

Annual Review of Ecology, Evolution, and Systemati↗

USGS2011

Local richness along gradients in the Siskiyou herb flora: R. H. Whittaker revisited

In his classic study in the Siskiyou Mountains (Oregon, USA), one of the most botanically rich forested regions in North America, R. H. Whittaker (1960 ) foreshadowed many modern ideas on the multivariate control of local species richness along environmental gradients related to productivity. Using a structural equation model to analyze his data, which were never previously statistically analyzed, we demonstrate that Whittaker was remarkably accurate in concluding that local herb richness in these late‐seral forests is explained to a large extent by three major abiotic gradients (soils, topography, and elevation), and in turn, by the effects of these gradients on tree densities and the numbers of individual herbs. However, while Whittaker also clearly appreciated the significance of large‐scale evolutionary and biogeographic influences on community composition, he did not fully articulate the more recent concept that variation in the species richness of local communities could be explained in part by variation in the sizes of regional species pools. Our model of his data is among the first to use estimates of regional species pool size to explain variation in local community richness along productivity‐related gradients. We find that regional pool size, combined with a modest number of other interacting abiotic and biotic factors, explains most of the variation in local herb richness in the Siskiyou biodiversity hotspot.

Oregon↗

USGS1992

Associations between benthic flora and diel changes in dissolved arsenic, phosphorus, and related physico-chemical parameters

Diel relationships between physical and chemical parameters and biomass were examined along a 57-km reach of Whitewood Creek, South Dakota, between 29 August and 2 September 1988. A time lag of ∼3-6 h for fluctuations in soluble reactive phosphorus (SRP) concentrations (ranging from 0.1 to 0.5 μM at the downstream sites) relative to dissolved arsenic (ranging from 0.3 to 1.2 μM as arsenate (pentavalent arsenic)) was consistent with our laboratory studies (reported elsewhere) showing preferential cell sorption of orthophosphate over arsenate by creek periphyton. The potential biological effects on SRP diel fluctuations contrasts with abiotic sorption controls for dissolved arsenate (a chemically similar anion). Cycles for pH, like water temperature cycles, lagged irradiance cycles by 1-3 h. Like pH, the amplitude of dissolved arsenic diel cycles was greatest at the site with most abundant biomass. Diel fluctuations in specific conductance (an indicator of groundwater inputs at elevated conductivity relative to the water column) were out of phase with both SRP and dissolved arsenic concentrations suggesting that groundwater was not the direct source of these solutes.

Freshwater Science↗

USGS1981

Post-fire succession of the herbaceous flora in southern California chaparral

Postfire succesion of the temporary herbaceous and suffrutescent cover was studied after chaparral fires in San Diego County, California, USA. Four categories of species make up the temporary cover. (1) "Generalized herbaceous perennials" are present before and after fire. Populations of these herbs are sparse under the shrub canopy. They resprout after fire from bulbs or other underground parts and postfire populations are sparse. (2) "Generalized annuals" are present in openings before fire but produce their peak population size in the first few years after fire. (3) Specialized "fire—annuals" are more or less restricted to the 1st postfire yr. (4) Specialized "fire—perennials" (subshrubs) are uncommon before fire, establish from seed in the 1st postfire yr and reach maximum cover in the 3rd and 4th yr. Community—level changes in cover and diversity are interpreted in light of differences in population dynamics of the four groups. Specis richness was highest in the 1st yr after fire because this was the only time all four groups were present together. Throughout succession herbaceous species richness was positively related to herb cover, negatively related to elevation and unrelated to slope aspect. The number of annual species fluctuated greatly through succession at all sites, but the number of herbaceous perennials did not. Herb cover fluctuated markedly from year to year and was positively related to amount of annual precipitation and negatively related to subshrub or "fire—perennial" cover. Artificial seeding with annual rye grass Lolium multiflorum had not apparent effect on total herb cover since sites with poor Lolium establishment had as high or higher herb cover as sites with high Lolium establishment. Lolium success was at the expense of the native cover and this negative effect was greatest on the "fire annuals."

Ecology↗

USGS1997