Volume VI: Contributions to the fossil flora of the Western Territories, Part I: The Cretaceous flora
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Monograph↗
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Volume VII: Contributions to the fossil flora of the Western Territories, Part II: The Tertiary flora
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Monograph↗
Volume VIII: Contributions to the fossil flora of the Western Territories, Part III: The Cretaceous and Tertiary flora
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Monograph↗
Nested taxa-area curves for eastern United States floras
The slopes of log-log species-area curves have been studied extensively and found to be influenced by the range of areas under study. Two such studies of eastern United States floras have yielded species-area curve slopes which differ by more than 100%: 0.251 and 0.113. The first slope may be too steep because the flora of the world was included, and both may be too steep because noncontiguous areas were used. These two hypotheses were tested using a set of nested floras centered in Ohio and continuing up to the flora of the world. The results suggest that this set of eastern United States floras produces a log-log species-area curve with a slope of approximately 0.20 with the flora of the world excluded, and regardless of whether or not the floras are from nested areas. Genera- and family-area curves are less steep than species-area curves and show similar patterns. Taxa ratio curves also increase with area, with the species/family ratio showing the steepest slope.
Ohio↗
The flora of the Catahoula Sandstone
During the progress of my studies of the fossil floras of the Gulf Coastal Plain, embracing all horizons from the Lower Cretaceous to the Pleistocene and prosecuted under the general direction of T. Wayland Vaughan, material representing the floras of all the major stratigraphic units in the area extending from western Florida to central Texas has been discovered. Field work and office studies of all these floras have proceeded more or less simultaneously, and a large amount of manuscript in various stages of completion has been accumulated. The floras of the Upper Cretaceous and Eocene of South Carolina and Georgia have been described and a report on the very large lower Eocene floras is now in press.
Professional Paper↗
Alaskan Cretaceous-Tertiary floras and Arctic origins
Cretaceous floras in Alaska, when compared to those at mid-latitudes, generally indicate later appearances in Alaska of major clades and major leaf morphologies. Compared to mid-latitude floras , Alaskan Late Cretaceous floras contain few major clades. The Alaskan clades diversified but at a low taxonomic level. Migrational pathways into high latitudes were probably along streams. Similar patterns characterized the Alaskan Tertiary , although some southward migrations of lineages occurred during the Neogene. Review of other Arctic paleontological data from Ellesmere Island, previously used to suggest that the Arctic was a major center of origin during the Late Cretaceous , indicates that the ages of supposedly substantiating dinoflagellate floras were misinterpreted. When the dinoflagellate data are interpreted according to standard methodology, first occurrences of genera and species groups on Ellesmere are, like the Alaskan occurrences, later than first occurrences at middle latitudes.
Paleobiology↗
A diatom voucher flora from selected southeast rivers (USA)
This flora is intended to serve as an image voucher for samples analyzed for the U.S. Geological Survey Southeast Stream Quality Assessment (SESQA). The SESQA study included measurement of watershed and water quality parameters to determine the factors that have the greatest potential to alter biotic condition. Algal samples were collected at 108 sites in 2014, from streams representing gradients in chemical and physical alteration across the southeast region. More than 375 taxa were identified during analysis for species composition and abundance. This manuscript documents the flora with light micrographs of specimens representative of their morphologic range. We define “voucher flora” as images of specimens and the names applied to those specimens for a given project. Taxonomic vouchers from federal programs have generally not been made public, yet they are a salient element of a well-documented species dataset, particularly for long-term studies. This study is part of a broader effort to improve and encourage taxonomic consistency in federal, state and local programs by accessible identification resources and inter-lab comparisons.
Phytotaxa↗
Climate change effects on an endemic-rich edaphic flora: resurveying Robert H. Whittaker's Siskiyou sites (Oregon, USA)
Species with relatively narrow niches, such as plants restricted (endemic) to particular soils, may be especially vulnerable to extinction under a changing climate due to the enhanced difficulty they face in migrating to suitable new sites. To test for community-level effects of climate change, and to compare such effects in a highly endemic-rich flora on unproductive serpentine soils vs. the flora of normal (diorite) soils, in 2007 we resampled as closely as possible 108 sites originally studied by ecologist Robert H. Whittaker from 1949 to 1951 in the Siskiyou Mountains of southern Oregon, USA. We found sharp declines in herb cover and richness on both serpentine and diorite soils. Declines were strongest in species of northern biogeographic affinity, species endemic to the region (in serpentine communities only), and species endemic to serpentine soils. Consistent with climatic warming, herb communities have shifted from 1949-1951 to 2007 to more closely resemble communities found on xeric (warm, dry) south-facing slopes. The changes found in the Siskiyou herb flora suggest that biotas rich in narrowly distributed endemics may be particularly susceptible to the effects of a warming climate.
Oregon↗
Vascular flora of Izembek National Wildlife Refuge, westernmost Alaska Peninsula, Alaska
The vascular flora of Izembek National Wildlife Refuge (NWR), where few previous collections had been reported, was collected and recorded at sites selected to represent the totality of environmental variation. A total of 349 species (339 native and 10 introduced) was identified. To provide a comparative phytogeographic framework, we analyzed data from published reports that categorized vascular plant distribution patterns from a circumpolar, North American, and Alaskan perspective. The native flora of the Izembek NWR primarily includes species of circumpolar (38%), eastern Asian (23%), Eurasian (18%), and North American (13%) distribution. The most important longitudinal distributional classes in North America consist of transcontinental (62%) and extreme western species (31%). The annotated list of species in Izembek NWR expands the range of many species, filling a distributional gap in Hulte??n's Western Pacific Coast district. Forty notable range extensions are reported. The flora of Izembek NWR is primarily made up of boreal species and lacks many of the species considered to be Arctic. Comparison with the Raunkiaer life-form spectrum similarly points to the boreal.
Rhodora↗
The lasting effects of tank maneuvers on desert soils and intershrub flora
Mojave Desert soils and intershrub flora sustained lasting disturbances during military training maneuvers initiated by General George Patton, Jr. in the 1940s, and during Operation Desert Strike in 1964. At six sites, mean desert pavement clast size was significantly smaller by 15% to 50% in single tank tracks compared to undisturbed surfaces. The finer-grained tracks yielded significantly higher surface reflectance values at two of three sites. At one site, Patton era tank tracks cross centuries-old "intaglios" and there was no significant difference in clast size between the disturbances. Full recovery of pavement surfaces may require a change in climate since pavements formed in Pleistocene times under climatic conditions that no longer exist. Tank tracks of both ages exhibited significant levels of soil compaction, as indicated by penetrometer resistance values that were 51% to 120% greater than those in undisturbed soils to 0.3 m depth. Soil bulk density in tracks was 4% to 6% higher than in undisturbed soils. Soil compaction lowered infiltration rates in tank tracks by 24% to 55% in comparison to undisturbed soils. Compaction has prevented the intershrub flora from recovering in tank tracks. Annual and herbaceous perennial plant density was higher by 13% to 56% in tank tracks than in undisturbed soils, but compaction has restricted the growth of individual plants. This was reflected in plant cover values, which were 3% to 16% lower in tank tracks than in undisturbed soils. Soil compaction also altered the species composition. Species with long taproots, such as Chaenactis fremontii, were reduced in density and cover in tank tracks, whereas grass species with shallow, fibrous root systems had large density increases in tracks. Another important element of the intershrub flora, cryptobiotic crust, exhibited a low rate of recovery from the impact of tank travel at one site. The cover of the most well-developed component of the crusts, growing on delicate soil pedicels in undisturbed soils, was reduced by 50% in tank tracks because of destruction and compaction of the uppermost soil layers.
Arizona;California;Nevada↗
Covariance of lichen and vascular plant floras
The geographic relationships among taxonomic groups are important to study to determine patterns of biodiversity and whether or not associations occur between large groups, e.g., birds and vascular plants. This study was undertaken to determine relationships between higher plants and lower plants, specifically vascular plant and lichen floras in nine national parks of the Great Lakes region. No significant relationship was found between vascular plant floras and lichen floras in this area, which spans 1200 km longitudinally, or between an additional 19 areas from North America that were less than 1000 km(2) in area. For areas larger than 1000 km(2), however, a significant positive relationship existed for 33 areas that span one to approximately 150 million km(2). The ratio of numbers of vascular plants to lichens appeared to average just over 6 across the 33 areas. In the Great Lakes parks, between 28-30% of either the vascular plant or lichen species were singletons (occurring in only one park), but the parks that contained the most singletons were not congruent: Isle Royale had the most singleton lichens, while Indiana Dunes had the most vascular plant singletons. Fewer lichen species (2%) than vascular plants (4%) occurred in all nine parks. Latitude appeared to explain some of the variation between the two groups: vascular plants decreased with increasing latitude, while lichens increased.
Illinois, Indiana, Michigan, Minnesota, Ohio, Wisc↗
The flora of Oktibbeha County, Mississippi
We surveyed the flora of Oktibbeha County, Mississippi, U.S.A., from February 1994 to 1996. Occupying 118 square kilometers in east-central Mississippi, Oktibbeha County lies among 3 physiographic regions that include, from west to east, Interior Flatwoods, Pontotoc Ridge, and Black Prairie. Accordingly, the county harbors a diverse flora. Based on field work, as well as an extensive review of published literature and herbarium records at IBE and MISSA, we recorded a total of 1,148 taxa (1,125 species, 7 hybrids, 16 infraspecific taxa) belonging to 514 genera in 160 families, over 85% of all taxa documented were native. Compared to 3 other counties in east-central Mississippi, Oktibbeha County has the second largest recorded flora. The number of state-listed (endangered, threatened, or of special concern) taxa (67) documented in this survey far exceeds that reported from any other county in the region. Three introduced species, Ilex cornuta Lindl. & Paxton, Mahonia bealei (Fortune) Carrie??re, and Nandina domestica Thunb., are reported in a naturalized state for the first time from Mississippi. We also describe 16 different plant communities belonging to 5 broad habitat categories: bottomland forests, upland forests and prairies, aquatic habitats, seepage areas, and human-influenced habitats. A detailed description of the vegetation associated with each of these communities is provided.
SIDA, Contributions to Botany↗
Variation in leaf reflectance spectra across the California flora partitioned by evolutionary history, geographic origin, and deep time
Evolutionary relatedness underlies patterns of functional diversity in the natural world. Hyperspectral remote sensing has the potential to detect these patterns in plants through inherited patterns of leaf reflectance spectra. We collected leaf reflectance data from across the California flora from plants grown in a common garden. Regions of the reflectance spectra vary in the depth and strength of phylogenetic signal. We also show that these differences are much greater than variation due to the geographic origin of the plant. At the phylogenetic extent of the California flora, spectral variation explained by the combination of ecotypic variation (divergent evolution) and convergent evolution of disparate lineages was minimal (3 to 7 %) but statistically significant. Interestingly, at the extent of a single genus ( Arctostaphylos ) no unique variation could be attributed to geographic origin. However, up to 18% of the spectral variation among Arctostaphylos individuals was shared between phylogeny and intraspecific variation stemming from ecotypic differences (i.e., geographic origin). Future studies could conduct more structured experiments (e.g., transplants or observations along environmental gradients) to disentangle these sources of variation and include other intraspecific variation (e.g., plasticity). We constrain broad scale spectral variability due to ecotypic sources, providing further support for the idea that phylogenetic clusters of species might be detectable through remote sensing. Phylogenetic clusters could represent a valuable dimension of biodiversity monitoring and detection.
California↗
Paleobotany of Livingston Island: The first report of a Cretaceous fossil flora from Hannah Point
This is the first report of a fossil flora from Hannah Point, Livingston Island, South Shetland Islands, Antarctica. The fossiliferous content of an outcrop, located between two igneous rock units of Cretaceous age are mainly composed of leaf imprints and some fossil trunks. The leaf assemblage consists of 18 taxa of Pteridophyta, Pinophyta and one angiosperm. The plant assemblage can be compared to other Early Cretaceous floras from the South Shetland Islands, but several taxa have an evidently Late Cretaceous affinity. A Coniacian-Santonian age is the most probable age for the outcrops, supported by previous K/Ar isotopic studies of the basalts over and underlying the fossiliferous sequence
Open-File Report↗
A fossil flora from the Frontier formation of southwestern Wyoming
This paper deals with a small but important fossil flora, now known to be of Colorado age, from the vicinity of Cumberland, Lincoln County, Wyo. It was for many years thought to be of Jurassic age, and only within the last decade has its stratigraphic position been established. Although small in number of species, this flora offers information bearing on the physical and climatic conditions that prevailed during early Upper Cretaceous time in this region, and, moreover, it furnishes a series of stratigraphic marks that may be used in the recognition of this horizon elsewhere.
Wyoming↗
The flora of the Denver and associated formations of Colorado
In the introduction to my report on the Laramie flora of the Denver Basin I stated that that was the first of what was proposed to be a series of papers dealing with the stratigraphy and paleobotany of certain Upper Cretaceous and lower Tertiary plant-bearing formtions of the Rocky Mountain region. The present paper is the second of this series and deals with the flora of the Denver formation and certain identical or closely related formations that occur mainly in or adjacent to the Denver Basin of Colorndo. The additional formational units treated are the Arapahoe formation, the Dawson arkose, and the Middle Park formation.
Colorado↗
The physical conditions and age indicated by the flora of the Alum Bluff formation
The present paper has for its purpose the description of a small flora collected from the Alum Bluff formation, representing a horizon hitherto unrepresented paleobotanically in southeastern North America, and the discussion of the bearing of this flora on the physical conditions of deposition and the probable age of the deposits.
Florida↗
The flora of the Cottonwood Lake Study Area, Stutsman County, North Dakota
The 92 ha Cottonwood Lake Study Area is located in south-central North Dakota along the eastern edge of a glacial stagnation moraine known as the Missouri Coteau. The study area has been the focus of biologic and hydrologic research since the U.S. Fish and Wildlife Service purchased the site in 1963. We studied the plant communities of the Cottonwood Lake Study Area from 1992 to 2001. During this time period, the vascular flora of the study area consisted of 220 species representing 51 families. Over half of the species were perennial forbs (117 species). Perennial grasses (26 species) and annual forbs (22 species) made up the next two largest physiognomic groupings. The flora, having a mean Coefficient of Conservatism of 4.6 and a Floristic Quality Index of 62, consisted of 187 native species. Thirty-three species were non-natives. Our annotated list should provide information useful to researchers, graduate students, and others as they design and implement future studies in wetlands and uplands both in and around the Cottonwood Lake Study Area.
Prairie Naturalist↗