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At least 37 records · Page 2Linked to original sources
USGS2011

Geographic profiling to assess the risk of rare plant poaching in natural areas

We demonstrate the use of an expert-assisted spatial model to examine geographic factors influencing the poaching risk of a rare plant (American ginseng, Panax quinquefolius L.) in Shenandoah National Park, Virginia, USA. Following principles of the analytic hierarchy process (AHP), we identified a hierarchy of 11 geographic factors deemed important to poaching risk and requested law enforcement personnel of the National Park Service to rank those factors in a series of pair-wise comparisons. We used those comparisons to determine statistical weightings of each factor and combined them into a spatial model predicting poaching risk. We tested the model using 69 locations of previous poaching incidents recorded by law enforcement personnel. These locations occurred more frequently in areas predicted by the model to have a higher risk of poaching than random locations. The results of our study can be used to evaluate resource protection strategies and to target law enforcement activities.

Environmental Management↗
USGS2016

Local biotic adaptation of trees and shrubs to plant neighbors

Natural selection as a result of plant–plant interactions can lead to local biotic adaptation. This may occur where species frequently interact and compete intensely for resources limiting growth, survival, and reproduction. Selection is demonstrated by comparing a genotype interacting with con- or hetero-specific sympatric neighbor genotypes with a shared site-level history (derived from the same source location), to the same genotype interacting with foreign neighbor genotypes (from different sources). Better genotype performance in sympatric than allopatric neighborhoods provides evidence of local biotic adaptation. This pattern might be explained by selection to avoid competition by shifting resource niches (differentiation) or by interactions benefitting one or more members (facilitation). We tested for local biotic adaptation among two riparian trees, Populus fremontii and Salix gooddingii , and the shrub Salix exigua by transplanting replicated genotypes from multiple source locations to a 17 000 tree common garden with sympatric and allopatric treatments along the Colorado River in California. Three major patterns were observed: 1) across species, 62 of 88 genotypes grew faster with sympatric neighbors than allopatric neighbors; 2) these growth rates, on an individual tree basis, were 44, 15 and 33% higher in sympatric than allopatric treatments for P. fremontii, S. exigua and S. gooddingii , respectively, and; 3) survivorship was higher in sympatric treatments for P. fremontii and S. exigua . These results support the view that fitness of foundation species supporting diverse communities and dominating ecosystem processes is determined by adaptive interactions among multiple plant species with the outcome that performance depends on the genetic identity of plant neighbors. The occurrence of evolution in a plant-community context for trees and shrubs builds on ecological evolutionary research that has demonstrated co-evolution among herbaceous taxa, and evolution of native species during exotic plants invasion, and taken together, refutes the concept that plant communities are always random associations.

Arizona↗
USGS2019

Bryophyte abundance, composition and importance to woody plant recruitment in natural and restoration forests

Restoration of tropical forests can lead to enhanced ecosystem services and increases in native biodiversity. Bryophytes may be an integral part of the forest restoration process and can serve a critical role in forest functioning. However, the recovery of bryophytes and their ability to facilitate woody plant establishment during restoration remains poorly studied, especially in the tropics. We investigate how bryophyte abundance and community composition, as well as woody plant seedling associations with bryophyte mats and other ground cover types change from under the canopy of intact forest to under trees in restoration corridor plantings in Hawaii. Restoration corridors consisted of corridors of koa (Acacia koa) trees that were planted roughly 30 years ago. Some corridors were planted around remnant ʻōhiʻa trees (Metrosideros polymorpha) that can be several hundred years old. We sampled under ʻōhiʻa in intact forest and both koa and ʻōhiʻa trees in restoration corridors. In restoration corridors, bryophyte abundance was low relative to intact forest and species diversity was a subset of that found in intact forest despite restoration corridors being several decades old. Seedlings strongly associated with bryophytes across all habitats suggesting that bryophytes may significantly enhance forest seedling establishment when present in restoration corridors. Other ground cover types like woody litter and nurse logs also had a positive association with forest seedlings but were rare in restoration corridors. Grass remained a dominant ground cover type in restoration corridors under koa and remnant ʻōhiʻa trees and only a single seedling was ever found growing in this grass. Enhancing bryophyte growth and recovery within restoration plantings through the reduction of grass cover could facilitate native plant establishment.

Hawaii↗
USGS1984

First evidence of successful natural reproduction by planted lake trout in Lake Huron

Twenty-two lake trout (Salvelinus namaycush) swim-up fry, 24-27 mm long, were captured with emergent fry traps and a tow net in northwestern Lake Huron on a small nearshore reef off Alpena, Michigan, between May 10 and June 1, 1982. These catches represent the first evidence of successful production of swim-up fry by planted, hatchery-reared lake trout in Lake Huron since the lake trout rehabilitation program began in 1973.

North American Journal of Fisheries Management↗
USGS2021

Fine-scale plant defence variability increases top-down control of an herbivore

Herbivore populations are regulated by a combination of plant defences and natural enemies. While plant defence can suppress herbivore populations, these defences can also adversely affect natural enemies, thereby releasing herbivores from top-down control. Over their life spans, herbivores and their natural enemies may experience substantial variation in plant defence. Recent studies have demonstrated that individual herbivores feeding on diets containing variable concentrations of plant toxins suffer substantially reduced fitness compared to herbivores feeding on a constant toxin concentration, even when both groups of herbivores experience equivalent means. However, the impacts of defence variability on natural enemies and top-down control of herbivores are unknown. Using artificial diets, we independently manipulated the mean concentration and variation of a plant toxin experienced by individual Trichoplusia ni caterpillars and its parasitoid Copidosoma floridanum . Additionally, by combining the performance of individual caterpillars on different constant diet concentrations of toxin, we were able to estimate the effect of toxin variability between herbivores using nonlinear averaging. Increases in the mean toxin concentration in the diet of parasitized T. ni hosts decreased the fitness of C. floridanum , while variance in individual diets did not impact parasitoid fitness, even though both mean and variance decreased the fitness of T. ni caterpillars. Increased variability in encountered plant defences suppressed individual herbivore fitness with no perceptible cost to top-down control. At the population level, however, increased variability between individual herbivore diets decreased the success of parasitoids relative to herbivores, thus reducing the strength of top-down control. Our study highlights the importance of defence variability at different scales in regulating herbivore performance. Variability in plant defence has the potential to reduce herbivore populations through a combination of bottom-up and top-down effects, but only at small spatial scales experienced by individual herbivores.

Functional Ecology↗
USGS2024

Naturalized species drive functional trait shifts in plant communities

Despite decades of research documenting the consequences of naturalized and invasive plant species on ecosystem functions, our understanding of the functional underpinnings of these changes remains rudimentary. This is partially due to ineffective scaling of trait differences between native and naturalized species to whole plant communities. Working with data from over 75,000 plots and over 5,500 species from across the United States, we show that changes in the functional composition of communities associated with increasing abundance of naturalized species mirror the differences in traits between native and naturalized plants. We find that communities with greater abundance of naturalized species are more resource acquisitive aboveground and belowground, shorter, more shallowly rooted, and increasingly aligned with an independent strategy for belowground resource acquisition via thin fine roots with high specific root length. We observe shifts toward herbaceous-dominated communities but shifts within both woody and herbaceous functional groups follow community-level patterns for most traits. Patterns are remarkably similar across desert, grassland, and forest ecosystems. Our results demonstrate that the establishment and spread of naturalized species, likely in combination with underlying environmental shifts, leads to predictable and consistent changes in community-level traits that can alter ecosystem functions.

Proceedings of the National Academy of Sciences↗
USGS2020

Nature’s Notebook-A tool for recording the timing of seasonal activity of plants and animals

Nature's Notebook is a customizable program used by individual observers and Federal Government partners to document patterns in phenology—the timing of seasonal activity of plants and animals over the course of the calendar year. The USA National Phenology Network (USA-NPN) established Nature's Notebook in 2009 to create a standard approach for collecting phenology data on plants and animals across the country. Currently, about half of the data are submitted by independent backyard observers at individual sites and half are submitted by groups of participants as part of a Local Phenology Program. With support from the U.S. Geological Survey, the USA-NPN collects, organizes, and shares data on phenology. This information aids decision making, scientific discovery, and the development of a broader understanding of phenology.

Fact Sheet↗
USGS2001

Early post-fire succession in California chaparral: Changes in diversity, density, cover and biomass

For four consecutive years, following the fires in November 1993, temporal variations in species richness, cover and biomass of component plant groups in early post-fire chaparral succession were monitored on different aspects at the Stunt Ranch Santa Monica Mountains Reserve, southern California. Plant groups were categorized based on growth form, life form, ability to fix nitrogen, geographic origin and regeneration strategies. North-facing slopes exhibited higher species richness, higher species turnover rate over time and faster vegetation recovery in terms of biomass accumulation and return to pre-fire species composition. This was probably due to higher species richness and biomass of nitrogen-fixing species found on north-facing slopes in comparison to south-facing slopes. On both north- and south-facing slopes, annuals had the highest species turnover rate, followed by herbaceous perennials and shrubs. In the first four post-fire years, annual species were the largest floristic group, but herbaceous perennials and shrubs were the major contributors to community biomass. Nitrogen-fixing species and exotics contributed significantly to early post-fire community structure. Although the general trends in post-fire succession are clear in terms of temporal changes in the relative proportions of different plant groups, environmental variation and the nature of plant life histories of component species, especially dominant species, could alter such trends significantly.

Ecological Research↗
USGS2010

Adaptation and survival of plants in high stress habitats via fungal endophyte conferred stress tolerance

From the Arctic to the Antarctic, plants thrive in diverse habitats that impose different levels of adaptive pressures depending on the type and degree of biotic and abiotic stresses inherent to each habitat (Stevens, 1989). At any particular location, the abundance and distribution of individual plant species vary tremendously and is theorized to be based on the ability to tolerate a wide range of edaphic conditions and habitat-specific stresses (Pianka, 1966). The ability of individual plant species to thrive in diverse habitats is commonly referred to as phenotypic plasticity and is thought to involve adaptations based on changes in the plant genome (Givnish, 2002; Pan et al., 2006; Robe and Griffiths, 2000; Schurr et al., 2006). Habitats that impose high levels of abiotic stress are typically colonized with fewer plant species compared to habitats imposing low levels of stress. Moreover, high stress habitats have decreased levels of plant abundance compared to low stress habitats even though these habitats may occur in close proximity to one another (Perelman et al., 2007). This is particularly interesting because all plants are known to perceive, transmit signals, and respond to abiotic stresses such as drought, heat, and salinity (Bartels and Sunkar, 2005; Bohnert et al., 1995). Although there has been extensive research performed to determine the genetic, molecular, and physiological bases of how plants respond to and tolerate stress, the nature of plant adaptation to high stress habitats remains unresolved (Leone et al., 2003; Maggio et al., 2003; Tuberosa et al., 2003). However, recent evidence indicates that a ubiquitous aspect of plant biology (fungal symbiosis) is involved in the adaptation and survival of at least some plants in high stress habitats (Rodriguez et al., 2008).

Book chapter↗
USGS1997

The effects of pollutants on wildlife

In this chapter, selected sources of information which address the effects of pollutants on wildlife are reviewed. Although naturally occurring plant and animal toxins also affect wildlife, the focus of this review is xenobiotic toxicants. Xenobiotic substances are chemicals introduced into the environment in the form of pesticides, heavy metals, polychlorinated biphenyls (PCBs), and other by-products of human activities. The science of examining the effects of these substances on animal and plant life is multi-disciplinary in nature and contributors to the literature in this field include toxicologists, wildlife and aquatic ecologists, chemists and those in the veterinary and medical professions.

Book chapter↗
USGS1999

Carbon isotopic constraints on the contribution of plant material to the natural precursors of trihalomethanes

The δ 13 C values of individual trihalomethanes (THM) formed on reaction of chlorine with dissolved organic carbon (DOC) leached from maize (corn; Zea maize L. ) and Scirpus acutus (an aquatic bulrush), and with DOC extracted from agricultural drainage waters were determined using purge and trap introduction into a gas chromatograph-combustion-isotope ratio monitoring mass spectrometer. We observed a 16.8‰ difference between the δ 13 C values of THM produced from the maize and Scirpus leachates, similar to the isotopic difference between the whole plant materials. Both maize and Scirpus formed THM 12‰ lower in 13 C than whole plant material. We suggest that the low value of the THM relative to the whole plant material is evidence of distinct pools of THM-forming DOC, representing different biochemical types or chemical structures, and possessing different environmental reactivity.

Organic Geochemistry↗
USGS1997

Early vegetational changes on a forested wetland constructed for mitigation

Changes in vegetation were studied on 15 acres of a 35 acre forested wetland created as a mitigation site in Anne Arundel County, Maryland during 1994-96. Meter-square sampling on four different hydrologic elevations determined that grasses initially dominated the area, but decreased from 59 percent in 1994 to 51 percent in 1995 and 30 percent in 1996. Herbaceous non-grass plants (forbs) increased from 19 percent to 56 percent in the three-year period. Area with no plant cover decreased from 21 percent in 1994 to 11 percent in 1995, and 10 percent in 1996. Woody plants comprised 2 percent of the cover in 1994, increased to 4 percent in 1995, and remained at 4 percent in 1996. The increase of woody plants was mainly from natural regeneration (pioneer) plants. Monitoring of the transplanted trees and shrubs indicated 35 percent mortality and little growth of surviving plants. The pioneer woody plant forming most of the cover was black willow (Salix nigra). Differences in the vegetation were observed among the four elevations, although no differences were observed for the major vegetation classes between plots that were planted and those that were not planted with woody plants. Dominant grass species was redtop (Agrostis stolonifera), which comprised 51 percent of the cover in 1994 and 42 percent cover in 1995 and 23 percent in 1996. Other species that were common were bush clover (Lespedeza cuneata), Japanese clover (Lespedeza striata) and flat pea (Lathyrus sylvestris). All four of these dominant species were part of the original seed mixtures that were seeded on the site. A total of 134 species of plants was recorded on the site indicating a fairly diverse community for a newly established habitat.

Wetland Journal↗
USGS2012

Status and limiting factors of two rare plant species in dry montane communities of Hawai`i Volcanoes National Park.

Two rare plants native to montane dry forests and woodland communities of Hawai`i Volcanoes National Park (HAVO) were studied for more than two years to determine their stand structure, short-term mortality rates, patterns of reproductive phenology, success of fruit production, floral visitor composition, seed germination rates in the greenhouse, and survival of both natural and planted seedlings. Phyllostegia stachyoides , a shrubby Hawaiian mint (Lamiaceae) that is a species of concern, was studied within two small kīpuka at a natural population on the park’s Mauna Loa Strip, and three plantings at sites along the Mauna Loa Road were also monitored. Silene hawaiiensis , a threatened shrub species in the pink family (Caryophyllaceae), was monitored at two natural populations, one on Mauna Loa at the Three Trees Kīpuka and the second on Kīlauea Crater Rim south of Halema`uma`u. Silene hawaiiensis plantings were also made inside and outside ungulate exclosures at the park’s Kahuku Unit Phyllostegia stachyoides appeared to have a relatively stable natural population in HAVO with approximately 19% adult plant mortality over three years and recruitment of natural seedlings. Despite high mortality (~98%), some seedlings persisted for more than a year, and recruitment of new plants into the population exceeded the losses of adult plants. Flowering and fruiting phenology was annual and seasonal with peak appearance of buds and flowers in spring and greatest abundance of mature fruit in the summer and fall. Successful production of green fruit from buds and flowers was very high (45%), and green fruit transitioned to mature fruit at a rate of 17.8%. Five insect species were observed visiting flowers, and those with the greatest visitation rates were the alien hover fly Allograpta obliqua (Syrphidae) and the endemic yellowfaced bee Hylaeus difficilis (Colletidae). Both insect species were shown to be carrying pollen of P. stachyoides . Seed germination rates in the greenhouse were variable but ranged as high as 80.4%. Mortality of seedlings planted at three sites along the Mauna Loa Road was very high (~90%) within 2–3 years of planting. There was no significant difference in the mortality or growth of seedlings planted in areas with little grass compared to those in adjacent areas with high grass cover. Silene hawaiiensis had a stable population structure at the Mauna Loa study area, but its population structure at the Kīlauea study site was flat to declining. Mortality of adult plants was low on Mauna Loa (6.5%), but was greater than 30% at the Kīlauea Crater Rim site. Among regularly monitored plants at the Kīlauea site, losses were observed in all size classes between 2006 and 2008. Natural seedling recruitment was observed in stand structure plots at both sites between 2006 and 2007, but numbers of seedlings were low and did not compensate for losses of adult plants. Reproductive phenology was annual with buds and flowers observed in summer and fall, and fruit formed in the fall and winter. The production of immature fruit capsules from buds and flowers was high (51.2%) and tagged immature fruit became mature fruit at a high rate of 66.7%. Floral visitation rates were very low in timed observations and only three insect species were identified visiting S. hawaiiensis flowers: native yellow-faced bees Hylaeus difficilis and H. volcanicus , and the alien hover fly Allograpta exotica . A seed dispersal experiment at the Kīlauea Crater Rim site demonstrated that wind dispersed seeds could travel at least 40 m from S. hawaiiensis plants with mature open capsules. Seed germination rates varied from 7.0 to 73.0% in greenhouse trials. Mortality of planted seedlings at Kahuku was not significantly greater outside ungulate exclosures than inside, but growth in height and production of reproductive structures was significantly greater in protected areas inside exclosures. In the current study, the seedling stage was the most vulnerable part of the life cycle for both P . stachyoides and S. hawaiiensis , and low seedling recruitment appeared to be the most important limiting factor for these species

Hawaii↗
USGS2020

Book review of "Plant anatomy—A concept based approach to the structure of seed plants"

Plant Anatomy: A Concept-Based Approach to the Structure of Seed Plants by Crang, Lyons-Sobaski, and Wise is a beautifully-illustrated, 600+ page textbook highlighting the wonderful diversity of anatomical form in plants. The layout of the chapters follows many traditional plant anatomy textbooks. Plant Anatomy begins with an overview of plant morphology and proceeds through evolutionary time and across systems (Chapter 1. The Nature of Plants) before zooming into the microscopic, internal world of plant structures and their function (Chapter 2. Microscopy and Imaging through Chapter 8. Phloem). Quite fortunately, historical context is described throughout these sections, highlighting seminal studies that have shaped the plant sciences over the past 300+ years.

Plant Science Bulletin↗
USGS2010

Limiting factors of four rare plant species in `Ōla`A Forest of Hawai'i Volcanoes National Park

Three endangered or candidate endangered plant species native to `Ōla`a Forest ( Cyrtandra giffardii , ha`iwale; Phyllostegia floribunda , a mint with no common name; and Sicyos alba , `ānunu) were studied for more than 2 years to determine their stand structures, short-term mortality rates, patterns of reproductive phenology, success of fruit production, seed germination rates in the greenhouse, presence of soil seed bank, and survival of both natural and planted seedlings. The role of rodents as seed predators was evaluated for S. alba using seed offerings in open and closed stations. A 4th endangered species at a remote site in `Ōla`a ( Cyrtandra tintinnabula ) was visited to determine its stand structure and mortality rate. Cyrtandra giffardii displayed a stable population structure with many adults and few small or very large plants; the monitored population had a mortality rate of 7.3% over 3 years. Mortality of plantings from 2003-2004 in a re-introduced population of Phyllostegia floribunda was 21.4%. The stand structure of C. tintinnabula indicated a relatively stable population with both small and large plants present and a short-term mortality rate between visits of 14.5- 17.0%. Four groups of S. alba vines were monitored; 3 of these have persisted in place for at least 15 years. All species monitored had annual patterns of flower and fruit phenology, although male inflorescences of S. alba showed a subannual pattern. Successful transition of flowers to fruit was high for P. floribunda (51.5%), moderate for C. giffardii (23.3%) and undetermined for S. alba . High percentage viability was demonstrated for seeds of P. floribunda and S. alba (78.5-100% positive to strongly positive in tetrazolium tests), but seed viability was not tested for C. giffardii . Greenhouse germination rates were high for P. floribunda (88.0-92.0%), but variable and relatively low for C. giffardii (0-19.3%) and S. alba (4.0-11.1% in 2007 and 0 in 2008). No soil seed bank was detected for S. alba in 3 seasonal samplings, but P. floribunda was found to have a viable seed bank in April that persisted from at least the previous summer. Rodent predation of S. alba seeds was 93.3% in fruit offerings in accessible bait stations. Mortality of natural seedlings was high for both P. floribunda (90.2%) and S. alba (69.7%). Planted seedlings of P. floribunda produced flowers and fruit in their first year, and reproduction was higher in sunny plots than in shady plots. Mortality was high in both planting treatments, and survival rates did not differ significantly in sun and shade (χ 2 =0.48, df = 1, p = 0.490). Three planted seedlings of S. alba survived for 12-16 months but did not reproduce. Floral visitors were observed at C. giffardii and P. floribunda using digital video cameras and recorders. In almost 200 hours of observation, no visitors entered the flowers of C. giffardii , although 1 very small insect, either a micro-wasp (Hymenoptera) or fly (Diptera) was seen on the exterior of a corolla. In almost 300 hours of video observation, 3 floral visitors were identified at P. floribunda flowers. Honeybees ( Apis mellifera ) were likely pollinators, as they contacted both anthers and stigma of flowers. The mean visitation rate of honeybees was 0.003 visit/flower/hour, and visit duration ranged from 2 to 17 seconds. Fruit flies (Drosophilidae of undetermined species) crawled around flower interiors, but did not seem to forage for either nectar or pollen. Fruit fly mean visitation rate was 0.006 visit/flower/hour, and visit duration was 28 to 1,424 seconds. The 3rd observed insect visitor was an endemic geometrid moth caterpillar ( Lophoplusia giffardi ), which was seen feeding on foliage and flowers of P. floribunda . In conclusion, 2 of the 3 regularly-monitored rare plant species of `Ōla`a Forest appeared to have more than 1 limiting factor inhibiting the natural increase in their populations, while for P. floribunda the most important factor was high seedling mortality. Most plants of the monitored C. giffardii population appeared to be hybrids, probably with the more common species C. lysiosepala . Seed germination rates were low, and natural seedlings were not observed. Pollinators were not seen in many hours of observation, indicating that cross pollination is a rare or uncommon event. The re-introduced population of P. floribunda had relatively low mortality, and reproduction was successful with high rates of fruit formation from abundant flowers. Seed germination rates were high, and a soil seed bank was detected. Natural seedling recruitment was observed, but high seedling mortality indicated that this life stage was the most vulnerable in the species. The population of S. alba was small and the vine life form precluded an accurate estimate of the number of adult plants in `Ōla`a Forest. Natural dormancy was likely a factor in the observed low rate of seed germination. No soil seed bank was detected, and alien rodents were implicated as seed predators. Natural recruitment was observed at multiple sites in `Ōla`a, but seedling mortality was high. The cause of seedling mortality was not identified.

Hawaii↗
USGS2009

Symbiotic lifestyle expression by fungal endophytes and the adaptation of plants to stress: unraveling the complexities of intimacy

The fossil record indicates that fungal symbionts have been associated with plants since the Ordovician period (approximately 400 million years ago), when plants first became established on land (Pirozynski and Malloch, 1975; Redecker et al., 2000; Remy et al., 1994; Simon et al., 1993). Transitioning from aquatic to terrestrial habitats likely presented plants with new stresses, including periods of desiccation. Since symbiotic fungi are known to confer drought tolerance to plants (Bacon, 1993; Read and Camp, 1986), it has been suggested that fungal symbiosis was involved with or responsible for the establishment of land plants (Pirozynski and Malloch, 1975). Symbiosis was first defined by De Bary in 1879, and since that time, all plants in natural ecosystems have been found to be colonized with fungal and bacterial symbionts. It is clear that individual plants represent symbiotic communities with microorganisms associated in or on tissues below- and aboveground. There are two major classes of fungal symbionts associated with internal plant tissues: fungal endophytes that reside entirely within plants and may be associated with roots, stems leaves, or flowers; and mycorrhizal fungi that reside only in roots but extend out into the rhizosphere. In addition, fungal endophytes may be divided into two classes: (1) a relatively small number of fastidious species that are limited to a few monocot hosts (Clay and Schardl, 2002), and (2) a large number of tractable species with broad host ranges, including both monocots and eudicots (Stone et al., 2000). While significant resources and research have been invested in mycorrhizae and class 1 endophytes, comparatively little is known about class 2 endophytes, which may represent the largest group of fungal symbionts. This is partially because the symbiotic functionalities of class 2 endophytes have only recently been elucidated and shown to be responsible for the adaptation of some plants to high-stress environments (Redman et al., 1999, 2001, 2002a; Arnold et al., 2003; Dingle and McGee, 2003; Ernst et al., 2003). In this chapter, we focus on symbiotic interactions between class 2 endophytes and a variety of monocot and eudicot host species. Specifically, we will discuss the ability of endophytes to express more than one symbiotic lifestyle, fungal taxonomy vs. lifestyle expression, the adaptive nature of symbioses, mechanisms of symbiotically conferred stress tolerance, and the evolutionary implications of adaptive symbiosis. We will refer to class 2 endophytes as fungal endophytes throughout the text.

Book chapter↗
USGS2002

Palynology and palynostratigraphy of the Hell Creek Formation in North Dakota: A microfossil record of plants at the end of Cretaceous time

The Hell Creek Formation of North Dakota preserves a rich and varied palynoflora including pollen, spores, and algal cysts; this palynoflora provides insight into the nature of plant life in the region in late Maastrichtian time. This palynological record supplements extensive data from the same ancient vegetation preserved in the megafloral record, and it provides background biostratigraphic data necessary to determine the nature of the Cretaceous-Tertiary (K-T) boundary event. This study of the Hell Creek palynoflora is based upon occurrences of palynomorphs in 71 samples from 20 measured sections in Bowman and Slope Counties, southwestern North Dakota . The palynoflora documented includes 115 or more palynomorph species, 98 of which are described. Three new genera are proposed, three new species are described, and five new nomenclatural combinations are made. The new taxa are Palaeoisoetes gen. nov., Styxpollenites gen. nov., Tschudypollis gen. nov., Aquilapollenites marmarthensis sp. nov., Osmundacidites stanleyi sp. nov., Styxpollenites calamitas sp. nov., Polyatriopollenites levis (Stanley 1965) comb. nov., Palaeoisoetes subengelmannii (Elsik 1968) comb. nov., Triporopollenites triplicatus (Anderson 1960) comb. nov., Tschudypollis retusus (Anderson 1960) comb. nov., and Tschudypollis thalmannii (Anderson 1960) comb. nov. The palynofloral taxa include 67 angiosperms, eight gymnosperms, 19 pteridophytes, and three bryophytes. Of these, 33 are regarded as characteristically uppermost Cretaceous taxa (K taxa). A few of the K taxa do not range all the way to the K-T boundary. Extinction of the Hell Creek palynoflora at the K-T boundary is ∼30%. The Hell Creek Formation is within theWodehouseia spinata Assemblage Zone.

North Dakota↗