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At least 37 records · Page 2Linked to original sources
USGS2022

Invasive plant hitchhikers: Appalachian Trail thru-hiker knowledge and attitudes of invasive plants and Leave No Trace practices

Hiking and backpacking on American National Scenic Trails has increased in popularity in recent years. To encourage responsible and sustainable outdoor recreation on these much-loved trails, direct and indirect management strategies must be employed by managerial agencies. The Leave No Trace (LNT) education program aims to protect natural resources by promoting minimum-impact behaviours that lessen environmental impacts. The accidental introduction and dispersal of non-native invasive flora by hikers is little studied but can have a detrimental environmental impact on protected areas. The purpose of our study was to understand whether Appalachian Trail thru-hikers are: 1) aware of this problem, 2) adhering to LNT principles to reduce this problem, and 3) willing to learn and adopt minimum-impact behaviours to address this problem. We found that thru-hiker knowledge of invasive plants was limited and that very few thru-hikers adopted low-impact practices to minimise plant introduction and spread. Promisingly, we found that most thru-hikers, once aware of the problems, were willing to learn and apply low-impact practices to minimise plant introduction and spread. We discuss the barriers to their adoption of these behaviours and present a comprehensive list of suggested LNT practices to limit invasive plant introduction and spread. We conclude that, whilst challenging, protected area managers can help deter the spread of invasive plants along trails by improving educational messaging, signage, personal communication, and providing supporting infrastructure that encourages visitors to adopt specific practices to minimise invasive plant introduction and spread within protected areas.

Virginia, West Virginia↗
USGS2012

Climate impacts on bird and plant communities from altered animal-plant interactions

The contribution of climate change to declining populations of organisms remains a question of outstanding concern. Much attention to declining populations has focused on how changing climate drives phenological mismatches between animals and their food. Effects of climate on plant communities may provide an alternative, but particularly powerful, influence on animal populations because plants provide their habitats. Here, we show that abundances of deciduous trees and associated songbirds have declined with decreasing snowfall over 22 years of study in montane Arizona, USA. We experimentally tested the hypothesis that declining snowfall indirectly influences plants and associated birds by allowing greater over-winter herbivory by elk (Cervus canadensis). We excluded elk from one of two paired snowmelt drainages (10 ha per drainage), and replicated this paired experiment across three distant canyons. Over six years, we reversed multi-decade declines in plant and bird populations by experimentally inhibiting heavy winter herbivory associated with declining snowfall. Moreover, predation rates on songbird nests decreased in exclosures, despite higher abundances of nest predators, demonstrating the over-riding importance of habitat quality to avian recruitment. Thus, our results suggest that climate impacts on plant–animal interactions can have forceful ramifying effects on plants, birds, and ecological interactions.

Arizona↗
USGS2008

More than 400 million years of evolution and some plants still can't make it on their own: Plant stress tolerance via fungal symbiosis

All plants in natural ecosystems are thought to be symbiotic with mycorrhizal and/or endophytic fungi. Collectively, these fungi express different symbiotic lifestyles ranging from parasitism to mutualism. Analysis of Colletotrichum species indicates that individual isolates can express either parasitic or mutualistic lifestyles depending on the host genotype colonized. The endophyte colonization pattern and lifestyle expression indicate that plants can be discerned as either disease, non-disease, or non-hosts. Fitness benefits conferred by fungi expressing mutualistic lifestyles include biotic and abiotic stress tolerance, growth enhancement, and increased reproductive success. Analysis of plant-endophyte associations in high stress habitats revealed that at least some fungal endophytes confer habitat-specific stress tolerance to host plants. Without the habitat-adapted fungal endophytes, the plants are unable to survive in their native habitats. Moreover, the endophytes have a broad host range encompassing both monocots and eudicots, and confer habitat-specific stress tolerance to both plant groups. ?? The Author [2008]. Published by Oxford University Press [on behalf of the Society for Experimental Biology]. All rights reserved.

Conference Paper↗
USGS2023

Do seeding and seedling planting result in similar restored plant communities?

Aims Restoration practitioners often face a tradeoff between low cost but risky seeding vs expensive but more reliable seedling planting to meet revegetation goals. Knowing under what environmental and management conditions direct seeding vs seedling planting benefit different species could improve restoration practice. Methods We compared seed emergence to planted-seedling survival among perennial herbaceous species commonly used in restoration across eight experimental restoration sites on the Colorado Plateau, USA. We used linear models to assess relationships between emergence and survival among species, and to assess the effects of site climate and seeding pre-treatments on those relationships. Results We found that among species, emergence was positively correlated with survival in the cooler sites, meaning that species with high emergence also had high survival and vice versa, but had no relationship in the hottest sites. Furthermore, pre-treatments to enhance soil moisture in seeded plots, specifically microtopography (pits) and mulch, also resulted in positive relationships between emergence and survival among species, while seeding without additional soil pre-treatments did not. Seedling planting cost 14 times as much as direct seeding alone, dropping to nine times as much when pre-treatments were combined with seeding. Conclusions Taken together, these results suggest that investments in seedling planting at hotter dryland sites, or in creating microtopography or mulching prior to seeding across sites, are likely to promote establishment success compared to simple seeding methods in degraded dryland ecosystems. These findings also identify opportunities for hybrid seeding and planting approaches that balance tradeoffs between risk and cost, respectively.

Applied Vegetation Science↗
USGS2008

Mechanisms of plant survival and mortality during drought: Why do some plants survive while others succumb to drought?

Severe droughts have been associated with regional-scale forest mortality worldwide. Climate change is expected to exacerbate regional mortality events; however, prediction remains difficult because the physiological mechanisms underlying drought survival and mortality are poorly understood. We developed a hydraulically based theory considering carbon balance and insect resistance that allowed development and examination of hypotheses regarding survival and mortality. Multiple mechanisms may cause mortality during drought. A common mechanism for plants with isohydric regulation of water status results from avoidance of drought-induced hydraulic failure via stomatal closure, resulting in carbon starvation and a cascade of downstream effects such as reduced resistance to biotic agents. Mortality by hydraulic failure per se may occur for isohydric seedlings or trees near their maximum height. Although anisohydric plants are relatively drought-tolerant, they are predisposed to hydraulic failure because they operate with narrower hydraulic safety margins during drought. Elevated temperatures should exacerbate carbon starvation and hydraulic failure. Biotic agents may amplify and be amplified by drought-induced plant stress. Wet multidecadal climate oscillations may increase plant susceptibility to drought-induced mortality by stimulating shifts in hydraulic architecture, effectively predisposing plants to water stress. Climate warming and increased frequency of extreme events will probably cause increased regional mortality episodes. Isohydric and anisohydric water potential regulation may partition species between survival and mortality, and, as such, incorporating this hydraulic framework may be effective for modeling plant survival and mortality under future climate conditions.

New Phytologist↗
USGS1997

Perception of neighboring plants by rhizomes and roots: Morphological manifestations of a clonal plant

A previous study showed that clonal morphology of the rhizomatous grass Elymus lanceolatus ssp. lanceolatus (Scibner & J.G. Smith Gould) was influenced more by neighbouring root systems than by the local distribution of nutrients. In this study we determine whether individual rhizomes or roots of E . lanceolatus perceive neighbouring root systems and how this is manifested in morphological responses of E . lanceolatus clones. Elymus lanceolatus was grown in the same bin with Pseudoroegneria spicata (Pursh) A. Love or Agropyron desertorum (Fisch. ex Link) Schult. plants. Elymus lanceolatus was separated from its neighbours by different barriers. The barriers allowed either only E . lanceolatus roots; only a single E . lanceolatus primary rhizome; or both roots and rhizomes to contact the neighbour root system. When only a single E . lanceolatus primary rhizome with potentially developing branching rhizomes made contact with the neighbour, the clonal structure of E . lanceolatus was modified more with P . spicata as the neighbour than with A . desertorum . With root contact of E . lanceolatus alone there was a similar effect with the neighbouring plants, but there was a more marked inhibitory effect on E . lanceolatus clonal growth with P . spicata than with A . desertorum , compared with the treatment with only a single rhizome in contact with the neighbour. Root resource competition in the unconstrained treatment (roots and rhizomes) between neighbouring plant and E . lanceolatus was more apparent with A . desertorum than with P . spicata . This study is one of the first to document that rhizome and root contact of a clonal plant with its neighbours may induce different clonal responses depending on the species of neighbour. Key words : Agropyron desertorum , clonal morphology, Elymus lanceolatus ssp. lanceolatus , plant interference, plant contact, Pseudoroegneria spicata , rhizome structure, root systems.

Canadian Journal of Botany↗
USGS2006

Fire severity and plant age in postfire resprouting of woody plants in sage scrub and chaparral

Postfire resprouting by woody plants confers a marked advantage in rate of recovery over species that regenerate entirely from seed. However, the predictability of this advantage varies markedly between species, with some showing nearly 100% rootcrown survival and others often much lower. This study examined patterns of fire-caused mortality and tested the relative importance of fire severity and plant age between various shrubs and subshrubs characteristic of chaparral and sage scrub associations. Resprouting success varied from about 10% for Eriogonum fasciculatum to a high of 98% for Quercus berberidifolia . For most of the shrub species, skeletons of resprouting plants were significantly taller than those of dead individuals of the same species, indicating less biomass consumption, and thus lower severity fires were associated with higher resprouting success. This pattern was less strongly the case with sage scrub species. Shrubs and subshrubs, however, differed in the effect of aboveground plant age (as estimated by basal diameter) on resprouting success. For most chaparral shrubs, age was not related to resprouting success, whereas in four out of five subshrub species, including Artemisia californica , Eriogonum fasciculatum , Salvia leucophylla , and S. mellifera , the youngest plants exhibited the highest resprouting success. I hypothesize that the reason for this inverse relationship between age and resprouting in certain sage scrub species is that, as these subshrubs age, there is a tendency to loose the resprouting ability and the mechanism is quite possibly because adventitious buds responsible for sprouting become buried by woody tissues. Patterns of character evolution in these sage scrub lineages support the hypothesis that the herbaceous perennial mode of seasonal aestivation evolved early and lignification is a more recently derived trait and this may have negative effects on resprouting as the plant ages.

Madroño↗
USGS2011

Dynamics of a plant-herbivore-predator system with plant-toxicity

A system of ordinary differential equations is considered that models the interactions of two plant species populations, an herbivore population, and a predator population. We use a toxin-determined functional response to describe the interactions between plant species and herbivores and use a Holling Type II functional response to model the interactions between herbivores and predators. In order to study how the predators impact the succession of vegetation, we derive invasion conditions under which a plant species can invade into an environment in which another plant species is co-existing with a herbivore population with or without a predator population. These conditions provide threshold quantities for several parameters that may play a key role in the dynamics of the system. Numerical simulations are conducted to reinforce the analytical results. This model can be applied to a boreal ecosystem trophic chain to examine the possible cascading effects of predator-control actions when plant species differ in their levels of toxic defense.

Mathematical Biosciences↗
USGS2007

Did debris-covered glaciers serve as pleistocene refugia for plants? A new hypothesis derived from observations of recent plant growth on glacier surfaces

This study proposes a new hypothesis: Debris-covered glaciers served as Pleistocene biological refugia. This is based on detailed studies of vascular plant growth on six debris-mantled glaciers, literally around the world, as well as many casual observations also across the globe. We find that such glaciers are quite common and are distributed globally. Using Carbon Glacier, Mount Rainier, U.S.A., as a type locality and case study, we show aspects of the floristic and structural diversity as well as spatial patterns of plant growth on the glacier surface. Migration strategies, root characteristics, and origin and dispersal strategies for vascular plant species are documented. Also reported are special microclimatic conditions in these areas allowing for this remarkable plant ecology. We find that alpine taxa can grow considerably below their usual altitudinal niche due to the cooler subsurface soil temperatures found on glacial debris with ice underneath, and that may have significantly altered the spatial distribution of such flora during full glacial conditions. This in turn creates previously undocumented areas from which alpine, and perhaps arctic, plant species reestablished in post-glacial time. This hypothesis is complementary to both the nunatak hypothesis and tabula rasa theory and possibly helps solve the ongoing controversy between them. ?? 2007 Regents of the University of Colorado.

Arctic, Antarctic, and Alpine Research↗
USGS2008

Forewarned is forearmed! Progress in development of the U.S. National Early Detection and Rapid Response System for invasive plants: Proposal for a North American early warning system for invasive plants

Currently, a National Early Detection and Rapid Response System (EDRR) for Invasive Plants is being developed in the United States. Conceptually, the system is a coordinated framework of local, state, and national interagency groups that is designed to prevent the establishment and spread of new invasive plants through early detection and reporting of suspected new invaders, identification and vouchering of specimens by cooperating botanists, archiving of confirmed new records in regional and national plant databases, rapid assessment of confirmed new exotic species by federal and state scientists, and rapid control response to new incursions that can be eradicated. A National EDRR Framework is also being developed in Canada, through the work of the federal ministries, as well as provincial invasive species councils. With a functional EDRR communications structure in place in Canada and the U.S., a North American Early Warning System for Invasive Plants can be developed to help publicize information about new and emerging invasive plants across the continent.

Conference Paper↗
USGS2019

Effect of permafrost thaw on plant and soil fungal community in the boreal forest: Does fungal community change mediate plant productivity response?

Permafrost thaw is leading to rapid shifts in boreal ecosystem function. Permafrost thaw affects soil carbon turnover through changes in soil hydrology, however, the biotic mechanisms regulating plant community response remain elusive. Here, we measured the response of fungal community composition and soil nutrient content in an intact permafrost plateau forest soil and an adjacent thermokarst bog using barcoded amplicon targeting ITS2 and 28S rRNA genes. Next, we used the soils from the permafrost plateau and the thermokarst bog as soil inoculum in a greenhouse experiment to measure whether shifts in fungal community and soil water level regulate plant productivity. Overall, we found that fungal community composition differed significantly between the thawed and intact permafrost sites, but soil nutrient content did not. Relative abundance of mycorrhizal fungal taxa decreased while relative abundance of putative fungal pathogens increased with permafrost thaw. In the greenhouse, we found that ecto- and arbuscular associated host plants had higher productivity in permafrost-intact soils relative to thawed soils. However, productivity of non-mycorrhizal tussock grass was more affected by soil water levels than soil communities. Our results suggest that fungal communities are crucial in mediating plant response to permafrost thaws inducing hydrology changes.

Alaska↗
USGS2015

Plant-plant interactions in a subtropical mangrove-to-marsh transition zone: effects of environmental drivers

Questions Does the presence of herbaceous vegetation affect the establishment success of mangrove tree species in the transition zone between subtropical coastal mangrove forests and marshes? How do plant–plant interactions in this transition zone respond to variation in two primary coastal environmental drivers? Location Subtropical coastal region of the southern United States. Methods We conducted a greenhouse study to better understand how abiotic factors affect plant species interactions in the mangrove-to-marsh transition zone, or ecotone. We manipulated salinity (fresh, brackish or salt water) and hydrologic conditions (continuously saturated or 20-cm tidal range) to simulate ecotonal environments. Propagules of the mangroves Avicennia germinans and Laguncularia racemosa were introduced to mesocosms containing an established marsh community. Both mangrove species were also introduced to containers lacking other vegetation. We monitored mangrove establishment success and survival over 22 mo. Mangrove growth was measured as stem height and above-ground biomass. Stem height, stem density and above-ground biomass of the dominant marsh species were documented. Results Establishment success of A. germinans was reduced under saturated saltwater conditions, but establishment of L. racemosa was not affected by experimental treatments. There was complete mortality of A. germinans in mesocosms under freshwater conditions, and very low survival of L. racemosa . In contrast, survival of both species in monoculture under freshwater conditions exceeded 62%. The marsh species Distichlis spicata and Eleocharis cellulosa suppressed growth of both mangroves throughout the experiment, whereas the mangroves did not affect herbaceous species growth. The magnitude of growth suppression by marsh species varied with environmental conditions; suppression was often higher in saturated compared to tidal conditions, and higher in fresh and salt water compared to brackish water. Conclusions Our results indicate that herbaceous marsh species can suppress mangrove early seedling growth. Depending on species composition and density, marsh plants can slow mangrove landward migration under predicted climate change scenarios as salinity in freshwater and oligohaline wetlands increases with rising sea levels. Change in the relative coverage of mangrove forests and marshes will depend on both the ability of marsh species to migrate further inland as mangroves advance, and the ability of shoreline mangroves to adjust to rising sea level through accretionary processes.

Journal of Vegetation Science↗
USGS1947

The zinc content of plants on the Freidensville zinc slime ponds in relation to biogeochemical prospecting

The zinc content of thirty different kinds of plants growing on slime ponds containing on the average 12.5 per cent zinc were determined by the dithizone method. The zinc content ranged from 39 p.p.m. in the fruit of the false solomon's seal (Smilacina racemosa) to 5,400 in the horsetail (Equiseteum arvense}. This latter plant varied considerably in zinc at different places on the slime ponds. The zinc contents of the aspen (Populus grandidentata}, ragweed {Ambrosia artemisiifolia), and horsetail grown on normal soils are compared to those on the slime ponds and it is recommended that the poplar and ragweed be studied further as indicators of zinc ore bodies.

Pennsylvania↗
USGS2023

Selection of microhabitats, plants, and plant parts eaten by a threatened tortoise: Observations during a superbloom

Populations of the threatened desert tortoise ( Gopherus agassizii ) continue to decline throughout the geographic range, in part because of degraded and fragmented habitats in the Mojave and western Sonoran deserts. The species is herbivorous and highly selective in choice of plant species. To increase options for recovery, we analyzed behaviors, patterns of movements while foraging, and parts of plants consumed during a superbloom. We characterized foraging routes and the habitat strata and microhabitats where tortoises traveled to eat preferred wildflower species. Tortoises walked one foraging route per day in early spring, often switched to two routes per day in middle and late spring with rise of midday temperatures. They chose habitat strata (primarily hills and ephemeral stream channels) and three of seven microhabitats for foraging on preferred food plants. Preferred microhabitats were intershrub open space and small (1–2 m wide) ephemeral stream channels. They rarely took bites of forbs growing under and in the dripline of shrubs or nonnative forbs and grasses. Tortoises typically did not select specific plant parts to eat but important exceptions occurred. For example, they usually ignored the inflorescences of the annual Eremothera boothii and, when eating the non-native annual Erodium cicutarium , tended to focus on fruits. All such information aids recovery efforts to restore declining tortoise populations.

California↗
USGS2025

Impact of thermoelectric power plant operations and water use reporting methods on thermoelectric power plant water use

Thermoelectric power generation accounts for over 41% of total U.S. freshwater withdrawals, making understanding the determinants of power plants’ water withdrawals (WW) and consumption (WC) critical for reducing the sector’s reliance on increasingly scarce water resources. However, reported data inconsistencies and incomplete analysis of potential determinants of thermoelectric water use hinder such understanding. We address these challenges by introducing a novel data filtering method and a more complete assessment of water use determinants. First, we applied a power-cooling ratio as an operations-based data filter that removed operationally implausible records while retaining more original data, outperforming previous statistical filtering methods. Second, we found that different water use reporting methods (WURMs) provided statistically significantly different WW and WC values, revealing the importance of this previously unrecognized feature in reported water use records. Third, our data-driven approach showed that traditionally emphasized features─such as cooling technology and gross generation─are of primary importance but can be surpassed by other, often overlooked, features when modeling WW or WC individually. The plant configuration, cooling technology, and gross generation were the most important features of WW, whereas WURM, cooling technology, and reporting month were the most important for WC. These findings can improve thermoelectric power plant management, water use reporting accuracy, and water use modeling.

Environmental Science & Technology↗
USGS2007

Invasive plants and their ecological strategies: Prediction and explanation of woody plant invasion in New England

Effective management of introduced species requires the early identification of species that pose a significant threat of becoming invasive. To better understand the invasive ecology of species in New England, USA, we compiled a character data set with which to compare non-native species that are known invaders to non-native species that are not currently known to be invasive. In contrast to previous biological trait-based models, we employed a Bayesian hierarchical analysis to identify sets of plant traits associated with invasiveness for each of three growth forms (vines, shrubs, and trees). The resulting models identify a suite of 'invasive traits' highlighting the ecology associated with invasiveness for each of three growth forms. The most effective predictors of invasiveness that emerged from our model were 'invasive elsewhere', 'fast growth rate', 'native latitudinal range', and 'growth form'. The contrast among growth forms was pronounced. For example, 'wind dispersal' was positively correlated with invasiveness in trees, but negatively correlated in shrubs and vines. The predictive model was able to correctly classify invasive plants 67% of the time (22/33), and non-invasive plants 95% of the time (204/215). A number of potential future invasive species in New England that deserve management consideration were identified. ?? 2007 The Authors.

Diversity and Distributions↗
USGS1979

Low-flow characteristics of Wisconsin streams at sewage-treatment plants and industrial plants

Low-flow characteristics of Wisconsin streams at 397 sewage-treatment plants and 143 industrial plants in 30 river basins are presented in this report. The low-flow characteristics are the annual minimum 7-day mean flow below which the flow will fall on the average of once in 2 years (Q 7,2 ) and the annual minimum 7-day mean flow below which the flow will fall on the average of once in 10 years (Q 7, 10 ). The low-flow characteristics at most sewage-treatment and industrial plants (project stations) were determined by correlating base-flow measurements at the project stations with the concurrent daily mean flow at continuous-record gaging stations in the area. The Q 7, 2 and Q 7,10 discharges determined by a frequency analysis at the continuous-record gaging stations were used to estimate the Q 7,2 and Q 7,10 at the project stations. For some project stations the low-flow characteristics also were determined by frequency analysis at nearby continuous-record gaging stations or correlation analysis at nearby low-flow partial-record stations. The Q 7, 2 values ranged from 0 to 3,770 ft 3 /s and Q 7, 10 values ranged from 2,790 ft 3 /s. The accuracy of the estimated low-flow characteristics is evaluated according to the type and amount of data used to determine the low-flow characteristics. The accuracy determined by the standard error of estimate for the 10-year low flow (SE 7, 10 )) ranged from an average of 18 percent at continuous-record gaging stations to an average of h6 percent when only three base-flow measurements were available.

Wisconsin↗
USGS2015

Prediction of plant vulnerability to salinity increase in a coastal ecosystem by stable isotopic composition (δ 18 O) of plant stem water: a model study

Sea level rise and the subsequent intrusion of saline seawater can result in an increase in soil salinity, and potentially cause coastal salinity-intolerant vegetation (for example, hardwood hammocks or pines) to be replaced by salinity-tolerant vegetation (for example, mangroves or salt marshes). Although the vegetation shifts can be easily monitored by satellite imagery, it is hard to predict a particular area or even a particular tree that is vulnerable to such a shift. To find an appropriate indicator for the potential vegetation shift, we incorporated stable isotope 18 O abundance as a tracer in various hydrologic components (for example, vadose zone, water table) in a previously published model describing ecosystem shifts between hammock and mangrove communities in southern Florida. Our simulations showed that (1) there was a linear relationship between salinity and the δ 18 O value in the water table, whereas this relationship was curvilinear in the vadose zone; (2) hammock trees with higher probability of being replaced by mangroves had higher δ 18 O values of plant stem water, and this difference could be detected 2 years before the trees reached a tipping point, beyond which future replacement became certain; and (3) individuals that were eventually replaced by mangroves from the hammock tree population with a 50% replacement probability had higher stem water δ 18 O values 3 years before their replacement became certain compared to those from the same population which were not replaced. Overall, these simulation results suggest that it is promising to track the yearly δ 18 O values of plant stem water in hammock forests to predict impending salinity stress and mortality.

Ecosystems↗