SEARCH · Search USGS

Results for “Plant Ecology”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources

USGS2016

Negative impacts of invasive plants on conservation of sensitive desert wildlife

Habitat disturbance from development, resource extraction, off-road vehicle use, and energy development ranks highly among threats to desert systems worldwide. In the Mojave Desert, United States, these disturbances have promoted the establishment of nonnative plants, so that native grasses and forbs are now intermixed with, or have been replaced by invasive, nonnative Mediterranean grasses. This shift in plant composition has altered food availability for Mojave Desert tortoises ( Gopherus agassizii ), a federally listed species. We hypothesized that this change in forage would negatively influence the physiological ecology, immune competence, and health of neonatal and yearling tortoises. To test this, we monitored the effects of diet on growth, body condition, immunological responses (measured by gene transcription), and survival for 100 captive Mojave tortoises. Tortoises were assigned to one of five diets: native forbs, native grass, invasive grass, and native forbs combined with either the native or invasive grass. Tortoises eating native forbs had better body condition and immune functions, grew more, and had higher survival rates (>95%) than tortoises consuming any other diet. At the end of the experiment, 32% of individuals fed only native grass and 37% fed only invasive grass were found dead or removed from the experiment due to poor body conditions. In contrast, all tortoises fed either the native forb or combined native forb and native grass diets survived and were in good condition. Health and body condition quickly declined for tortoises fed only the native grass ( Festuca octoflora ) or invasive grass ( Bromus rubens ) with notable loss of fat and muscle mass and increased muscular atrophy. Bromus rubens seeds were found embedded in the oral mucosa and tongue in most individuals eating that diet, which led to mucosal inflammation. Genes indicative of physiological, immune, and metabolic functions were transcribed at lower levels for individuals fed B. rubens , indicating potential greater susceptibility to disease or other health-related problems. This study highlights the negative indirect effects of invasive grasses, such as red brome, in desert ecosystems, and provides definitive evidence of a larger negative consequence to health, survival, and ultimately population recruitment for Mojave Desert tortoises than previously understood.

Ecosphere↗

USGS2022

The hydroclimate niche: A tool for predicting and managing riparian plant community responses to streamflow seasonality

Habitat suitability is a consequence of interacting environmental factors. In riparian ecosystems, suitable plant habitat is influenced by interactions between stream hydrology and climate, hereafter referred to as “hydroclimate”. We tested the hypothesis that hydroclimate variables would improve the fit of ecological niche models for a suite of riparian species using occurrence data from the western United States. We focus on the climate conditions (temperature, precipitation and vapor pressure deficit) during the months of lowest and highest streamflow as integrative hydroclimate metrics of resource and stress levels. We found that the inclusion of hydroclimate variables improved model fit for all species in the western USA dataset. We then tested the utility of the improved habitat suitability models by projecting them onto a regulated segment of the Colorado River to assess potential impacts of streamflow seasonality on vegetation metrics of management concern. Species frequency derived from independent survey data in the Colorado River segment was significantly higher for species with predicted suitable habitat than for species without predicted suitable habitat. Under different simulated hydrographs for the Colorado River, overall species richness was predicted to be greatest with peak streamflows during summer, and native-to-non-native species ratios were predicted to be greatest with lowest streamflows in winter. Summer high flows were particularly associated with higher predicted habitat suitability for species that have increased in cover over recent decades (e.g., Pluchea sericea, Baccharis species). We conclude that hydroclimate covariates can be useful tools for predicting how riparian vegetation communities respond to changes in the seasonal timing of low and high streamflows.

River Research and Applications↗

USGS2020

Mapping hotspots of potential ecosystem fragility using commonly available spatial data

Effective conservation requires prioritizing areas that are vulnerable to large, irreversible changes. Unfortunately, rigorously documenting these changes with experiments and long-term monitoring is not only costly, but may provide evidence that is too late to facilitate proactive decisions. We use a simple model to illustrate that commonly available short-term spatial, “snapshot”, data from a given ecosystem along an environmental gradient can be used to identify environmental conditions under which different ecosystem states (e.g. different species compositions) co-occur in space. These environmental conditions are those under which future perturbations have the potential for discontinuous large, sometimes irreversible, effects; and can be mapped in space to predict potential spatial hotspots of ecosystem fragility. We apply these insights to ecologically important high-elevation subalpine meadows of the Sierra Nevada (California). Our analysis reveals specific areas within meadows that may be more vulnerable than others because their plant communities have the potential to shift to a different state. These shifts can be mechanistically explained by interactions between the vegetation and the local water regimes and/or the upper soil conditions. Our study provides a simple workflow using commonly available data to help prioritize conservation areas based on their potential sensitivity to upcoming perturbations. Such an approach could be very valuable to make most efficient use of conservation and management resources in the context of ongoing global changes.

California↗

USGS2026

A review of extraction techniques for per- and polyfluoroalkyl substances in graminaceous plants

Per- and polyfluoroalkyl substances (PFAS) are a wide-ranging class of manufactured chemicals that are environmentally persistent. Due to their ubiquity and resistance to degradation, PFAS readily bioaccumulate in a variety of environmental matrices and elicit a range of toxicological impacts. Despite an increase in research into these compounds, there is a clear gap in consensus on extraction techniques to quantify many PFAS in certain environmental media, particularly at critical points in agricultural food systems such as pasture grasses and feedstocks. Developing methods for more comprehensive and accurate extraction of PFAS in plant tissues is crucial for the biomonitoring of PFAS contamination in these ecosystems. This review seeks to identify relevant information pertaining to the partitioning of PFAS in plant matrices and evaluate the performance of previously established methods for the extraction of PFAS in graminaceous plants. Evaluated methods varied widely in extraction techniques, limits of detection and accuracy. This review provides a framework for enhancing PFAS analysis by tailoring extraction and cleanup strategies to both complex plant matrices and diverse analyte properties. Standardizing these methodologies will provide the high-quality data essential for ecotoxicologists and policymakers to accurately map the metabolic fate and ecological risks of these pollutants across food webs.

Critical Reviews in Analytical Chemistry↗

USGS2004

Nutrient controls on biocomplexity of mangrove ecosystems

Mangrove forests are important coastal ecosystems that provide a variety of ecological and societal services. These intertidal, tree-dominated communities along tropical coastlines are often described as “simple systems,” compared to other tropical forests with larger numbers of plant species and multiple understory strata; however, mangrove ecosystems have complex trophic structures, and organisms exhibit unique physiological, morphological, and behavioral adaptations to environmental conditions characteristic of the land-sea interface. Biogeochemical functioning of mangrove forests is also controlled by interactions among the microbial, plant, and animal communities and feedback linkages mediated by hydrology and other forcing functions. Scientists with the U.S. Geological Survey (USGS) at the National Wetlands Research Center are working to understand more fully the impact of nutrient variability on these delicate and important ecosystems.

Fact Sheet↗

USGS2006

Potential effects of elevated atmospheric carbon dioxide (CO 2 ) on coastal wetlands

Carbon dioxide (CO 2 ) concentration in the atmosphere has steadily increased from 280 parts per million (ppm) in preindustrial times to 381 ppm today and is predicted by some models to double within the next century. Some of the important pathways whereby changes in atmospheric CO 2 may impact coastal wetlands include changes in temperature, rainfall, and hurricane intensity ( fig. 1 ). Increases in CO 2 can contribute to global warming, which may (1) accelerate sea-level rise through melting of polar ice fields and steric expansion of oceans, (2) alter rainfall patterns and salinity regimes, and (3) change the intensity and frequency of tropical storms and hurricanes. Sea-level rise combined with changes in storm activity may affect erosion and sedimentation rates and patterns in coastal wetlands and maintenance of soil elevations. Feedback loops between plant growth and hydroedaphic conditions also contribute to maintenance of marsh elevations through accumulation of organic matter. Although increasing CO 2 concentration may contribute to global warming and climate changes, it may also have a direct impact on plant growth and development by stimulating photosynthesis or improving water use efficiency. Scientists with the U.S. Geological Survey are examining responses of wetland plants to elevated CO 2 concentration and other factors. This research will lead to a better understanding of future changes in marsh species composition, successional rates and patterns, ecological functioning, and vulnerability to sea-level rise and other global change factors.

Fact Sheet↗

USGS2007

The diversity-biomass-productivity relationships in grassland management and restoration

Diversity, biomass, and productivity, the three key community/ecosystem variables, are interrelated and pose reciprocal influences on each other. The relationships among the three variables have been a central focus in ecology and formed two schools of fundamentally different nature with two related applications: (1) management - how biomass manipulation (e.g., grazing, burning) affects diversity and productivity, and (2) restoration - how diversity manipulation (e.g., seeding, planting) affects biomass and productivity. In the past, the two apparently related aspects have been studied intensively but separately in basic research and the reciprocal effects of the three variables and applied aspects have not been jointly addressed. In most cases, optimal management often involves regulating biomass so that high diversity and productivity or other preferred habitat characteristics can be achieved and maintained, while restoration usually involves planting/seeding a certain number and/or combination of native species so that the native structure and function of the habitat can be restored and degraded ecosystems can recover faster. This article attempts to unify these two schools and discusses the significance and implications of the diversity-biomass-productivity relationships in practice, with particular emphasis on grassland ecosystems. ?? 2006 Gesellschaft fu??r O??kologie.

Basic and Applied Ecology↗

USGS2014

Strategies for preventing invasive plant outbreaks after prescribed fire in ponderosa pine forest

Land managers use prescribed fire to return a vital process to fire-adapted ecosystems, restore forest structure from a state altered by long-term fire suppression, and reduce wildfire intensity. However, fire often produces favorable conditions for invasive plant species, particularly if it is intense enough to reveal bare mineral soil and open previously closed canopies. Understanding the environmental or fire characteristics that explain post-fire invasive plant abundance would aid managers in efficiently finding and quickly responding to fire-caused infestations. To that end, we used an information-theoretic model-selection approach to assess the relative importance of abiotic environmental characteristics (topoedaphic position, distance from roads), pre-and post-fire biotic environmental characteristics (forest structure, understory vegetation, fuel load), and prescribed fire severity (measured in four different ways) in explaining invasive plant cover in ponderosa pine forest in South Dakota’s Black Hills. Environmental characteristics (distance from roads and post-fire forest structure) alone provided the most explanation of variation (26%) in post-fire cover of Verbascum thapsus (common mullein), but a combination of surface fire severity and environmental characteristics (pre-fire forest structure and distance from roads) explained 36–39% of the variation in post-fire cover of Cirsium arvense (Canada thistle) and all invasives together. For four species and all invasives together, their pre-fire cover explained more variation (26–82%) in post-fire cover than environmental and fire characteristics did, suggesting one strategy for reducing post-fire invasive outbreaks may be to find and control invasives before the fire. Finding them may be difficult, however, since pre-fire environmental characteristics explained only 20% of variation in pre-fire total invasive cover, and less for individual species. Thus, moderating fire intensity or targeting areas of high severity for post-fire invasive control may be the most efficient means for reducing the chances of post-fire invasive plant outbreaks when conducting prescribed fires in this region.

South Dakota, Wyoming↗

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↗

USGS2019

Patterns of big sagebrush plant community composition and stand structure in the western United States

Big sagebrush ( Artemisia tridentata Nutt.) plant communities are found in western North America and comprise a mix of shrubs, forbs, and grasses. Climate, topography, and soil water availability are important factors that shape big sagebrush stand structure and plant community composition; however, most studies have focused on understanding these relationships at sites in a small portion of the big sagebrush region. Our goal was to characterize detailed stand structure and plant composition patterns and identify environmental variables related to those patterns by sampling 15 sites distributed across the western United States. In each site, we characterized stand structure at the individual shrub level and at the site level. We quantified size distributions and assessed relationships among canopy volume, age, and height. We also characterized functional type cover and species composition and related those to climatic, topographic, and edaphic variables. Mean big sagebrush age ranged from 21 (± 8) to 57 (± 22) yr at individual sites, mean height ranged from 0.23 (± 0.12) to 0.67 (± 0.23) m, and mean canopy volume ranged from 0.03 (± 0.04) to 0.62 (± 0.51) m 3 . Bare ground and litter contributed the most cover (mean = 64%), followed by big sagebrush (mean = 39% of vascular plant cover). There was a negative relationship between big sagebrush cover and grass and forb cover. Species composition was related to both climate and elevation, likely because these variables influence water availability. Although our study was limited to 15 field sites, our detailed descriptions of widely distributed sites provide insight into the magnitude of variability in big sagebrush plant community structure.

Rangeland Ecology and Management↗

USGS2015

Does the stress-gradient hypothesis hold water? Disentangling spatial and temporal variation in plant effects on soil moisture in dryland systems

The nature of the relationship between water limitation and facilitation has been one of the most contentious debates surrounding the stress-gradient hypothesis (SGH), which states that plant-plant interactions shift from competition to facilitation with increasing environmental stress. We take a closer look at the potential role of soil moisture in mediating plant-plant interaction outcomes by assessing effects of climate and soil texture on plant modulation of soil moisture. Using an empirically-parameterized soil moisture model, we simulated soil moisture dynamics beneath shrubs and in un-vegetated coarse and fine soils for 1000 sites in the Western United States with <700 mm mean annual precipitation. This threshold reflects the transition from dryland (<600 mm precipitation) to mesic ecosystems. Positive effects of shrubs on shallow soil moisture (i.e. the difference between shrub and interspace soil moisture) decreased along the aridity gradient when long-term average conditions were considered, contrary to expectations based on the SGH. Negative effects of shrubs on deeper soil moisture also increased with aridity. However, when extreme years were considered, positive effects of shrub on soil moisture were greatest at intermediate points along the spatial aridity gradient, consistent with a hump-backed model of plant-plant interactions. When viewed through time within a site, shrub effects on shallow soil moisture were positively related to precipitation, with more complex relationships exhibited in deeper soils Taken together, the results of this simulation study suggest that plant effects on soil moisture are predictable based on relatively general relationships between precipitation inputs and differential evaporation and transpiration rates between plant and interspace microsites that are largely driven by temperature. In particular, this study highlights the importance of differentiating between temporal and spatial variation in weather and climate, respectively, in determining plant effects on available soil moisture. Rather than focusing on the somewhat coarse-scale predictions of the SGH, it may be more beneficial to explicitly incorporate plant effects on soil moisture into predictive models of plant-plant interaction outcomes in drylands.

Functional Ecology↗

USGS1998

Herbivore effects on plant species density at varying productivity levels

Artificially increasing primary productivity decreases plant species richness in many habitats; herbivory may affect this outcome, but it has rarely been directly addressed in fertilization studies. This experiment was conducted in two Louisiana coastal marshes to examine the effects of nutrient enrichment and sediment addition on herbaceous plant communities with and without vertebrate herbivory. After three growing seasons, fertilization increased community biomass in all plots, but decreased species density (the number of species per unit area) only in plots protected from herbivory. Herbivory alone did not alter species density at either site. At the brackish marsh, herbivory caused a shift in dominance in the fertilized plots from a species that is considered the competitive dominant, but is selectively eaten, to another less palatable species. At the fresh marsh, increased dead biomass in the absence of herbivory and in the fertilized plots probably contributed to the decrease in species density, perhaps by limiting germination of annuals. Our results support those of other fertilization studies in which plant species density decreases with increased biomass, but only in those plots protected from herbivory.

Louisiana↗

USGS2024

Assessing the attractiveness of native wildflower species to bees (Hymenoptera: Anthophila) in the southeastern United States

Habitat loss, agricultural intensification, pesticide use, disease and climate change have contributed to the decline of numerous insect groups. Recent government initiatives have recognized the importance of supplementary wildflower plantings to support native bee populations, yet little information exists on the attractiveness of recommended plant species to bees. With the use of network analysis and generalized linear mixed models, we evaluated the attractiveness of 18 wildflower species belonging to 6 families (Apiaceae, Apocynaceae, Asteraceae, Fabaceae, Lamiaceae and Verbenaceae) planted in a randomized block design by conducting timed targeted sweep netting surveys. We also evaluated the floral preferences of four bee species ( Apis mellifera , Halictus poeyi/ligatus , Bombus griseocollis and Bombus impatiens ) to the planted wildflower species with the use of GLMs. We found that Asclepias tuberosa, Gaillardia pulchella and Verbena hastata attracted the greatest abundance, richness and diversity of native bees compared to the other wildflower species. Collectively, Asclepias tuberosa, Gaillardia pulchella and Verbena hastata attracted 89% of all bee taxa in the study, which exemplifies the importance of including them in a wildflower mixture to attract native bees. While several wildflower species attracted low abundance, richness and diversity of native bees such as Monarda fistulosa, Symphyotrichum pilosum and Eryngium yuccifolium , they are still ecologically important for attracting uncommon or specialist bee species and should be included in seed mixes for this reason. Solution . Our results highlight that each species of native wildflower varies in the abundance, richness and diversity of native bees they attract; this could be considered in the decision-making of landowners and land managers to promote wildflower plantings to reflect the needs of certain groups of bees of conservation interest.

Alabama↗

USGS2012

Control of reed canarygrass promotes wetland herb and tree seedling establishment in an upper Mississippi River Floodplain forest

Phalaris arundinacea (reed canarygrass) is recognized as a problematic invader of North American marshes, decreasing biodiversity and persisting in the face of control efforts. Less is known about its ecology or management in forested wetlands, providing an opportunity to apply information about factors critical to an invader's control in one wetland type to another. In a potted plant experiment and in the field, we documented strong competitive effects of reed canarygrass on the establishment and early growth of tree seedlings. In the field, we demonstrated the effectiveness of a novel restoration strategy, combining site scarification with late fall applications of pre-emergent herbicides. Treatments delayed reed canarygrass emergence the following spring, creating a window of opportunity for the early growth of native plants in the absence of competition from the grass. They also allowed for follow-up herbicide treatments during the growing season. We documented greater establishment of wetland herbs and tree seedlings in treated areas. Data from small exclosures suggest, however, that deer browsing can limit tree seedling height growth in floodplain restorations. Slower tree growth will delay canopy closure, potentially allowing reed canarygrass re-invasion. Thus, it may be necessary to protect tree seedlings from herbivory to assure forest regeneration.

Wisconsin↗

USGS2000

Sensitivity of a high-elevation Rocky Mountain watershed to altered climate and CO2

We explored the hydrologic and ecological responses of a headwater mountain catchment, Loch Vale watershed, to climate change and doubling of atmospheric CO 2 scenarios using the Regional Hydro-Ecological Simulation System (RHESSys). A slight (2°C) cooling, comparable to conditions observed over the past 40 years, led to greater snowpack and slightly less runoff, evaporation, transpiration, and plant productivity. An increase of 2°C yielded the opposite response, but model output for an increase of 4°C showed dramatic changes in timing of hydrologic responses. The snowpack was reduced by 50%, and runoff and soil water increased and occurred 4–5 weeks earlier with 4°C warming. Alpine tundra photosynthetic rates responded more to warmer and wetter conditions than subalpine forest, but subalpine forest showed a greater response to doubling of atmospheric CO 2 than tundra. Even though water use efficiency increased with the double CO 2 scenario, this had little effect on basin-wide runoff because the catchment is largely unvegetated. Changes in winter and spring climate conditions were more important to hydrologic and vegetation dynamics than changes that occurred during summer.

Water Resources Research↗

USGS2017

Novel observations of larval fire survival, feeding behavior, and host plant use in the regal fritillary, Speyeria idalia (Drury) (Nymphalidae)

Speyeria idalia is a prairie specialist that has experienced dramatic population declines throughout its range. Speyeria idalia is nearly extirpated from the eastern portion of its former range; however, populations within Kansas are relatively stable. We made several previously undescribed field observations of late-instar larvae and post-diapause female S. idalia in northeastern Kansas during 2014–2016. We report finding late-instar larvae at locations that were burned within weeks of detection. The observations of larvae shortly following a burn suggests that S . idalia larvae are capable of surviving fire and contradicts our current knowledge of this species. Additionally, we describe a feeding behavior characteristic of late-instar larvae. Larvae observed in the field and lab stripped leaves of host plants leaving only stems. This strip-style feeding behavior provided unique feeding evidence that was valuable to detecting the presence of larvae in the field. Finally, we documented larvae and post-diapause, egg depositing females using Viola sororia. The use of this relatively widespread and common plant by S. idalia populations in the Central Great Plains has only been implicitly documented but may have important conservation implications. These novel observations further our knowledge of the ecology of this imperiled species and provide timely information that may improve research and conservation management efforts directed toward S . idalia populations.

Journal of the Lepidopterists' Society↗

USGS2003

Perennial vegetation data from permanent plots on the Nevada Test Site, Nye County, Nevada

Perennial vegetation data from 68 permanent plots on the Nevada Test Site, Nye County, Nevada, are given for the period of 1963 through 2002. Dr. Janice C. Beatley established the plots in 1962 and then remeasured them periodically from 1963 through 1975. We remeasured 67 of these plots between 2000 and 2003; the remaining plot was destroyed at some time between 1975 and 1993. The plots ranged from 935 to 2,274 m in elevation and are representative of common plant associations of the Mojave Desert, the transition to Great Basin Desert, and pinyon-juniper woodlands. The purpose of this report is to describe the complete set of ecological data that Beatley collected from the Nevada Test Site from 1963 through 1975 and to present the data for perennial vegetation collected from 2000 through 2003.

Open-File Report↗

USGS2025

What is a specialist? Quantifying host breadth enables impact prediction for invasive herbivores

Herbivores are commonly classified as host specialists or generalists for various purposes, yet the definitions of these terms, and their intermediates, are often imprecise and ambiguous. We quantified host breadth for 240 non-native, tree-feeding insects in North America using phylogenetic diversity. We demonstrated that a partitioning of host breadth: (1) causes 67% of non-native insects to shift from a generalist to specialist category, (2) displays a reduction in host breadth from the native to introduced range, (3) identifies an inflection point in a model predicting the likelihood of non-native insect ecological impact, with a corresponding change in behaviour associated with specialists versus generalists, and (4) enables three models for strong prediction of whether a non-native forest insect will cause high impacts. Together, these results highlight the primacy of how herbivore host recognition and plant defences mediate whether novel host interactions will result in high impact after invasion.

Ecology Letters↗