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At least 1,081 records · Page 60Linked to original sources
USGS2011

Effects of herbivory and flooding on reforestation of baldcypress ( Taxodium distichum [L.]) saplings planted in Caddo Lake, Texas

The effects of herbivory and flooding were examined on survival and growth of planted baldcypress ( Taxodium distichum (L.) Rich.) saplings at three sites in Caddo Lake, TX, over a 4-yr period. There were two flood regimes (shallow periodic and deep continuous), where half of the saplings in each flood regime were protected by tree shelters to prevent herbivory. By the end of the first year, over 80% of saplings survived with half of saplings classified as healthy. By the end of the fourth year, only half of the saplings were alive and one-third were healthy. At all three sites, the combination of no protection and continuous flooding resulted in a significant number of missing saplings. Likewise, most unprotected saplings in periodic flooding were missing by the end of the study. Saplings clipped by herbivores showed about 50% chance of recovery, but many of the sprouts were of poor quality. Protected saplings in tree shelters achieved significantly greater survival and height growth.

Louisiana, Texas↗
USGS2001

The condition of browse plants at the Theodore Roosevelt Memorial Ranch (TRMR)

The Theodore Roosevelt Memorial Ranch (TRM), owned and operated by the Boone and Crockett Club, spans 6,000 acres along the Rocky Mountain East Front. The ranch is located west of Dupuyer, Montana, on the forks of Dupuyer and Scoffin Creeks. Each fall, mule deer migrate from the Bob Marshall Wilderness and adjacent Lewis and Clark and Flathead National Forests to the ranch and adjacent private lands. Winter counts and classifications have been conducted since the mid-1970’s by Montana Fish, Wildlife & Parks personnel. In addition to mule deer, domestic livestock, whitetailed deer and elk compete for space and forage on the winter range. Browse species such as chokecherry, aspen, serviceberry, red osier dogwood, horizontal juniper, and willows are utilized by all ungulates in the area. The Dupuyer Creek winter range shows evidence of severe over-browsing on these species. Coincidentally, mule deer and elk populations have historically been higher here than other areas along the mountain front. Over the past 22 years, mule deer densities have been calculated at over 75 deer per square mile over the entire winter range and up to 200 per square mile on the TRM itself. Winter ranges are occupied from mid-November through May. Winter counts are conducted in January and again in March to assess fawn and adult survival. An average of 2,100 mule deer are surveyed annually, with fawn/doe ratios of 71, fawn/adult ratios of 54, and buck/does ratios of 33 (ratios are expressed as animals per 100 does or adults). Mule deer migrate back to higher elevation summer ranges in mid- to late-May, traveling as far north as Glacier National Park and westward to the South Fork of the Flathead River. Less than 15 percent of the wintering population remains along the mountain front during the summer. Movements back to winter range may occur in early October, with the majority of animals present by November 15th. As background for a more comprehensive study, we collected data in September and October 1999 from which to assess the impact of ungulates on browse plants. There were three general objectives: 1) determine the current level of browsing intensity, 2) reconstruct histories of browsing, and 3) determine the effect of browsing on rate of stem growth.

Montana↗
USGS1999

New plant records from East Maui for 1998

The following contributions include new island records, new naturalized records, a range extension, and a name change of plants located on East Maui, Hawaii. Also included is a map of Maui showing locations of collections discussed in text. Voucher specimens are housed in the Bishop Museum, Honolulu (BISH).

Bishop Museum Occasional Papers↗
USGS2011

Waste isolation and contaminant migration - Tools and techniques for monitoring the saturated zone-unsaturated zone-plant-atmosphere continuum

In 1976 the U.S. Geological Survey (USGS) began studies of unsaturated zone hydrology next to the Nation’s first commercial disposal facility for low-level radioactive waste (LLRW) near Beatty, NV. Recognizing the need for long-term data collection, the USGS in 1983 established research management areas in the vicinity of the waste-burial facility through agreements with the Bureau of Land Management and the State of Nevada. Within this framework, the Amargosa Desert Research Site (ADRS; http://nevada.usgs.gov/adrs/) is serving as a field laboratory for the sustained study of water-, gas-, and contaminant-transport processes, and the development of models and methods to characterize flow and transport. The research is built on multiple lines of data that include: micrometeorology; evapotranspiration; plant metrics; soil and sediment properties; unsaturated-zone moisture, temperature, and gas composition; geology and geophysics; and groundwater. Contaminant data include tritium, radiocarbon, volatile-organic compounds (VOCs), and elemental mercury. Presented here is a summary of monitoring tools and techniques that are being applied in studies of waste isolation and contaminant migration.

Conference Paper↗
USGS2024

Permafrost history in the sporadic zone as context for recent carbon loss using acryostratigraphy, plant macrofossil, and stable isotope approach

Permafrost and landscape history, in addition to ground ice content, are increasingly identified as important components in predicting permafrost thaw trajectories. Together with cryostratigraphy, plant remains and stable isotopes can provide useful information about past permafrost aggradation and thaw. We applied these methods with radiocarbon dating on peat and permafrost cores in the sporadic zone on the Kenai Peninsula, Alaska, to provide a longterm framework for understanding recent thaw and implications for carbon loss.

Alaska↗
USGS1980

Pyrometallurgical recovery of Chromium from scrap metals: Laboratory studies and pilot plant design

As part of an effort to establish processes that could be exploited in case of adverse changes in international chromium production and trading patterns, this study was sponsored by the Federal Emergency Management Agency (formerly the Federal Preparedness Agency) through the Bureau of Mines, U.S. Department of the Interior, to experimentally determine the feasibility of recovering chromium from critical scrap metals containing significant quantities of this element. Based on a conceptual pyrometallurgical chromium recovery flowsheet developed at Arthur D. Little, Inc., the experimental program described in this report demonstrated key process steps for the recovery of chromium as ferrochromium in a batch process. The process involves oxidation of chromium into a slag phase, subsequent separation of the slag phase from the remaining metal, followed by reduction of chromium from the slag phase to produce ferrochromium. Drawing on this experimental program, descriptive material and cost estimates are developed for a pilot plant to demonstrate the process.

Report↗
USGS2001

Type characters of non-native plant species in Great Lakes national parks (USA)

Non-native plant species are increasing in frequency and abundance in many natural areas in the United States. In Midwestern National Parks, as much as one third of the flora may be non-native. It was hypothesized that botanical characters of these species could be used to typify them and improve the methods of predicting invasions. Data on 19 characters of 341 non-native species from the four Great Lakes national lakeshores (Apostle Islands, Indiana Dunes, Pictured Rocks, and Sleeping Bear Dunes) and invasive non-native species for the State of Wisconsin were collected and studied. For many of the species, little data could be found, but for 139 of them, data were collected for at least 80% of the characters. The frequencies of classes of the characters were tabulated and ranked to typify the most common non-native species. This led to a description of a 'type species' just for these four National Parks. Three species of Cirsium, including Canada (C. arvense), marsh (C. palustre) and bull thistle (C. vulgare), matched the type species better than other species. C. vulgare occurs in more National Parks than the other thistles.

Indiana, Michigan, Wisconsin↗
USGS2004

Temporal and spatial patterns in emergence and early survival of perennial plants in the Sonoran Desert

Seedling emergence and survival of 15 perennial species were studied for six years in a 557-m2 permanent plot at Tumamoc Hill, Arizona, USA, an ungrazed site in the northern Sonoran Desert. The minimum rain required for germination and emergence ranged from 17.5 to 35.6 mm. Few species emerged in every year of the study. First-year survival averaged across all 15 species was 3.7%; only 0.1% of seedlings lived as long as four years. The odds of survival in the first year improved with increased rain. About three times as many seedlings died from predation as desiccation. In 2-m2 subplots, mortality of three woody species in the first 30 days after emergence appeared to be independent of seedling density. Short-, moderate-, and long-lived species displayed distinct survival strategies. Long-lived species compensated for generally poor seedling survival by frequent germination and emergence. Moderate-lived species exhibited highly episodic germination and emergence, a potentially risky behavior that might have been offset to some extent by relatively good long-term survival. Short-lived species had the highest seedling survival. Because these species can bloom in their first year, good early survival meant that some individuals were able to reproduce before they died.

Plant Ecology↗
USGS2015

Effects of topoclimatic complexity on the composition of woody plant communities

Topography can create substantial environmental variation at fine spatial scales. Shaped by slope, aspect, hill-position and elevation, topoclimate heterogeneity may increase ecological diversity, and act as a spatial buffer for vegetation responding to climate change. Strong links have been observed between climate heterogeneity and species diversity at broader scales, but the importance of topoclimate for woody vegetation across small spatial extents merits closer examination. We established woody vegetation monitoring plots in mixed evergreen-deciduous woodlands that spanned topoclimate gradients of a topographically heterogeneous landscape in northern California. We investigated the association between the structure of adult and regenerating size classes of woody vegetation and multidimensional topoclimate at a fine scale. We found a significant effect of topoclimate on both single-species distributions and community composition. Effects of topoclimate were evident in the regenerating size class for all dominant species (four Quercus spp. , Umbellularia californica and Pseudotsuga menziesii ) but only in two dominant species ( Quercus agrifolia and Quercus garryana ) for the adult size class. Adult abundance was correlated with water balance parameters (e.g. climatic water deficit) and recruit abundance was correlated with an interaction between the topoclimate parameters and conspecific adult abundance (likely reflecting local seed dispersal). However, in all cases, the topoclimate signal was weak. The magnitude of environmental variation across our study site may be small relative to the tolerance of long-lived woody species. Dispersal limitations, management practices and patchy disturbance regimes also may interact with topoclimate, weakening its influence on woody vegetation distributions. Our study supports the biological relevance of multidimensional topoclimate for mixed woodland communities, but highlights that this relationship might be mediated by interacting factors at local scales.

California↗
USGS2003

Native weeds and exotic plants: relationships to disturbance in mixed grass prairie

The paper compares distributions of native weedy species and exotic species with respect to three kinds of disturbance, roads, trails, and prairie dog towns. Data were collected at the north and south units of Theodore Roosevelt National Park and at Wind Cave National Park. The paper concludes that many exotic species differ substantially from native weeds in their exploitation of disturbance. It is thus not useful to manage exotics as if they were just another weed.

Plant Ecology↗
USGS2019

Changes in behavior are unable to disrupt a trophic cascade involving a specialist herbivore and its food plant

Changes in ecological conditions can induce changes in behavior and demography of wild organisms, which in turn may influence population dynamics. Pacific black brant (Branta bernicla nigricans) nesting in colonies on the Yukon-Kuskokwim Delta (YKD) in western Alaska have declined substantially (~50%) since the turn of the century. Pacific black brant are herbivores that rely heavily on Carex subspathacea (Hoppner’s sedge) during growth and development. The availability of C. subspathacea affects gosling growth rates, which subsequently affect pre- and post-fledging survival, as well as size and breeding probability as an adult. We predicted that long-term declines in C. subspathacea have affected gosling growth rates, despite the potential of behavior to buffer changes in food availability during brood rearing. We used Bayesian hierarchical mixed-effects models to examine long-term (1987 – 2015) shifts in brant behavior during brood-rearing, forage availability, and gosling growth rates at the Tutakoke River colony. We showed that locomotion behaviors have increased (β = 0.05, 95% CRI 0.032 – 0.068) while resting behaviors have decreased (β = -0.024, 95% CRI -0.041 – -0.007), potentially in response to long-term shifts in forage availability and brood density. Concurrently, gosling growth rates have decreased substantially (β = -0.096, 95% CRI -0.198 – -0.014) despite shifts in behavior, mirroring long-term declines in the abundance of C. subspathacea (β = -0.194, 95% CRI -0.350 – -0.037). These results have important implications for individual fitness and population viability, where shifts in gosling behavior putatively fail to mitigate long-term declines in forage availability.

Article↗
USGS2013

Strong species-environment feedback shapes plant community assembly along environmental gradients

An aim of community ecology is to understand the patterns of competing species assembly along environmental gradients. All species interact with their environments. However, theories of community assembly have seldom taken into account the effects of species that are able to engineer the environment. In this modeling study, we integrate the species' engineering trait together with processes of immigration and local dispersal into a theory of community assembly. We quantify the species' engineering trait as the degree to which it can move the local environment away from its baseline state towards the optimum state of the species (species-environment feedback). We find that, in the presence of immigration from a regional pool, strong feedback can increase local species richness; however, in the absence of continual immigration, species richness is a declining function of the strength of species-environment feedback. This shift from a negative effect of engineering strength on species richness to a positive effect, as immigration rate increases, is clearer when there is spatial heterogeneity in the form of a gradient in environmental conditions than when the environment is homogeneous or it is randomly heterogeneous. Increasing the scale over which local dispersal occurs can facilitate species richness when there is no species-environment feedback or when the feedback is weak. However, increases in the spatial scale of dispersal can reduce species richness when the species-environment feedback is strong. These results expand the theoretical basis for understanding the effects of the strength of species-environment feedback on community assembly.

Ecology and Evolution↗
USGS2017

Effects of experimentally reduced snowpack and passive warming on montane meadow plant phenology and floral resources

Climate change can have a broad range of effects on ecosystems and organisms, and early responses may include shifts in vegetation phenology and productivity that may not coincide with the energetics and forage timing of higher trophic levels. We evaluated phenology, annual height growth, and foliar frost responses of forbs to a factorial experiment of snow removal (SR) and warming in a high-elevation meadow over two years in the Rocky Mountains, United States. Species included arrowleaf balsamroot ( Balsamorhiza sagittata , early-season emergence and flowering) and buckwheat ( Eriogonum umbellatum, semi-woody and late-season flowering), key forbs for pollinator and nectar-using animal communities that are widely distributed and locally abundant in western North America. Snow removal exerted stronger effects than did warming, and advanced phenology differently for each species. Specifically, SR advanced green-up by a few days for B. sagittata to >2 wk in E. umbellatum , and led to 5- to 11-d advances in flowering of B. sagittata in one year and advances in bud break in 3 of 4 species/yr combinations. Snow removal increased height of E. umbellatum appreciably (~5 cm added to ~22.8 cm in control), but led to substantial increases in frost damage to flowers of B. sagittata . Whereas warming had no effects on E. umbellatum , it increased heights of B. sagittata by >6 cm (compared to 30.7 cm in control plots) and moreover led to appreciable reductions in frost damage to flowers. These data suggest that timing of snowmelt, which is highly variable from year to year but is advancing in recent decades, has a greater impact on these critical phenological, growth, and floral survival traits and floral/nectar resources than warming per se, although warming mitigated early effects of SR on frost kill of flowers. Given the short growing season of these species, the shifts could cause uncoupling in nectar availability and timing of foraging.

Ecosphere↗