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At least 1,657 records · Page 92Linked to original sources
USGS2001

Quality of life on the Colorado Plateau: a report to the respondents in southwestern Colorado and northwestern New Mexico

During the fall of 1998, scientists from the Midcontinent Ecological Science Center (MESC) of the U.S. Geological Survey (USGS) a?? sent a survey by mail to residents in southwest Colorado and northwest New Mexico to better understand quality of life issues in this area of the Colorado Plateau. Collaborators in this study included the Bureau of Land Management and U.S. Forest Service offices located in Durango, Colorado. The information was collected to determine: *what elements of the community and surrounding landscapes contribute to the quality of like among resident populations, and *what critical areas, elements, and special places are essential to retain quality of life.

Open-File Report↗
USGS2012

Ecology and conservation biology of avian malaria

Avian malaria is a worldwide mosquito-borne disease caused by Plasmodium parasites. These parasites occur in many avian species but primarily affect passerine birds that have not evolved with the parasite. Host pathogenicity, fitness, and population impacts are poorly understood. In contrast to continental species, introduced avian malaria poses a substantial threat to naive birds on Hawaii, the Galapagos, and other archipelagoes. In Hawaii, transmission is maintained by susceptible native birds, competence and abundance of mosquitoes, and a disease reservoir of chronically infected native birds. Although vector habitat and avian communities determine the geographic distribution of disease, climate drives transmission patterns ranging from continuous high infection in warm lowland forests, seasonal infection in midelevation forests, and disease-free refugia in cool high-elevation forests. Global warming is expected to increase the occurrence, distribution, and intensity of avian malaria across this elevational gradient and threaten high-elevation refugia, which is the key to survival of many susceptible Hawaiian birds. Increased temperatures may have already increased global avian malaria prevalence and contributed to an emergence of disease in New Zealand.

Hawai'i↗
USGS2023

Captivity, reintroductions, and the rewilding of amphibian-associated bacterial communities

Many studies have noted differences in microbes associated with animals reared in captivity compared to their wild counterparts, but few studies have examined how microbes change when animals are reintroduced to the wild after captive rearing. As captive assurance populations and reintroduction programs increase, a better understanding of how microbial symbionts respond during animal translocations is critical. We examined changes in microbes associated with boreal toads ( Anaxyrus boreas ), a threatened amphibian, after reintroduction to the wild following captive rearing. Previous studies demonstrate that developmental life stage is an important factor in amphibian microbiomes. We collected 16S marker-gene sequencing datasets to investigate: (i) comparisons of the skin, mouth, and fecal bacteria of boreal toads across four developmental life stages in captivity and the wild, (ii) tadpole skin bacteria before and after reintroduction to the wild, and (iii) adult skin bacteria during reintroduction to the wild. We demonstrated that differences occur across skin, fecal, and mouth bacterial communities in captive versus wild boreal toads, and that the degree of difference depends on developmental stage. Skin bacterial communities from captive tadpoles were more similar to their wild counterparts than captive post-metamorphic individuals were to their wild counterparts. When captive-reared tadpoles were introduced to a wild site, their skin bacteria changed rapidly to resemble wild tadpoles. Similarly, the skin bacterial communities of reintroduced adult boreal toads also shifted to resemble those of wild toads. Our results indicate that a clear microbial signature of captivity in amphibians does not persist after release into natural habitat.

Colorado↗
USGS2025

Reproductive output of the rare plant Arctomecon californica does not appear to be limited by its floral visitor community

The majority of plants rely on animal-mediated pollination for reproduction. Reductions in pollinator visitations can lead to pollen limitation and declines in seed production. Arctomecon californica, the Las Vegas bearpoppy, is a rare plant native to the northeastern Mojave Desert. It is pollinator dependent for reproduction as it is self-incompatible, but associated pollinator populations can fluctuate greatly year to year. We therefore investigated if the reproductive output of A. californica is reduced in a year with lower pollinator visitation (2022) compared to a year when visitors were more abundant (2023). We documented the visiting bee community across both years and compared rates of A. californica seed fertilization and development across populations and between the two years. We collected and identified bees from 18 genera visiting A. californica flowers over the two years, with significant differences in the bee communities between years. There were significantly fewer overall bee visits to A. californica flowers in 2022 compared to 2023, but we found no impact on reproductive output, with overall high rates of seed production in both years.

Nevada↗
USGS2009

Plant community, primary productivity, and environmental conditions following wetland re-establishment in the Sacramento-San Joaquin Delta, California

Wetland restoration can mitigate aerobic decomposition of subsided organic soils, as well as re-establish conditions favorable for carbon storage. Rates of carbon storage result from the balance of inputs and losses, both of which are affected by wetland hydrology. We followed the effect of water depth (25 and 55 cm) on the plant community, primary production, and changes in two re-established wetlands in the Sacramento San-Joaquin River Delta, California for 9 years after flooding to determine how relatively small differences in water depth affect carbon storage rates over time. To estimate annual carbon inputs, plant species cover, standing above- and below-ground plant biomass, and annual biomass turnover rates were measured, and allometric biomass models for Schoenoplectus (Scirpus) acutus and Typha spp., the emergent marsh dominants, were developed. As the wetlands developed, environmental factors, including water temperature, depth, and pH were measured. Emergent marsh vegetation colonized the shallow wetland more rapidly than the deeper wetland. This is important to potential carbon storage because emergent marsh vegetation is more productive, and less labile, than submerged and floating vegetation. Primary production of emergent marsh vegetation ranged from 1.3 to 3.2 kg of carbon per square meter annually; and, mid-season standing live biomass represented about half of the annual primary production. Changes in species composition occurred in both submerged and emergent plant communities as the wetlands matured. Water depth, temperature, and pH were lower in areas with emergent marsh vegetation compared to submerged vegetation, all of which, in turn, can affect carbon cycling and storage rates. ?? Springer Science+Business Media B.V. 2009.

Wetlands Ecology and Management↗
USGS2026

Environmental tradeoffs of urban stream restoration in Fairfax County, Virginia

Regulatory mandates to improve water quality and stream health have driven substantial investment in stream restoration. Most projects aim to improve channel-floodplain connectivity, reduce sediment erosion, and enhance habitat for aquatic organisms, yet few include adequate pre- and post-restoration monitoring to assess outcomes. Since 2007, Fairfax County, Virginia, and the U.S. Geological Survey have partnered to monitor and evaluate water-quality conditions in Flatlick Branch. In 2018, a 1.72-km reach of stream above the monitoring station was restored using a Natural Channel Design approach. This study applied the Stream Functions Pyramid (SFP) framework to evaluate restoration tradeoffs. Post-restoration, watershed hydrology remained largely unchanged, but channel modifications increased flow capacity, reduced velocity, and further disconnected the channel from the floodplain. Nutrient and sediment reductions exceeded expected amounts, but the removal of over 20 % of riparian tree canopy increased physicochemical variability and the frequency and magnitude of water temperature heatwaves. Post-restoration, state standards for low dissolved oxygen and elevated pH were exceeded 2.5 and 7.5 times more often, respectively. Gross primary production and ecosystem respiration increased and organic matter sources supporting metabolism shifted from allochthonous to autochthonous. Trends in several benthic macroinvertebrate metrics, which were improving prior to construction, have since plateaued or declined, and the fish assemblage shifted from a native minnow dominated community to non-native, warmwater tolerant taxa. This study highlights the need for comprehensive assessments of stream restoration and benefits of using the SFP to understand the consequences and possible tradeoffs of different ecosystem management decisions.

Virginia↗
USGS1997

Habitat associations and effects of urbanization on macroinvertebrates of a small, high-plains stream

We described the relations between abundance of macroinvertebrates and several habitat variables in Crow Creek within F.E. Warren Air Force Base, Laramie County, Wyoming. Water velocity and longitudinal location showed the highest numbers of significant correlations with abundance of macroinvertebrate taxa. Changes in the macroinvertebrate community with changes in longitudinal location appeared to result from increasing urbanization with downstream movement. Caenis lattipennis , Ceratopogonidae, and Dubiraphia sp. were rare in the downstream portion of the study reach that has received substantial human disturbance.

Journal of Freshwater Ecology↗
USGS2018

Microbial community composition of a hydrocarbon reservoir 40 years after a CO2 enhanced oil recovery flood

Injecting CO 2 into depleted oil reservoirs to extract additional crude oil is a common enhanced oil recovery (CO 2 -EOR) technique. However, little is known about how in situ microbial communities may be impacted by CO 2 flooding, or if any permanent microbiological changes occur after flooding has ceased. Formation water was collected from an oil field that was flooded for CO 2 -EOR in the 1980s, including samples from areas affected by or outside of the flood region, to determine the impacts of CO 2 -EOR on reservoir microbial communities. Archaea, specifically methanogens, were more abundant than bacteria in all samples, while identified bacteria exhibited much greater diversity than the archaea. Microbial communities in CO 2 -impacted and non-impacted samples did not significantly differ (ANOSIM: Statistic R = -0.2597, significance = 0.769). However, several low abundance bacteria were found to be significantly associated with the CO 2 -affected group; very few of these species are known to metabolize CO 2 or are associated with CO 2 -rich habitats. Although this study had limitations, on a broad scale, either the CO 2 flood did not impact the microbial community composition of the target formation, or microbial communities in affected wells may have reverted back to pre-injection conditions over the ca. 40 years since the CO 2 -EOR.

Louisiana↗
USGS2021

The influence of species life history and distribution characteristics on species responses to habitat fragmentation in an urban landscape

Fragmentation within urbanized environments often leads to a loss of native species diversity; however, variation exists in responses among-species and among-populations within species. We aimed to identify patterns in species biogeography in an urbanized landscape to understand anthropogenic effects on vertebrate communities and identify species that are more sensitive or resilient to landscape change. We investigated patterns in species richness and species responses to fragmentation in southern Californian small vertebrate communities using multispecies occupancy models and determined factors associated with overall commonness and sensitivity to patch size for 45 small vertebrate species both among and within remaining non-developed patches. In general, smaller patches had fewer species, with amphibian species richness being particularly sensitive to patch size effects. Mammals were generally more common, occurring both in a greater proportion of patches and a higher proportion of the sites within occupied patches. Alternatively, amphibians were generally restricted to larger patches but were more ubiquitous within smaller patches when occupied. Species range size was positively correlated with how common a species was across and within patches, even when controlling for only patches that fell within a species' range. We found sensitivity to patch size was greater for more fecund species and depended on where the patch occurred within a species' range. While all taxa were more likely to occur in patches in the warmer portions of their ranges, amphibians and mammals were more sensitive to fragmentation in these warmer areas as compared to the rest of their ranges. Similarly, amphibians occurred at a smaller proportion of sites within patches in drier portions of their ranges. Mammals occurred at a higher proportion of sites that were also in drier portions of their range while reptiles did not differ in their sensitivity to patch size by range position. We demonstrate that taxonomy, life history, range size and range position can predict commonness and sensitivity of species across this highly fragmented yet biodiverse landscape. The impacts of fragmentation on species communities within an urban landscape depend on scale, with differences emerging among and within species and populations.

California↗
USGS2020

Changes to Monitoring Trends in Burn Severity Program’s production procedures and data products

The Monitoring Trends in Burn Severity (MTBS) program has been providing the fire science community with large fire perimeter and burn severity data for the past 14 years. As of October 2019, 22 969 fires have been mapped by the MTBS program and are available on the MTBS website ( https://www.mtbs.gov ). These data have been widely used by researchers to examine a variety of fire and climate science topics. However, MTBS has undergone significant changes to its fire mapping methodology, the remotely sensed imagery used to map fires, and the subsequent fire occurrence, burned boundary, and severity databases. To gather a better understanding of these changes and the potential impacts that they may have on the user community, we examined the changes to the MTBS burn mapping protocols and whether remapped burned area boundary and severity products differ significantly from the original MTBS products.

Fire Ecology↗
USGS2011

Local richness along gradients in the Siskiyou herb flora: R. H. Whittaker revisited

In his classic study in the Siskiyou Mountains (Oregon, USA), one of the most botanically rich forested regions in North America, R. H. Whittaker (1960 ) foreshadowed many modern ideas on the multivariate control of local species richness along environmental gradients related to productivity. Using a structural equation model to analyze his data, which were never previously statistically analyzed, we demonstrate that Whittaker was remarkably accurate in concluding that local herb richness in these late‐seral forests is explained to a large extent by three major abiotic gradients (soils, topography, and elevation), and in turn, by the effects of these gradients on tree densities and the numbers of individual herbs. However, while Whittaker also clearly appreciated the significance of large‐scale evolutionary and biogeographic influences on community composition, he did not fully articulate the more recent concept that variation in the species richness of local communities could be explained in part by variation in the sizes of regional species pools. Our model of his data is among the first to use estimates of regional species pool size to explain variation in local community richness along productivity‐related gradients. We find that regional pool size, combined with a modest number of other interacting abiotic and biotic factors, explains most of the variation in local herb richness in the Siskiyou biodiversity hotspot.

Oregon↗
USGS1989

Retention and transport of nutrients in a third-order stream: Channel processes

Chloride was injected as a conservative tracer with nitrate to examine nitrate retention (storage plus biotic uptake) and transport in a 327—m reach of a third—order stream draining a forested basin in northwestern California. Prior to injections, diel patterns of nutrient concentrations were measured under background conditions. Nitrate concentration of stream water increased downstream, indicating that the reach was a source of dissolved inorganic nitrogen to downstream communities under background, low—flow conditions, despite uptake by photoautotrophs. At the onset of continuous solute injection over a 10—d period, timing the passage of the solute front indicated that storage dominated nitrate retention. Instantaneous concentration differences at the base of the reach at hour 24 indicated that biotic uptake accounted for 13% of the nitrate amendment while hydrologic storage constituted 29%. Corrected for groundwater dilution (11.7%), saturation of the stream's channel and hyporheic zones was not complete until 6.8 d of continuous injection. By day 3 nitrate retention was dominated by biotic processes. Biotic uptake was greatest during daylight hours indicating retention by photoautotrophs, but also occurred during darkness. After 10 d of continuous injection, mass balance calculations indicated that 29% of N (339 g) was retained from the total injected (1155 g), while the balance of injected nitrate was transported downstream. Storage of NO 3 — N was 117 g or 10% while biotic uptake was 222 g or 19%. Periphyton biomass on slides, chlorophyll a both on slides and on natural cobbles, and net community primary production all indicated a lag in periphyton response to nitrate amendment. Earliest indicators of a biotic response to nutrient amendment were decreases in both tissue C/N and epilithic respiration.

Ecology↗
USGS2023

A prioritization protocol for coastal wetland restoration on Molokaʻi, Hawaiʻi

Hawaiian coastal wetlands provide important habitat for federally endangered waterbirds and socio-cultural resources for Native Hawaiians. Currently, Hawaiian coastal wetlands are degraded by development, sedimentation, and invasive species and, thus, require restoration. Little is known about their original structure and function due to the large-scale alteration of the lowland landscape since European contact. Here, we used 1) rapid field assessments of hydrology, vegetation, soils, and birds, 2) a comprehensive analysis of endangered bird habitat value, 3) site spatial characteristics, 4) sea-level rise projections for 2050 and 2100 and wetland migration potential, and 5) preferences of the Native Hawaiian community in a GIS site suitability analysis to prioritize restoration of coastal wetlands on the island of Molokaʻi. The site suitability analysis is the first, to our knowledge, to incorporate community preferences, habitat criteria for endangered waterbirds, and sea-level rise into prioritizing wetland sites for restoration. The rapid assessments showed that groundwater is a ubiquitous water source for coastal wetlands. A groundwater-fed, freshwater herbaceous peatland or “coastal fen” not previously described in Hawaiʻi was found adjacent to the coastline at a site being used to grow taro, a staple crop for Native Hawaiians. In traditional ecological knowledge, such a groundwater-fed, agro-ecological system is referred to as a loʻipūnāwai (spring pond). Overall, 39 plant species were found at the 12 sites; 26 of these were wetland species and 11 were native. Soil texture in the wetlands ranged from loamy sands to silt and silty clays and the mean % organic carbon content was 10.93% ± 12.24 (sd). In total, 79 federally endangered waterbirds, 13 Hawaiian coots (‘alae keʻokeʻo; Fulica alai ) and 66 Hawaiian stilts (aeʻo; Himantopus mexicanus knudseni ), were counted during the rapid field assessments. The site suitability analysis consistently ranked three sites the highest, Kaupapaloʻi o Kaʻamola, Kakahaiʻa National Wildlife Refuge, and ʻŌhiʻapilo Pond, under three different weighting approaches. Site prioritization represents both an actionable plan for coastal wetland restoration and an alternative protocol for restoration decision-making in places such as Hawaiʻi where no pristine “reference” sites exist for comparison.

Hawaii↗
USGS2019

Interactive range‐limit theory (iRLT): An extension for predicting range shifts

A central theme of range‐limit theory (RLT) posits that abiotic factors form high‐latitude/altitude limits, whereas biotic interactions create lower limits. This hypothesis, often credited to Charles Darwin, is a pattern widely assumed to occur in nature. However, abiotic factors can impose constraints on both limits and there is scant evidence to support the latter prediction. Deviations from these predictions may arise from correlations between abiotic factors and biotic interactions, as a lack of data to evaluate the hypothesis, or be an artifact of scale. Combining two tenets of ecology—niche theory and predator–prey theory—provides an opportunity to understand how biotic interactions influence range limits and how this varies by trophic level. We propose an expansion of RLT, interactive RLT (iRLT), to understand the causes of range limits and predict range shifts. Incorporating the main predictions of Darwin's hypothesis, iRLT hypothesizes that abiotic and biotic factors can interact to impact both limits of a species’ range. We summarize current thinking on range limits and perform an integrative review to evaluate support for iRLT and trophic differences along range margins, surveying the mammal community along the boreal‐temperate and forest‐tundra ecotones of North America. Our review suggests that range‐limit dynamics are more nuanced and interactive than classically predicted by RLT. Many (57 of 70) studies indicate that biotic factors can ameliorate harsh climatic conditions along high‐latitude/altitude limits. Conversely, abiotic factors can also mediate biotic interactions along low‐latitude/altitude limits (44 of 68 studies). Both scenarios facilitate range expansion, contraction or stability depending on the strength and the direction of the abiotic or biotic factors. As predicted, biotic interactions most often occurred along lower limits, yet there were trophic differences. Carnivores were only limited by competitive interactions ( n = 25), whereas herbivores were more influenced by predation and parasitism (77%; 55 of 71 studies). We highlight how these differences may create divergent range patterns along lower limits. We conclude by (a) summarizing iRLT; (b) contrasting how our model system and others fit this hypothesis and (c) suggesting future directions for evaluating iRLT.

Journal of Animal Ecology↗
USGS2019

Evaluating community-level response to management actions across a diverse Hawaiian forest bird community

Although species‐specific approaches are necessary to understand the dynamics of individual species composing a community, they do not offer a framework for making optimal management decisions at the community level. Here, we present a simple framework for comparing the response of entire communities to multiple management scenarios. Our approach uses a weighted average of standardized species‐specific responses to produce a single integrative measure of the community response and employs mixed‐effect linear models to quantify the increase in the community response due to each management action, or combination of actions. We demonstrate our approach with a simulation study assessing the potential benefits of multiple management actions on the avian community of Hakalau Forest National Wildlife Refuge, Hawaiʻi, which is composed of eight native species with conservation status varying from endangered to least concern. Management actions considered included a reduction of avian malaria transmission risk, reducing rat predation, and increasing forest habitat. We used three different prioritization (weighting) schemes to assess whether the response to management actions differed along a conservation gradient (from endangered to least concern). We also investigated whether future changes in disease distribution as a result of climate change will alter the relationship between management practices and community response. Our community‐level analysis produced three important insights, highlighting the need to consider the response from multiple species to changing threats and management actions. First, increasing the amount of habitat always had the greatest positive impact on the avian community, regardless of the weighting scheme. Second, the community response to management was different under current vs. future conditions, with increased benefit in the future when disease risks were higher. Third, the response to management varied along the conservation gradient. Reducing malaria transmission risk in 2100 had the greatest benefit to endangered species, while increasing forest habitat had the greatest benefit to “least concern” species. However, reducing rat predation appeared to benefit a subset of species based on ecological factors unrelated to rarity, such as nest accessibility. Our approach is widely applicable using experimental, observational, or simulation‐based data, allowing managers to consider the response of all species while weighting their priority levels.

Hawaii↗
USGS2019

Invasive plant species

Invasive species may be one of the worts environmental problems facing the conservation of natural areas, because of their role in changing ecosystem function. At the same time, invasive species cause much human suffering and economic loss. The approach to eliminating invasive species can be improved by a better understanding of the various types of invasive species, and the scientific hypotheses surrounding their ability to invade novel environments. Despite the billions of dollars spent each year, invasive species are difficult if not impossible to eliminate after they have established. Various methods of eliminating plant species from natural communities are described in this review. An increased understanding of the nature of invasive species including their genetic relationship to their progenitors, hypotheses regarding their invasive qualities, and effective approaches for their removal from ecosystems are all sorely needed. Volunteers can help in the invasive species effort by working on local plant/animal removal projects, reporting invasive species sightings to appropriate officials, or working with scientists to collect basic data for ecological research.

Book chapter↗
USGS2009

Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail

A robust food web is one in which few secondary extinctions occur after removing species. We investigated how parasites affected the robustness of the Carpinteria Salt Marsh food web by conducting random species removals and a hypothetical, but plausible, species invasion. Parasites were much more likely than free-living species to suffer secondary extinctions following the removal of a free-living species from the food web. For this reason, the food web was less robust with the inclusion of parasites. Removal of the horn snail, Cerithidea californica , resulted in a disproportionate number of secondary parasite extinctions. The exotic Japanese mud snail, Batillaria attramentaria , is the ecological analogue of the native California horn snail and can completely replace it following invasion. Owing to the similarities between the two snail species, the invasion had no effect on predator–prey interactions. However, because the native snail is host for 17 host-specific parasites, and the invader is host to only one, comparison of a food web that includes parasites showed significant effects of invasion on the native community. The hypothetical invasion also significantly reduced the connectance of the web because the loss of 17 native trematode species eliminated many links.

Philosophical Transactions of the Royal Society B:↗
USGS2004

Predicting patterns of non-native plant invasions in Yosemite National Park, California, USA

One of the major issues confronting management of parks and reserves is the invasion of non-native plant species. Yosemite National Park is one of the largest and best-known parks in the United States, harbouring significant cultural and ecological resources. Effective management of non-natives would be greatly assisted by information on their potential distribution that can be generated by predictive modelling techniques. Our goal was to identify key environmental factors that were correlated with the percent cover of non-native species and then develop a predictive model using the Genetic Algorithm for Rule-set Production technique. We performed a series of analyses using community-level data on species composition in 236 plots located throughout the park. A total of 41 non-native species were recorded which occurred in 23.7% of the plots. Plots with non-natives occurred most frequently at low- to mid-elevations, in flat areas with other herbaceous species. Based on the community-level results, we selected elevation, slope, and vegetation structure as inputs into the GARP model to predict the environmental niche of non-native species. Verification of results was performed using plot data reserved from the model, which calculated the correct prediction of non-native species occurrence as 76%. The majority of the western, lower-elevation portion of the park was predicted to have relatively low levels of non-native species occurrence, with highest concentrations predicted at the west and south entrances and in the Yosemite Valley. Distribution maps of predicted occurrences will be used by management to: efficiently target monitoring of non-native species, prioritize control efforts according to the likelihood of non-native occurrences, and inform decisions relating to the management of non-native species in postfire environments. Our approach provides a valuable tool for assisting decision makers to better manage non-native species, which can be readily adapted to target non-native species in other locations.

Diversity and Distributions↗