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At least 379 records · Page 21Linked to original sources
USGS2017

An expert elicitation process to project the frequency and magnitude of Florida manatee mortality events caused by red tide (Karenia brevis)

Red tides (blooms of the harmful alga Karenia brevis ) are one of the major sources of mortality for the Florida manatee ( Trichechus manatus latirostris ), especially in southwest Florida. It has been hypothesized that the frequency and severity of red tides may increase in the future because of global climate change and other factors. To improve our ecological forecast for the effects of red tides on manatee population dynamics and long-term persistence, we conducted a formal expert judgment process to estimate probability distributions for the frequency and relative magnitude of red-tide-related manatee mortality (RTMM) events over a 100-year time horizon in three of the four regions recognized as manatee management units in Florida. This information was used to update a population viability analysis for the Florida manatee (the Core Biological Model). We convened a panel of 12 experts in manatee biology or red-tide ecology; the panel met to frame, conduct, and discuss the elicitation. Each expert provided a best estimate and plausible low and high values (bounding a confidence level of 80 percent) for each parameter in each of three regions (Northwest, Southwest, and Atlantic) of the subspecies’ range (excluding the Upper St. Johns River region) for two time periods (0−40 and 41−100 years from present). We fitted probability distributions for each parameter, time period, and expert by using these three elicited values. We aggregated the parameter estimates elicited from individual experts and fitted a parametric distribution to the aggregated results. Across regions, the experts expected the future frequency of RTMM events to be higher than historical levels, which is consistent with the hypothesis that global climate change (among other factors) may increase the frequency of red-tide blooms. The experts articulated considerable uncertainty, however, about the future frequency of RTMM events. The historical frequency of moderate and intense RTMM (combined) in the Southwest region was 0.35 (80-percent confidence interval [CI]: 0.21−0.52), whereas the forecast probability was 0.48 (80-percent CI: 0.30−0.64) over a 40-year projected time horizon. Moderate and intense RTMM events are expected to continue to be most frequent in the Southwest region, to increase in mean frequency in the Northwest region (historical frequency of moderate and intense RTMM events [combined] in the Northwest region was 0, whereas the forecast probability was 0.12 [80-percent CI: 0.02−0.39] over a 40-year projected time horizon) and in the Atlantic region (historical frequency of moderate and intense RTMM events [combined] in the Atlantic region was 0.05 [80-percent CI: 0.005–0.18], whereas the forecast probability was 0.11 [80-percent CI: 0.03−0.25] over a 40-year projected time horizon), and to remain absent from the Upper St. Johns River region. The impact of red-tide blooms on manatee mortality has been measured for the Southwest region but not for the Northwest and Atlantic regions, where such events have been rare. The expert panel predicted that the median magnitude of RTMM events in the Atlantic and Northwest regions will be much smaller than that in the Southwest; given the large uncertainties, however, they acknowledged the possibility that these events could be larger in their mortality impacts than in the Southwest region. By its nature, forecasting requires expert judgment because it is impossible to have empirical evidence about the future. The large uncertainties in parameter estimates over a 100-year timeframe are to be expected and may also indicate that the training provided to panelists successfully minimized one common pitfall of expert judgment, that of overconfidence. This study has provided useful and needed inputs to the Florida manatee population viability analysis associated with an important and recurrent source of mortality from harmful algal blooms.

Open-File Report↗
USGS2025

Developing biocrust field cultivation techniques for soil restoration: An assessment of bacterial communities

Biological soil crusts (biocrusts) are a coherent, thin soil surface layer, engineered and inhabited by a diverse community of moss, lichen, cyanobacteria, and other microorganisms. Biocrusts provide critical functions in dryland systems and may be lost from the ecosystem through physical disturbance or other global change drivers. Once biocrusts are lost, natural recovery can occur very slowly. This has led to the development of biocrust rehabilitation strategies, including cultivation of biocrust propagules to inoculate degraded sites. As the need for biocrust restoration grows in scale and across different regions, inoculum cultivation and application methods are being asked to keep up. In this work, we evaluate cyanobacterial community composition and abundance in greenhouse and field cultivation systems, with and without growth substrate and shade treatments. We also consider cultivation of locally and non-locally sourced biocrust inocula at a single cultivation facility on the Colorado Plateau. We found that field cultivation is a viable option for biocrust cultivation. For almost all cyanobacteria, habitat amelioration was necessary for growth in the field. Despite differences in inocula composition following cultivation, restoration outcomes five months after inoculation were poor with no significant increases in cyanobacterial abundance, soil chlorophyll a , or soil exopolysaccharide content. Thus, more work is needed to boost the initial growth and survival of biocrust inocula, regardless of the method of cultivation (i.e., greenhouse or field). Future work focused on assessing opportunities for habitat amelioration during application to improve biocrust establishment during this critical restoration phase would be highly valuable.

Utah↗
USGS2016

Global assessment of schistosomiasis control over the past century shows targeting the snail intermediate host works best

Background Despite control efforts, human schistosomiasis remains prevalent throughout Africa, Asia, and South America. The global schistosomiasis burden has changed little since the new anthelmintic drug, praziquantel, promised widespread control. Methodology We evaluated large-scale schistosomiasis control attempts over the past century and across the globe by identifying factors that predict control program success: snail control (e.g., molluscicides or biological control), mass drug administrations (MDA) with praziquantel, or a combined strategy using both. For data, we compiled historical information on control tactics and their quantitative outcomes for all 83 countries and territories in which: (i) schistosomiasis was allegedly endemic during the 20 th century, and (ii) schistosomiasis remains endemic, or (iii) schistosomiasis has been "eliminated," or is "no longer endemic," or transmission has been interrupted. Principal Findings Widespread snail control reduced prevalence by 92 ± 5% (N = 19) vs. 37 ± 7% (N = 29) for programs using little or no snail control. In addition, ecological, economic, and political factors contributed to schistosomiasis elimination. For instance, snail control was most common and widespread in wealthier countries and when control began earlier in the 20 th century. Conclusions/Significance Snail control has been the most effective way to reduce schistosomiasis prevalence. Despite evidence that snail control leads to long-term disease reduction and elimination, most current schistosomiasis control efforts emphasize MDA using praziquantel over snail control. Combining drug-based control programs with affordable snail control seems the best strategy for eliminating schistosomiasis.

PLoS Neglected Tropical Diseases↗
USGS2007

Climate Change Research at USGS Center for Earth Resources Observation and Science (EROS)

Research and development projects at EROS apply unique resources to support the USGS mission of developing understanding, monitoring, and modeling of climate variability and change and their human, physical, and biological impacts. Remote sensing resources, both new and archived, form the core of our ability to determine changes in the state or condition of the Earth’s surface and its dynamic landscape and ecosystem processes. This rich resource provides powerful biophysical information for local to global areas. Archival data form the basis for assessing human and climate impacts on the land surface, trends of land use, and an understanding of climate and management impacts. Biophysical information from satellite data is assimilated into quantitative models that allow all disciplines of the USGS to understand impacts on ecosystem processes. Major processes and problems we address include: carbon fluxes, hydrological processes, albedo changes and regional climates, mangroves and wetland protection of coastal environments, natural and manmade hazards (e.g., fire and drought), ecosystem change and succession, land use and land cover change, and more. The integration of remote sensing, modeling, and multidisciplinary approaches fosters international scientific leadership across all disciplines for the USGS.

Fact Sheet↗
USGS2014

Sources of global climate data and visualization portals

Climate is integral to the geophysical foundation upon which ecosystems are structured. Knowledge about mechanistic linkages between the geophysical and biological environments is essential for understanding how global warming may reshape contemporary ecosystems and ecosystem services. Numerous global data sources spanning several decades are available that document key geophysical metrics such as temperature and precipitation, and metrics of primary biological production such as vegetation phenology and ocean phytoplankton. This paper provides an internet directory to portals for visualizing or servers for downloading many of the more commonly used global datasets, as well as a description of how to write simple computer code to efficiently retrieve these data. The data are broadly useful for quantifying relationships between climate, habitat availability, and lower-trophic-level habitat quality - especially in Arctic regions where strong seasonality is accompanied by intrinsically high year-to-year variability. If defensible linkages between the geophysical (climate) and the biological environment can be established, general circulation model (GCM) projections of future climate conditions can be used to infer future biological responses. Robustness of this approach is, however, complicated by the number of direct, indirect, or interacting linkages involved. For example, response of a predator species to climate change will be influenced by the responses of its prey and competitors, and so forth throughout a trophic web. The complexities of ecological systems warrant sensible and parsimonious approaches for assessing and establishing the role of natural climate variability in order to substantiate inferences about the potential effects of global warming.

Conference Paper↗
USGS2005

Challenges in evaluating the impact of the trade in amphibians and reptiles on wild populations

Amphibians and reptiles are taken from the wild and sold commercially as food, pets, and traditional medicines. The overcollecting of some species highlights the need to assess the trade and ensure that it is not contributing to declines in wild populations. Unlike most countries, the United States tracks the imports and exports of all amphibians and reptiles. Records from 1998 to 2002 reveal a US trade of several million wild-caught amphibians and reptiles each year, although many shipments are not recorded at the species level. The magnitude and content of the global commercial trade carries even greater unknowns. The absence of accurate trade and biological information for most species makes it difficult to establish whether current take levels are sustainable. The void of information also implies that population declines due to overcollecting could be going undetected. Policy changes to acquire baseline biological information and ensure a sustainable trade are urgently needed.

BioScience↗
USGS2013

Roles of patch characteristics, drought frequency, and restoration in long-term trends of a widespread amphibian

Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long-term rates of change for a single species across a large geographic area. We analyzed growth in annual egg-mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades. On the basis of data collected by multiple partners from 98 water bodies between 1991 and 2011, we used state-space and linear-regression models to measure effects of patch characteristics, frequency of summer drought, and wetland restoration on population growth. Abundance increased in the 2 clades with greatest decline history, but declined where populations are considered most secure. Population growth was negatively associated with temporary hydroperiods and landscape modification (measured by the human footprint index), but was similar in modified and natural water bodies. The effect of drought was mediated by the size of the water body: populations in large water bodies maintained positive growth despite drought, whereas drought magnified declines in small water bodies. Rapid growth in restored wetlands in areas of historical population declines provided strong evidence of successful management. Our results highlight the importance of maintaining large areas of habitat and underscore the greater vulnerability of small areas of habitat to environmental stochasticity. Similar long-term growth rates in modified and natural water bodies and rapid, positive responses to restoration suggest pond construction and other forms of management can effectively increase population growth. These tools are likely to become increasingly important to mitigate effects of increased drought expected from global climate change.

Conservation Biology↗
USGS2015

Quantitative attribution of major driving forces on soil organic carbon dynamics

Soil organic carbon (SOC) storage plays a major role in the global carbon cycle and is affected by many factors including land use/management changes (e.g., biofuel production-oriented changes). However, the contributions of various factors to SOC changes are not well understood and quantified. This study was designed to investigate the impacts of changing farming practices, initial SOC levels, and biological enhancement of grain production on SOC dynamics and to attribute the relative contributions of major driving forces (CO 2 enrichment and farming practices) using a fractional factorial modeling design. The case study at a crop site in Iowa in the United States demonstrated that the traditional corn-soybean (CS) rotation could still accumulate SOC over this century (from 4.2 to 6.8 kg C/m 2 ) under the current condition; whereas the continuous-corn (CC) system might have a higher SOC sequestration potential than CS. In either case, however, residue removal could reduce the sink potential substantially. Long-term simulation results also suggested that the equilibrium SOC level may vary greatly (∼5.7 to ∼11 kg C/m 2 ) depending on cropping systems and management practices, and projected growth enhancement could make the magnitudes higher (∼7.8 to ∼13 kg C/m 2 ). Importantly, the factorial design analysis indicated that residue management had the most significant impact (contributing 49.4%) on SOC changes, followed by CO 2 Enrichment (37%), Tillage (6.2%), the combination of CO 2 Enrichment-Residue removal (5.8%), and Fertilization (1.6%). In brief, this study is valuable for understanding the major forces driving SOC dynamics of agroecosystems and informative for decision-makers when seeking the enhancement of SOC sequestration potential and sustainability of biofuel production, especially in the Corn Belt region of the United States.

Journal of Advances in Modeling Earth Systems↗
USGS2019

Where has turtle ecology been, and where is it going?

Over 9000 articles have been published on turtles and tortoises (excluding sea turtles) since 1950 according to the Web of Science, including over 8000 contained in a personal bibliography that we analyze in this paper. Research had a slow start from 1900 to 1950, with mostly anecdotal additions to our knowledge until the contributions of F. Cagle and A. Carr took turtle research to new levels as the cofathers of turtle ecology in the middle of the last century. Books written in 1939, 1952, and 1972 that compiled existing literature on turtles in the United States and Canada set the stage for growing interest in turtles. The first global compilation of turtle species did not become available until 1961. Publication frequency increased in the 1960s and especially the 1970s as interest in turtles grew, and a wave of turtle biologists emerged from doctoral degree programs. We briefly review the contributions of scientists who published extensively on turtle ecology in those and later decades up to the present. We also review advances in our knowledge of various topics, including the global distribution of turtle research efforts; changes in our perceptions of turtle species diversity over time; turtle community ecology; sex ratios, sex-determination, and climate change; overwintering behavior; sexual size dimorphism and sexual dichromatism; analyses of population genetics; turtles and vocalization; and the emergence of turtle conservation biology efforts. We conclude with a discussion of future opportunities and challenges for working with turtles.

Herpetologica↗
USGS2014

Acute survivorship of the deep-sea coral Lophelia pertusa from the Gulf of Mexico under acidification, warming, and deoxygenation

Changing global climate due to anthropogenic emissions of CO2 are driving rapid changes in the physical and chemical environment of the oceans via warming, deoxygenation, and acidification. These changes may threaten the persistence of species and populations across a range of latitudes and depths, including species that support diverse biological communities that in turn provide ecological stability and support commercial interests. Worldwide, but particularly in the North Atlantic and deep Gulf of Mexico, Lophelia pertusa forms expansive reefs that support biological communities whose diversity rivals that of tropical coral reefs. In this study, L. pertusa colonies were collected from the Viosca Knoll region in the Gulf of Mexico (390 to 450 m depth), genotyped using microsatellite markers, and exposed to a series of treatments testing survivorship responses to acidification, warming, and deoxygenation. All coral nubbins survived the acidification scenarios tested, between pH of 7.67 and 7.90 and aragonite saturation states of 0.92 and 1.47. However, net calcification generally declined with respect to pH, though a disparate response was evident where select individuals net calcified and others exhibited net dissolution near a saturation state of 1. Warming and deoxygenation both had negative effects on survivorship, with up to 100% mortality observed at temperatures above 14°C and oxygen concentrations of approximately 1.5 ml· l−1. These results suggest that, over the short-term, climate change and OA may negatively impact L. pertusa in the Gulf of Mexico, though the potential for acclimation and the effects of genetic background should be considered in future research.

Gulf of Mexico↗
USGS1991

Pliocene climates of the Northern Hemisphere; abstracts of the joint US/USSR workshop on Pliocene paleoclimates, Moscow, USSR, April, 1990

A joint US-USSR workshop met at the Laboratory of Paleogeography of the Academy of Sciences of the USSR in Moscow from April 20th to 23rd, 1990 to discuss Pliocene paleoclimates and to develop a joint long- term research program. Soviet participants included more than fifteen scientists from across the USSR, and the United States was represented by four scientists from the U.S. Geological Survey (Table 1). As with the 1989 Denver Pliocene workshop (Gosnell and Poore, 1990), the objectives of the 1990 Moscow workshop included establishing the chronology and amplitude of Pliocene climatic changes, mapping the spatial patterns in these variations, and determining the biologic responses to climatic change (see also Cronin and Dowsett, 1991, for further Pliocene paleoclimatic studies). These data will form the basis for explorations of General Circulation Model simulations of Pliocene paleoclimates and will provide insights into the nature of climatic circulation in a warmer-than-modern mean global climate state.

Open-File Report↗
USGS2021

Sedex hydrothermal systems triggered upheavals to marine chemistry and mass extinctions: Applications for ore genesis research and mineral exploration

New USGS research reveals that the discharge of metal-rich brine that formed sedex deposits on ancient seafloors had profound effects on global ocean chemistry and biologic evolution. For example, brine expulsion caused short-duration positive excursions (“spikes”) in the global marine Sr isotope record. While these spikes are unexplained by conventional oceanic models, our chronostratigraphic correlations of major sedex events, combined with mass balance evidence and oceanographic modeling, confirm that the flux of radiogenic Sr from sedex brines during ore formation was sufficient to cause these once enigmatic 87Sr/86Sr spikes. Recognition that the timing of peak 87 Sr/ 86 Sr spikes correlates exactly with global δ 13 C (and δ 18 O) spikes, climate change, deposition of metal-rich black shales and ironstones, metal-induced malformation (teratology) of marine organisms, and mass extinctions, establishes a causal relationship between sedex deposits and these dramatic events in earth history. The relationships among these features are not fully understood. However, our new model demonstrates that the flux of key biolimiting nutrients and metals contained in sedex brines exceeds that of the total modern riverine flux to the ocean. Undoubtably, these immense nutrient fluxes spurred ocean eutrophication, which, ultimately, through a series of positive feedback mechanisms, may be a previously unrecognized trigger of global ocean anoxic events (OAEs) that produced these chemical and biological perturbations. A derivative result from this integrative research is the recognition that OAEs resulted in the formation of “bathtub rim” deposits at redox boundaries along continental margins that concentrated various redox sensitive critical minerals. For example, we have identified midcontinent phosphorite deposits that contains heavy REE grades and tonnages that rival any REE deposit in the world. The recognition that sedex-forming fluid expulsion events are recorded in the global marine isotopic, geologic, and biological records, defines a new approach to the study of and exploration for sedex deposits. Traditional ore genesis research, coupled with chronostratigraphic correlation and high-resolution 87 Sr/ 86 Sr isotope chemostratigraphy can be used to answer long-standing questions about geologic processes responsible for formation of these extraordinary deposits. This approach allows us to constrain, for the first time, the age, duration, and fluxes of fluids and metals vented into the ocean by these giant hydrothermal systems. Accordingly, the fact that large mineralizing events are recorded in the marine sedimentary record opens the tantalizing prospect that we have the ability to conduct effective resource assessments and define prospective basins anywhere in the world. This innovative approach allows for identification of favorable stratigraphic ages and basins and remote evaluation of the size (and, thus, the mineral potential) of undiscovered mineral deposits. This methodology could be applied on regional basin-wide assessments, to evaluate sedimentary basin prospectivity, resource favorability of specific horizons therein, and to the evaluation of the potential of early-stage prospects.

Geological Society of Nevada Newsletter↗
USGS2010

Management intensity alters decomposition via biological pathways

Current conceptual models predict that changes in plant litter chemistry during decomposition are primarily regulated by both initial litter chemistry and the stage-or extent-of mass loss. Far less is known about how variations in decomposer community structure (e.g., resulting from different ecosystem management types) could influence litter chemistry during decomposition. Given the recent agricultural intensification occurring globally and the importance of litter chemistry in regulating soil organic matter storage, our objectives were to determine the potential effects of agricultural management on plant litter chemistry and decomposition rates, and to investigate possible links between ecosystem management, litter chemistry and decomposition, and decomposer community composition and activity. We measured decomposition rates, changes in litter chemistry, extracellular enzyme activity, microarthropod communities, and bacterial versus fungal relative abundance in replicated conventional-till, no-till, and old field agricultural sites for both corn and grass litter. After one growing season, litter decomposition under conventional-till was 20% greater than in old field communities. However, decomposition rates in no-till were not significantly different from those in old field or conventional-till sites. After decomposition, grass residue in both conventional- and no-till systems was enriched in total polysaccharides relative to initial litter, while grass litter decomposed in old fields was enriched in nitrogen-bearing compounds and lipids. These differences corresponded with differences in decomposer communities, which also exhibited strong responses to both litter and management type. Overall, our results indicate that agricultural intensification can increase litter decomposition rates, alter decomposer communities, and influence litter chemistry in ways that could have important and long-term effects on soil organic matter dynamics. We suggest that future efforts to more accurately predict soil carbon dynamics under different management regimes may need to explicitly consider how changes in litter chemistry during decomposition are influenced by the specific metabolic capabilities of the extant decomposer communities.

Biogeochemistry↗
USGS2009

The Vigil Network: A means of observing landscape change in drainage basins

Long-term monitoring of geomorphic, hydrological, and biological characteristics of landscapes provides an effective means of relating observed change to possible causes of the change. Identification of changes in basin characteristics, especially in arid areas where the response to altered climate or land use is generally rapid and readily apparent, might provide the initial direct indications that factors such as global warming and cultural impacts have affected the environment. The Vigil Network provides an opportunity for earth and life scientists to participate in a systematic monitoring effort to detect landscape changes over time, and to relate such changes to possible causes. The Vigil Network is an ever-increasing group of sites and basins used to monitor landscape features with as much as 50 years of documented geomorphic and related observations.

Hydrological Sciences Journal↗
USGS2009

Forest Vegetation Monitoring Protocol for National Parks in the North Coast and Cascades Network

Plant communities are the foundation for terrestrial trophic webs and animal habitat, and their structure and species composition are an integrated result of biological and physical drivers (Gates, 1993). Additionally, they have a major role in geologic, geomorphologic and soil development processes (Jenny, 1941; Stevens and Walker, 1970). Throughout most of the Pacific Northwest, environmental conditions support coniferous forests as the dominant vegetation type. In the face of anthropogenic climate change, forests have a global role as potential sinks for atmospheric carbon (Goodale and others, 2002). Consequently, knowledge of the status of forests in the three large parks of the NCCN [that is, Mount Rainier (MORA), North Cascades (NOCA), and Olympic (OLYM) National Parks] is fundamental to understanding the condition of Pacific Northwest ecosystems. Diverse climate and soil properties across the Pacific Northwest result in a variety of forest types (Franklin and Dyrness, 1973; Franklin and others, 1988; Henderson and others, 1989, 1992). The mountainous terrain of Mount Rainier, North Cascades, and Olympic National Parks create steep elevational and precipitation gradients within and among the parks: collectively, these parks span from sea level to more than 4,200 m; and include areas with precipitation from 90 to more than 500 cm. The resulting forests range from coastal rainforests with dense understories and massive trees draped with epiphytes; to areas with drought-adapted Ponderosa pines; to high-elevation subalpine fir forests interspersed with meadows just below treeline (table 1). These forests, in turn, are the foundation for other biotic communities constituting Pacific Northwest ecosystems.

Techniques and Methods↗
USGS2025

Wet meadow regeneration through restoration of biophysical feedbacks

Wet meadows are globally significant ecosystems that provide critical hydrological, ecological, and biogeochemical functions, yet their extent has declined dramatically due to land use changes and hydrologic alteration. These sedge-dominated wetlands exist at the drier end of the wetland gradient, maintained by shallow groundwater and periodic inundation. This paper is a global synthesis of the ecological, geomorphic, and hydrological dynamics of wet meadows, with an emphasis on alluvial systems, to inform effective restoration strategies. We compare wet meadows to other wetlands, classify them into palustrine, lacustrine, and alluvial types, then focus on alluvial wet meadows and discuss how their formation and persistence depend on ground and surface water interactions, sediment deposition and flow obstructions, all mediated by biological processes. In particular, we highlight the role of hydric graminoids in resisting erosion and maintaining soil cohesion, how beaver promote meadow persistence, and the significance of wet meadows as carbon sinks. We also present stratigraphic evidence demonstrating that incision, often triggered by anthropogenic activity or changing climate, is the primary mechanism of alluvial wet meadow degradation, resulting in water table decline and shifts in vegetation composition. Restoration requires reversing these incisional processes through techniques that elevate water tables, disperse flow and retain sediment—methods traditionally associated with either soil conservation or stream restoration. These include nature-based solutions that create obstructions such as beaver dams and their analogues, rock and wood-based obstructions and incision trench or gully filling and grading. Given their multifunctional value—including but not limited to flood attenuation, biodiversity support, and carbon sequestration—wet meadows warrant a focused restoration framework. This review advocates for a valley-floor scale restoration paradigm that integrates hydrological reconnection, sediment retention, and biological reinforcement to ensure long-term resilience of these systems in the face of changing climate and land use pressures.

Frontiers in Environmental Science↗
USGS2014

The influence of interspecific interactions on species range expansion rates

Ongoing and predicted global change makes understanding and predicting species’ range shifts an urgent scientific priority. Here, we provide a synthetic perspective on the so far poorly understood effects of interspecific interactions on range expansion rates. We present theoretical foundations for how interspecific interactions may modulate range expansion rates, consider examples from empirical studies of biological invasions and natural range expansions as well as process-based simulations, and discuss how interspecific interactions can be more broadly represented in process-based, spatiotemporally explicit range forecasts. Theory tells us that interspecific interactions affect expansion rates via alteration of local population growth rates and spatial displacement rates, but also via effects on other demographic parameters. The best empirical evidence for interspecific effects on expansion rates comes from studies of biological invasions. Notably, invasion studies indicate that competitive dominance and release from specialized enemies can enhance expansion rates. Studies of natural range expansions especially point to the potential for competition from resident species to reduce expansion rates. Overall, it is clear that interspecific interactions may have important consequences for range dynamics, but also that their effects have received too little attention to robustly generalize on their importance. We then discuss how interspecific interactions effects can be more widely incorporated in dynamic modeling of range expansions. Importantly, models must describe spatiotemporal variation in both local population dynamics and dispersal. Finally, we derive the following guidelines for when it is particularly important to explicitly represent interspecific interactions in dynamic range expansion forecasts: if most interacting species show correlated spatial or temporal trends in their effects on the target species, if the number of interacting species is low, and if the abundance of one or more strongly interacting species is not closely linked to the abundance of the target species.

Ecography↗
USGS1998

Making a world of difference; recent USGS contributions to the Nation

Public service is about making a difference. As the Federal government's principal natural science and information agency, the USGS is committed to providing excellence in public service and to making a difference to the world we live in. Our motto conveys an enduring message: science for a changing world . The changing nature of the natural and physical world is the primary driving force and motivation behind all of the work USGS does in biology, geology, mapping, and water. We live our motto each day in fulfilling our mission to provide reliable, impartial information to the citizen of this country and to the global community.

General Information Product↗