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At least 1,081 records · Page 60Linked to original sources
USGS2021

Drought resistance and resilience: The role of soil moisture–plant interactions and legacies in a dryland ecosystem

In many regions of the world, climate change is projected to reduce water availability through changes in the hydrological cycle, including more frequent and intense droughts, as well as seasonal shifts in precipitation. In water-limited ecosystems, such as drylands, lower soil water availability may exceed the adaptive capacity of many organisms, leading to cascading ecological effects during (concurrent effects) and after drought (legacy effects). The magnitude and duration of concurrent and legacy effects depends on drought intensity, duration and timing as well as the resistance and resilience of the ecosystem. Here, we investigated the effects of drought seasonality and plant community composition on two dominant perennial grasses, Achnatherum hymenoides (C 3 photosynthesis) and Pleuraphis jamesii (C 4 photosynthesis), in a dryland ecosystem. The experiment consisted of three precipitation treatments: control (ambient precipitation), cool-season drought (−66% ambient precipitation November–April) and warm-season drought (−66% ambient precipitation May–October), applied in two plant communities (perennial grasses with or without a large shrub, Ephedra viridis ) over a 3-year period. We examined the concurrent and legacy effects of seasonal drought on soil moisture, phenology and biomass. Drought treatments had strong concurrent and legacy effects on soil moisture, which impacted the phenology and biomass of the two grasses. Drought reduced growing season length by delaying green-up (cool-season drought) or advancing senescence (warm-season drought) and reduced biomass for both species. Biomass and phenology legacy effects from drought emerged in the second and third years of the experiment. While we observed differential sensitivity to drought legacies between the two grasses, we found limited evidence that shrub presence had interactive effects with the drought treatment. Synthesis . The results from this study highlight how abiotic and biotic legacies can develop and influence a community's resistance and resilience to subsequent droughts. When the frequency of repeated extreme events, such as recurring seasonal droughts, exceeds the capacity of organisms or ecosystems to recover (i.e. resilience), persistent drought legacies can reduce the resistance to subsequent drought events. Overall, these results highlight how drought legacies are a product of ecological resistance and resilience to past drought and can influence ecosystem vulnerability to future droughts.

Utah↗
USGS2006

Integrating human impacts and ecological integrity into a risk-based protocol for conservation planning

Conservation planning aims to protect biodiversity by sustainng the natural physical, chemical, and biological processes within representative ecosystems. Often data to measure these components are inadequate or unavailable. The impact of human activities on ecosystem processes complicates integrity assessments and might alter ecosystem organization at multiple spatial scales. Freshwater conservation targets, such as populations and communities, are influenced by both intrinsic aquatic properties and the surrounding landscape, and locally collected data might not accurately reflect potential impacts. We suggest that changes in five major biotic drivers—energy sources, physical habitat, flow regime, water quality, and biotic interactions—might be used as surrogates to inform conservation planners of the ecological integrity of freshwater ecosystems. Threats to freshwater systems might be evaluated based on their impact to these drivers to provide an overview of potential risk to conservation targets. We developed a risk-based protocol, the Ecological Risk Index (ERI), to identify watersheds with least/most risk to conservation targets. Our protocol combines risk-based components, specifically the frequency and severity of human-induced stressors, with biotic drivers and mappable land- and water-use data to provide a summary of relative risk to watersheds. We illustrate application of our protocol with a case study of the upper Tennessee River basin, USA. Differences in risk patterns among the major drainages in the basin reflect dominant land uses, such as mining and agriculture. A principal components analysis showed that localized, moderately severe threats accounted for most of the threat composition differences among our watersheds. We also found that the relative importance of threats is sensitive to the spatial grain of the analysis. Our case study demonstrates that the ERI is useful for evaluating the frequency and severity of ecosystemwide risk, which can inform local and regional conservation planning.

Tennessee↗
USGS2022

NABat ML: Utilizing deep learning to enable crowdsourced development of automated, scalable solutions for documenting North American bat populations

Bats play crucial ecological roles and provide valuable ecosystem services, yet many populations face serious threats from various ecological disturbances. The North American Bat Monitoring Program (NABat) aims to use its technology infrastructure to assess status and trends of bat populations, while developing innovative and community-driven conservation solutions. Here, we present NABat ML , an automated machine-learning algorithm that improves the scalability and scientific transparency of NABat acoustic monitoring. This model combines signal processing techniques and convolutional neural networks (CNNs) to detect and classify recorded bat echolocation calls. We developed our CNN model with internet-based computing resources (‘cloud environment’), and trained it on >600,000 spectrogram images. We also incorporated species range maps to improve the robustness and accuracy of the model for future ‘unseen’ data. We evaluated model performance using a comprehensive, independent, holdout dataset. NABat ML successfully distinguished 31 classes (30 species and a noise class) with overall weighted-average accuracy and precision rates of 92%, and ≥90% classification accuracy for 19 of the bat species. Using a single cloud-environment computing instance, the entire model training process took <16 h. Synthesis and applications . Our convolutional neural network (CNN)-based model, NABat ML , classifies 30 North American bat species using their recorded echolocation calls with an overall accuracy of 92%. In addition to providing highly accurate species-level classification, NABat ML and its outputs are compatible with Bayesian and other statistical techniques for measuring uncertainty in classification. Our model is open-source and reproducible, enabling future implementations as software on end-user devices and cloud-based web applications. These qualities make NABat ML highly suitable for applications ranging from grassroots community science initiatives to big-data methods developed and implemented by researchers and professional practitioners. We believe the transparency and accessibility of NABat ML will encourage broad-scale participation in bat monitoring, and enable development of innovative solutions needed to conserve North American bat species.

Journal of Applied Ecology↗
USGS2016

Landscape ecology of the Upper Mississippi River System: Lessons learned, challenges and opportunities

The Upper Mississippi River System (UMRS) is a mosaic of river channels, backwater lakes, floodplain forests, and emergent marshes. This complex mosaic supports diverse aquatic and terrestrial plant communities, over 150 fish species; 40 freshwater mussel species; 50 amphibian and reptile species; and over 360 bird species, many of which use the UMRS as a critical migratory route. The river and floodplain are also hotspots for biogeochemical activity as the river-floodplain collects and processes nutrients derived from the UMR basin. These features qualify the UMRS as a Ramsar wetland of international significance. Two centuries of land-use change, including construction for navigation and conversion of large areas to agriculture, has altered the broad-scale structure of the river and changed local environmental conditions in many areas. Such changes have affected rates of nutrient processing and transport, as well as the abundance of various fish, mussel, plant, and bird species. However, the magnitude and spatial scale of these effects are not well quantified, especially in regards to the best methods and locations for restoring various aspects of the river ecosystem. The U.S. Congress declared the navigable portions of the Upper Mississippi River System (UMRS) a “nationally significant ecosystem and nationally significant commercial navigation system” in the Water Resources Development Act of 1986 (Public Law 99-662) and launched the Upper Mississippi River Restoration (UMRR) Program, the first comprehensive program for ecosystem restoration, monitoring, and research on a large river system. This fact sheet focuses on landscape ecological studies conducted by the U.S. Geological Survey to support decision making by the UMRR with respect to ecosystem restoration.

Upper Mississippi River System↗
USGS2026

From understanding to action: Integrating new and old methodologies to manage marine infectious disease

Marine diseases can have far-reaching effects on population, community and ecosystem health; however, our ability to track, predict and manage these diseases has, historically, been poor. As a result, the fields of disease ecology and epidemiology have developed at a slower pace for marine than terrestrial systems [ 1 ]. New methodologies, including genomic tools for diagnostics [ 2 , 3 ], transcriptomic tools for measuring host and pathogen responses to infection (e.g. [ 4 , 5 ]), regional oceanic modelling systems that estimate environmental conditions influencing pathogen dispersal and disease progression [ 6 ], artificial intelligence methods for quantifying pathology from images (e.g. [ 7 ]) and advanced disease modelling techniques [ 8 , 9 ] are precipitating a rapid increase in our understanding of marine pathosystems. In 2016, these efforts led to the first special issue of Philosophical Transactions of the Royal Society B ( Marine diseases, volume 371, issue 1689) focused entirely on marine disease ecology and evolution, and in 2020, the first book, Marine disease ecology, was devoted to this topic [ 10 ]. This special issue, focused on marine disease management , is being published a decade after the first Philosophical Transactions special issue on marine diseases. The shift to a management focus reflects an urgent need for management strategies to address high-impact diseases and the rapid methodological advances that have resulted. The papers included in this issue demonstrate the value of combining classical approaches (e.g. routine disease surveillance, reductionistic pathogen challenge trials, rapid throughput diagnostics) with cutting-edge technologies (e.g. high-resolution oceanographic models, Bayesian models, replicated transcriptomic studies) to identify drivers of disease, quantify impacts and suggest management strategies.

Philosophical Transactions of the Royal Society, S↗
USGS2024

Metagenomic sequencing sheds light on microbes putatively associated with pneumonia-related fatalities of white-tailed deer (Odocoileus virginianus)

With emerging infectious disease outbreaks in human, domestic and wild animal populations on the rise, improvements in pathogen characterization and surveillance are paramount for the protection of human and animal health, as well as the conservation of ecologically and economically important wildlife. Genomics offers a range of suitable tools to meet these goals, with metagenomic sequencing facilitating the characterization of whole microbial communities associated with emerging and endemic disease outbreaks. Here, we use metagenomic sequencing in a case-control study to identify microbes in lung tissue associated with newly observed pneumonia-related fatalities in 34 white-tailed deer ( Odocoileus virginianus ) in Wisconsin, USA. We identified 20 bacterial species that occurred in more than a single individual. Of these, only Clostridium novyi was found to substantially differ (in number of detections) between case and control sample groups; however, this difference was not statistically significant. We also detected several bacterial species associated with pneumonia and/or other diseases in ruminants ( Mycoplasma ovipneumoniae , Trueperella pyogenes , Pasteurella multocida , Anaplasma phagocytophilum , Fusobacterium necrophorum ); however, these species did not substantially differ between case and control sample groups. On average, we detected a larger number of bacterial species in case samples than controls, supporting the potential role of polymicrobial infections in this system. Importantly, we did not detect DNA of viruses or fungi, suggesting that they are not significantly associated with pneumonia in this system. Together, these results highlight the utility of metagenomic sequencing for identifying disease-associated microbes. This preliminary list of microbes will help inform future research on pneumonia-associated fatalities of white-tailed deer.

Microbial Genomics↗
USGS2004

Global change impacts on mangrove ecosystems

Mangroves are tropical/subtropical communities of primarily tree species that grow in the intertidal zone. These tidal forests are important coastal ecosystems that are valued for a variety of ecological and societal goods and services. Major local threats to mangrove ecosystems worldwide include clearcutting and trimming of forests for urban, agricultural, or industrial expansion; hydrological alterations; toxic chemical spills; and eutrophication. In many countries with mangroves, much of the human population resides in the coastal zone, and their activities often negatively impact the integrity of mangrove forests. In addition, eutrophication, which is the process whereby nutrients build up to higher than normal levels in a natural system, is possibly one of the most serious threats to mangroves and associated ecosystems such as coral reefs. Scientists with the U.S. Geological Survey (USGS) at the National Wetlands Research Center are working to more fully understand global impacts on these significant ecosystems. Changes in climate and other factors may also affect mangroves, but in complex ways. Global warming may promote expansion of mangrove forests to higher latitudes and accelerate sea-level rise through melting of polar ice or steric expansion of oceans. Changes in sea level would alter flooding patterns and the structure and areal extent of mangroves. Climate change may also alter rainfall patterns, which would in turn change local salinity regimes and competitive interactions of mangroves with other wetland species. Increases in frequency or intensity of tropical storms and hurricanes in combination with sea-level rise may alter erosion and sedimentation rates in mangrove forests. Another global change factor that may directly affect mangrove growth is increased atmospheric carbon dioxide (CO 2 ), caused by burning of fossil fuels and other factors. Elevated CO 2 concentration may increase mangrove growth by stimulating photosynthesis or improving water use efficiency, but the consequences of this growth enhancement for the ecosystem are unknown.

Fact Sheet↗
USGS2004

Fort Collins Science Center: Ecosystem Dynamics

Many challenging natural resource management issues require consideration of a web of interactions among ecosystem components. The spatial and temporal complexity of these ecosystem problems demands an interdisciplinary approach integrating biotic and abiotic processes. The goals of the Ecosystem Dynamics Branch are to provide sound science to aid federal resource managers and use long-term, place-focused research and monitoring on federal lands to advance ecosystem science. Current studies fall into five general areas. Herbivore-Ecosystem Interactions examines the efficacy of multiple controls on selected herbivore populations and cascading effects through predator-herbivore-plant-soil linkages. Riparian Ecology is concerned with interactions among streamflow, fluvial geomorphology, and riparian vegetation. Integrated Fire Science focuses on the effects of fire on plant and animal communities at multiple scales, and on the interactions between post-fire plant, runoff, and erosion processes. Reference Ecosystems comprises long-term, place-based studies of ecosystem biogeochemistry. Finally, Integrated Assessments is investigating how to synthesize multiple ecosystem stressors and responses over complex landscapes in ways that are useful for management and planning.

Fact Sheet↗
USGS2020

Stable isotope dynamics of herbivorous reef fishes and their ectoparasites

Acanthurids (surgeonfishes) are an abundant and diverse group of herbivorous fishes on coral reefs. While their contribution to trophic linkages and dynamics in coral reef systems has received considerable attention, the role of linkages involving their parasites has not. As both consumers of fish tissue and prey to microcarnivores, external parasites may play a significant role in trophic transfer between primary consumers (and hence their predominantly algae-based diet) and the broader coral reef community. Stable isotope analysis is a common tool for studying trophic linkages which can be used for studies involving parasites. We examined the stable isotope ecology ( 13 C and 15 N) of copepod ( Caligus atromaculatus ) and monogenean ( Neobenedenia sp.) ectoparasites collected from two species of Caribbean acanthurids ( Acanthurus coeruleus and Acanthurus bahianus ). There were significant intraspecific differences in isotope discrimination factors between parasites collected from the two different host species as well as interspecific differences between parasites collected from the same host species. Discrimination factors for 15 N were consistently positive but varied in magnitude depending on host and parasite species and were slightly lower than what would be expected for consumers. The 13 C discrimination factors for both monogeneans and copepods collected from A. coeruleus were consistently positive but were negative for copepods collected from A. bahianus . These findings emphasize the complexity of the stable isotope trophic interactions occurring between parasites and their hosts, highlighting the value of these types of host-parasite isotopic studies.

Diversity↗
USGS1997

Management of Sequoiadendron giganteum and Sequoia sempervirens forests in the reserves of California - Considerations of ecology and conservation

Giant sequoia ( Sequoiadendron giganteum ), also known as “Bigtree” and “Sierra Redwood,” is entirely restricted to the Sierra Nevada mountain range in the State of California, while coast redwood ( Sequoia sempervirens ) is restricted to coastal northern California, extending northward slightly into the State of Oregon. Both charismatic species, members of the family Taxodiaceae, have served as important cultural icons in America, and both have played important roles in the history of nature conservation. The two species share important ecological similarities as well as significant differences; these ecological factors have become increasingly important in effecting their conservation, and in developing successful strategies for the long-term sustainable management of the forest communities in which they occur. The bulk of giant sequoia groves occur in reserves protected from logging, while only a small proportion of coast redwoods are similarly protected. For most of its history in the 20th century, conservation has been concerned with protecting uncut “old-growth” forest stands of giant trees. While this remains of great concern to the public, scientists and reserve managers have, in recent decades, extended their interest to what is known as “ecosystem management,” which includes all aspects of the natural ecosystems in which coast redwoods and giant sequoias occur. For the first time, attempts are presently beginning--in those areas outside the national parks, state parks, and other reserves, to reconcile some levels of timber harvest with the long-term sustainable preservation of the character and biodiversity of giant sequoia and redwood forests.

California↗
USGS1986

Changing landscapes and the cosmopolitism of the eastern Colorado avifauna

The avifauna of continental North America has changed dramatically since colonial times. Excessive hunting contributed, at least in part, to the extinction of birds such as the great auk ( Pinguinus impennis ) and passenger pigeon ( Ectopistes migratorius ), while more recently organochlorine insecticide residues have resulted in drastic reductions in numbers of brown pelicans ( Pelecanus occidentalis ) (Anderson et al. 1975) and other species. Generally, however, vertebrate populations change in direct response to changes in their habitats. For example, herring gulls ( Larus argentatus ) have increased in numners (Kadlec and Drury 1968) with urbanization of the New England coastline, in the same locations formerly occupied by the extinct heath hen ( Tympanuchus cupido cupido ). Also, passerine birds of forest interiors have declined in numbers with fragmentation of the eastern deciduous forest into small stands; this fragmentation has led to increases in numbers of edge species (Robbins 1979, Ambuel and Temple 1983). Even subtle community shifts can introduce new competitive processes that can augment population changes among species (Brittingham and Temple 1983). Such studies of broad-scale changes in vegetative communities and their influence on native wildlife species have fostered the recent topical emphasis on "conservation biology" (Soule and Wilcox 1980, Soule 1985) and "landscape ecology" (Burgess and Sharpe 1981, Harris 1984:25-43). As changes in landscapes are causing subtle (but potentially dramatic) changes in the distribution of native species, conservation biologists are finding that mere presence-absence data on populations, or even accurate information on reproductive success, is inadequate to evaluate management activities or environmental perturbations. The principles of "conservation genetics" are attracting interest in the management of natural preserves especially (Schonewald-Cox et al. 1983). Changing patterns in landscape complexion or genetic makeup of a population are difficult to detect locally. Contemporary issues in the conservation of native species demand regional and continental perspectives (Samson and Knopf 1982). Thus, management activities at specific sites are often viewed as short-sighted by planners and conservation critics. This paper illustrates how these contemporary theories can influence a local conservation perspective. That perspective is developed around historical processes that have led to cosmopolitism of the local avifauna on the Colorado Division of Wildlife's South Platte Wildlife Management Area (SPWMA) near Crook, Colorado.

Colorado↗
USGS2003

Quantitative characterization of the regressive ecological succession by fractal analysis of plant spatial patterns

We studied the effect of grazing on the degree of regression of successional vegetation dynamic in a semi-arid Mediterranean matorral. We quantified the spatial distribution patterns of the vegetation by fractal analyses, using the fractal information dimension and spatial autocorrelation measured by detrended fluctuation analyses (DFA). It is the first time that fractal analysis of plant spatial patterns has been used to characterize the regressive ecological succession. Plant spatial patterns were compared over a long-term grazing gradient (low, medium and heavy grazing pressure) and on ungrazed sites for two different plant communities: A middle dense matorral of Chamaerops and Periploca at Sabinar-Romeral and a middle dense matorral of Chamaerops, Rhamnus and Ulex at Requena-Montano. The two communities differed also in the microclimatic characteristics (sea oriented at the Sabinar-Romeral site and inland oriented at the Requena-Montano site). The information fractal dimension increased as we moved from a middle dense matorral to discontinuous and scattered matorral and, finally to the late regressive succession, at Stipa steppe stage. At this stage a drastic change in the fractal dimension revealed a change in the vegetation structure, accurately indicating end successional vegetation stages. Long-term correlation analysis (DFA) revealed that an increase in grazing pressure leads to unpredictability (randomness) in species distributions, a reduction in diversity, and an increase in cover of the regressive successional species, e.g. Stipa tenacissima L. These comparisons provide a quantitative characterization of the successional dynamic of plant spatial patterns in response to grazing perturbation gradient. ?? 2002 Elsevier Science B.V. All rights reserved.

Cabo de Gata Natural Park↗
USGS2023

Mountain glaciers influence biogeochemical and ecological characteristics of high-elevation lakes across the northern Rocky Mountains, USA

Mountain glaciers are retreating rapidly due to climate change, leading to the formation of downstream lakes. However, little is known about the physical and biogeochemical conditions in these lakes across a range of glacial influence. We surveyed alpine lakes fed by both glacial and snowpack meltwaters and those fed by snowpack alone to compare nutrient concentrations, stoichiometry, water clarity, chlorophyll, and zooplankton communities. Total phosphorus (TP) and soluble reactive phosphorus were two times higher in glacial lakes than in non-glacial lakes, while nitrate concentrations were three times higher. However, organic carbon concentrations in glacial lakes were two times lower than in non-glacial lakes. The carbon-to-phosphorus ratio and the nitrogen-to-phosphorus ratio of lake seston increased with water clarity in glacial lakes, suggesting that turbidity from glacial flour increases light limitation and increases stoichiometric food quality for zooplankton in newly formed lakes. However, chlorophyll a concentrations did not differ between lake types. Through structural equation modeling, we found that glaciers exhibit a bidirectional association with nitrate and TP concentrations, perhaps mediated through landscape vegetation and lake clarity. Zooplankton communities in high-turbidity glacial lakes were largely composed of cyclopoid copepods and rotifers (i.e., non-filter feeders), while non-glacial lakes tended to be dominated by calanoid copepods and cladocerans (i.e., filter feeders). Our results show that glacier-influenced lakes have biogeochemical and ecological characteristics distinct from snow-fed mountain lakes. Sustained studies are needed to assess the dynamics of these unique features as the influence of the alpine cryosphere fades under ongoing climate change.

Montana↗
USGS2003

Population characteristics and ecological role of northern pike in shallow natural lakes in Nebraska

Northern pike Esox lucius were sampled in Nebraska's Sandhill lakes during 1998 and 1999 to determine population characteristics and their influence on the fish community in these shallow, warm lakes at the southwestern edge of this species' natural range. Density-dependent growth, size structure, and condition were not evident in the northern pike populations sampled. Relative abundance of largemouth bass Micropterus salmoides was positively related to size structure of yellow perch Perca flavescens and bluegills Lepomis macrochirus when northen pike were absent. When northern pike and largemouth bass populations were sympatric, these relationships were less evident. Population size structure of yellow perch was lower in lakes with northern pike, but decreased size structure was not evident for bluegills. Northern pike growth decreased with July bottom water temperature, which ranged from 20??C to 25??C. Recruitment patterns of northern pike in the Sandhill lakes appeared to be lake-specific, strong and weak year-classes occurring in the same year among different populations. Northern pike in these shallow, warm lakes act as a top-down predator and appear to structure fish communities predominated by largemouth bass and panfish. Biologists managing warmwater Midwestern lakes thus should consider the effect of northern pike on fish communities.

North American Journal of Fisheries Management↗
USGS2024

The state of the science and practice of stream restoration in the Chesapeake: Lessons learned to inform better implementation, assessment and outcomes

The Chesapeake Bay Program’s (CBP) Science and Technical Advisory Committee (STAC) organized and led a workshop on the science and practice of stream restoration in order to summarize the state of knowledge in order to identify ways to improve stream restoration outcomes. The workshop identified a general framework for explaining the main factors leading to stream restoration outcomes: stream degradation has occurred, leading to regulatory and policy motivations that prioritize project goals, which leads to restoration approaches, assessment and monitoring efforts, and ultimately stream restoration outcomes. In the Chesapeake Bay watershed, stream restoration often occurs in response to Clean Water Act (CWA) mandates to reduce nitrogen, phosphorus, and sediment loads to the Bay. Reviews of stream restoration outcomes summarized at the workshop showed that, in general, stream restorations have led to minimal improvement to stream aquatic biota, effective ‘stabilization’ of channel form over time, moderate improvements to water quality, and short-term negative impacts to riparian vegetation. The fundamental finding of the workshop was that often the primary goal of stream restoration projects is to improve geomorphic stability in the restored reach and downstream water quality, and not to improve local ecological conditions through ‘uplift’ (improvement of one or more ecosystem functions through a restorative activity; a term defined in Appendix D), and therefore these projects often do not improve aquatic macroinvertebrate or fish communities. This conflict in goals is a shortcoming of the currently most common regulatory driver for stream restoration (reducing downstream loads of N, P, and sediment) that could be addressed directly through diversifying goals to include biotic uplift, as biological benefit is an assumed condition for the permitting and crediting of stream restoration projects. It is also likely that current understanding of stressors and drivers of stream ecosystem health is insufficient, and that reach-scale restoration focused on geomorphic restoration is not removing the actual sources of stream health impairment that may arise in the upstream watershed. More science could help to identify how to improve the ecological condition of streams through management. The outcome of stream restoration monitoring has revealed that while geomorphic and hydrodynamic functions of stream restoration projects may be achieved, biotic stream function improvements remain elusive. As such, ensuring uplift may be achieved by avoiding restoration projects that risk resources in higher-quality streams and riparian corridors. Reach-scale restoration often does not effectively mitigate the watershed-scale stressors of stream ecosystems. If a desired outcome of stream restoration includes ecological uplift, then focusing efforts on improving stream ecology could help meet that goal.

Chesapeake Bay watershed↗
USGS2002

Ecological resource management: A call to arms

As the human population enlarges, it becomes increasingly difficult to sus tain valued ecological resources. Hu man use of resources, whether it is t h e harvest of ocean fisheries, logging of forests, or farming of arable lands, has resulted in significant population de clines i n many wildlife species. The growth of urban areas and the exp ansion of impermeable surfaces alter landscape diversity and modify hydro logic patterns in ways that decrease habitat quality for many desired plant, fish, and wildlife species. Impaired wa ter, air, and soil quality related to in dustrial, municipal, and agricultural ac tivities have altered the composition of aquatic and terrestrial communities.

Ecological Society Bulletin↗
USGS2010

Ecological hierarchies and self-organisation - Pattern analysis, modelling and process integration across scales

A continuing discussion in applied and theoretical ecology focuses on the relationship of different organisational levels and on how ecological systems interact across scales. We address principal approaches to cope with complex across-level issues in ecology by applying elements of hierarchy theory and the theory of complex adaptive systems. A top-down approach, often characterised by the use of statistical techniques, can be applied to analyse large-scale dynamics and identify constraints exerted on lower levels. Current developments are illustrated with examples from the analysis of within-community spatial patterns and large-scale vegetation patterns. A bottom-up approach allows one to elucidate how interactions of individuals shape dynamics at higher levels in a self-organisation process; e.g., population development and community composition. This may be facilitated by various modelling tools, which provide the distinction between focal levels and resulting properties. For instance, resilience in grassland communities has been analysed with a cellular automaton approach, and the driving forces in rodent population oscillations have been identified with an agent-based model. Both modelling tools illustrate the principles of analysing higher level processes by representing the interactions of basic components.The focus of most ecological investigations on either top-down or bottom-up approaches may not be appropriate, if strong cross-scale relationships predominate. Here, we propose an 'across-scale-approach', closely interweaving the inherent potentials of both approaches. This combination of analytical and synthesising approaches will enable ecologists to establish a more coherent access to cross-level interactions in ecological systems. ?? 2010 Gesellschaft f??r ??kologie.

Basic and Applied Ecology↗
USGS2018

Identifying management-relevant research priorities for responding to disease-associated amphibian declines

A research priority can be defined as a knowledge gap that, if resolved, identifies the optimal course of conservation action. We (a group of geographically distributed and multidisciplinary research scientists) used tools from nominal group theory and decision analysis to collaboratively identify and prioritize information needs within the context of disease-associated amphibian decline , in order to develop a strategy that would support US management agency needs. We developed iterated influence diagrams to create and assess a unified research strategy. We illustrated a transparent process for identifying specific knowledge gaps in amphibian disease ecology relevant to environmental management, and then constructed a research plan to address these uncertainties. The resulting priorities include a need to: (1) understand the drivers of the community-disease relationship, (2) determine the mechanisms by which exposure to contaminants influence disease outcomes, (3) identify elements of terrestrial and aquatic habitats that stabilize host-pathogen dynamics, (4) discuss how metapopulations may be managed to reduce the speed and intensity of disease outbreaks, and (5) define the relationship between habitat management and the environmental and host microbiomes. Along with identifying research priorities for disease management, we present the details of the process used to develop a consensus plan for addressing disease-related declines in amphibians on federally managed lands of the United States.

Global Ecology and Conservation↗