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USGS2023

Ecological effects of pinyon-juniper removal in the Western United States—A synthesis of scientific research, January 2014–March 2021

Executive Summary Increasing density of pinyon ( Pinus spp. ) and juniper ( Juniperus spp. ) woodlands (hereinafter “pinyon-juniper”), as well as expansion of these woodlands into adjacent shrublands and grasslands, has altered ecosystem function and wildlife habitat across large areas of the interior western United States. Although there are many natural and human-caused drivers of woodland infilling and expansion, restoration of sagebrush ( Artemisia spp. ) habitat through removal of pinyon-juniper is considered an urgent management objective in many locations, particularly in support of sagebrush-dependent wildlife species of conservation concern. In December 2020, the Bureau of Land Management (BLM) established the Pinyon-Juniper Management Categorical Exclusion (PJCX) to expedite the regulatory process for pinyon-juniper removal projects on public lands, largely intended to benefit mule deer ( Odocoileus hemionus ) and greater sage-grouse ( Centrocercus urophasianus ) habitats. During final preparation of this report, the BLM discontinued use of the PJCX (as of November, 2022), but the pinyon-juniper tree removal techniques assessed in this report are commonly used and understanding their effects remains relevant to land use planning. To address areas of uncertainty relative to potential ecological effects of the PJCX, we conducted a review of the peer-reviewed science literature to better understand the likely responses of vegetation, environmental (for example, soils), and wildlife variables to specific tree removal techniques permitted by the PJCX. In brief, the PJCX permitted removal of trees by either manual cutting, mechanical cutting, or mastication; allowed certain methods to redistribute or remove resulting tree biomass after treatment; and prohibited broadcast burning, roadbuilding, removal of old-growth, and seeding of non-native species. Specifically, we conducted our review to address the following questions: How will PJCX removal techniques affect plant communities, soils, and abiotic resources? How do these pinyon-juniper removal techniques affect wildlife communities, including both woodland- and sagebrush-dependent species? What are the potential ecological implications of different pinyon-juniper removal treatment types and implementation strategies (for example, treatment sizes) over time? What are the most important gaps in our scientific understanding of how treatments might affect targeted ecosystems over space and time (for example, potential effects of climate change)? To answer these questions, we considered studies related to pinyon-juniper ecosystems, focusing on research that occurred over a large portion of the interior western United States that is the primary focus of the PJCX. We also focused on papers published from 2014 onward, to avoid excessive overlap with other recent reviews on pinyon-juniper management effects. Using strict criteria, including only considering research that tested responses for statistical significance, we identified 48 papers that primarily examined treatment effects on vegetation and other environmental variables (1,709 responses), and 11 papers that addressed effects on wildlife (132 responses). Responses to the PJCX-permitted treatments were summarized as either positive (that is, a significant increase), negative (that is, a significant decrease), or non-significant (that is, no significant difference). Responses were assigned to categories (for example, Native Annual Grass/Forb Abundance) and hierarchical treatment levels. We found that there were large proportions of non-significant responses among all categories combined, with roughly half or more of all responses non-significant (48 percent for wildlife, 60 percent for vegetation-environmental), comparable to other recent systematic reviews of pinyon-juniper treatment effects. However, we also found that when there were significant responses, some important trends potentially emerged. Important undesirable outcomes included far more positive than negative responses of exotic grass and forb abundance among nearly all treatment types. Cutting treatments were also more likely to decrease biocrust cover and microbial activity. Potentially beneficial outcomes included mostly positive responses among sagebrush obligate species, including more positive than negative responses for mule deer and sage-grouse. Some treatment types (for example, mastication) also resulted in more positive than negative responses for native grasses and forbs (although, non-significant responses were the majority). We also highlighted many limitations of this review, including how responses often come from few studies, and how some response-treatment category combinations lack adequate response data. Moreover, the existing research is often insufficient to address many key questions about treatment effects, largely owing to short time-scales and limited spatial extents of observations, which do not match the size of treatments being implemented by land managers, nor capture long-term, post-treatment ecological dynamics. We also identify a lack of research that addresses key interactions that could undermine restoration objectives, including potential effects of climate change and grazing on post-treatment environments. Thus, we emphasize the importance of integrating these factors into future pinyon-juniper treatment research, and we stress the need for use of monitoring programs and research studies that partake in data collection and analysis over long durations and broad spatial scales.

Open-File Report↗

USGS2020

Visualizing the ecological importance of pre-Euro-American settlement fire across three Midwestern landscapes

Bearing-tree data were used to calculate an index, pyrophilic percentage, depicting the importance of fire before Euro-American settlement on three landscapes, two within the Prairie Peninsula and one outside the region. Based on functional traits, bearing trees were classified as either pyrophilic or pyrophobic, applied to Public Land Survey points, and the pyrophilic percentage was calculated for each point. Kriging was applied to this point database to create a continuous surface of pyrophilic percentages. Regression analysis was used to relate this surface to environmental factors. Regression models created separately for each study area explained 38 to 53% of the variation in pyrophilic percentage. A positive association between pyrophilic percentage and distance to water and summer potential evapotranspiration was consistent across all study sites. The consistently high values and spatial patterns of pyrophilic percentage revealed fire-dominated landscapes interspersed with patches of pyrophobic vegetation. The restriction of pyrophobic areas to the leeside (east) of waterbodies indicated these served as firebreaks in a fire-swept landscape. Lake Michigan must have had a profound effect on pre- Euro-American settlement fire environments, serving as a massive physical firebreak while casting a moist maritime climate eastward. In southern and southwestern Illinois, the Mississippi River and associated tributaries along with an increase in topographic complexity also served as firebreaks, with pyrophobic forests restricted to riparian zones which progressively graded to pyrophilic vegetation on surrounding uplands. Our analysis expands the use of Public Land Survey data by converting bearing trees into a meaningful fire ecology index. While much of the landscape included in our study area is now in agriculture or urbanized, pyrophilic percentage maps can help guide land managers in the application of fire for restoration, conservation, and forestry purposes.

Illinois, Indiana, Michigan, Wisconsin↗

USGS2016

Interactions of landscape disturbances and climate change dictate ecological pattern and process: spatial modeling of wildfire, insect, and disease dynamics under future climates

Context Interactions among disturbances, climate, and vegetation influence landscape patterns and ecosystem processes. Climate changes, exotic invasions, beetle outbreaks, altered fire regimes, and human activities may interact to produce landscapes that appear and function beyond historical analogs. Objectives We used the mechanistic ecosystem-fire process model FireBGCv2 to model interactions of wildland fire, mountain pine beetle ( Dendroctonus ponderosae ), and white pine blister rust ( Cronartium ribicola ) under current and future climates, across three diverse study areas. Methods We assessed changes in tree basal area as a measure of landscape response over a 300-year simulation period for the Crown of the Continent in north-central Montana, East Fork of the Bitterroot River in western Montana, and Yellowstone Central Plateau in western Wyoming, USA. Results Interacting disturbances reduced overall basal area via increased tree mortality of host species. Wildfire decreased basal area more than beetles or rust, and disturbance interactions modeled under future climate significantly altered landscape basal area as compared with no-disturbance and current climate scenarios. Responses varied among landscapes depending on species composition, sensitivity to fire, and pathogen and beetle suitability and susceptibility. Conclusions Understanding disturbance interactions is critical for managing landscapes because forest responses to wildfires, pathogens, and beetle attacks may offset or exacerbate climate influences, with consequences for wildlife, carbon, and biodiversity.

Landscape Ecology↗

USGS2023

Habitat utilization, demography, and behavioral observations of the squat lobster, Eumunida picta (Crustacea: Anomura: Eumunididae), on western North Atlantic deep-water coral habitats

Deep-sea coral habitats, comprising mostly Lophelia pertusa (Linnaeus 1758), are well developed on the upper and middle continental slope off the southeastern United States (SEUS). These habitats support a diverse and abundant invertebrate fauna, yet ecology and biology of most of these species are poorly known. Ten cruises conducted off the SEUS (Summer–Fall; Cape Lookout, NC–Cape Canaveral, FL) from 2000 to 2005, and in 2009 provided an opportunity to investigate abundance and distribution of Eumunida picta Smith1883, a large-sized species of squat lobster commonly associated with these deep-water coral habitats. Video analysis from 70 manned-submersible dives documented occurrence, density, location on the coral colony, and behavioral observations for 5774 individuals of E . picta . Individuals collected (n = 178) from coral and adjacent habitats (e.g., rubble, soft sediments) were measured and their sex determined. Males and females were comparable in size (to 53.5 mm carapace length) and exhibited a sex ratio of approximately 1:1. Eumunida picta were most frequently observed as solitary individuals on high-profile coral matrix and were noted only infrequently on coral rubble, or rarely on soft substratum. Presence of coral habitat (i.e., live/dead L. pertusa ), geographic region within the sampling area, and depth significantly influenced abundances of E. picta . Additionally, coral habitat (dead versus live coral), vertical position on the coral (upper, middle, or lower zone), as well as horizontal position in relation to the coral matrix (outer surface versus embedded in coral matrix) were significant factors influencing E. picta distributions within the coral habitat. More individuals were found on dead versus live coral, and most frequently occurred on the outer surfaces of coral branches located on the upper portion or near the tops of coral colonies. Eumunida picta were most often observed with claws extended into the water column. This unique hunting stance provides this squat lobster the opportunity to capture prey from the water column. An active predator, this species utilizes both pelagic (i.e., fishes, pyrosomes) and benthic (e.g., scavenging and grazing) food resources, and may function as an important trophic link between the water column and the benthos. Although considered a facultative reef associate in the strictest sense of the term, E. picta has a complex and intimate relationship with L. pertusa . Based on observations from dive videos, E. picta is a dominant and ecologically important member of the invertebrate assemblage associated with deep-sea coral habitats off the SEUS. As such, this species figures prominently in the structure and function of this ecosystem.

western North Atlantic↗

USGS2024

Projecting the long-term effects of large-scale human influence on the spatial and functional persistence of extant longleaf pine ecosystems in the Florida Flatwoods Pyrome

Decades of human activities and fire suppression have adversely affected longleaf pine ( Pinus palustris ) ecosystems, which are home to high levels of diversity and endemism. These iconic ecosystems also now face challenges from urbanization and climate change, which will alter conservation outcomes over the remainder of the 21st century. To explore how long-term, large-scale human influences could affect the spatial and functional persistence of extant longleaf pine ecosystems in the Florida Flatwoods Pyrome, we extracted a set of 2400 longleaf pine patches ≥40 ha in size from the Florida Longleaf Pine Ecosystem Geodatabase. Projections from the FUTURES urban growth model and the Florida 2070 project indicate that development will lead to losses of existing longleaf pine habitat, reductions in longleaf pine patch size, and patches that are predominantly located in close proximity to developed areas. Finer-scale patterns of longleaf pine loss in three focal landscapes highlighted differences in land protection, ecological setting, and development pressure and the value of using of multiple urbanization iterations. The occurrence of suitable conditions to conduct prescribed fires, a crucial tool for maintaining, improving, and restoring longleaf pine ecosystems, is projected to decrease seasonally throughout the study area. As a result, the functional persistence of ecosystems is at risk due to climate changes that increase barriers to the safe and reliable application of intentional fire. The long-term viability of this critical ecosystem will warrant the evaluation of adaptive strategies that explicitly account for the individual and compounding effects of urban development and changing fire management conditions when considering options for ecosystem protection, management, and restoration.

Florida↗

USGS2019

Spatial integration of biological and social objectives to identify priority landscapes for waterfowl habitat conservation

Waterfowl population management and habitat conservation compose one of the oldest and most successful adaptive management frameworks in the world. Since its inception, the North American Waterfowl Management Plan (NAWMP) has emphasized strategically targeted conservation investments in regions that most affect waterfowl population dynamics. By 2012, regional conservation had progressively become more science-based and strategic: many migratory bird partnerships had initiated or completed projects on mapping and modeling waterfowl distribution and abundances using geospatial techniques. However, when developing a map depicting and titled “Areas of Greatest Continental Significance to North American Ducks, Geese, and Swans” for the 2012 NAWMP Revision, waterfowl professionals articulated the need for improved decision frameworks and use of consistent datasets for refining large-scale spatial products depicting priority areas for waterfowl and people. This report describes a framework for developing a spatial value model to support the identification of North American geographies of importance to waterfowl during the breeding and non-breeding periods and to resource users who could potentially support (financially and (or) politically) waterfowl habitat conservation. Objectives used to identify priority geographies were determined through a collaborative process of the NAWMP Science Support Team, Priority Landscapes Committee (PLC), and other experts in the fields of waterfowl biology and ecology, environmental science, and human dimensions. ArcGIS Desktop was used as the platform for managing, analyzing, combining and displaying the spatial data as well as producing new data through spatial analysis functions. Thirty-eight spatial layers were developed, and several composite spatially explicit products (maps of North America) were produced based on PLC recommendations. The composite products have extensive similarities to the 2012 NAWMP map depicting areas of greatest continental significance to North American waterfowl. There are also some differences, especially in regions of the high Arctic and in Mexico. These differences between spatial value model maps and the 2012 NAWMP output likely arose from inclusion of social objectives, reduced dependence on expert opinion to generate abundance estimates, lack of population surveys in some regions and availability of expanded survey data in other regions, and use of model-based waterfowl population estimates for some unsurveyed areas. The structured decision-making framework application in this study is discussed, and the appropriate use of the products and their limitations are outlined. Additionally, options for future improvements are presented by identifying gaps in data collection, waterfowl-habitat association assumptions, and uncertainties related to social objectives. These spatial products are intended for use by national, regional, and province/state level wildlife professionals to aid their decisions in targeting waterfowl habitat conservation.

Open-File Report↗

USGS2023

Climate change and pulse migration: Intermittent Chugach Inuit occupation of glacial fiords on the Kenai Coast, Alaska

For millennia, Inuit peoples of the Arctic and Subarctic have been challenged by the impacts of climate change on the abundance of key subsistence species. Responses to climate-induced declines in animal populations included switching to alternative food sources and/or migrating to regions of greater availability. We examine these dynamics for the Chugach Inuit (Sugpiat) people of southern coastal Alaska by synthesizing a large body of evidence from archeological sites, including radiocarbon dates and archaeofaunal assemblages, and by applying contemporary knowledge of glaciomarine ecosystems, spatial patterns of resource richness, and ocean-climate induced regime shifts in the Gulf of Alaska. We hypothesize that Chugach groups migrated from Cook Inlet and Prince William Sound to the Kenai Peninsula during periods of low sea surface temperatures (SSTs) to harvest harbor seals, which were seasonally aggregated near tidewater glaciers during pupping season, as well as piscivorous seabirds, Pacific cod, and other species that thrive under cool ocean conditions. During warming phases, the Chugach returned to Cook Inlet and Prince William Sound to fish for salmon and other species that abound during higher SSTs. Drivers of this coupled human-natural system of repeated (pulse) migration include the Pacific Decadal Oscillation (PDO), the dominant pattern of sea surface temperatures in the North Pacific that has been shown to generate step-like regime shifts in the marine food web; and coastal glaciers that structure the functioning of fiord ecosystems and support high levels of biological productivity. The culturally-constructed Chugach niche in the glaciomarine habitat of the Gulf of Alaska was based on intergenerationally transmitted ecological knowledge that enabled a resilient, mobile response to climate and resource variation.

Alaska↗

USGS1997

Development of an IBI-based assessment of depressional wetlands in Maryland and Delaware

The hydrogeomorphic approach (HGM) of wetland assessment emphasizes functional components of wetlands such as water storage, transformation and cycling of elements, accumulation of sediments, and preservation of habitats. Many of the elements measured in HGM are physical rather than ecological or biological. The HGM approach, therefore, provides information on certain aspects of wetlands and omits other aspects. In contrast, the Index of Biological Integrity (IBI) approach focuses on biological components of wetlands such as species richness, the presence or proportion of certain 'indicator' species, representation of different trophic levels, and measures of wildlife or fish health. Here too, some aspects of a wetland are omitted and others not covered by HGM are included. We contend that these differences in focus add strengths and weaknesses to each method. This paper reviews progress on the development of IBIs for restored depressional wetlands in the Mid-Atlantic States, especially Maryland and Delaware. During our first field season we identified 25 wetlands ranging from 1-10 acres, most of which were restored with federal, state, and private landowner cooperation over hydric soils. Separate IBIs are being created for macrophytes, macroinvertebrates, amphibians, and data on mammal and avian populations are being collected. Simultaneously, chemical and physical data are being collected on water DO, turbidity, temperature, conductivity, nitrates, ammonia, chlorophyll, pH; soil metal levels and texture; and wetland size, configuration, hydrology, drainage area, and surrounding land use.

Book chapter↗

USGS2024

Disentangling drivers of annual grass invasion: Abiotic susceptibility vs. fire-induced conversion to cheatgrass dominance in the sagebrush biome

Invasive annual grasses are often facilitated by fire, yet they can become ecologically dominant in susceptible locations even in the absence of fire. We used an extensive vegetation plot database to model susceptibility to the invasive annual grass cheatgrass ( Bromus tectorum L.) in the sagebrush biome as a function of climate and soil water availability variables. We built random forest models predicting cheatgrass presence or dominance (greater than 15 % relative cover) under unburned (37,219 plots) and burned conditions (6340 plots). We mapped predicted probability of cheatgrass presence and dominance, conditional on burning. We combined predicted susceptibility with burn probability to quantify the 10-year total risk of cheatgrass dominance. Finally, we identified portions of the landscape (1) at risk of fire-induced conversion to cheatgrass dominance, (2) consistently susceptible to cheatgrass dominance, or (3) consistently resistant to cheatgrass dominance. At the scale of the sagebrush biome, we found that abiotic susceptibility to cheatgrass dominance drives total risk, regardless of fire. At local scales (i.e., individual 30 m pixels), burning increased the probability of cheatgrass dominance by a median of 14 %. Threshold-based analyses indicate that 10–31 % of the sagebrush biome was at risk of fire-induced dominance, with 55 % exhibiting abiotic resistance and 5 % exhibiting abiotic susceptibility to dominance regardless of fire. Burn probability was higher in areas predicted to be susceptible to dominance, illustrating how cheatgrass invasion can cause ecosystem conversions that are then sustained by grass-fire cycles. Disentangling the influence of abiotic conditions and fire contributes to our understanding of the mechanisms driving invasion dynamics, and modeling the probability of dominance can help anticipate where ecological transformations are at risk of occurring. Our approach can facilitate the prioritization of management actions in the sagebrush biome and be used as a framework for modeling invasion risk in other disturbance-prone ecosystems.

Biological Conservation↗

USGS2024

Predicting responses to climate change using a joint species, spatially dependent physiologically guided abundance model

Predicting the effects of warming temperatures on the abundance and distribution of organisms under future climate scenarios often requires extrapolating species–environment correlations to climatic conditions not currently experienced by a species, which can result in unrealistic predictions. For poikilotherms, incorporating species' thermal physiology to inform extrapolations under novel thermal conditions can result in more realistic predictions. Furthermore, models that incorporate species and spatial dependencies may improve predictions by capturing correlations present in ecological data that are not accounted for by predictor variables. Here, we present a joint species, spatially dependent physiologically guided abundance (jsPGA) model for predicting multispecies responses to climate warming. The jsPGA model uses a basis function approach to capture both species and spatial dependencies. We apply the jsPGA model to predict the response of eight fish species to projected climate warming in thousands of lakes in Minnesota, USA. By the end of the century, the cold-adapted species was predicted to have high probabilities of extirpation across its current range—with 10% of lakes currently inhabited by this species having an extirpation probability >0.90. The remaining species had varying levels of predicted changes in abundance, reflecting differences in their thermal physiology. Though the model did not identify many strong species dependencies, the variation in estimated spatial dependence across species suggested that accounting for both dependencies was important for predicting the abundance of these fishes. The jsPGA model provides a new tool for predicting changes in the abundance, distribution, and extirpation probability of poikilotherms under novel thermal conditions.

Minnesota↗

USGS2019

Assessing the ecological impacts of biomass harvesting along a disturbance severity gradient

Disturbance is a central driver of forest development and ecosystem processes with variable effects within and across ecosystems. Despite the high levels of variation in disturbance severity often observed in forests following natural and anthropogenic disturbance, studies quantifying disturbance impacts often rely on categorical classifications, thus limiting opportunities to examine potential gradients in ecosystem response to a given disturbance or management regime. Given the potential increases in disturbance severity associated with global change, as well as shifts in management regimes related to procurement of biofuel feedstocks, there is an increasing need to quantitatively describe disturbance severity and associated responses of forest development, soil processes, and structural conditions. This study took advantage of two, replicated large-scale studies of forest biomass harvesting in Populus tremuloides and Pinus bansksiana forests, respectively, to develop and test the utility of a continuous, quantitative index of disturbance severity (DSI) for describing post-harvest response of plant communities and nutrient pools to different levels of biomass removal and legacy retention (i.e., live trees and coarse woody material). There was a high-degree of variability in DSI within categorical treatments associated with different levels of legacy retention and regression models using DSI as a predictor explained a portion of the variation (>50%) for many of the ecosystem- and community-level responses to biomass harvesting examined. Nutrient losses associated with biomass harvesting were positively related to disturbance severity, particularly in P. tremuloides forests, with post-harvest nutrient availability generally declining along the gradient of impacts. Consistent with expectations from ecological theory, species richness and diversity of woody plant communities were greatest at intermediate disturbance severities and regeneration densities of dominant trees species most abundant at highest levels of disturbance. Although categorical benchmarks will continue to be the primary way through which management guidelines are conveyed to practitioners, evaluation of their effectiveness at sustaining ecosystem functioning should be through continuous analyses, such as the DSI approach used in this study, to allow for the identification of minimum benchmarks that ensure a range of desirable outcomes exist across managed landscapes.

Ecological Applications↗

USGS2017

Streamflow characteristics from modelled runoff time series: Importance of calibration criteria selection

Ecologically relevant streamflow characteristics (SFCs) of ungauged catchments are often estimated from simulated runoff of hydrologic models that were originally calibrated on gauged catchments. However, SFC estimates of the gauged donor catchments and subsequently the ungauged catchments can be substantially uncertain when models are calibrated using traditional approaches based on optimization of statistical performance metrics (e.g., Nash–Sutcliffe model efficiency). An improved calibration strategy for gauged catchments is therefore crucial to help reduce the uncertainties of estimated SFCs for ungauged catchments. The aim of this study was to improve SFC estimates from modeled runoff time series in gauged catchments by explicitly including one or several SFCs in the calibration process. Different types of objective functions were defined consisting of the Nash–Sutcliffe model efficiency, single SFCs, or combinations thereof. We calibrated a bucket-type runoff model (HBV – Hydrologiska Byråns Vattenavdelning – model) for 25 catchments in the Tennessee River basin and evaluated the proposed calibration approach on 13 ecologically relevant SFCs representing major flow regime components and different flow conditions. While the model generally tended to underestimate the tested SFCs related to mean and high-flow conditions, SFCs related to low flow were generally overestimated. The highest estimation accuracies were achieved by a SFC-specific model calibration. Estimates of SFCs not included in the calibration process were of similar quality when comparing a multi-SFC calibration approach to a traditional model efficiency calibration. For practical applications, this implies that SFCs should preferably be estimated from targeted runoff model calibration, and modeled estimates need to be carefully interpreted.

Tennessee↗

USGS2015

Aerobic biodegradation potential of endocrine disrupting chemicals in surface-water sediment at Rocky Mountains National Park, USA

Endocrine disrupting chemicals (EDC) in surface water and bed sediment threaten the structure and function of aquatic ecosystems. In natural, remote, and protected surface-water environments where contaminant releases are sporadic, contaminant biodegradation is a fundamental driver of exposure concentration, timing, duration, and, thus, EDC ecological risk. Anthropogenic contaminants, including known and suspected EDC, were detected in surface water and sediment collected from 2 streams and 2 lakes in Rocky Mountains National Park (ROMO). The potential for aerobic EDC biodegradation was assessed in collected sediments using 6 14 C-radiolabeled model compounds. Aerobic microbial mineralization of natural (estrone and 17β-estradiol) and synthetic (17α-ethinylestradiol) estrogen was significant at all sites. ROMO bed sediment microbial communities also effectively degraded the xenoestrogens, bisphenol-A and 4-nonylphenol. The same sediment samples exhibited little potential for aerobic biodegradation of triclocarban, however, illustrating the need to assess a wider range of contaminant compounds. The current results support recent concerns over the widespread environmental occurrence of carbanalide antibacterials, like triclocarban and triclosan, and suggest that backcountry use of products containing these compounds should be discouraged.

Rocky Mountain National Park↗

USGS2007

Tidal freshwater forested wetlands: Future research needs and an overview of restoration: Chapter 17

Studies of tidal freshwater forested wetlands are few in contrast to the diversity of conditions and information needs that exist for this ecosystem type. Basic information is lacking on the physiological ecology of major wetland tree species under natural settings, the structure and dynamics of pure and mixed species communities, soil-plant interactions, biogeochemistry, hydrology, soils, wildlife habitat, primary biotic and abiotic functions, and the response of these systems to natural and human-caused disruptions. Existing information is often not in a form that can be applied to ecosystem problems, especially those related to management, restoration, or creation of tidal swamps. Accordingly, there is a critical need for research on fundamental biotic and abiotic processes and functions in tidal forested wetland landscapes on a local and regional scale. In this chapter, we detail those research needs, and we highlight some restoration ideas for tidal freshwater forested wetlands with the hope that much additional research will follow.

Book chapter↗

USGS2012

Competing risks and the development of adaptive management plans for water resources: Field reconnaissance investigation of risks to fishes and other aquatic biota exposed to endocrine disrupting chemicals (edcs) in lake mead, Nevada USA

The analysis and characterization of competing risks for water resources rely on a wide spectrum of tools to evaluate hazards and risks associated with their management. For example, waters of the lower Colorado River stored in reservoirs such as Lake Mead present a wide range of competing risks related to water quantity and water quality. These risks are often interdependent and complicated by competing uses of source waters for sustaining biological resources and for supporting a range of agricultural, municipal, recreational, and industrial uses. USGS is currently conducting a series of interdisciplinary case-studies on water quality of Lake Mead and its source waters. In this case-study we examine selected constituents potentially entering the Lake Mead system, particularly endocrine disrupting chemicals (EDCs). Worldwide, a number of environmental EDCs have been identified that affect reproduction, development, and adaptive behaviors in a wide range of organisms. Many EDCs are minimally affected by current treatment technologies and occur in treated sewage effluents. Several EDCs have been detected in Lake Mead, and several substances have been identified that are of concern because of potential impacts to the aquatic biota, including the sport fishery of Lake Mead and endangered razorback suckers (Xyrauchen texanus) that occur in the Colorado River system. For example, altered biomarkers relevant to reproduction and thyroid function in fishes have been observed and may be predictive of impaired metabolism and development. Few studies, however, have addressed whether such EDC-induced responses observed in the field have an ecologically significant effect on the reproductive success of fishes. To identify potential linkages between EDCs and species of management concern, the risk analysis and characterization in this reconnaissance study focused on effects (and attendant uncertainties) that might be expressed by exposed populations. In addition, risk reduction measures that may be of interest to resource managers are considered relative to emerging contaminants in treated effluents, interdependencies among biological resources at risk, and uses of reservoir waters derived from multiple inflows of widely varying qualities. ??2009 ASCE.

Nevada↗

USGS2016

Nest survival is influenced by parental behaviour and heterospecifics in a mixed-species colony

Studies of avian nest success often focus on examining influences of variation in environmental and seasonal factors. However, in-depth evaluations can also incorporate variation in individual incubation behaviour to further advance our understanding of avian reproductive ecology. We examined these relationships in colonially nesting Black-crowned Night-Herons Nycticorax nycticorax using intensive video-monitoring methods to quantify incubation behaviours. We modelled nest survival as a function of both extrinsic factors and incubation behaviours over a 3-year period (2010–12) on Alcatraz Island, USA. Model-averaged parameter estimates indicated that nest survival increased as a function of greater incubation constancy (% of time spent incubating eggs within a 24-h period), and average daily precipitation throughout the nesting stage. Common Ravens Corvus corax are the only known nest predator of Night-Herons on Alcatraz Island, as on many other coastal Pacific islands. We also investigated the effects of heterospecific nesting of California Gulls Larus californicus and Western Gulls Larus occidentalis in a mixed-species colony with Night-Herons, based on nesting proximity data collected over a 2-year period (2011–12). This second analysis indicated that, in addition to incubation behaviours, nesting heterospecifics are an important factor for explaining variation in Night-Heron nest survival. However, contrary to our original expectation, we found that Night-Herons experienced increased nest survival with increasing distance from gull colony boundaries. These results may apply to other areas with multiple colonial nesting species and similar predator communities and climatic patterns.

Ibis↗

USGS2014

Nutritional stress affects corticosterone deposition in feathers of Caspian tern chicks

Stressful environmental conditions affect the adrenocortical function of developing animals, which can have consequences for their fitness. Discovery of the avian stress hormone corticosterone (CORT) in feathers has the potential to broaden the application of endocrine research in ecological and evolutionary studies of wild birds by providing a long-term measure of CORT secretion. Mechanisms of CORT deposition in feathers are not well known and few studies have related feather CORT to circulating plasma CORT during feather growth. Our objective was to experimentally test the validity of using feather CORT as a measure of CORT secretion in developing birds experiencing nutritional stress. Caspian tern Hydroprogne caspia chicks were fed ad libitum or restricted (35% less than ad libitum) diets for four weeks. We measured CORT in feathers from these chicks to examine the relationship between feather CORT concentrations and nutritional limitation, circulating plasma CORT, and feather development. We found that feather CORT was higher in controls fed ad libitum than in restricted individuals, despite higher levels of plasma CORT in restricted chicks compared to controls. Feather mass and growth rates were strongly and positively related to feather CORT concentrations in both treatments. This is the first experimental study to show that feather CORT concentrations can be lower in response to nutritional stress, even when plasma CORT concentrations are elevated. Our results indicate that CORT deposition in feathers may be confounded when feather mass and growth rates are compromised by nutritional stress. We conclude that feather CORT can be used for assessing nutritional stress in growing birds, but the direction of response depends on how strongly stress affects feather development.

Journal of Avian Biology↗

USGS2021

Optimization of salt marsh management at the Moosehorn National Wildlife Refuge, Maine, through use of structured decision making

Structured decision making is a systematic, transparent process for improving the quality of complex decisions by identifying measurable management objectives and feasible management actions; predicting the potential consequences of management actions relative to the stated objectives; and selecting a course of action that maximizes the total benefit achieved and balances tradeoffs among objectives. The U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, applied an existing, regional framework for structured decision making to develop a prototype tool for optimizing tidal marsh management decisions at the Moosehorn National Wildlife Refuge in Maine. Refuge biologists, refuge managers, and research scientists identified multiple potential management actions to improve the ecological integrity of four marsh management units within the refuge, totaling about 13 hectares, and estimated the outcomes of each action in terms of performance metrics associated with each management objective. Value functions previously developed at the regional level were used to transform metric scores to a common utility scale, and utilities were summed to produce a single score representing the total management benefit that could be accrued from each potential management action. Constrained optimization was used to identify the set of management actions, one per marsh management unit, that could maximize total management benefits at different cost constraints at the refuge scale. Results indicated that, for the objectives and actions considered here, total management benefits may increase consistently up to $ 1,000, and may continue to increase at a lower rate with further expenditures. Potential management actions in optimal portfolios at total costs less than or equal to $ 1,000 included improving nesting habitat for Ammodramus nelsoni (Nelson’s sparrow) or restoring hydrologic connections to the upper marsh in one marsh management unit (Hobart Stream West). The potential management benefits were derived from expected increases in the density of nekton and of spiders (as an indicator of trophic health). The prototype presented here does not resolve management decisions; rather, it provides a framework for decision making at the Moosehorn National Wildlife Refuge that can be updated for implementation as new data and information become available. Insights from this process may also be useful to inform future habitat management planning at the refuge.

Maine↗