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At least 685 records · Page 38Linked to original sources
USGS2007

Current and potential ant impacts in the Pacific region

Worldwide, ants are a powerful ecological force, and they appear to be dominant components of animal communities of many tropical and temperate ecosystems in terms of biomass and numbers of individuals (Bluthgen et al. 2000). For example, ants comprise up to 94% of arthropod individuals in fogging samples taken from diverse lowland tropical rainforest canopies, and 86% of the biomass (Davidson et al. 2003). The majority of these ant species and individuals obtain carbohydrates either from extrafloral nectaries or from sap-feeding Hemiptera that pass carbohydrate-rich “honeydew” to attending ants while concentrating nitrogen (N) from N-poor plant sap (Davidson et al. 2003). Honeydew and nectar represent key resources for arboreal ant species, although most ant species are at least partly carnivorous or scavengers (Bluthgen et al. 2004). In contrast to most of the terrestrial world, the biotas of many Pacific islands evolved without ants. Whereas endemic ant species are found in New Zealand (ca. 10 spp.), Tonga (ca. 10 spp.), and Samoa (ca. 12 spp.), other islands of Polynesia and parts of Micronesia likely lack native ants (Wilson and Taylor 1967, Wetterer 2002, Wetterer and Vargo 2003). About 20 Indo-Australian and western Pacific ant species range to the east and north of Samoa, but it is unclear how many of these were transported there by humans at some time (Wilson and Taylor 1967). Most of the remainder of the ant species currently found on Pacific islands are widespread species that fall in the category of “tramp species,” dispersed by recent human commerce and generally closely tied to human activity and urban areas (Wilson and Taylor 1967, McGlynn 1999). In Pacific island situations, some of these tramp ant species are able to thrive beyond areas of human activity. Relatively few ant species have been successful invaders of native communities on continents, and these include most of the species that pose the greatest problems for Pacific islands. They generally have multiple queens per colony, are unicolonial (lacking internest aggression), quickly recruit to food items, thrive in a variety of habitats including disturbed areas, and can be highly aggressive to other ant species (McGlynn 1999). Hawaii’s arthropod fauna evolved in the absence of ants and has been observed by many biologists to be highly vulnerable to displacement by non-native ants. Pacific island biotas have also very likely suffered greatly from displacement by ants. However, in contrast to Hawaii, virtually nothing has been published on effects of non-native ants on native arthropod fauna elsewhere on Pacific islands, with the exception of the Galapagos archipelago, which may have at least four species of endemic ants (Lubin 1984, Nishida and Evenhuis 2000) and New Caledonia (Jourdan et al. 2001, Le Breton et al. 2005). In addition, many ant species in the Pacific have long been a nuisance for humans, and significant agricultural impacts have occurred from ants tending hemipteran insects of crop plants.

Proceedings of the Hawaiian Entomological Society↗
USGS2010

Saltcedar and Russian olive interactions with wildlife: Chapter 4

Riparian areas of flood plains typically provide a mosaic of productive habitats (Stanford and others, 2005; Latterell and others, 2006) capable of supporting many wildlife species, particularly in the arid and semiarid Western United States. The establishment of nonnative invasive plants can alter riparian habitat by inhibiting native plant recruitment and by increasing the risk of wildfire (Howe and Knopf, 1991; Busch and Smith, 1995). However, the effects of nonnative plants are not necessarily always negative. Many wildlife species will use the exotic plants to some extent, especially when mixed with native vegetation (van Riper and others, 2008), but overall, species of wildlife exhibit a negative or neutral response to exotic habitat. In many areas of the Western United States where riparian systems have been degraded via anthropogenic activities (for example, flood control or groundwater pumping), native vegetation may have difficulty persisting and nonnative vegetation may provide the only available habitat for some species of wildlife (Katz and Shafroth, 2003; Stromberg and others, 2007). Therefore, where possible, the ultimate goal of ecological restoration activities should be the reestablishment of native riparian plant communities and a return to more natural hydrological regimes. Nonnative saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia) are the second and fifth most abundant plants in riparian areas in the Western United States (see chap. 2, this volume; Friedman and others, 2005). Methods for controlling nonnative vegetation can alter riparian areas, often in unpredictable ways, and have the potential to impact a variety of habitat types used by wildlife (Bateman, Chung-MacCoubrey, Finch, and others, 2008). Therefore, understanding how wildlife utilize saltcedar and Russian olive and the effects of control activities on wildlife are important for resource managers who must balance management decisions such as nonnative plant control with protecting critical wildlife habitat. In this chapter, we present a synthesis of published literature on the use of saltcedar and Russian olive by wildlife and discuss how wildlife respond or are likely to respond to control measures for saltcedar and Russian olive and subsequent restoration efforts. We discuss responses of several groups of wildlife, including arthropods, birds, mammals, herpetofauna, and fish.

Book chapter↗
USGS2014

Plants in alpine environments

Alpine and subalpine plant species are of special interest in ecology and ecophysiology because they represent life at the climate limit and changes in their relative abundances can be a bellwether for climate-change impacts. Perennial life forms dominate alpine plant communities, and their form and function reflect various avoidance, tolerance, or resistance strategies to interactions of cold temperature, radiation, wind, and desiccation stresses that prevail in the short growing seasons common (but not ubiquitous) in alpine areas. Plant microclimate is typically uncoupled from the harsh climate of the alpine, often leading to substantially warmer plant temperatures than air temperatures recorded by weather stations. Low atmospheric pressure is the most pervasive, fundamental, and unifying factor for alpine environments, but the resulting decrease in partial pressure of CO 2 does not significantly limit carbon gain by alpine plants. Factors such as tree islands and topographic features create strong heterogeneous mosaics of microclimate and snow cover that are reflected in plant community composition. Factors affecting tree establishment and growth and formation of treeline are key to understanding alpine ecology. Carbohydrate and other carbon storage, rapid development in a short growing season, and physiological function at low temperature are prevailing attributes of alpine plants. A major contemporary research theme asks whether chilling at alpine-treeline affects the ability of trees to assimilate the growth resources and particularly carbon needed for growth or whether the growth itself is limited by the alpine environment. Alpine areas tend to be among the best conserved, globally, yet they are increasingly showing response to a range of anthropogenic impacts, such as atmospheric deposition.

Book chapter↗
USGS2020

Fisheries research and monitoring activities of the Lake Erie Biological Station, 2019

A comprehensive understanding of fish populations and their interactions is the cornerstone of modern fishery management and the basis for Fish Community Goals and Objectives for Lake Erie (Ryan et al. 2003). This report is responsive to U.S. Geological Survey (USGS) obligations via Memorandum of Understanding (MOU) with the Great Lakes Council of Lake Committees (CLC) to provide scientific information in support of fishery management. Goals for the USGS Great Lakes Deepwater Fish Assessment and Ecological Studies in 2019 were to monitor long-term changes in the fish community and population dynamics of key fishes of interest to management agencies. Specific to Lake Erie, expectations of this agreement were sustained investigations of native percids, forage (prey) fish populations, and Lake Trout. Our 2019 deepwater program operations began in April and concluded in December, and utilized trawl, gillnet, hydroacoustic, lower trophic sampling, and telemetry methods. This work resulted in 88 bottom trawls covering 65 ha of lake-bottom and catching 24,140 fish totaling 3,622 kg during three separate trawl surveys in the West and Central basins of Lake Erie. Overnight gillnet sets (n=44) for cold water species were performed at 42 unique locations in the West and East basins of Lake Erie. A total of 8.0 km of gillnet was deployed during these surveys, which caught 286 fish, 114 of which were native coldwater species: Lake Trout, Burbot, and Lake Whitefish. USGS hydroacoustic surveys in 2019 produced 240 km of transects, and lower trophic sampling provided data from zooplankton samples (n=21) and water quality profiles (n=21) to populate a database maintained by the Ontario Ministry of Natural Resources and Forestry (OMNRF), Ohio Division of Natural Resources (ODNR), Michigan Division of Natural Resources (MDNR), Pennsylvania Fish and Boat Commission (PFBC), and New York State Department of Environmental Conservation (NYSDEC). USGS also assisted CLC member agencies with deployment and maintenance of the Great Lakes Acoustic Telemetry Observation System (GLATOS) throughout all three Lake Erie sub-basins, supporting multiple coordinated telemetry investigations. In 2019, Lake Trout investigations included annual gill net surveys and acoustic telemetry of spawning migration and habitat use in coordination with OMNRF, NYSDEC, and PFBC. Results from Lake Trout investigations were reported in the Coldwater Task Group annual report to the Great Lakes Fishery Commission (GLFC) and the CLC (Coldwater Task Group 2020). Likewise, interagency forage fish assessments conducted with hydroacoustics were summarized and reported in the Forage Task Group annual report (Forage Task Group 2020). This report presents biomass-based summaries of fish communities in western Lake Erie derived from USGS bottom trawl surveys conducted from 2013 to 2019 during June and September. The survey design provided temporal and spatial coverage that did not exist in the historic interagency trawl database, and thus complemented the August ODNR-OMNRF effort to reinforce stock assessments with more robust data. Analyses herein evaluated trends in: total biomass, abundance of dominant predator and forage species, non-native species composition, biodiversity and community structure. Data from this effort can be explored interactively online (https://lebs.shinyapps.io/western-basin/), and are accessible for download (https://doi.org/10.5066/P9LL6YOR, Keretz et al. 2020). Annual survey data are added to these sources as the data become available.

Lake Erie↗
USGS2017

Feeding ecology and niche overlap of Lake Ontario offshore forage fish assessed with stable isotopes

The forage fish communities of the Laurentian Great Lakes continue to experience changes that have altered ecosystem structure, yet little is known about how they partition resources. Seasonal, spatial and body size variation in δ13C and δ15N was used to assess isotopic niche overlap and resource and habitat partitioning among the five common offshore Lake Ontario forage fish species (n = 2037) [Alewife (Alosa pseudoharengus), Rainbow Smelt (Osmerus mordax), Round Goby (Neogobius melanostomus), and Deepwater (Myoxocephalus thompsonii) and Slimy (Cottus cognatus) Sculpin]. Round Goby had the largest isotopic niche (6.1‰2, standard ellipse area (SEAC)), followed by Alewife (3.4‰2) while Rainbow Smelt, Slimy Sculpin and Deepwater Sculpin had the smallest and similar niche size (1.7-1.8‰2), with only the Sculpin species showing significant isotopic niche overlap (>63%). Stable isotopes in Alewife, Round Goby and Rainbow Smelt varied with location, season and size, but did not in the Sculpin spp. Lake Ontario forage fish species have partitioned food and habitat resources, and non-native Alewife and Round Goby have the largest isotopic niche, suggestive of a boarder ecological niche, and may contribute to their current high abundance.

Lake Ontario↗
USGS2016

Differences found in the macroinvertebrate community composition in the presence or absence of the invasive alien crayfish, Orconectes hylas

Introductions of alien species into aquatic ecosystems have been well documented, including invasions of crayfish species; however, little is known about the effects of these introductions on macroinvertebrate communities. The woodland crayfish ( Orconectes hylas (Faxon)) has been introduced into the St. Francis River watershed in southeast Missouri and has displaced populations of native crayfish. The effects of O . hylas on macroinvertebrate community composition were investigated in a fourth-order Ozark stream at two locations, one with the presence of O . hylas and one without. Significant differences between sites and across four sampling periods and two habitats were found in five categories of benthic macroinvertebrate metrics: species richness, percent/composition, dominance/diversity, functional feeding groups, and biotic indices. In most seasons and habitat combinations, the invaded site had significantly higher relative abundance of riffle beetles (Coleoptera: Elmidae), and significantly lower Missouri biotic index values, total taxa richness, and both richness and relative abundance of midges (Diptera: Chironomidae). Overall study results indicate that some macroinvertebrate community differences due to the O . hylas invasion were not consistent between seasons and habitats, suggesting that further research on spatial and temporal habitat use and feeding ecology of Ozark crayfish species is needed to improve our understanding of the effects of these invasions on aquatic communities.

PLoS ONE↗
USGS2004

Implications of hydrologic variability on the succession of plants in Great Lakes wetlands

Primary succession of plant communities directed toward a climax is not a typical occurrence in wetlands because these ecological systems are inherently dependent on hydrology, and temporal hydrologic variability often causes reversals or setbacks in succession. Wetlands of the Great Lakes provide good examples for demonstrating the implications of hydrology in driving successional processes and for illustrating potential misinterpretations of apparent successional sequences. Most Great Lakes coastal wetlands follow cyclic patterns in which emergent communities are reduced in area or eliminated by high lake levels and then regenerated from the seed bank during low lake levels. Thus, succession never proceeds for long. Wetlands also develop in ridge and swale terrains in many large embayments of the Great Lakes. These formations contain sequences of wetlands of similar origin but different age that can be several thousand years old, with older wetlands always further from the lake. Analyses of plant communities across a sequence of wetlands at the south end of Lake Michigan showed an apparent successional pattern from submersed to floating to emergent plants as water depth decreased with wetland age. However, paleoecological analyses showed that the observed vegetation changes were driven largely by disturbances associated with increased human settlement in the area. Climate-induced hydrologic changes were also shown to have greater effects on plant-community change than autogenic processes. Other terms, such as zonation, maturation, fluctuations, continuum concept, functional guilds, centrifugal organization, pulse stability, and hump-back models provide additional means of describing organization and changes in vegetation; some of them overlap with succession in describing vegetation processes in Great Lakes wetlands, but each must be used in the proper context with regard to short- and long-term hydrologic variability.

Aquatic Ecosystem Health & Management↗
USGS2012

Seed harvesting by a generalist consumer is context-dependent: Interactive effects across multiple spatial scales

Granivore foraging decisions affect consumer success and determine the quantity and spatial pattern of seed survival. These decisions are influenced by environmental variation at spatial scales ranging from landscapes to local foraging patches. In a field experiment, the effects of seed patch variation across three spatial scales on seed removal by western harvester ants Pogonomyrmex occidentalis were evaluated. At the largest scale we assessed harvesting in different plant communities, at the intermediate scale we assessed harvesting at different distances from ant mounds, and at the smallest scale we assessed the effects of interactions among seed species in local seed neighborhoods on seed harvesting (i.e. resource–consumer interface). Selected seed species were presented alone (monospecific treatment) and in mixture with Bromus tectorum (cheatgrass; mixture treatment) at four distances from P. occidentalis mounds in adjacent intact sagebrush and non-native cheatgrass-dominated communities in the Great Basin, Utah, USA. Seed species differed in harvest, with B. tectorum being least preferred. Large and intermediate scale variation influenced harvest. More seeds were harvested in sagebrush than in cheatgrass-dominated communities (largest scale), and the quantity of seed harvested varied with distance from mounds (intermediate-scale), although the form of the distance effect differed between plant communities. At the smallest scale, seed neighborhood affected harvest, but the patterns differed among seed species considered. Ants harvested fewer seeds from mixed-seed neighborhoods than from monospecific neighborhoods, suggesting context dependence and potential associational resistance. Further, the effects of plant community and distance from mound on seed harvest in mixtures differed from their effects in monospecific treatments. Beyond the local seed neighborhood, selection of seed resources is better understood by simultaneously evaluating removal at multiple scales. Associational effects provide a useful theoretical basis for better understanding harvester ant foraging decisions. These results demonstrate the importance of ecological context for seed removal, which has implications for seed pools, plant populations and communities.

Oikos↗
USGS2020

Storm impacts on phytoplankton community dynamics in lakes

In many regions across the globe, extreme weather events such as storms have increased in frequency, intensity, and duration due to climate change. Ecological theory predicts that such extreme events should have large impacts on ecosystem structure and function. High winds and precipitation associated with storms can affect lakes via short‐term runoff events from watersheds and physical mixing of the water column. In addition, lakes connected to rivers and streams will also experience flushing due to high flow rates. Although we have a well‐developed understanding of how wind and precipitation events can alter lake physical processes and some aspects of biogeochemical cycling, our mechanistic understanding of the emergent responses of phytoplankton communities is poor. Here we provide a comprehensive synthesis that identifies how storms interact with lake and watershed attributes and their antecedent conditions to generate changes in lake physical and chemical environments. Such changes can restructure phytoplankton communities and their dynamics, as well as result in altered ecological function (e.g., carbon, nutrient and energy cycling) in the short‐ and long‐term. We summarize the current understanding of storm‐induced phytoplankton dynamics, identify knowledge gaps with a systematic review of the literature, and suggest future research directions across a gradient of lake types and environmental conditions.

Global Change Biology↗
USGS2026

Bridging ecology and geosciences in riverscapes: Implications for process-based restoration

There has been a growing interest in integrating geological and ecological processes for sustainable river management and restoration. Lotic systems are shaped by diverse physical processes, including geology, geomorphology, hydrology, and interactions with terrestrial processes. However, restoration practices often prioritize specific habitats or river forms without fully considering the underlying physical processes that support biological communities and ecosystem functions. In this paper, we synthesize studies that integrally examine geological and ecological processes across different scales and components of riverscapes, including geohydrological processes, which have been less investigated in riverscape studies. We begin by examining processes at broader spatial scales, including river–watershed and river–riparian interactions, and gradually narrow our focus to the dynamics that occur among habitats within river channels, through which we highlight the significance of conceptualizing rivers as dynamic “networks” rather than linear features. Finally, we identify both scientific and practical challenges that can be addressed to bridge the gap between basic-science implications and their implementation in riverscape restorations.

Ecological Research↗
USGS2010

Water quality and hydrology of the Silver River Watershed, Baraga County, Michigan, 2005-08

The Silver River Watershed comprises about 69 square miles and drains part of northeastern Baraga County, Michigan. For generations, tribal members of the Keweenaw Bay Indian Community have hunted and fished in the watershed. Tribal government and members of Keweenaw Bay Indian Community are concerned about the effect of any development within the watershed, which is rural, isolated, and lightly populated. For decades, the area has been explored for various minerals. Since 2004, several mineral-exploration firms have been actively investigating areas within the watershed; property acquisition, road construction, and subsurface drilling have taken place close to tributary streams of the Silver River. The U.S. Geological Survey, in cooperation with Keweenaw Bay Indian Community, conducted a multi-year water-resources investigation of the Silver River Watershed during 2005-08. Methods of investigation included analyses of streamflow, water-quality sampling, and ecology at eight discrete sites located throughout the watershed. In addition, three continuous-record streamgages located within the watershed provided stage, discharge, specific conductance, and water-temperature data on an hourly basis. Water quality of the Silver River Watershed is typical of many streams in undeveloped areas of Upper Michigan. Concentrations of most analytes typically were low, although several exceeded applicable surface-water-quality standards. Seven samples had concentrations of copper that exceeded the Michigan Department of Environmental Quality standards for wildlife, and one sample had concentrations of cyanide that exceeded the same standards. Concentrations of total mercury at all eight sampling sites exceeded the Great Lakes Basin water-quality standard, but the ratio of methylmercury to total mercury was similar to the 5 to 10 percent found in most natural waters. Concentrations of arsenic and chromium in bed sediments were near the threshold-effect concentration. A qualitative ecological assessment of fishes and macroinvertebrates showed that intolerant salmonids were present at most sampled sites, and macroinvertebrate communities were indicative of near-excellent or excellent conditions at all eight sites. This baseline information will aid in an ongoing monitoring effort designed to protect the water resources of the

Scientific Investigations Report↗
USGS2015

Tidal marsh susceptibility to sea-level rise: importance of local-scale models

Increasing concern over sea-level rise impacts to coastal tidal marsh ecosystems has led to modeling efforts to anticipate outcomes for resource management decision making. Few studies on the Pacific coast of North America have modeled sea-level rise marsh susceptibility at a scale relevant to local wildlife populations and plant communities. Here, we use a novel approach in developing an empirical sea-level rise ecological response model that can be applied to key management questions. Calculated elevation change over 13 y for a 324-ha portion of San Pablo Bay National Wildlife Refuge, California, USA, was used to represent local accretion and subsidence processes. Next, we coupled detailed plant community and elevation surveys with measured rates of inundation frequency to model marsh state changes to 2100. By grouping plant communities into low, mid, and high marsh habitats, we were able to assess wildlife species vulnerability and to better understand outcomes for habitat resiliency. Starting study-site conditions were comprised of 78% (253-ha) high marsh, 7% (30-ha) mid marsh, and 4% (18-ha) low marsh habitats, dominated by pickleweed Sarcocornia pacifica and cordgrass Spartina spp. Only under the low sea-level rise scenario (44 cm by 2100) did our models show persistence of some marsh habitats to 2100, with the area dominated by low marsh habitats. Under mid (93 cm by 2100) and high sea-level rise scenarios (166 cm by 2100), most mid and high marsh habitat was lost by 2070, with only 15% (65 ha) remaining, and a complete loss of these habitats by 2080. Low marsh habitat increased temporarily under all three sea-level rise scenarios, with the peak (286 ha) in 2070, adding habitat for the endemic endangered California Ridgway’s rail Rallus obsoletus obsoletus . Under mid and high sea-level rise scenarios, an almost complete conversion to mudflat occurred, with most of the area below mean sea level. Our modeling assumed no marsh migration upslope due to human levee and infrastructure preventing these types of processes. Other modeling efforts done for this area have projected marsh persistence to 2100, but our modeling effort with site-specific datasets allowed us to model at a finer resolution with much higher local confidence, resulting in different results for management. Our results suggest that projected sea-level rise will have significant impacts on marsh plant communities and obligate wildlife, including those already under federal and state protection. Comprehensive modeling as done here improves the potential to implement adaptive management strategies and prevent marsh habitat and wildlife loss in the future.

California↗
USGS2021

A comparison of plant communities in restored, old field, and remnant coastal prairies

Temperate grasslands are experiencing worldwide declines due to habitat conversion. Grassland restoration efforts are employed to compensate for these losses. However, there is a need to better understand the ecological effects of grassland restoration and management practices. We investigated the effects of three different grassland management regimes on plant communities of coastal prairie ecosystems in southwest Louisiana (USA). We compared old fields, prairie remnants, and restored prairies. Coastal prairies are a unique type of grassland historically present across southeast Texas and southwest Louisiana. Old fields represent former coastal prairie habitats allowed to revegetate naturally without active management. Remnant coastal prairies are small, isolated patches of comparatively intact prairie. Restored coastal prairies have been actively restored by planting native coastal prairie vegetation and managed with prescribed burning, mowing, and/or removal of invasive non‐native species. Our work was conducted in 3 old fields, 4 remnants, and 4 restored prairies. Old fields were dominated by non‐native species with low conservation value, whereas remnant prairies were dominated by native species with high conservation value. Remnants had a mean species richness of 75 species per site, which is higher than most other tallgrass prairie ecosystems in North America. Restored sites were dominated by native species with high conservation value, although the composition differed between restored and remnant sites. Collectively, our results: (1) reinforce the importance of identifying and preserving remnant coastal prairies; and (2) show that restoration of degraded coastal prairies is a viable strategy for supporting the persistence of these unique grassland ecosystems.

Louisiana↗
USGS2011

Avian community responses to juniper woodland structure and thinning treatments on the Colorado Plateau

Federal land managers are increasingly implementing fuels-reduction treatments throughout the western United States with objectives of ecological restoration and fire hazard reduction in pinyon-juniper (Pinus spp.-Juniperus spp.) woodlands. The pinyon-juniper woodland ecosystem complex is highly variable across the western landscape, as is bird community composition. We investigated relations between breeding birds and vegetation characteristics in modified pinyon-juniper woodlands at three sites (BLM, USFS, NPS) on the Colorado Plateau. During the breeding seasons of 2005 and 2006, we surveyed birds and measured vegetation in 74 study plots. These plots were each 3.1 hectares (ha; 7.6 acres), located across the range of natural variation, with 41 control sites and 33 plots in areas previously thinned by hand-cutting or chaining. We found that relations of avian pinyon-juniper specialists and priority species to vegetation characteristics were generally in agreement with the findings of previous studies and known nesting and feeding habits of those birds. Relatively high density of pinyon pines was important to species richness and abundance in 6 of 14 species. Abundance of all species was related to treatment method, and we found no difference in bird communities at chaining and hand-cut sites. We also studied responses of breeding birds to mechanical reduction of pinyon-juniper woodlands scattered across sagebrush steppe in 11 control and 9 treatment plots at Grand Staircase-Escalante National Monument, Utah, in 2005 and 2006. We surveyed birds in 3.1-ha (7.6-acre) plots during the breeding season before and following treatment. Thinning in April 2006 removed a mean of 92 percent (standard error = 6.4 percent) of the live trees from treatment plots. Two of 14 species, Gray Vireo (Vireo vicinior) and Brown-headed Cowbird (Molothrus ater), were not detected after thinning. Shrub-nesting birds, including sagebrush specialist Brewer's Sparrow (Spizella breweri), increased in relative abundance in treatment areas compared to controls. However, some species may exhibit a time lag in response, and further changes in community composition and abundance could result. Our findings lend support to the concept that multiple small-scale fuels-reduction treatments, applied over the landscape, may provide the variety of successional stages needed to support a full assemblage of avian species in pinyon-juniper woodlands on the Colorado Plateau. Limiting scale and increasing precision of fuels-reduction projects in pinyon-juniper vegetation communities may maximize the benefits of management to both the pinyon-juniper and sagebrush steppe avian communities. We conclude that small-scale fuels-reduction treatments can benefit many bird species while reducing fire risk and restoring an ecological balance.

Open-File Report↗
USGS2014

Nesting ecology and nest survival of lesser prairie-chickens on the Southern High Plains of Texas

The decline in population and range of lesser prairie-chickens ( Tympanuchus pallidicinctus ) throughout the central and southern Great Plains has raised concerns considering their candidate status under the United States Endangered Species Act. Baseline ecological data for lesser prairie-chickens are limited, especially for the shinnery oak-grassland communities of Texas. This information is imperative because lesser prairie-chickens in shinnery oak grasslands occur at the extreme southwestern edge of their distribution. This geographic region is characterized by hot, arid climates, less fragmentation, and less anthropogenic development than within the remaining core distribution of the species. Thus, large expanses of open rangeland with less anthropogenic development and a climate that is classified as extreme for ground nesting birds may subsequently influence nest ecology, nest survival, and nest site selection differently compared to the rest of the distribution of the species. We investigated the nesting ecology of 50 radio-tagged lesser prairie-chicken hens from 2008 to 2011 in the shinnery oak-grassland communities in west Texas and found a substantial amount of inter-annual variation in incubation start date and percent of females incubating nests. Prairie-chickens were less likely to nest near unimproved roads and utility poles and in areas with more bare ground and litter. In contrast, hens selected areas dominated by grasses and shrubs and close to stock tanks to nest. Candidate models including visual obstruction best explained daily nest survival; a 5% increase in visual obstruction improved nest survival probability by 10%. The model-averaged probability of a nest surviving the incubation period was 0.43 (SE = 0.006; 95% CI: 0.23, 0.56). Our findings indicate that lesser prairie-chicken reproduction during our study period was dynamic and was correlated with seasonal weather patterns that ultimately promoted greater grass growth earlier in the nesting season that provided visual obstruction from predators.

Texas↗
USGS2003

Amphibian decline: An integrated analysis of multiple stressor effects

Capturing the attention and imagination of the public and the scientific community alike, the mysterious decline in amphibian populations drew scientists and resource managers from ecotoxicology and chemistry, ecology and field biology, conservation biology, and natural resource policy to a SETAC–Johnson Foundation workshop. Facilitating environmental stewardship, increasing capacity of the sciences to explain complex stressors, and educating the public on relationships among communities of all types motivated these experts to address amphibian decline and the role of various stressors in these losses.

Book↗
USGS2018

Native peoples’ relationship to the California chaparral

Ethnographic interviews and historical literature reviews provide evidence that for many tribes of California, chaparral plant communities were a rich source of food, medicines, and technologies and that they supplemented natural fires with deliberate burning of chaparral to maximize its ability to produce useful products. Many of the most important chaparral plant species used in the food and material culture have strong adaptations to fire. Particularly useful were many annual and perennial herbs, which proliferate after fire from seed and bulb banks, shrub resprouts that made superb cordage and basketry material, as well as animals that were more readily caught in postfire environments. The reasons for burning in chaparral are grouped into seven ecological categories, each relying on a known response to fire of the chaparral community. The authors posit that tribes employed intentional burning to maintain chaparral in different ages and size classes to meet diverse food and material needs, tracking the change in plant and animal abundance and diversity, and shifts in shrub architecture and habitat structure during the recovery of the chaparral community. Areas were burned in ways designed to create a mosaic of open grassland and recently burned, young and mature stands of chaparral with different combinations of species and densities. This management conferred on chaparral plant communities a degree of spatial, structural, successional, and biotic diversity that exceeded what would have been the case in the absence of human intervention. These impacts are still evident on contemporary landscapes.

California↗
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.

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