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At least 919 records · Page 51Linked to original sources

USGS1969

Paleogene floras from the Gulf of Alaska

Numerous collections of fossil plants from the Gulf of Alaska region were obtained from rocks that are well dated by marine mollusks. The mollusks indicate that the oldest possible age for the lowest plant assemblage is middle Eocene (Domengine) and that the youngest possible age for the highest Paleogene plant assemblage is middle Oligocene (Lincoln). Paleobotanical correlations indicate that the lowest plant assemblage is of early late Eocene (early Ravenian) age and the highest plant assemblage is of early Oligocene (Kummerian) age. A new provincial stage--the Angoonian--is proposed, based on assemblages from rocks in southeastern Alaska. The Angoonian is thought to be of late Oligocene (early Blakeley) age. Only one stratigraphically isolated assemblage from the Gulf of Alaska region has been recognized as of Angoonian age. The biostratigraphy of the Gulf of Alaska region and of other regions in Alaska indicates that the Seldovian, Homerian, and Clamgulchian Stages are probably entirely of Neogene age. The early Ravenian assemblages represent Paratropical Rain forest (that is, similar to vegetation of a narrow region bordering the Tropical Rain forest) based on the physiognomic analysis of foliage; the most diverse families represented are Menispermaceae and Icacinaceae. These are accompanied by palms, Anonaceae, tjristicaceae, Dipterocarpaceae, Barringtoniaceae, and Myrtaceae. A minor element is represented by broad-leaved deciduous plants. The middle Ravenian was somewhat cooler, as indicated by foliar physiognomy, the fewer Tropical Rain forest elements, and the diversity of Lauraceae. The late Ravenian assemblage represents a broad-leaved deciduous forest indicating a temperate climate. The Kummerian assemblages were again dominated by Lauraceae, and the physiognomic characters of the foliage indicate that Subtropical forest was again represented. The existence of a broad-leaved evergreen forest in Alaska such as that of the early Ravenian indicates that extended periods of darkness could probably not have existed at that time. The Alaskan Paleogene floras, as well as those from other regions, indicate that the earth's axis of rotation may not have had as great an inclination in the past. Strong climatic fluctuations evidenced by foliar physiognomy of Tertiary floras is thought to have been the result of changes in the inclination of the earth's axis. The history of the development of the Arcto-Tertiary concept is reviewed, and the fundamental lack of evidence for this concept is shown. An alternative, more complex, concept is proposed for the development of the Mixed Mesophytic forest. Paleobotanical evidence indicates that tolerances of many genera have changed during the Tertiary. Many Mixed Mesophytic genera--particularly those that are today temperate outliers of basically tropical groups--may have had a wide distribution in the Paleogene Paratropical Rain and Subtropical forests and have entered the warm temperate forests only during the later Paleogene or Neogene. Some Mixed Mesophytic groups appear to be of later Neogene origin and have been significant members of the warm temperate forests since that time. Some Mixed Mesophytic genera apparently were members of the Paratropical Rain forest only in the earliest Paleogene and became adapted to warm temperate climates by the late Eocene or perhaps even earlier. The Mixed Mesophytic forest may have developed independently in Eurasia, western North America, and eastern North America.

Alaska↗

USGS1963

Two pollen diagrams from southeastern Minnesota: Problems in the regional late-glacial and postglacial vegetational history

Kirchner Marsh and Lake Carlson are located 3 miles apart in Dakota County about 15 miles south of Minneapolis in the St. Croix moraine, which was formed by the Superior lobe during the Gary phase of the Wisconsin glaciation. During the Mankato phase that followed, the Des Moines lobe advanced to within a few miles of the sites. The region today is in a mixed-oak forest, with a maplebasswood forest 15 miles to the west and a re-entrant of the prairie on the sand plain south of the moraine. The general limit of coniferous trees is about 50 miles northeast of the sites, although outliers, especially of Pinus strobus, may be found along the Mississippi Valley a few miles to the east. One sediment core 12-13 m long from each site was analyzed for pollen content at 5-25-cm intervals. Diagrams based on percentage of total pollen (trees, shrubs, wind-pollinated herbs) show essentially identical sequences at the two sites, starting with the late-glacial phase of ice retreat. The diagrams have been subdivided into pollen zones according to the A-B-C sequence introduced by Deevey for New England. The late-glacial pollen record starts at Kirchner Marsh with a short Picea-Cyperaceae-Gramineae phase (Zone K), believed to represent a spruce parkland. Its C-14 date of 13,270 BP and the stratigraphy indicate a pre- Two Creeks and post- Gary correlation. Apparently the Kirchner site did not become established as a lake until this time owing to persistence of dead ice in the moraine. The absence of pollen of specific tundra indicators and the presence of pollen of such thermophilous plants as Fraxinus, Quercus, Corylus, Ambrosia, Humulus, and Typha latifolia imply that the climate was cool rather than cold. Zone A-a, which follows, correlates with the Two Creeks interstade. It is marked by the dominance of Picea, with appreciable percentages of Fraxinus and Ambrosia and with minor amounts of other thermophilous plants and the normal boreal associates of spruce like Betula, Larix, and Salix. Zone A-b, starting 12,050 C-14 years ago, correlates with the Valders ice advance. It is represented at both Kirchner and Carlson and shows the withdrawal of Fraxinus and Ambrosia and the slight rise of Artemisia. Except for the absence of pine in the late-glacial assemblage the vegetation implied by these three zones seems to have its closest modern counterpart in the southern fringe of the Boreal Forest of the Riding Mountain region of southwest Manitoba. It is concluded that pine did not migrate southward with the spruce during the Wisconsin glaciation, at least in the western Great Lakes region, and was thus eliminated from this region. During the lateglacial phases of ice retreat, herbs and spruce pioneered on the deglaciated terrain; pine did not follow until the destruction of the spruce forest at the end of the late-glacial phase. Zone B introduces postglacial time. It represents the time of rapid Vegetational succession following the deterioration of the spruce forest. Simultaneous maxima of Betula, Alnus, Fraxinus, and Abies occurred 10,230 years ago at Kirchner Marsh. These were followed rapidly by a Pinus maximum and then a rise of Ulmus, Quercus, and other deciduous types, dated as 9300 years ago at the correlative site of Madeha. This succession may represent differential rates of migration from refuges south and east of Minnesota . Deciduous trees dominate the C Zones. Zone C-a shows Ulmus and Ostrya /Carpinus followed by Quercus; it probably represents principally a mesic maple-basswood forest changing to oak. Zone C-b represents the advance of prairie into the region at the expense of the oak woodland or savanna. The large and abrupt fluctuations in the curves for Ambrosia-type and Chenopodiineae, especially at the Carlson site, may record encroachment of annual weeds onto intermittently dried lake bottoms. C-14 dates place Zone C-b between 7100 and 5100 years ago. In Zone C-c the Quercus again dominates until the abrupt increase in Ambrosiatype and Chenopodiineae that marks the time of forest clearance and land settlement 50-75 years ago.

Minnesota↗

USGS2013

Geographic variation in migration chronology and winter distribution of midcontinent greater white-fronted geese

We evaluated spatial and temporal differences in migratory behavior among different breeding groups of midcontinent greater white-fronted geese (Anser albifrons) using band-recovery data and observations of neck collared geese during migration and winter. Birds from different breeding areas were initially delineated by geographic distance into 6 banding reference areas (BRAs): 1) interior Alaska, 2) North Slope of Alaska, 3) western Northwest Territories (NWT), 4) western Nunavut, 5) central Nunavut, and 6) eastern Nunavut. The banding groups also differed by breeding habitat, with geese from interior Alaska nesting in the boreal forest (taiga), and all other groups breeding in tundra habitats. Geese from interior Alaska migrated earlier during autumn, and were more likely to winter farther south (in Mexico) than geese from other breeding areas. Geese banded in central and eastern Nunavut (Queen Maud Gulf and Inglis River) wintered farther east (in Louisiana) than geese from other breeding areas. Small-scale (within-state) geographic segregation of wintering flocks was evidenced by the recent (post-1990) nearly exclusive use of a new wintering area in north central Texas by geese from interior Alaska. Segregation among BRAs was also apparent in Mexico, where taiga geese were found predominantly in the central Highlands (states of Zacatecas and Durango), whereas tundra geese mostly used states along the Gulf Coast (primarily Tamaulipas). Interior Alaska birds initiated spring migration earlier than geese from other areas, and were more likely than others to stop in the Rainwater Basin of Nebraska, a region where cholera outbreaks periodically kill thousands of geese. Geese from interior Alaska were the first to arrive at spring staging areas in prairie Canada where BRAs exhibited spatial delineation (a longitudinal cline) in relation to breeding areas. Our results show significant geographic and temporal variation among taiga and tundra breeding cohorts during autumn, winter, and spring. Temporal and spatial differences in migratory behavior may allow management practices that accommodate potential demographic differences between taiga and tundra populations.

Journal of Wildlife Management↗

USGS2025

Context matters: Intrinsic and extrinsic factors modulate habitat choices in an endangered forest bat

Effective management of declining species depends upon fundamental understanding of habitat preferences during key life stages such as reproduction. Peripheral populations of wildlife are often poorly understood and rarely the focus of study, despite their contribution to genetic diversity and their potential to aid in recolonization if a species becomes endangered. We assessed the maternal roost-site preferences of the endangered northern long-eared bat ( Myotis septentrionalis ) within a managed forest near the western edge of their range in the Black Hills region of Wyoming, USA. We further examined whether habitat preferences and roost-switching varied by reproductive state (pregnant or lactating) or proximate weather conditions. Bats were more likely to roost in quaking aspens during pregnancy, and when weather was cooler and wetter. Conversely, bats roosted more in ponderosa pines ( Pinus ponderosa) post-parturition, and when temperatures were warmer. Bats also were more likely to switch to a new roost after periods of warmer temperature and reduced solar radiation. Our results support growing evidence that habitat choices can be modulated proximately by intrinsic and extrinsic factors. Northern long-eared bats in the Black Hills relied on a variety of roost types, from healthy live trees to snags at different decay stages depending on reproductive stage and ambient weather. Our study highlights the importance of considering diverse contexts when characterizing habitat preferences, particularly for endangered species in a rapidly changing world.

Wyoming↗

USGS2021

The roles of antimicrobial resistance, phage diversity, isolation source, and selection in shaping the genomic architecture of Bacillus anthracis

Bacillus anthracis, the causative agent of anthrax disease, is a worldwide threat to livestock, wildlife and public health. While analyses of genetic data from across the globe have increased our understanding of this bacterium’s population genomic structure, the influence of selective pressures on this successful pathogen is not well understood. In this study, we investigate the effects of antimicrobial resistance, phage diversity, geography and isolation source in shaping population genomic structure. We also identify a suite of candidate genes potentially under selection, driving patterns of diversity across 356 globally extant B. anthracis genomes. We report ten antimicrobial resistance genes and 11 different prophage sequences, resulting in the first large-scale documentation of these genetic anomalies for this pathogen. Results of random forest classification suggest genomic structure may be driven by a combination of antimicrobial resistance, geography and isolation source, specific to the population cluster examined. We found strong evidence that a recombination event linked to a gene involved in protein synthesis may be responsible for phenotypic differences between comparatively disparate populations. We also offer a list of genes for further examination of B. anthracis evolution, based on high-impact single nucleotide polymorphisms (SNPs) and clustered mutations. The information presented here sheds new light on the factors driving genomic structure in this notorious pathogen and may act as a road map for future studies aimed at understanding functional differences in terms of B. anthracis biogeography, virulence and evolution.

Microbial Genomics↗

USGS2024

Tropical forests and global change: Biogeochemical responses and opportunities for cross-site comparisons, an organized INSPIRE session at the 108th Annual Meeting, Ecological Society of America, Portland, Oregon, USA, August 2023

Tropical forests play a critical role in the global carbon (C) cycle. These ecosystems maintain the highest rates of net primary production (NPP) on Earth (Hengl et al ., 2017 ), contain c . 30% of terrestrial C stocks (Jobbagy & Jackson, 2000 ), and have some of the largest stores of fine-root biomass globally (Jackson et al ., 1996 ), as well as higher fine-root production and turnover rates compared with other biomes (Cusack et al ., 2021 ). Tropical forest responses to projected warming, altered rainfall regimes, and elevated CO 2 concentrations (IPCC, 2021 ) are likely to be different from other ecosystems because of their unique characteristics (Box 1 ), making targeted research and model development important for understanding tropical forest–climate feedbacks. There is now a critical mass of long-term global change field experiments and modeling efforts in tropical forests, yet thus far there has been little synthesis, cross-site comparison, or multi-site standardized experimentation among tropical forests to help us understand how these biomes are changing. An organized INSPIRE session at the 108 th Annual Meeting of the Ecological Society of America set out to tackle just this. Speakers covered large-scale tropical forest field experiments and modeling efforts, with an emphasis on changes in ecosystem biogeochemistry under warming, drying, elevated atmospheric CO 2 , and changing nutrient status. In this Meeting report, we provide an overview of the large-scale global change experiments presented and highlight the main objectives and opportunities for tropical forest research that emerged, including cross-site comparisons and integration with ecosystem-scale models (Fig. 1 ).

New Phytologist↗

USGS2024

Intraguild interactions and abiotic conditions mediate occupancy of mammalian carnivores: Co-occurrence of coyotes–fishers–martens

The widespread eradication of large carnivores and subsequent expansion of top mesopredators has the potential to impact species and community interactions with ecosystem-wide implications. An example of these trophic dynamics is the widespread establishment of coyotes following extirpation of wolves and mountain lions in eastern North America. Here, we examined occupancy of three carnivores in northern New York considering both environmental/habitat factors and interspecific interactions. We estimated the co-occurrence of coyotes, fishers, and martens from a landscape-scale winter camera trap survey repeated annually for three years. Martens occurred independently of both coyotes and fishers, while fishers and coyotes displayed positive intraguild interactions that were constant across the landscape. Both marten and fisher first-order occupancy were driven by a combination of biotic and abiotic factors, with both species displaying positive associations with forest cover but antithetical responses to average snow depth. The integral and antithetical role of snow depth in driving the occurrence of martens (positive) and fishers (negative) in the landscape indicates that future climatic warming could reduce the availability of current spatial refuges for martens created by severe winter conditions. Climate-driven alterations to established competitive interactions and co-existence patterns between marten and fisher have critical implications for the species survival and conservation. We provide correlational evidence consistent with the potential for positive top–down effects of dominant mesocarnivores on subordinate species, with fisher occupancy increasing conditional on the presence of coyotes across the landscape. These findings align with the hypothesis that under certain conditions, coyotes may facilitate certain subordinate carnivores. The evidence produced here is consistent with hypotheses on the dynamic nature of trophic niches. We demonstrate the need to consider the interplay between climate, habitat, and interspecific interactions to understand wildlife occupancy patterns and inform wildlife management in a rapidly changing world.

New York↗

USGS2019

The state of the world’s mangrove forests: Past, present, and future

Intertidal mangrove forests are a dynamic ecosystem experiencing rapid changes in extent and habitat quality over geological history, today and into the future. Climate and sea level have drastically altered mangrove distribution since their appearance in the geological record ∼75 million years ago (Mya), through to the Holocene. In contrast, contemporary mangrove dynamics are driven primarily by anthropogenic threats, including pollution, overextraction, and conversion to aquaculture and agriculture. Deforestation rates have declined in the past decade, but the future of mangroves is uncertain; new deforestation frontiers are opening, particularly in Southeast Asia and West Africa, despite international conservation policies and ambitious global targets for rehabilitation. In addition, geological and climatic processes such as sea-level rise that were important over geological history will continue to influence global mangrove distribution in the future. Recommendations are given to reframe mangrove conservation, with a view to improving the state of mangroves in the future.

Annual Review of Environment and Resources↗

USGS2025

Thirty years of the U.S. National Land Cover Database: Impacts and future direction

The National Land Cover Database (NLCD), developed through the Multi-Resolution Land Characteristics Consortium, was initiated 30 years ago and has continually provided critical, Landsat-based landcover and land-change information for the United States. Originally launched to address the lack of national-scale, moderate-resolution land-cover data, NLCD has evolved from the pioneering 1992 dataset into a comprehensive, annually updated product suite. Key innovations include the introduction of impervious surface mapping, forest canopy mapping, standardized Landsat mosaics, national-scale accuracy assessments, continual evolution of deep learning and artificial intelligence methodologies, and a transition toward operational, change-focused monitoring. The NLCD has become an essential resource for scientific research, land management, and policy development, with extensive adoption across federal, state, and local agencies; academia; and the private sector. The NLCD data underpin a wide array of applications, including biodiversity conservation, urban planning, hydrology, human health studies, and natural hazard assessment. As new global and high-resolution commercial land-cover products emerge, the NLCD continues to distinguish itself through its temporal depth, federal backing, and thematic consistency. Moving forward, the NLCD will maintain its niche as the leading, moderate-resolution, long-term land-cover and land-change dataset for the United States, ensuring continued support for broad national applications while complementing higher-resolution and global-mapping efforts.

Photogrammetric Engineering & Remote Sensing↗

USGS2005

Grazing by the intertidal gastropod Melampus coffeus greatly increases mangrove leaf litter degradation rates

Melampus coffeus , a pulmonate gastropod, forages for mangrove leaf litter at low tide and climbs tree trunks to avoid inundation during high tide. Unlike many grazers, these snails can assimilate mangrove leaf material. At Boca Ceiga Bay, Florida, densities of adult snails were high (>100 snails m –2 ) throughout a 130 m wide intertidal zone. A mark–recapture study indicated that over the course of 1 mo 48.6 ± 6.1% of snails returned to their initial tree during high tides, while those that did relocate moved 6.66 ± 0.60 m and were recorded from 33 new trees at high tide. A field experiment comparing tethered leaves with small and large litter bags showed that snail grazing greatly increased the rate of red ( Rhizophora mangle ) and black ( Avicennia germinans ) leaf litter breakdown. Grazing by M. coffeus resulted in 90% weight loss in <4 wk ( A. germinans ) and 7 wk ( R. mangle ), compared to slower breakdown in litter bags (12 to 26 wk, A. germinans ; >26 wk, R. mangle ). Another experiment showed greater leaf litter accumulation on the forest floor in plots where M. coffeus was excluded. The decomposition coefficient ( k ) was 10× greater when M. coffeus grazing was allowed than k for any studies that enclosed leaves in litterbags. During our experiment, M. coffeus consumed an estimated 40.5% of mangrove leaf fall, and 19.8% of leaf litter was exported as particulate or dissolved material. This M. coffeus population can produce an estimated 3 × 10 6 larvae m –2 yr –1 , which suggests that the larval pathway is an important conduit of mangrove leaf resources to the estuarine food web.

Florida↗

USGS2021

Classifying crop types using two generations of hyperspectral sensors (Hyperion and DESIS) with machine learning on the cloud

Advances in spaceborne hyperspectral (HS) remote sensing, cloud-computing, and machine learning can help measure, model, map and monitor agricultural crops to address global food and water security issues, such as by providing accurate estimates of crop area and yield to model agricultural productivity. Leveraging these advances, we used the Earth Observing-1 (EO-1) Hyperion historical archive and the new generation DLR Earth Sensing Imaging Spectrometer (DESIS) data to evaluate the performance of hyperspectral narrowbands in classifying major agricultural crops of the U.S. with machine learning (ML) on Google Earth Engine (GEE). EO-1 Hyperion images from the 2010–2013 growing seasons and DESIS images from the 2019 growing season were used to classify three world crops (corn, soybean, and winter wheat) along with other crops and non-crops near Ponca City, Oklahoma, USA. The supervised classification algorithms: Random Forest (RF), Support Vector Machine (SVM), and Naive Bayes (NB), and the unsupervised clustering algorithm WekaXMeans (WXM) were run using selected optimal Hyperion and DESIS HS narrowbands (HNBs). RF and SVM returned the highest overall producer’s, and user’s accuracies, with the performances of NB and WXM being substantially lower. The best accuracies were achieved with two or three images throughout the growing season, especially a combination of an earlier month (June or July) and a later month (August or September). The narrow 2.55 nm bandwidth of DESIS provided numerous spectral features along the 400–1000 nm spectral range relative to smoother Hyperion spectral signatures with 10 nm bandwidth in the 400–2500 nm spectral range. Out of 235 DESIS HNBs, 29 were deemed optimal for agricultural study. Advances in ML and cloud-computing can greatly facilitate HS data analysis, especially as more HS datasets, tools, and algorithms become available on the Cloud.

Remote Sensing↗

USGS2014

Songbirds as sentinels of mercury in terrestrial habitats of eastern North America

Mercury (Hg) is a globally distributed environmental contaminant with a variety of deleterious effects in fish, wildlife, and humans. Breeding songbirds may be useful sentinels for Hg across diverse habitats because they can be effectively sampled, have well-defined and small territories, and can integrate pollutant exposure over time and space. We analyzed blood total Hg concentrations from 8,446 individuals of 102 species of songbirds, sampled on their breeding territories across 161 sites in eastern North America [geometric mean Hg concentration = 0.25 μg/g wet weight (ww), range <0.01–14.60 μg/g ww]. Our records span an important time period—the decade leading up to implementation of the USEPA Mercury and Air Toxics Standards, which will reduce Hg emissions from coal-fired power plants by over 90 %. Mixed-effects modeling indicated that habitat, foraging guild, and age were important predictors of blood Hg concentrations across species and sites. Blood Hg concentrations in adult invertebrate-eating songbirds were consistently higher in wetland habitats (freshwater or estuarine) than upland forests. Generally, adults exhibited higher blood Hg concentrations than juveniles within each habitat type. We used model results to examine species-specific differences in blood Hg concentrations during this time period, identifying potential Hg sentinels in each region and habitat type. Our results present the most comprehensive assessment of blood Hg concentrations in eastern songbirds to date, and thereby provide a valuable framework for designing and evaluating risk assessment schemes using sentinel songbird species in the time after implementation of the new atmospheric Hg standards.

Ecotoxicology↗

USGS2024

Simulating past and future fire impacts on Mediterranean ecosystems

Worldwide, large wildfires are becoming increasingly common, leading to economic damages and threatening ecosystems and human health. Under future climate change, more frequent fire disturbance may push ecosystems into non-forested alternative stable states. Fire-prone ecosystems such as those in the Mediterranean Basin are expected to be particularly vulnerable, but the position of tipping points is unclear. We compare long-term palaeoecological data from Sardinia with output from a process-based dynamic vegetation model to investigate the mechanisms controlling the complex interactions between fire, climate, and vegetation in the past and the future. Our results show that past vegetation changes from Erica -shrublands to mixed evergreen-broadleaved Quercus ilex -dominated forests were driven by a climate-induced fire regime shift. By simulating vegetation dynamics under varying fire regimes, we could reproduce Holocene vegetation trajectories and mechanistically identify tipping points. Without an immediate reduction of greenhouse gas emissions, we simulate future expansion of fire-prone Mediterranean maquis and increasing fire occurrence. Similarly, high anthropogenic ignition frequencies and plantations of non-native, highly flammable trees could induce a shift to fire-adapted Erica shrublands. However, our simulations indicate that if global warming can be kept below 2°C, Quercus ilex forests will be able to persist and effectively reduce fire occurrences and impacts, making them a valuable restoration target in Mediterranean ecosystems. Synthesis . By combining long-term records of ecosystem change with a dynamic vegetation model, we show that past climate-driven fire regime shifts were the main driver of vegetation change, creating alternative stable states that persisted over centuries. Projected future climate change exceeding Holocene variability leads to pronounced vegetation changes and increased fire risks in our simulations, requiring new fire management strategies to maintain current ecosystem services.

Journal of Ecology↗

USGS2017

Mapping tree density in forests of the southwestern USA using Landsat 8 data

The increase of tree density in forests of the American Southwest promotes extreme fire events, understory biodiversity losses, and degraded habitat conditions for many wildlife species. To ameliorate these changes, managers and scientists have begun planning treatments aimed at reducing fuels and increasing understory biodiversity. However, spatial variability in tree density across the landscape is not well-characterized, and if better known, could greatly influence planning efforts. We used reflectance values from individual Landsat 8 bands (bands 2, 3, 4, 5, 6, and 7) and calculated vegetation indices (difference vegetation index, simple ratios, and normalized vegetation indices) to estimate tree density in an area planned for treatment in the Jemez Mountains, New Mexico, characterized by multiple vegetation types and a complex topography. Because different vegetation types have different spectral signatures, we derived models with multiple predictor variables for each vegetation type, rather than using a single model for the entire project area, and compared the model-derived values to values collected from on-the-ground transects. Among conifer-dominated areas (73% of the project area), the best models (as determined by corrected Akaike Information Criteria (AICc)) included Landsat bands 2, 3, 4, and 7 along with simple ratios, normalized vegetation indices, and the difference vegetation index ( R 2 values for ponderosa: 0.47, piñon-juniper: 0.52, and spruce-fir: 0.66). On the other hand, in aspen-dominated areas (9% of the project area), the best model included individual bands 4 and 2, simple ratio, and normalized vegetation index ( R 2 value: 0.97). Most areas dominated by ponderosa, pinyon-juniper, or spruce-fir had more than 100 trees per hectare. About 54% of the study area has medium to high density of trees (100–1000 trees/hectare), and a small fraction (4.5%) of the area has very high density (>1000 trees/hectare). Our results provide a better understanding of tree density for identifying areas in need of treatment and planning for more effective treatment. Our analysis also provides an integrated method of estimating tree density across complex landscapes that could be useful for further restoration planning.

New Mexico↗

USGS2022

Do unpublished data help to redraw distributions? The case of the spectacled bear in Peru

Data availability remains a principal factor limiting the use of species distribution models (SDMs) as tools for wildlife conservation and management of rare species. Although data collected in systematic and rigorous fashion are preferable, available data for most species of conservation interest are usually low in both quality and number. Here we show that combining records published in peer-reviewed journals and gray literature sources (e.g., theses, government, and NGO reports) with unpublished records obtained by personal communications from relevant stakeholders affect the predicted distribution of spectacled bears ( Tremarctos ornatus ) in Peru. We built SDMs using generalized linear models, random forest, and Maxent, first using a dataset that only included published records, and second with a dataset using both published and unpublished records. All models were replicated ten times with random subsets with controlled sample size. Models that combined published and unpublished spectacled bear records had a better performance, irrespective of with SDM method used, increasing the connectivity of the species’ range, and increasing the overall predicted distribution area than models that only included published records. This was because unpublished records added key new localities, reducing spatial sampling biases. Our study shows that the inclusion of commonly disregarded data such as opportunistic records, reports from natural park rangers, student theses, and data-deficient small studies can make an important contribution to the overall ecological knowledge of rare and difficult-to-study species such as the spectacled bear.

Mammal Research↗

USGS2003

Recent and historical distributions of Canada lynx in Maine and the Northeast

The contiguous United States population of Canada lynx ( Lynx canadensis Kerr) is listed as threatened under the federal Endangered Species Act. However, the historic distribution of lynx in the Northeast is poorly understood. We used museum records, bibliographic records, and interviews to reconstruct the past distribution of lynx in Maine, which is at the current southern limit of the species' distribution in the eastern United States. We found a total of 118 records, representing at least 509 lynx in Maine. Lynx were observed throughout Maine, 1833–1912, with the exception of coastal areas. After 1913, lynx were most common in the forests of western and northern Maine, and absent to rare along the coast, but had not returned to southern Maine by 1999. Thirty-nine kittens representing at least 21 litters were distributed throughout northern and western Maine, 1864–1999. Populations apparently fluctuated, and in some years 200–300 lynx were harvested in Maine. Prior to the 1900s, lynx were much more widely distributed in the Northeast, ranging from Pennsylvania north into Quebec. Because Canada lynx have had a long presence in northern New England, and at times were relatively common, this species merits serious consideration in conservation planning in this region.

Northeast United States↗

USGS1987

Stratification of a cityscape using census and land use variables for inventory of building materials

A cityscape (or any landscape) can be stratified into environmental units using multiple variables of information. For the purposes of sampling building materials, census and land use variables were used to identify similar strata. In the Metropolitan Statistical Area of a cityscape, the census tract is the smallest unit for which census data are summarized and digitized boundaries are available. For purposes of this analysis, census data on total population, total number of housing units, and number of singleunit dwellings were aggregated into variables of persons per square kilometer and proportion of housing units in single-unit dwellings. The level 2 categories of the U.S. Geological Survey's land use and land cover data base were aggregated into variables of proportion of residential land with buildings, proportion of nonresidential land with buildings, and proportion of open land. The cityscape was stratified, from these variables, into environmental strata of Urban Central Business District, Urban Livelihood Industrial Commercial, Urban Multi-Family Residential, Urban Single Family Residential, Non-Urban Suburbanizing, and Non-Urban Rural. The New England region was chosen as a region with commonality of building materials, and a procedure developed for trial classification of census tracts into one of the strata. Final stratification was performed by discriminant analysis using the trial classification and prior probabilities as weights. The procedure was applied to several cities, and the results analyzed by correlation analysis from a field sample of building materials. The methodology developed for stratification of a cityscape using multiple variables has application to many other types of environmental studies, including forest inventory, hydrologic unit management, waste disposal, transportation studies, and other urban studies. Multivariate analysis techniques have recently been used for urban stratification in England. ?? 1987 Annals of Regional Science.

The Annals of Regional Science↗

USGS1993

Acid Rain

Acid deposition, or acid rain as it is more commonly referred to, has become a widely publicized environmental issue in the U.S. over the past decade. The term usually conjures up images of fish kills, dying forests, "dead" lakes, and damage to monuments and other historic artifacts. The primary cause of acid deposition is emission of S0 2 and NO x to the atmosphere during the combustion of fossil fuels. Oxidation of these compounds in the atmosphere forms strong acids - H 2 SO 4 and HNO 3 - which are returned to the Earth in rain, snow, fog, cloud water, and as dry deposition. Although acid deposition has only recently been recognized as an environmental problem in the U.S., it is not a new phenomenon (Cogbill & Likens 1974). As early as the middle of the 17th century in England, the deleterious effects of industrial emissions on plants, animals, and humans, and the atmospheric transport of pollutants between England and France had become issues of concern (Evelyn 1661, Graunt 1662). It is interesting that well over three hundred years ago in England, recommendations were made to move industry outside of towns and build higher chimneys to spread the pollution into "distant parts." Increasing the height of smokestacks has helped alleviate local problems, but has exacerbated others. In the U.S. the height of the tallest smokestack has more than doubled, and the average height of smokestacks has tripled since the 1950s (Patrick et al 1981). This trend occurred in most industrialized nations during the 20th century and has had the effect of transforming acid rain from a local urban problem into a problem of global scale.

Annual Review of Earth and Planetary Sciences↗