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At least 325 records · Page 18Linked to original sources

Characterizing 12 years of wildland fire science at the U.S. Geological Survey: Wildland Fire Science Publications, 2006–17

Wildland fire characteristics, such as area burned, number of large fires, burn intensity, and fire season duration, have increased steadily over the past 30 years, resulting in substantial increases in the costs of suppressing fires and managing damages from wildland fire events (National Academies of Sciences, Engineering, and Medicine, 2017). Wildland fire management could benefit from sound decision making based on reliable scientific information. Fire scientists produce data, tools, and information to support fire and land management decision making. With ever-changing land use scenarios, environmental conditions, and emerging technological capabilities, new assessments and studies are continually needed. Established by Congress in 1879, the U.S. Geological Survey (USGS) is the primary science branch of the Department of the Interior (DOI), which manages more than 400 million acres of public lands in the United States. The USGS has more than 100 scientists across seven Mission Areas that help address the wildland fire science needs of DOI bureaus and their stakeholders. The diverse expertise of these scientists allows them to address complex interdisciplinary challenges. In this report, we identify and characterize scientific literature produced by USGS scientists during 2006–17 that addresses topics associated with wildland fire science. Our goals were to (1) make the most complete list possible of product citations readily available in an organized format, and (2) use bibliometric analysis approaches to highlight the productivity of USGS scientists and the impact of contributions that the Bureau has provided to the scientific, land management, and fire management communities.

Open-File Report↗

Landscape transcriptomic analysis detects thermal stress responses and potential adaptive variation in wild brook trout (Salvelinus fontinalis) during successive heatwaves

Extreme weather events, such as heatwaves, are becoming more frequent and intense as a result of climate change. Critically, such extreme weather events can be more important drivers of extirpation and selection than changes in annual or seasonal averages and they pose a particularly large threat to poikilothermic organisms. In this study, we evaluated the transcriptomic response of a coldwater adapted fish species, the eastern brook trout ( Salvelinus fontinalis ), to two successive heatwaves during July and August 2022. We sampled brook trout at eight time points from four streams ( N = 116 fish), sequenced mRNA from gill samples using TagSeq, and quantified expression levels of 32,670 unique transcripts. Multivariate analyses found that overall expression patterns in response to water temperature change were similar among streams. These analyses further detected groups of genes involved in immune response and oxygen carrier activity that were upregulated and downregulated respectively at higher water temperatures. We also detected 43 genes that were differentially expressed at different time points and followed the same expression pattern during the two heatwaves. Of these genes, 42 covaried with water temperature and most (27, 62.8 %) exhibited responses that varied by stream. Some of the differentially expressed genes, including heat shock proteins and cold-inducible RNA binding proteins, have been widely linked to temperature responses in experimental studies, whereas other genes we identified have functions that have not been well-studied in relationship to temperature or have unknown functions. This study shows the utility of landscape transcriptomic approaches to identify important biological processes governing wild organismal responses to short-term stressors. The results of this study can guide future investigations to identify phenotypic and genetic diversity that contribute to adaptive responses to heatwaves and improve predictions of how populations will respond to future climate change.

Pennsylvania↗

Flowering phenology shifts in response to biodiversity loss

Observational studies and experimental evidence agree that rising global temperatures have altered plant phenology—the timing of life events, such as flowering, germination, and leaf-out. Other large-scale global environmental changes, such as nitrogen deposition and altered precipitation regimes, have also been linked to changes in flowering times. Despite our increased understanding of how abiotic factors influence plant phenology, we know very little about how biotic interactions can affect flowering times, a significant knowledge gap given ongoing human-caused alteration of biodiversity and plant community structure at the global scale. We experimentally manipulated plant diversity in a California serpentine grassland and found that many plant species flowered earlier in response to reductions in diversity, with peak flowering date advancing an average of 0.6 days per species lost. These changes in phenology were mediated by the effects of plant diversity on soil surface temperature, available soil N, and soil moisture. Peak flowering dates were also more dispersed among species in high-diversity plots than expected based on monocultures. Our findings illustrate that shifts in plant species composition and diversity can alter the timing and distribution of flowering events, and that these changes to phenology are similar in magnitude to effects induced by climate change. Declining diversity could thus contribute to or exacerbate phenological changes attributed to rising global temperatures.

Proceedings of the National Academy of Sciences↗

Long-term patterns in growth of White Sturgeon in the Sacramento-San Joaquin River basin, California.

Introduction: The Sacramento-San Joaquin River system (SSJ) of California includes both riverine, delta, and estuarine habitats and is among the most modified aquatic ecosystems in the United States. Water development projects in the system are associated with declines of many native species, including White Sturgeon Acipenser transmontanus . Methods: We used White Sturgeon pectoral fin rays collected from 1983 to 2016 throughout the SSJ to assess long-term changes in growth and associations with thermal and hydrological conditions (i.e., temperature, discharge, salinity). Age and growth were estimated from 1,897 White Sturgeon varying in fork length from 25 to 210 cm and from age 0 to 33. Results: Age structure varied through time with the oldest fish generally sampled during the mid-1980s. Growth of White Sturgeon in 1951–1970 was slower than growth of fish in 1971–1990 and 1991–2012. Growth of White Sturgeon during 1991–2012 was ~10% higher than during other time periods. Discussion: Little variation in growth was explained by environmental covariates, suggesting that annual growth was likely influenced by factors not measured in our study. Alternatively, population structure and movement behavior of White Sturgeon in the SSJ may be such that the scale (i.e., spatial or temporal) of available habitat covariates was mismatched to the scale at which growth of White Sturgeon responds. Increased growth in recent times may be partly due to density-dependent processes in association with substantial declines in White Sturgeon population abundance over the last several decades. This research provides important information on long-term patterns in growth that contributes to the conservation and management of White Sturgeon in the SSJ and beyond.

California↗

Geodetic investigations of the Europa Clipper mission

The Europa Clipper mission will investigate the geophysical properties of Europa, one of Jupiter’s Galilean moons, to assess its habitability. Geodetic measurements will play a critical role in determining Europa’s internal structure, rotational state, and tidal deformation. The Geodesy Focus Group (GFG) coordinates cross-instrument efforts to measure Europa’s global shape, rotational parameters, gravity field, and degree-2 tidal Love numbers ( k 2 and h 2 ). The data provided by the Gravity/Radio Science (G/RS) investigation, Europa Imaging System (EIS), Radar for Europa Assessment and Sounding (REASON), and Europa Ultraviolet Spectrometer (UVS) will be used to infer geodetic constraints on the interior structure and construct a precise cartographic reference system. This combined dataset will provide new constraints on Europa’s tidal response, ice shell thickness, and the properties of its subsurface ocean. The resulting geodetic information will contribute to a deeper understanding of Europa’s internal dynamics and the potential habitability of its ocean.

Space Science Reviews↗

Gulf of Mexico Integrated Science - Tampa Bay Study: Watershed and Estuary Mapping

Tampa Bay, Florida, and its environs have experienced phenomenal urban growth and significant changes in land-use practices over the past 50 years. This trend is expected to continue, with human activity intensifying and affecting a wider geographic region. Urbanization creates impervious surfaces, which increase stormwater runoff and contribute to greater amounts of chemicals flowing into coastal waters. Man-made structures including bridges, a gas pipeline, desalination plant, ports, navigation channels, and extensive sea walls have been built and will continue to be maintained and modified. This task of the Tampa Bay Study aims to provide a better understanding of these and other man-made impacts on the Tampa Bay region.

Open-File Report↗

Patterns of marsh surface accretion rates along salinity and hydroperiod gradients between active and inactive coastal deltaic floodplains

High subsidence rates are inherent to coastal deltas worldwide, contributing to rapid rates of relative sea-level rise and compromising the sustainability of coastal wetlands. Different parts of river deltas, however, experience accretion or erosion, depending on the coupling between ecological and morphological processes. Wetland expansion occurs in active deltaic coastal basins that are connected to riverine sedimentation. In contrast, wetland degradation occurs in inactive deltaic coastal basins where river engineering strategies associated with flood control restrict river connectivity. Here, we investigated the relative role of inorganic and organic loading to marsh accretion rates spanning fresh to brackish to saline zones between active and inactive coastal deltaic floodplains of the Mississippi River Delta. Marsh surface accretion rates monitored over 36 months using the feldspar marker horizon technique ranged from 1.24 ± 0.35 cm yr −1 in the freshwater marsh to 2.94 ± 0.51 cm yr −1 in the saline marsh in the inactive coastal basin compared to an opposite trend in the active coastal basin with a low vertical accretion rate in the saline site at 1.12 ± 0.17 cm yr −1 and higher accretion values at the freshwater site (2.14 ± 0.49 cm yr −1 ). Our results suggest that saline marshes have high resilience identified by high vertical accretion rates exceeding those of river-dominated freshwater marshes in active deltaic floodplains. Overall, the marsh surface accretionary patterns detected in this study underscores the relative contribution of organic and inorganic sediments to elevation capital across salinity gradients between active and inactive basins in coastal Louisiana with particular interest to river management and restoration strategies. These findings, however, are applicable to coastal deltaic floodplains elsewhere given the repetition geomorphic forcings (e.g., relative contribution of riverine, tidal and wave power) and coastal typologies worldwide.

Estuarine, Coastal, and Shelf Science↗

Climatic and topographic controls on the style and timing of Late Quaternary glaciation throughout Tibet and the Himalaya defined by 10Be cosmogenic radionuclide surface exposure dating

Temporal and spatial changes in glacier cover throughout the Late Quaternary in Tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region, and the lack of numerical dating. To help reconstruct the timing and extent of glaciation throughout Tibet and the bordering mountains, we use geomorphic mapping and 10Be cosmogenic radionuclide (CRN) surface dating in study areas in southeastern (Gonga Shan), southern (Karola Pass) and central (Western Nyainqentanggulha Shan and Tanggula Shan) Tibet, and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands. Each of the study regions receives its precipitation mainly during the south Asian summer monsoon when it falls as snow at high altitudes. Gonga Shan receives the most precipitation (>2000 mm a-1) while, near the margins of monsoon influence, the Karola Pass receives moderate amounts of precipitation (500-600 mm a-1) and, in the interior of the plateau, little precipitation falls on the western Nyainqentanggulha Shan (???300 mm a -1) and the Tanggula Shan (400-700 mm a-1). The higher precipitation values for the Tanggula Shan are due to strong orographic effects. In each region, at least three sets of moraines and associated landforms are preserved, providing evidence for multiple glaciations. The 10Be CRN surface exposure dating shows that the formation of moraines in Gonga Shan occurred during the early-mid Holocene, Neoglacial and Little Ice Age, on the Karola Pass during the Lateglacial, Early Holocene and Neoglacial, in the Nyainqentanggulha Shan date during the early part of the last glacial cycle, global Last Glacial Maximum and Lateglacial, and on the Tanggula Shan during the penultimate glacial cycle and the early part of the last glacial cycle. The oldest moraine succession in each of these regions varies from the early Holocene (Gonga Shan), Lateglacial (Karola Pass), early Last Glacial (western Nyainqentanggulha Shan), and penultimate glacial cycle (Tanggula Shan). We believe that the regional patterns and timing of glaciation reflect temporal and spatial variability in the south Asian monsoon and, in particular, in regional precipitation gradients. In zones of greater aridity, the extent of glaciation has become increasingly restricted throughout the Late Quaternary leading to the preservation of old (???100 ka) glacial landforms. In contrast, in regions that are very strongly influenced by the monsoon (???1600 mm a-1), the preservation potential of pre-Lateglacial moraine successions is generally extremely poor. This is possibly because Lateglacial and Holocene glacial advances may have been more extensive than early glaciations and hence may have destroyed any landform or sedimentary evidence of earlier glaciations. Furthermore, the intense denudation, mainly by fluvial and mass movement processes, which characterize these wetter environments, results in rapid erosion and re-sedimentation of glacial and associated landforms, which also contributes to their poor preservation potential. ?? 2004 Elsevier Ltd. All rights reserved.

Quaternary Science Reviews↗

Museum records provide unique information about the distribution of the Yellow Lampmussel Lampsilis cariosa (Unionidae)

Natural history museum records may provide unique information on the distribution of species that can supplement survey data collected by resource managers. However, there can be challenges to using museum data for analyses, such as spurious geographic information, misidentifications, and incorrect labeling. Museum records have been centralized by open-source repositories with flags for coordinate precision and out-of-range specimens, providing some information about record uncertainty in general. Verification of uncertain museum records could increase confidence in distribution data and improve understanding of biodiversity patterns and range dynamics through time. The goal of this study was to determine if museum records provide unique information about the distribution of the Yellow Lampmussel Lampsilis cariosa (Say, 1817), an at-risk freshwater mussel species. We created a dichotomous key based on a hierarchy of conchological characteristics to verify the taxonomic identity of flagged L. cariosa specimens and assessed records occurring outside of the species’ expected range as compiled from primary literature. Fifty percent of flagged specimens were confirmed as L. cariosa . Of the invalid records, 56% were misidentifications, mainly of other Lampsilis species. Overall, museum collections (1800s–present) contributed 32 unique watersheds not represented by modern survey records (1980s–present, comprising 92 watersheds) including 13 unexpected watersheds in regions of New York and Vermont (USA) and Québec and Ontario (Canada). Our study provides a reproducible method for the reverification of freshwater mussel museum records and highlights how these records can provide unique contributions to our understanding of the geographic range of a rare, at-risk mussel species.

New York, Vermont↗

Trends in plant cover derived from vegetation plot data using ordinal zero-augmented beta regression

Questions Plant cover values in vegetation plot data are bounded between 0 and 1, and cover is typically recorded in discrete classes with non-equal intervals. Consequently, cover data are skewed and heteroskedastic, which hampers the application of conventional regression methods. Recently developed ordinal beta regression models consider these statistical difficulties. Our primary question is whether we can detect species trends in vegetation plot time series data with this modelling approach. A second question is whether trends in cover have additional value compared to trends in occurrence, which are easier to assess for practitioners. Location The Netherlands, Western Europe. Methods We used vegetation plot data collected from 10,000 fixed plots which were surveyed once every four years during 1999–2022. We used the ordinal zero-augmented beta regression (OZAB) model, a hierarchical model consisting of a logistic regression for presence and an ordinal beta regression for cover. We adapted the OZAB model for longitudinal data and produced estimates of cover and occurrence for each four-year period. Thereafter we assessed trends in cover and in occurrence across all periods. Results We found evidence of a trend in cover in 318 out of the 721 species (44%) with sufficient data. Most species showed similar directional trends in occurrence and percent cover. No trend in occurrence was detected for 64 species that had evidence of a trend in cover. Declining species had stronger relative changes in cover than in occurrence. Conclusions Our model enables researchers to detect trends in cover using longitudinal vegetation plot data. Cover trends often corroborated trends in occurrence, but we also regularly found trends in cover even in the absence of evidence for trends in occurrence. Our approach thus contributes to a more complete picture of (changes in) vegetation composition based on large monitoring data sets.

Journal of Vegetation Science↗

Vibrio population dynamics in Mid-Atlantic surface waters during Saharan dust events

Vibrio is a cosmopolitan genus of marine bacteria, highly investigated in coastal and estuarine environments. Vibrio have also been isolated from pelagic waters, yet very little is known about the ecology of these oligotrophic species. In this study we examined the relative change in bacterial abundance and more specifically the dynamics of Vibrio in the tropical North Atlantic in response to the arrival of pulses of Saharan dust aerosols, a major source of biologically important nutrients for downwind marine surface waters. Aerosol and surface water samples were collected over 1 month coinciding with at least two distinct dust events. Total bacterial counts increased by 1.6-fold correlating with the arrival of Saharan dust ( r = 0.76; p = 0.001). Virus-like particles (VLP) also followed this trend and were correlated with bacterial counts ( r = 0.67; p = 0.01). Vibrio specific qPCR targeting the 16S rRNA gene ranged from below detection limits to a high of 9,145 gene copies ml −1 with the arrival of dust. This increase equated to 6.5 × 10 2 −1.5 × 10 3 individual genome equivalents ml −1 based on the known range of 16S rRNA copies among this genus. Vibrio exhibited bloom-bust cycles potentially attributed to selective viral lysis or bloom depletion of organic carbon. This work is one of the few studies to examine the open ocean ecology of Vibrio , a conditionally rare taxon, whose bloom-bust lifestyle likely is a contributing factor in the flow of nutrients and energy in pelagic ecosystems.

Frontiers in Marine Science↗

Comparison of stomach contents of haddock (Melanogrammus aeglefinus) from the 1981 and 1991 North Sea International Stomach Sampling Projects

This study analyses data from over 20 000 haddock stomachs collected during the 1981 and 1991 Stomach Sampling Projects of the North Sea. Sampling was within the framework of the Multispecies Virtual Population Analysis (MSVPA) for fisheries stock assessment. In 1981 stomachs were collected to calculate input feeding parameters from main predators. During 1991 the sampling exercise was repeated to test stability of the parameters in the region. We investigate stability of haddock stomach content weight between years accounting for ontogenic, spatial and temporal variations within the scope of the survey resolution. Analysis using generalized linear and additive models is performed for weight of the stomach content including and excluding empty stomachs and also for proportion of stomachs without food. Results indicate that haddock stomach contents varied significantly between years, quarters and North Sea roundfish areas. Content weights were overall higher in 1981 than in 1991. In 1981 levels were high from spring to fall and in 1991 mostly in spring. During both years levels were lowest in the central North Sea and in winter. Most of the deviance in modelling the stomach weight is explained by the length of the predator. Stomachs sampled in 1981 were most frequently empty in spring and those sampled in 1991 in winter. In both years, proportions decreased with fish length except in winter when levels increased. Proportion of empty stomachs was highest in the central region of the North Sea. Most of the proportion variation is explained by quarterly fluctuation. Variation of content weight can be related to prey composition found in the stomachs. High stomach contents are generally associated with high contribution of fish prey to the total stomach content, mainly sandeels. We propose that sandeels were more vulnerable to predation in 1981 than in 1991 due to colder temperatures. ?? 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd.

ICES Journal of Marine Science↗

Book review: Restoring paradise: Rethinking and rebuilding nature in Hawaii

The native ecosystems of Hawai‘i have been severely degraded by the introduction of herbivorous mammals and a myriad of invasive plant species. Left unmanaged, most natural areas would continue along a trajectory towards domination by nonnative species; however, several projects have undertaken the daunting task of ecological restoration, four of which are the subject of Restoring Paradise by Robert Cabin: Hakalau Forest National Wildlife Refuge; Hawai‘i Volcanoes National Park; the Auwahi dryland forest, Maui and Limahuli Garden and Preserve, Kaua‘i. After an introductory section discussing the setting and factors that have contributed to so much of the degradation and extinction of Hawai‘i’s native biota, Cabin outlines two different views of restoration in two central sections of the book: ad hoc, trial-and-error approaches versus the careful application of science to direct restoration. The time-tested methods of fence construction, ungulate removal, weed control, and replanting native species with the help of numerous volunteers and community support are presented in marked contrast to inconsistent applications of science in guiding restoration, and illustrated by some of the author’s unsuccessful research. The book is largely presented as a non-technical first-person account of travels and meetings with key personalities driving restoration projects. The philosophies of restoration practitioners are embedded in passages from interviews. Setbacks, obstacles, logistical constraints, and successes are narrated in between as Cabin revisits each of the restoration sites. The utility of science in restoration is frequently questioned by the author and sometimes abandoned by practitioners in favour of a ‘let-nature-take-its-course’ approach. Review info: Restoring Paradise: Rethinking and Rebuilding Nature in Hawaii . By Robert J. Cabin, 2013. ISBN: 978-0822836931, 236 pp.

Pacific Conservation Biology↗

Distinct pathways to stakeholder use versus academic contribution in climate adaptation research

Challenges facing societies around the globe as they plan for and adapt to climate change are so large that usable, research-driven recommendations to inform management actions are urgently needed. We sought to understand factors that influence the variation of academic contribution and use of collaborative research on climate change. We surveyed researchers ( n = 31), program-leaders ( n = 5), and stakeholders ( n = 81) from projects supported by a federally funded network across the United States. Our results suggest that peer-reviewed publications do not lead to use, but frequency of meetings with stakeholders significantly increased use. Overall, the factors needed for projects to have high degrees of academic contributions are distinct from those needed to be useful to stakeholders. Furthermore, leadership perceptions of use of projects were significantly different from users. Our quantitative results can inform future requests for proposals and better enable researchers using collaborative approaches to conduct science that is more often used by stakeholders.

Conservation Letters↗

Sharing knowledge to improve ecological restoration outcomes

Ecological restoration efforts are likely to be more successful when project components are informed by relevant stakeholders. However, key stakeholders are often not included in restoration design and deployment. This is largely driven by a lack of practitioner knowledge of and experience with stakeholder relations. However, inclusion of stakeholders across the entire restoration process can be accomplished by practitioners with no formal social science training. Here, we describe several easy (and usually inexpensive) ways to formally cultivate relationships among restoration practitioners, researchers, and stakeholders to improve restoration outcomes. These include: how to identify and work with stakeholders; how to recognize the unique needs and contributions of stakeholder groups, and how to provide information back to stakeholders through outreach. Although how this practice occurs is dependent on restoration context, integrating these approaches more regularly into ecological restoration projects will likely result in more successful, relevant, and community-supported management outcomes.

Restoration Ecology↗

Comparing catchment hydrologic response to a regional storm using specific conductivity sensors

A better understanding of stormwater generation and solute sources is needed to improve the protection of aquatic ecosystems, infrastructure, and human health from large runoff events. Much of our understanding of water and solutes produced during stormflow comes from studies of individual, small headwater catchments. This study compared many different types of catchments during a single large event to help isolate landscape controls on streamwater and solute generation, including human-impacted land cover. We used a distributed network of specific electrical conductivity sensors to trace storm response during the post-tropical cyclone Sandy event of October 2012 at 29 catchments across the state of New Hampshire. A citizen science sensor network, Lotic Volunteer for Temperature, Electrical Conductivity, and Stage, provided a unique opportunity to investigate high-temporal resolution stream behavior at a broad spatial scale. Three storm response metrics were analyzed in this study: (a) fraction of new water contributing to the hydrograph; (b) presence of first flush (mobilization of solutes during the beginning of the rain event); and (c) magnitude of first flush. We compared new water and first flush to 64 predictor attributes related to land cover, soil, topography, and precipitation. The new water fraction was positively correlated with low and medium intensity development in the catchment and riparian buffers and with the precipitation from a rain event 9 days prior to Sandy. The presence of first flush was most closely related (positively) to soil organic matter. Magnitude of first flush was not strongly related to any of the catchment variables. Our results highlight the potentially important role of human landscape modification in runoff generation at multiple spatial scales and the lack of a clear role in solute flushing. Further development of regional-scale in situ sensor networks will provide better understanding of stormflow and solute generation across a wide range of landscape conditions.

New Hampshire↗

Steady- and non-steady-state carbonate-silicate controls on atmospheric CO2

Two contrasting hypotheses have recently been proposed for the past long-term relation between atmospheric CO 2 and the carbonate-silicate geochemical cycle. One approach (Berner, 1990) suggests that CO 2 levels have varied in a manner that has maintained chemical weathering and carbonate sedimentation at a steady state with respect to tectonically controlled decarbonation reactions. A second approach (Raymo et al. , 1988), applied specificlly to the late Cenozoic, suggests a decrease in CO 2 caused by an uplift-induced increase in chemical weathering, without regard to the rate of decarbonation. According to the steady-state (first) hypothesis, increased weathering and carbonate sedimentation are generally associated with increasing atmospheric CO 2 , whereas the uplift (second) hypothesis implies decreasing CO 2 under the same conditions. An ocean-atmosphere-sediment model has been used to assess the response of atmospheric CO 2 and carbonate sedimentation to global perturbations in chemical weathering and decarbonation reactions. Although this assessment is theoretical and cannot yet be related to the geologic record, the model simulations compare steady-state and non-steady-state carbonate-silicate cycle response. The e-fold response time of the ‘CO 2 -weathering’ feedback mechanism is between 300 and 400 ka. The response of carbonate sedimentation is much more rapid. These response times provide a measure of the strength of steady-state assumptions, and imply that certain systematic relations are sustained throughout steady-state and non-steady-state scenarios for the carbonate-silicate cycle. The simulations suggest that feedbacks can maintain the system near a steady state, but that non-steady-state effects may contribute to long-term trends. The steady-state and uplift hypotheses are not necessarily incompatible over time scales of a few million years.

Quaternary Science Reviews↗