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USGS2020

Using video survey to examine the effect of habitat on gag grouper encounter

Gag is a reef fish that was declared overfished in the Gulf of Mexico (GOM) in 2009. Although Gag are no longer listed as overfished, fisheries managers are concerned that stocks may not be recovering. Our objective was to identify habitat characteristics important to Gag, and their effect on the probability of Gag occurrence. We obtained data from three separate fisheries-independent video surveys that sampled in the eastern GOM from 2010-2017: the National Atmospheric and Oceanic Administration (NOAA) Panama City, FL Office, the NOAA Southeast Area Monitoring and Assessment Program, and the Florida Fish and Wildlife Research Institute. We ran a separate mixed effects logistic regression for each survey, and used Akaike’s Information Criteria to determine the best fitting models. Some variables - percent rock coverage, vertical relief, latitude, and depth - were present in all confidence models. Depth did not have the same relationship with Gag across all surveys, suggesting that shallower habitats (<50 m) might be more suitable for juveniles, whereas deeper habitats (>50 m) might be more suitable for adults. Managers may be able to help Gag and encourage their recovery by using these data to establish or expand protected areas throughout shallower waters.

Florida↗

USGS2011

USGS global change science strategy: A framework for understanding and responding to climate and land-use change

This U.S. Geological Survey (USGS) Global Change Science Strategy expands on the Climate Variability and Change science component of the USGS 2007 Science Strategy, “Facing Tomorrow’s Challenges: USGS Science in the Coming Decade” (U.S. Geological Survey, 2007). Here we embrace the broad definition of global change provided in the U.S. Global Change Research Act of 1990 (Public Law 101–606,104 Stat. 3096–3104)—“Changes in the global environment (including alterations in climate, land productivity, oceans or other water resources, atmospheric chemistry, and ecological systems) that may alter the capacity of the Earth to sustain life”—with a focus on climate and land-use change. There are three major characteristics of this science strategy. First, it addresses the science required to broadly inform global change policy, while emphasizing the needs of natural-resource managers and reflecting the role of the USGS as the science provider for the Department of the Interior and other resource-management agencies. Second, the strategy identifies core competencies, noting 10 critical capabilities and strengths the USGS uses to overcome key problem areas. We highlight those areas in which the USGS is a science leader, recognizing the strong partnerships and effective collaboration that are essential to address complex global environmental challenges. Third, it uses a query-based approach listing key research questions that need to be addressed to create an agenda for hypothesis-driven global change science organized under six strategic goals. Overall, the strategy starts from where we are, provides a vision for where we want to go, and then describes high-priority strategic actions, including outcomes, products, and partnerships that can get us there. Global change science is a well-defined research field with strong linkages to the ecosystems, water, energy and minerals, natural hazards, and environmental health components of the USGS Science Strategy (2007). When science strategies that cover these other components are developed, coordinated implementation will be necessary to achieve Bureau-level synergies and optimize capabilities and expertise. In October 2010, USGS realigned its management and budget structure to implement its 2007 Science Strategy. The new organizational structure, in which “Global Change” is one of seven key mission areas, lends itself to the advancement of the established six strategic goals. USGS global change science is formally represented by the “Climate and Land-Use Change” Mission Area in the FY 2012 budget (USGS, 2011). This plan was developed by the USGS Global Change Science Strategy Planning Team (SSPT) appointed by the USGS Director on March 4, 2010 and charged with developing a Global Change Science Strategy for the coming decade (McNutt, 2010). USGS managers and science staff are the main audience for this science strategy. This document is also intended to serve as the foundation for consistent USGS collaboration and communication with partners and stakeholders.

Open-File Report↗

USGS2013

Linkages between lake shrinkage/expansion and sublacustrine permafrost distribution determined from remote sensing of interior Alaska, USA

[1] Linkages between permafrost distribution and lake surface-area changes in cold regions have not been previously examined over a large scale because of the paucity of subsurface permafrost information. Here, a first large-scale examination of these linkages is made over a 5150 km 2 area of Yukon Flats, Alaska, USA, by evaluating the relationship between lake surface-area changes during 1979–2009, derived from Landsat satellite data, and sublacustrine groundwater flow-path connectivity inferred from a pioneering, airborne geophysical survey of permafrost. The results suggest that the shallow (few tens of meters) thaw state of permafrost has more influence than deeper permafrost conditions on the evolving water budgets of lakes on a multidecadal time scale. In the region studied, these key shallow aquifers have high hydraulic conductivity and great spatial variability in thaw state, making groundwater flow and associated lake level evolution particularly sensitive to climate change owing to the close proximity of these aquifers to the atmosphere.

Alaska↗

USGS2017

Late Pleistocene C4 plant dominance and summer rainfall in the southwestern United States from isotopic study of herbivore teeth

Patterns of climate and C4 plant abundance in the southwestern United States during the last glaciation were evaluated from isotopic study of herbivore tooth enamel. Enamel ??13C values revealed a substantial eastward increase in C4 plant consumption for Mammuthus spp., Bison spp., Equus spp., and Camelops spp. The ??13C values were greatest in Bison spp. (-6.9 to + 1.7???) and Mammuthus spp. (-9.0 to +0.3???), and in some locales indicated C4-dominated grazing. The ??13C values of Antilocaprids were lowest among taxa (-12.5 to -7.9???) and indicated C3 feeding at all sites. On the basis of modern correlations between climate and C4 grass abundance, the enamel data imply significant summer rain in parts of southern Arizona and New Mexico throughout the last glaciation. Enamel ??18O values range from +19.0 to +31.0??? and generally increase to the east. This pattern could point to a tropical or subtropical source of summer rainfall. At a synoptic scale, the isotope data indicate that interactions of seasonal moisture, temperature, and lowered atmospheric pCO2 determined glacial-age C4 abundance patterns.

Quaternary Research↗

USGS2017

Expanding the role of reactive transport models in critical zone processes

Models test our understanding of processes and can reach beyond the spatial and temporal scales of measurements. Multi-component Reactive Transport Models (RTMs), initially developed more than three decades ago, have been used extensively to explore the interactions of geothermal, hydrologic, geochemical, and geobiological processes in subsurface systems. Driven by extensive data sets now available from intensive measurement efforts, there is a pressing need to couple RTMs with other community models to explore non-linear interactions among the atmosphere, hydrosphere, biosphere, and geosphere. Here we briefly review the history of RTM development, summarize the current state of RTM approaches, and identify new research directions, opportunities, and infrastructure needs to broaden the use of RTMs. In particular, we envision the expanded use of RTMs in advancing process understanding in the Critical Zone, the veneer of the Earth that extends from the top of vegetation to the bottom of groundwater. We argue that, although parsimonious models are essential at larger scales, process-based models offer tools to explore the highly nonlinear coupling that characterizes natural systems. We present seven testable hypotheses that emphasize the unique capabilities of process-based RTMs for (1) elucidating chemical weathering and its physical and biogeochemical drivers; (2) understanding the interactions among roots, micro-organisms, carbon, water, and minerals in the rhizosphere; (3) assessing the effects of heterogeneity across spatial and temporal scales; and (4) integrating the vast quantity of novel data, including “omics” data (genomics, transcriptomics, proteomics, metabolomics), elemental concentration and speciation data, and isotope data into our understanding of complex earth surface systems. With strong support from data-driven sciences, we are now in an exciting era where integration of RTM framework into other community models will facilitate process understanding across disciplines and across scales.

Earth-Science Reviews↗

USGS2008

Middle UV to near-IR spectrum of electron-excited SO 2

We investigated the electron impact–induced fluorescence spectrum of SO 2 to provide excitation cross sections for modeling Io's emission spectrum and analyzing Cassini Imaging Science Subsystem observations. The electron-excited middle-ultraviolet visible optical near-infrared (VOIR) emission spectrum of SO 2 gas was generated in the laboratory and studied from 2000 to 11,000 Å at a resolution of Δ λ &sim; 2.5 Å full width at half maximum (FWHM). The VOIR laboratory spectrum longward of 6000 Å consists entirely of S I, II and O I, II multiplets for electron impact energies above &sim;15 eV. Between 2000 and 6000 Å, we find previously identified molecular bands from both SO and SO 2 . This work represents a significant improvement in spectral resolution over our earlier work done at 18 Å FWHM. From a measurement of the medium-resolution spectrum, we provide detailed 25- and 100-eV emission cross sections for spectral features from 2000 to 11,000 Å. On the basis of these data, we suggest future ground-based and satellite telescopic observations in the VOIR that are of promise for understanding Io's atmosphere.

Journal of Geophysical Research E: Planets↗

USGS2004

Global land ice measurements from space (GLIMS): remote sensing and GIS investigations of the Earth's cryosphere

Concerns over greenhouse‐gas forcing and global temperatures have initiated research into understanding climate forcing and associated Earth‐system responses. A significant component is the Earth's cryosphere, as glacier‐related, feedback mechanisms govern atmospheric, hydrospheric and lithospheric response. Predicting the human and natural dimensions of climate‐induced environmental change requires global, regional and local information about ice‐mass distribution, volumes, and fluctuations. The Global Land‐Ice Measurements from Space (GLIMS) project is specifically designed to produce and augment baseline information to facilitate glacier‐change studies. This requires addressing numerous issues, including the generation of topographic information, anisotropic‐reflectance correction of satellite imagery, data fusion and spatial analysis, and GIS‐based modeling. Field and satellite investigations indicate that many small glaciers and glaciers in temperate regions are downwasting and retreating, although detailed mapping and assessment are still required to ascertain regional and global patterns of ice‐mass variations. Such remote sensing/GIS studies, coupled with field investigations, are vital for producing baseline information on glacier changes, and improving our understanding of the complex linkages between atmospheric, lithospheric, and glaciological processes.

Geocarto International↗

USGS2009

Atmospheric correction at AERONET locations: A new science and validation data set

This paper describes an Aerosol Robotic Network (AERONET)-based Surface Reflectance Validation Network (ASRVN) and its data set of spectral surface bidirectional reflectance and albedo based on Moderate Resolution Imaging Spectroradiometer (MODIS) TERRA and AQUA data. The ASRVN is an operational data collection and processing system. It receives 50 ?? 50 km 2 ; subsets of MODIS level 1B (L1B) data from MODIS adaptive processing system and AERONET aerosol and water-vapor information. Then, it performs an atmospheric correction (AC) for about 100 AERONET sites based on accurate radiative-transfer theory with complex quality control of the input data. The ASRVN processing software consists of an L1B data gridding algorithm, a new cloud-mask (CM) algorithm based on a time-series analysis, and an AC algorithm using ancillary AERONET aerosol and water-vapor data. The AC is achieved by fitting the MODIS top-of-atmosphere measurements, accumulated for a 16-day interval, with theoretical reflectance parameterized in terms of the coefficients of the Li SparseRoss Thick (LSRT) model of the bidirectional reflectance factor (BRF). The ASRVN takes several steps to ensure high quality of results: 1) the filtering of opaque clouds by a CM algorithm; 2) the development of an aerosol filter to filter residual semitransparent and subpixel clouds, as well as cases with high inhomogeneity of aerosols in the processing area; 3) imposing the requirement of the consistency of the new solution with previously retrieved BRF and albedo; 4) rapid adjustment of the 16-day retrieval to the surface changes using the last day of measurements; and 5) development of a seasonal backup spectral BRF database to increase data coverage. The ASRVN provides a gapless or near-gapless coverage for the processing area. The gaps, caused by clouds, are filled most naturally with the latest solution for a given pixel. The ASRVN products include three parameters of the LSRT model (kL, kG, and kV), surface albedo, normalized BRF (computed for a standard viewing geometry, VZA = 0, SZA = 45??), and instantaneous BRF (or one-angle BRF value derived from the last day of MODIS measurement for specific viewing geometry) for the MODIS 500-m bands 17. The results are produced daily at a resolution of 1 km in gridded format. We also provide a cloud mask, a quality flag, and a browse bitmap image. The ASRVN data set, including 6 years of MODIS TERRA and 1.5 years of MODIS AQUA data, is available now as a standard MODIS product (MODASRVN) which can be accessed through the Level 1 and Atmosphere Archive and Distribution System website ( http://ladsweb.nascom.nasa.gov/data/search.html). It can be used for a wide range of applications including validation analysis and science research. ?? 2006 IEEE.

IEEE Transactions on Geoscience and Remote Sensing↗

USGS2006

EMMMA: A web-based system for environmental mercury mapping, modeling, and analysis

Mercury in our environment - in our air, water, soil, and especially our food - poses significant hazards to human health, particularly for developing fetuses and young children. Because of the importance of this issue and the length of time it has been studied, large and complex data sets of mercury concentrations in various media and associated ancillary data have been generated by many Federal, State, Tribal, and local agencies. To facilitate efficient and effective use of these data in managing and mitigating human and wildlife exposure to mercury, the U.S. Geological Survey (USGS) and the National Institute of Environmental Health Sciences have developed a website for visualizing and studying the distribution of mercury in our environment. The Environmental Mercury Mapping, Modeling, and Analysis (EMMMA) website (http://emmma.usgs.gov) provides health and environmental researchers, managers, and other decision-makers the ability to: 1) Interactively view and access a nationwide collection of environmental mercury data (fish tissue, atmospheric emissions and deposition, stream sediments, soils, and coal) and mercuryrelated data (mine locations); 2) Interactively view and access predictions of the National Descriptive Model of Mercury in Fish (NDMMF) at 4,976 sites and 6,829 sampling events (events are unique combinations of site and sampling date) across the United States; and 3) Use interactive mapping and graphing capabilities to visualize spatial and temporal trends and study relationships between mercury and other variables.

Open-File Report↗

USGS1986

Water resources activities in Kentucky, 1986

The U.S. Geological Survey, Water Resources Division, conducts three major types of activities in Kentucky in order to provide hydrologic information and understanding needed for the best management of Kentucky 's and the Nation 's water resources. These activities are: (1) Data collection and dissemination; (2) Water-resources appraisals (interpretive studies); and (3) Research. Activities described in some detail following: (1) collection of surface - and groundwater data; (2) operation of stations to collect data on water quality, atmospheric deposition, and sedimentation; (3) flood investigations; (4) water use; (5) small area flood hydrology; (6) feasibility of disposal of radioactive disposal in deep crystalline rocks; (7) development of a groundwater model for the Louisville area; (8) travel times for streams in the Kentucky River Basin; (9) the impact of sinkholes and streams on groundwater flow in a carbonate aquifer system; (10) sedimentation and erosion rates at the Maxey Flats Radioactive Waste Burial site; and (11) evaluation of techniques for evaluating the cumulative impacts of mining as applied to coal fields in Kentucky. (Lantz-PTT)

Open-File Report↗

USGS2001

Core descriptions, core photographs, physical property logs and surface textural data of sediment cores recovered from the continental shelf of the Monterey Bay National Marine Sanctuary during the research cruises M-1-95-MB, P-2-95-MB, and P-1-97-MB

In response to the 1992 creation of the Monterey Bay National Marine Sanctuary (MBNMS), the United States Geological Survey (USGS) initiated a multiyear investigation of the Sanctuary continental margin. As part of the investigative effort, this report summarizes the shipboard procedures, subsequent laboratory analyses, and data results from three seafloor sampling cruises conducted on the continental shelf between Monterey peninsula, CA and San Francisco, CA. The cruises were conducted in 1995 aboard the NOAA Ship McArthur (M-1-95-MB) and in 1995 and 1997 aboard the R/V Point Sur (P-2-95-MB and P-1-97-MB). Scientists and representatives from the Environmental Protection Agency (EPA), the National Oceanic and Atmospheric Administration (NOAA), the California Department of Fish and Game (CDFG), the University of California Santa Cruz (UCSC), and the San Jose State University Moss Landing Marine Laboratory (SJSU-MLML) supported the research effort. In this report we present sediment descriptions, sediment textural data, physical property logs, station metadata, and photographs of subcores from a total of three hundred and eighty four sample stations. At these sites either a box corer, MultiCore™r, grab sampler or a combination of these sampling devices were used to collect the sea floor sediments. The report is presented in an interactive web-based format with each mapped core station linked to the corresponding description and photo, and to a spreadsheet of surface texture and other sampling data.

California↗

USGS2009

Planning for an uncertain future - Monitoring, integration, and adaptation

The 6.7 billion human inhabitants of the earth have the ability to drastically alter ecosystems and the populations of species that have taken eons to evolve. By better understanding how our actions affect the environment, we stand a better chance of designing successful strategies to manage ecosystems sustainably. Toward this end, the Third Interagency Conference on Research in the Watersheds (ICRW) was convened in Estes Park, CO, on September 8-11, 2008. The Conference provided a forum to present adaptive management as a practical tool for learning how to manage complex ecosystems more sustainably. Further complexity introduced by spatially variable and continuously changing environmental drivers favors this management approach because of its emphasis on adaptation in response to changing conditions or ineffective actions. For climate change in particular, an adaptive approach can more effectively accommodate the uncertainty in future climate scenarios. Scenarios compiled by the Intergovernmental Panel on Climate Change are built on distinct economic, energy, and societal models. The scenarios predict potential changes in greenhouse gases, temperature, precipitation, and atmospheric aerosols, which would have direct or indirect impacts on the timing, volume, and quality of runoff, vegetation, snowpack, stream temperature, groundwater, thawing permafrost, and icecaps. Through presentations and field trips, researchers and stakeholders described how their findings and issues fit into the adaptive management 'learning by doing' paradigm of Assess > Design > Implement > Monitor > Evaluate > Adjust > Assess.

Scientific Investigations Report↗

USGS2011

A geologic and anthropogenic journey from the Precambrian to the new energy economy through the San Juan volcanic field

The San Juan volcanic field comprises 25,000 km 2 of intermediate composition mid-Tertiary volcanic rocks and dacitic to rhyolitic calderas including the San Juan–Uncompahgre and La Garita caldera-forming super-volcanoes. The region is famous for the geological, ecological, hydrological, archeological, and climatological diversity. These characteristics supported ancestral Puebloan populations. The area is also important for its mineral wealth that once fueled local economic vitality. Today, mitigating and/or investigating the impacts of mining and establishing the region as a climate base station are the focuses of ongoing research. Studies include advanced water treatment, the acid neutralizing capacity (ANC) of propylitic bedrock for use in mine-lands cleanup, and the use of soil amendments including biochar from beetle-kill pines. Biochar aids soil productivity and revegetation by incorporation into soils to improve moisture retention, reduce erosion, and support the natural terrestrial carbon sequestration (NTS) potential of volcanic soils to help offset atmospheric CO 2 emissions. This field trip will examine the volcano-tectonic and cultural history of the San Juan volcanic field as well as its geologic structures, economic mineral deposits and impacts, recent mitigation measures, and associated climate research. Field trip stops will include a visit to (1) the Summitville Superfund site to explore quartz alunite-Au mineralization, and associated alteration and new water-quality mitigation strategies; (2) the historic Creede epithermal-polymetallic–vein district with remarkably preserved resurgent calderas, keystone-graben, and moat sediments; (3) the historic mining town of Silverton located in the nested San Juan–Silverton caldera complex that exhibits base-metal Au-Ag mineralization; and (4) the site of ANC and NTS studies. En route back to Denver, we will traverse Grand Mesa, a high NTS area with Neogene basalt-derived soils and will enjoy a soak in the geothermal waters of the Aspen anomaly at Glenwood Springs.

Colorado↗

USGS2009

Changes in the chemistry of shallow groundwater related to the 2008 injection of CO2 at the ZERT field site, Bozeman, Montana

Approximately 300 kg/day of food-grade CO 2 was injected through a perforated pipe placed horizontally 2–2.3 m deep during July 9–August 7, 2008 at the MSU-ZERT field test to evaluate atmospheric and near-surface monitoring and detection techniques applicable to the subsurface storage and potential leakage of CO 2 . As part of this multidisciplinary research project, 80 samples of water were collected from 10 shallow monitoring wells (1.5 or 3.0 m deep) installed 1–6 m from the injection pipe, at the southwestern end of the slotted section (zone VI), and from two distant monitoring wells. The samples were collected before, during, and following CO 2 injection. The main objective of study was to investigate changes in the concentrations of major, minor, and trace inorganic and organic compounds during and following CO 2 injection. The ultimate goals were (1) to better understand the potential of groundwater quality impacts related to CO 2 leakage from deep storage operations, (2) to develop geochemical tools that could provide early detection of CO 2 intrusion into underground sources of drinking water (USDW), and (3) to test the predictive capabilities of geochemical codes against field data. Field determinations showed rapid and systematic changes in pH (7.0–5.6), alkalinity (400–1,330 mg/l as HCO 3 ), and electrical conductance (600–1,800 μS/cm) following CO 2 injection in samples collected from the 1.5 m-deep wells. Laboratory results show major increases in the concentrations of Ca (90–240 mg/l), Mg (25–70 mg/l), Fe (5–1,200 ppb), and Mn (5–1,400 ppb) following CO 2 injection. These chemical changes could provide early detection of CO 2 leakage into shallow groundwater from deep storage operations. Dissolution of observed carbonate minerals and desorption-ion exchange resulting from lowered pH values following CO 2 injection are the likely geochemical processes responsible for the observed increases in the concentrations of solutes; concentrations generally decreased temporarily following four significant precipitation events. The DOC values obtained are 5 ± 2 mg/l, and the variations do not correlate with CO 2 injection. CO 2 injection, however, is responsible for detection of BTEX (e.g. benzene, 0–0.8 ppb), mobilization of metals, the lowered pH values, and increases in the concentrations of other solutes in groundwater. The trace metal and BTEX concentrations are all significantly below the maximum contaminant levels (MCLs). Sequential leaching of core samples is being carried out to investigate the source of metals and other solutes.

Montana↗

USGS1999

Air blasts generated by rockfall impacts: Analysis of the 1996 Happy Isles event in Yosemite National Park

The July 10, 1996, Happy Isles rockfall in Yosemite National Park, California, released 23,000 to 38,000 m 3 of granite in four separate events. The impacts of the first two events which involved a 550-m free fall, generated seismic waves and atmospheric pressure waves (air blasts). We focus on the dynamic behavior of the second air blast that downed over 1000 trees, destroyed a bridge, demolished a snack bar, and caused one fatality and several injuries. Calculated velocities for the air blast from a two-phase, finite difference model are compared to velocities estimated from tree damage. From tornadic studies of tree damage, the air blast is estimated to have traveled <108–120 m/s within 50 m from the impact and decreased to <10–20 m/s within 500 m from the impact. The numerical model simulates the two-dimensional propagation of an air blast through a dusty atmosphere with initial conditions defined by the impact velocity and pressure. The impact velocity (105–107 m/s) is estimated from the Colorado Rockfall Simulation Program that simulates rockfall trajectories. The impact pressure (0.5 MPa) is constrained by the kinetic energy of the impact (10 10 –10 12 J) estimated from the seismic energy generated by the impact. Results from the air blast simulations indicate that the second Happy Isles air blast (weak shock wave) traveled with an initial velocity above the local sound speed. The size and location of the first impact are thought to have injected <50 wt% dust into the atmosphere. This amount of dust lowered the local atmospheric sound speed to ∼220 m/s. The discrepancy between calculated velocity data and field estimated velocity data (∼220 m/s versus ∼110 m/s) is attributed to energy dissipated by the downing of trees and additional entrainment of debris into the atmosphere not included in the calculations.

Journal of Geophysical Research B: Solid Earth↗

USGS2014

Air-sea interactions during strong winter extratropical storms

A high-resolution, regional coupled atmosphere–ocean model is used to investigate strong air–sea interactions during a rapidly developing extratropical cyclone (ETC) off the east coast of the USA. In this two-way coupled system, surface momentum and heat fluxes derived from the Weather Research and Forecasting model and sea surface temperature (SST) from the Regional Ocean Modeling System are exchanged via the Model Coupling Toolkit. Comparisons are made between the modeled and observed wind velocity, sea level pressure, 10 m air temperature, and sea surface temperature time series, as well as a comparison between the model and one glider transect. Vertical profiles of modeled air temperature and winds in the marine atmospheric boundary layer and temperature variations in the upper ocean during a 3-day storm period are examined at various cross-shelf transects along the eastern seaboard. It is found that the air–sea interactions near the Gulf Stream are important for generating and sustaining the ETC. In particular, locally enhanced winds over a warm sea (relative to the land temperature) induce large surface heat fluxes which cool the upper ocean by up to 2 °C, mainly during the cold air outbreak period after the storm passage. Detailed heat budget analyses show the ocean-to-atmosphere heat flux dominates the upper ocean heat content variations. Results clearly show that dynamic air–sea interactions affecting momentum and buoyancy flux exchanges in ETCs need to be resolved accurately in a coupled atmosphere–ocean modeling framework.

Ocean Dynamics↗

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↗

USGS2016

Dendritic network models: Improving isoscapes and quantifying influence of landscape and in-stream processes on strontium isotopes in rivers

A critical challenge for the Earth sciences is to trace the transport and flux of matter within and among aquatic, terrestrial, and atmospheric systems. Robust descriptions of isotopic patterns across space and time, called “isoscapes,” form the basis of a rapidly growing and wide-ranging body of research aimed at quantifying connectivity within and among Earth's systems. However, isoscapes of rivers have been limited by conventional Euclidean approaches in geostatistics and the lack of a quantitative framework to apportion the influence of processes driven by landscape features versus in-stream phenomena. Here we demonstrate how dendritic network models substantially improve the accuracy of isoscapes of strontium isotopes and partition the influence of hydrologic transport versus local geologic features on strontium isotope ratios in a large Alaska river. This work illustrates the analytical power of dendritic network models for the field of isotope biogeochemistry, particularly for provenance studies of modern and ancient animals.

Geophysical Research Letters↗