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USGS2023

Historical fire regimes and contemporary fire effects within sagebrush habitats of Gunnison Sage-grouse

The historical role of fire in sagebrush ( Artemisia tridentata ) landscapes remains poorly understood, yet is important to inform management and conservation of obligate species such as the threatened Gunnison Sage-grouse (GUSG; Centrocercus minimus ). We reconstructed fire histories from tree-ring fire scars at sagebrush–forest ecotones (10 sites, 111 trees) to better understand the role of fire in sagebrush landscapes of the Upper Gunnison Basin (UGB), Colorado, and how fire may have changed following Euro-American settlement. We assessed likely influences of historical fire by surveying plant composition and structure at 100 sagebrush sites with and without recent (2001–2020) fires. Tree-ring fire scars revealed a history of repeated low-severity fire at sagebrush–forest ecotones until 1892, followed by over a century without fire. Between 1684 and 1892, the mean fire interval (MFI) among sites averaged 49.6 years (ranging from 18.2 to 119 years). Fire over this period occurred synchronously at two or more sites on average every 23.6 years, potentially indicative of spread between sites. Most (70%) of the historical fires burned in the early growing season, consistent with times of strong wind. Recent burns exhibited reductions in sagebrush cover (5% vs. 25% in unburned sites) and concomitant increases in herbaceous cover (55% vs. 40%). These differences declined over time but persisted for at least two decades. Burned sites were dominated by native perennial grasses, forbs, and resprouting shrub species. Historically, such openings may have served as seasonal GUSG habitat. Our results indicate that parts of the UGB sagebrush landscapes were characterized historically by frequent fire and dynamic vegetation mosaics that included open, grassy patches. These findings support the use of prescribed fire to restore and maintain this ecological process and vegetation heterogeneity. However, the contemporary context for fire has changed and now includes substantially reduced, Endangered Species Act (ESA)-listed GUSG populations, increased risk of non-native plant invasion, and climate warming. These circumstances highlight new risks, information needs, and opportunities for key knowledge co-production via management–research partnerships.

Colorado↗

USGS2017

Skagit River coho salmon life history model—Users’ guide

Natural resource management is conducted in the context of multiple anthropogenic stressors and is further challenged owing to changing climate. Experiments to determine the effects of climate change on complex ecological systems are nearly impossible. However, using a simulation model to synthesize current understanding of key ecological processes through the life cycle of a fish population can provide a platform for exploring potential effects of and management responses to changing conditions. Potential climate-change scenarios can be imposed, responses can be observed, and the effectiveness of potential actions can be evaluated. This approach is limited owing to future conditions likely deviating in range and timing from conditions used to create the model so that the model is expected to become obsolete. In the meantime, however, the modeling process explicitly states assumptions, clarifies information gaps, and provides a means to better understand which relationships are robust and which are vulnerable to changing climate by observing whether and why model output diverges from actual observations through time. The purpose of the model described herein is to provide such a decision-support tool regarding coho ( Oncorhynchus kisutch ) salmon for the Sauk-Suiattle Indian Tribe of Washington State. The Skagit coho salmon model is implemented in a system dynamics format and has three primary stocks—(1) predicted smolts, (2) realized smolts, and (3) escapement. “Predicted smolts” are the number of smolts expected based on the number of spawners in any year and the Ricker production curve. Pink salmon ( Oncorhynchus gorbuscha ) return to the Skagit River in odd years, and when they overlap with juvenile rearing coho salmon, coho smolt production is substantially higher than in non-pink years. Therefore, the model uses alternative Ricker equations to predict smolts depending on whether their juvenile year was a pink or non-pink year. The stock “realized smolts” is calculated based on the expected effect of streamflow conditions to alter the productivity predicted by the Ricker curve. Adverse conditions include scouring flow events that occur when redds are present; high-flow events during winter on juveniles, which can cause fish displacement and adverse water turbidity; and extremely low flows in summer. The stock “escapement” represents the fish remaining after accounting for ocean mortality and harvest. Ocean mortality has been linked with indices of ocean conditions, which are related to ocean biological productivity. Ocean survival also may have a density-dependent component such that lower survival is associated with higher numbers of smolts. The model allows the user to change certain model parameters and inputs, and choose among alternative predictors for certain modeled relations.

Washington↗

USGS2019

Simulating the effects of climate variability on waterbodies and wetland-dependent birds in the Prairie Pothole Region

Understanding how bird populations respond to changes in waterbody availability in the climatically variable Prairie Pothole Region (PPR) of North America hinges on being able to couple hydrological and climate modeling to represent potential future landscapes. Model experiments run with the Pothole Complex Hydrologic Model using downscaled climate data (variables relating to precipitation, temperature, and potential evapotranspiration at 1/8° spatial resolution under four general circulation climate models and two gas emissions scenarios) were used to forecast the abundances of six focal wetland‐dependent bird species in the Missouri Coteau portion of the PPR, providing ensemble scenarios at a spatial scale relevant to resource management. Although the projected number of May ponds (waterbodies present during bird breeding season) fluctuated through time with some decadal periodicity (and with the number present in a given year reflecting abundance over the previous three years), the ensemble model average indicated an increase in the average number of waterbodies present by the turn of the next century. Overall, the model experiments conservatively projected an 11.75% increase in the number of waterbodies present by 2090–2099 compared to a baseline period from 1967 to 2005 in the PPR. Wetland‐dependent bird occurrence and abundance were significantly associated with temporal patterns and decadal periodicity in waterbody dynamics. Because of the strong associations between wetland‐dependent bird occurrence and abundance and the number of prairie potholes, projected waterbody increases are forecasted to result in an 11.97% overall increase in occurrence and 8.63% increase in abundance of the six focal species by the end of the 21st century; these results contrast with forecasted drought‐associated declines in waterbodies and birds in the PPR. This integrated hydrological–climatological approach offers a means of assessing how wetland‐dependent bird populations may respond to changes in wetland habitat availability due to a changing climate. Our results provide information that can help managers decide how to mitigate the effects of climate shifts on the distribution of wetland habitat and biota.

North Dakota↗

USGS2009

DayCent-Chem simulations of ecological and biogeochemical processes of eight mountain ecosystems in the United States

Atmospheric deposition of nitrogen (N) and sulfur (S) cause complex responses in ecosystems, from fertilization to forest ecosystem decline, freshwater eutrophication to acidification, loss of soil base cations, and alterations of disturbance regimes. DayCent-Chem, an ecosystem simulation model that combines ecosystem nutrient cycling and plant dynamics with aqueous geochemical equilibrium calculations, was developed to address ecosystem responses to combined atmospheric N and S deposition. It is unique among geochemically-based models in its dynamic biological cycling of N and its daily timestep for investigating ecosystem and surface water chemical response to episodic events. The model was applied to eight mountainous watersheds in the United States. The sites represent a gradient of N deposition across locales, from relatively pristine to N-saturated, and a variety of ecosystem types and climates. Overall, the model performed best in predicting stream chemistry for snowmelt-dominated sites. It was more difficult to predict daily stream chemistry for watersheds with deep soils, high amounts of atmospheric deposition, and a large degree of spatial heterogeneity. DayCent-Chem did well in representing plant and soil carbon and nitrogen pools and fluxes. Modeled stream nitrate (NO 3 - ) and ammonium (NH 4 + ) concentrations compared well with measurements at all sites, with few exceptions. Simulated daily stream sulfate (SO 4 2- ) concentrations compared well to measured values for sites where SO 4 2- deposition has been low and where SO 4 2- adsorption/desorption reactions did not seem to be important. The concentrations of base cations and silica in streams are highly dependent on the geochemistry and weathering rates of minerals in each catchment, yet these were rarely, if ever, known. Thus, DayCent-Chem could not accurately predict weathering products for some catchments. Additionally, few data were available for exchangeable soil cations or the magnitude of base cation deposition as a result of dry and fog inputs. The uncertainties related to weathering reactions, deposition, soil cation exchange capacity, and groundwater contributions influenced how well the simulated acid neutralizing capacity (ANC) and pH estimates compared to observed values. Daily discharge was well represented by the model for most sites. The chapters of this report describe the parameterization for each site and summarize model results for ecosystem variables, stream discharge, and stream chemistry. This intersite comparison exercise provided insight about important and possibly not well understood processes.

Scientific Investigations Report↗

USGS2017

Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change

The degree to which cloud immersion provides water in addition to rainfall, suppresses transpiration, and sustains tropical montane cloud forests (TMCFs) during rainless periods is not well understood. Climate and land use changes represent a threat to these forests if cloud base altitude rises as a result of regional warming or deforestation. To establish a baseline for quantifying future changes in cloud base, we installed a ceilometer at 100 m altitude in the forest upwind of the TMCF that occupies an altitude range from ∼ 600 m to the peaks at 1100 m in the Luquillo Mountains of eastern Puerto Rico. Airport Automated Surface Observing System (ASOS) ceilometer data, radiosonde data, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite data were obtained to investigate seasonal cloud base dynamics, altitude of the trade-wind inversion (TWI), and typical cloud thickness for the surrounding Caribbean region. Cloud base is rarely quantified near mountains, so these results represent a first look at seasonal and diurnal cloud base dynamics for the TMCF. From May 2013 to August 2016, cloud base was lowest during the midsummer dry season, and cloud bases were lower than the mountaintops as often in the winter dry season as in the wet seasons. The lowest cloud bases most frequently occurred at higher elevation than 600 m, from 740 to 964 m. The Luquillo forest low cloud base altitudes were higher than six other sites in the Caribbean by ∼ 200–600 m, highlighting the importance of site selection to measure topographic influence on cloud height. Proximity to the oceanic cloud system where shallow cumulus clouds are seasonally invariant in altitude and cover, along with local trade-wind orographic lifting and cloud formation, may explain the dry season low clouds. The results indicate that climate change threats to low-elevation TMCFs are not limited to the dry season; changes in synoptic-scale weather patterns that increase frequency of drought periods during the wet seasons (periods of higher cloud base) may also impact ecosystem health.

Atmospheric Chemistry and Physics↗

USGS2022

Estimating the pelagic ocean’s benefits to humanity can enhance ocean governance

The human footprint on the global ocean is ever-increasing, particularly with new ways to grow food in the ocean, new technologies in marine energy production as a way to resolve climate change, and transport and commerce expanding across the ocean. Yet, human activities in the ocean have long been managed using a sectoral approach (e.g., fisheries, biodiversity protection, energy production, shipping) rather than a holistic integration of sector interactions, trade-offs, costs, and benefits. Coordination across sectors is now more critical than ever, not only because of the expanding human footprint but also because of climate change impacts on the ocean. Sustainable global ocean use can support the Blue Economy while also reversing negative climate impacts on the ocean. Advancements in science and technology, along with increasing momentum on global commitments to sound ocean governance, and science diplomacy internationally can support sustainable ocean use with accurate and timely information about the status and trends in the ocean’s ecosystem services (benefits) to society. Near-real time information about ecosystem services’ dynamics is critical to policymaking for a sustainable Blue Economy that works for nature and people in an ever-changing ocean. Here, we propose seven principles for ecosystem service assessments, essentially to international science diplomacy, for consideration by global marine policy communities.

Marine Policy↗

USGS2015

Understanding uncertainty in temperature effects on vector-borne disease: a Bayesian approach

Extrinsic environmental factors influence the distribution and population dynamics of many organisms, including insects that are of concern for human health and agriculture. This is particularly true for vector-borne infectious diseases like malaria, which is a major source of morbidity and mortality in humans. Understanding the mechanistic links between environment and population processes for these diseases is key to predicting the consequences of climate change on transmission and for developing effective interventions. An important measure of the intensity of disease transmission is the reproductive number R 0 . However, understanding the mechanisms linking R 0 and temperature, an environmental factor driving disease risk, can be challenging because the data available for parameterization are often poor. To address this, we show how a Bayesian approach can help identify critical uncertainties in components of R 0 and how this uncertainty is propagated into the estimate of R 0 . Most notably, we find that different parameters dominate the uncertainty at different temperature regimes: bite rate from 15°C to 25°C; fecundity across all temperatures, but especially ~25–32°C; mortality from 20°C to 30°C; parasite development rate at ~15–16°C and again at ~33–35°C. Focusing empirical studies on these parameters and corresponding temperature ranges would be the most efficient way to improve estimates of R 0 . While we focus on malaria, our methods apply to improving process-based models more generally, including epidemiological, physiological niche, and species distribution models.

Ecology↗

USGS2020

Introduction: Ecological subsidies as a framework for understanding contaminant fate, exposure, and effects at the land-water interface

Ecologists have long recognized that ecological subsidies (the flow of organic matter, nutrients, and organisms between ecosystems) can strongly affect ecosystem processes and community structure in the recipient ecosystem. Animal movements, organic matter flows, and food web dynamics between linked aquatic and terrestrial systems can also influence contaminant fate, exposure, and effects at the land-water interface. Here and in this book, we develop a broad framework that highlights two important ways that ecological subsidies and contaminants interact. Ecological subsidies from the donor system can drive exposure to recipient systems, and contaminant exposures in the donor system can control subsidies and contaminant fluxes to the recipient systems. In the case of prey movement between ecosystems, subsidies drive exposure when contaminants present in aquatic environments bioaccumulate in the tissues of prey organisms at levels that are relatively non-toxic to the prey themselves. Conversely, exposure in the aquatic system can limit subsidies when pollutants are relatively toxic to prey organisms themselves and the magnitude of the subsidy (i.e., biomass of aquatic insects emerging to the terrestrial environment) is reduced. These effects of contaminants on subsidies are shaped by other global stressors that are ubiquitous in aquatic-riparian ecosystems (e.g., climate and land use change, species extinction and invasion, and eutrophication). As our understanding of these ecological and toxicological processes advances, there are increasing opportunities to make landscape-scale predictions of contaminant and animal fluxes and to integrate this knowledge of aquatic-riparian linkages into managing contaminant risks. Through these efforts to integrate the fields of ecology and ecotoxicology on this subject, we expect to gain greater insight on the ecological effects of contaminants on linked ecosystems as well as the ways in which food web dynamics and ecosystem processes can themselves govern the fate, transport, and exposure to contaminants in the environment.

Book chapter↗

USGS2021

Climate change and other factors influencing the saguaro cactus

The saguaro cacti ( Carnegiea gigantea [Engelm.] Britton & Rose) is one of the world’s most iconic plants and a symbol of the desert Southwest. It is the namesake of Saguaro National Park, which was created (initially as a national monument) in 1933 to study, interpret, and protect the “giant cactus” and other unique Sonoran Desert species. Research on saguaros over the past century has revealed much about the plant’s growth, reproduction, population dynamics, and use by people and wildlife. Young saguaros grow very slowly, not reaching reproductive age until they are 35–65 years old. They produce white flowers that open at night during April through June, followed by large red fruits that are consumed by many desert animals. The saguaro fruit is also a traditional food source for the Tohono O’odham people, and the harvest of the saguaro fruit is a very important part of their culture (Bruhn 1971). Mature saguaros produce thousands of seeds each year, but establishment is episodic in that seedlings survive only during favorable periods with several consecutive years of cooler, wetter weather (Steenbergh and Lowe 1977).

Arizona↗

USGS2024

Going with the floe: Sea-ice movement affects distance and destination during Adélie penguin winter movements

Seasonal migration, driven by shifts in annual climate cycles and resources, is a key part of the life history and ecology of species across taxonomic groups. By influencing the amount of energy needed to move, external forces such as wind and ocean currents are often key drivers of migratory pathways exposing individuals to varying resources, environmental conditions, and competition pressures impacting individual fitness and population dynamics. Although wildlife movements in connection with wind and ocean currents are relatively well understood, movements within sea-ice fields have been much less studied, despite sea ice being an integral part of polar ecology. Adélie penguins ( Pygoscelis adeliae ) in the southern Ross Sea, Antarctica, currently exist at the southernmost edge of their range and undergo the longest (~12,000 km) winter migration known for the species. Within and north of the Ross Sea, the Ross Gyre drives ocean circulation and the large-scale movement of sea ice. We used remotely sensed sea-ice movement data together with geolocation-based penguin movement data to test the hypothesis that penguins use gyre-driven sea-ice movement to aid their migration. We found that penguins traveled greater distances when their movement vectors were aligned with those of sea ice (i.e., ice support) and the amount of ice support received depended on which route a penguin took. We also found that birds that took an eastern route traveled significantly further north in two of the 3 years we examined, coinciding with higher velocities of sea ice in those years. We compare our findings to patterns observed in migrating species that utilize air or water currents for their travel and with other studies showing the importance of ocean/sea-ice circulation patterns to wildlife movement and life history patterns within the Ross Sea. Changes in sea ice may have consequences not only for energy expenditure but, by altering migration and movement pathways, to the ecological interactions that exist in this region.

Ecology↗

USGS2015

Simulated big sagebrush regeneration supports predicted changes at the trailing and leading edges of distribution shifts

Many semi-arid plant communities in western North America are dominated by big sagebrush. These ecosystems are being reduced in extent and quality due to economic development, invasive species, and climate change. These pervasive modifications have generated concern about the long-term viability of sagebrush habitat and sagebrush-obligate wildlife species (notably greater sage-grouse), highlighting the need for better understanding of the future big sagebrush distribution, particularly at the species' range margins. These leading and trailing edges of potential climate-driven sagebrush distribution shifts are likely to be areas most sensitive to climate change. We used a process-based regeneration model for big sagebrush, which simulates potential germination and seedling survival in response to climatic and edaphic conditions and tested expectations about current and future regeneration responses at trailing and leading edges that were previously identified using traditional species distribution models. Our results confirmed expectations of increased probability of regeneration at the leading edge and decreased probability of regeneration at the trailing edge below current levels. Our simulations indicated that soil water dynamics at the leading edge became more similar to the typical seasonal ecohydrological conditions observed within the current range of big sagebrush ecosystems. At the trailing edge, an increased winter and spring dryness represented a departure from conditions typically supportive of big sagebrush. Our results highlighted that minimum and maximum daily temperatures as well as soil water recharge and summer dry periods are important constraints for big sagebrush regeneration. Overall, our results confirmed previous predictions, i.e., we see consistent changes in areas identified as trailing and leading edges; however, we also identified potential local refugia within the trailing edge, mostly at sites at higher elevation. Decreasing regeneration probability at the trailing edge underscores the Schlaepfer et al. Future regeneration potential of big sagebrush potential futility of efforts to preserve and/or restore big sagebrush in these areas. Conversely, increasing regeneration probability at the leading edge suggest a growing potential for conflicts in management goals between maintaining existing grasslands by preventing sagebrush expansion versus accepting a shift in plant community composition to sagebrush dominance.

Ecosphere↗

USGS2015

Southern Great Plains Rapid Ecoregional Assessment: pre-assessment report

The purpose of the Pre-Assessment Report for the Southern Great Plains Rapid Ecoregional Assessment (REA) is to document the selection process for and final list of Conservation Elements, Change Agents, and Management Questions developed during Phase I. The overall goal of the REAs being conducted for the Bureau of Land Management (BLM) is to provide information that supports regional planning and analysis for the management of ecological resources. The REA provides an assessment of baseline ecological conditions, an evaluation of current risks from drivers of ecosystem change, and a predictive capacity for evaluating future risks. The REA also may be used for identifying priority areas for conservation or restoration and for assessing the cumulative effects of a variety of land uses. There are several components of the REAs. Management Questions, developed by the BLM and partners for the ecoregion, identify the information needed for addressing land-management responsibilities. Conservation Elements represent regionally significant terrestrial and aquatic species and communities that are to be conserved and (or) restored. For each Conservation Element, key ecological attributes will be evaluated to determine the status of each species and community. The REA also will evaluate major drivers of ecosystem change, or Change Agents, currently affecting or likely to affect the status of Conservation Elements in the future. The relationships between Change Agents and key ecological attributes will be summarized using conceptual models. The REA process is a two-phase process. Phase I (pre-assessment) includes developing and finalizing the lists of priority Management Questions, Conservation Elements, and Change Agents, culminating in the REA Pre-Assessment Report. Chapter 1 provides an overview of the REA process. Chapter 2 describes the biophysical and anthropogenic features of the Southern Great Plains, and Chapter 3 explains the process used to identify Conservation Elements, Change Agents and Management Questionss. The remaining chapters each feature one of 19 Conservation Elements—6 ecological communities and 13 species (including 2 species assemblages)—to be addressed in Phase II. For each Conservation Element, we will address the four primary Change Agents—development, fire, invasive species, and climate change—required for the REA. In addition, we will evaluate insect pests and disease for particular Conservation Elements. Development includes effects related to energy and infrastructure, agricultural activities, and other human activities, including urbanization and recreation. An overview on the ecology and management issues for each Conservation Element is provided, including distribution and ecology, landscape structure and dynamics, and associated species of management concern affiliated with each Conservation Element. For each Conservation Element, effects of the Change Agents are described. An overview of potential key ecological attributes and potential Change Agents are summarized by conceptual models and tables. The tables provide an organizational framework and background information for evaluating the key ecological attributes and Change Agents in Phase II.

Colorado, Kansas, New Mexico, Oklahoma, Texas↗

USGS2016

@KarlTheFog has been mapped!

Within the world of mapping, clouds are a pesky interference to be removed from satellite remote sensed imagery. However, to many of us, that is a waste of pixels. Cloud maps are becoming increasingly valuable in the quest to understand land cover change and surface processes. In coastal California, the dynamic summertime interactions between air masses, the ocean, and topography result in blankets of fog and low clouds flowing into low lying areas of the San Francisco Bay Area. The low clouds and fog advected from the Pacific bring moisture and shade to coastal ecosystems. This acts to reduce temperatures and evapotranspiration stress during the otherwise arid Mediterranean climate season, in turn impacting vegetation distribution, irrigation needs, and urban energy consumption.

BayGEO Journal↗

USGS2025

Small waterbodies of large conservation concern: Towards an integrated approach to more accurately measuring surface water dynamics

Millions of small waterbodies are dispersed throughout the middle of the North American continent, and billions of dollars have been invested to conserve, restore, and manage these waterbodies in the 20th and 21st centuries. Small waterbody conservation has been supported by different stakeholders aiming at improving water quality, enhancing floodwater storage, and supporting migratory bird breeding habitat. Conservation agencies are using hydrological and biological monitoring, modeling, and mapping to adaptively manage small waterbodies in the face of stressors such as invasive species and climate change. As remote sensing estimates of small waterbody surface water extent have become easier to access, understanding the capabilities and limitations of using remote sensing, especially in areas lacking surface water monitoring, is important for conservation decision making. Here, we used in situ monitoring and process-based hydrological modeling to explore remote sensing accuracy, especially related to waterbody size, emergent aquatic vegetation cover, and climatic conditions. Overall, we found that the accuracy of satellite and aerial imagery surface water mapping approaches vastly decreased for waterbodies smaller than 2 ha. We also found emergent vegetation could be masking surface water in waterbodies larger than 2 ha and that accuracy of some remote sensing estimates may decrease during wetter climatic periods. These results indicate that sensors commonly used for surface water applications alone may not be able to accurately detect small waterbody surface water, which supports the need for combining monitoring and modeling to understand how small waterbodies may respond to future changes in climate and land use.

Minnesota↗

USGS2016

A primer on potential impacts, management priorities, and future directions for Elodea spp. in high latitude systems: learning from the Alaskan experience

Invasive species introductions in Arctic and Subarctic ecosystems are growing as climate change manifests and human activity increases in high latitudes. The aquatic plants of the genus Elodea are potential invaders to Arctic and Subarctic ecosystems circumpolar and at least one species is already established in Alaska, USA. To illustrate the problems of preventing, eradicating, containing, and mitigating aquatic, invasive plants in Arctic and Subarctic ecosystems, we review the invasion dynamics of Elodea and provide recommendations for research and management efforts in Alaska. Foremost, we conclude the remoteness of Arctic and Subarctic systems such as Alaska is no longer a protective attribute against invasions, as transportation pathways now reach throughout these regions. Rather, high costs of operating in remote Arctic and Subarctic systems hinders detection of infestations and limits eradication or mitigation, emphasizing management priorities of prevention and containment of aquatic plant invaders in Alaska and other Arctic and Subarctic systems.

Hydrobiologia↗

USGS2016

A cellular automata downscaling based 1 km global land use datasets (2010–2100)

Global climate and environmental change studies require detailed land-use and land-cover(LULC) information about the past, present, and future. In this paper, we discuss a methodology for downscaling coarse-resolution (i.e., half-degree) future land use scenarios to finer (i.e., 1 km) resolutions at the global scale using a grid-based spatially explicit cellular automata (CA) model. We account for spatial heterogeneity from topography, climate, soils, and socioeconomic variables. The model uses a global 30 m land cover map (2010) as the base input, a variety of biogeographic and socioeconomic variables, and an empirical analysis to downscale coarse-resolution land use information (specifically urban, crop and pasture). The output of this model offers the most current and finest-scale future LULC dynamics from 2010 to 2100 (with four representative concentration pathway (RCP) scenarios—RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5) at a 1 km resolution within a globally consistent framework. The data are freely available for download, and will enable researchers to study the impacts of LULC change at the local scale.

Science Bulletin↗

USGS2020

Large-scale erosion driven by intertidal eelgrass loss in an estuarine environment

Seagrasses influence local hydrodynamics by inducing drag on the flow and dampening near-bed velocities and wave energy. When seagrasses are lost, near-bed currents and wave energy can increase, which enhances bottom shear stresses, destabilizes sediment, and promotes suspension and erosion. Though seagrasses are being lost rapidly globally, the magnitude of change in sediment stabilization following ecosystem-wide eelgrass loss has rarely been measured. In this study, we explored the geomorphological changes associated with an unprecedented estuary-wide collapse of a seagrass (eelgrass, Zostera marina ) in Morro Bay, CA, USA. Morro Bay has historically suffered from accelerated sedimentation and accretion. However, following massive eelgrass loss since 2010, over 90% of locations that previously had eelgrass experienced erosion. Elevation losses (erosion) reached 0.50 m in some places (mean loss of 0.10 m) with as much as a 50% decrease (median decrease of 13.6%) in elevation (i.e., increase in depth) compared to pre-decline levels. In comparison, the mouth of the estuary, where eelgrass was largely retained, had only 27.7% of the locations with prior eelgrass experiencing erosion and underwent a mean elevation increase (accretion) of 0.32 m. Thus, the loss of eelgrass appears to have altered dynamics at the seabed and transitioned large regions of the estuary from an environment that promotes deposition and accretion to one that promotes suspension and erosion. Large-scale erosion following seagrass loss may be predictive of future shoreline and coastal habitat changes and is likely to be exacerbated by increased storm surge and sea level rise expected with climate change.

California↗

USGS2013

Trajectory of the arctic as an integrated system

Although much remains to be learned about the Arctic and its component processes, many of the most urgent scientific, engineering, and social questions can only be approached through a broader system perspective. Here, we address interactions between components of the Arctic System and assess feedbacks and the extent to which feedbacks (1) are now underway in the Arctic; and (2) will shape the future trajectory of the Arctic system. We examine interdependent connections among atmospheric processes, oceanic processes, sea-ice dynamics, marine and terrestrial ecosystems, land surface stocks of carbon and water, glaciers and ice caps, and the Greenland ice sheet. Our emphasis on the interactions between components, both historical and anticipated, is targeted on the feedbacks, pathways, and processes that link these different components of the Arctic system. We present evidence that the physical components of the Arctic climate system are currently in extreme states, and that there is no indication that the system will deviate from this anomalous trajectory in the foreseeable future. The feedback for which the evidence of ongoing changes is most compelling is the surface albedo-temperature feedback, which is amplifying temperature changes over land (primarily in spring) and ocean (primarily in autumn-winter). Other feedbacks likely to emerge are those in which key processes include surface fluxes of trace gases, changes in the distribution of vegetation, changes in surface soil moisture, changes in atmospheric water vapor arising from higher temperatures and greater areas of open ocean, impacts of Arctic freshwater fluxes on the meridional overturning circulation of the ocean, and changes in Arctic clouds resulting from changes in water vapor content.

Ecological Applications↗