Bryan N. Shuman

University of Wyoming

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John W. Williams

University of Wisconsin–Madison

W. Wyatt Oswald

Dana-Farber/Harvard Cancer Center

Patrick J. Bartlein

University of Oregon

Ioana C. Stefanescu

University of Wyoming

David R. Foster

Harvard University

W. John Calder

University of Wyoming

Jeremiah Marsicek

University of Wisconsin–Madison

Thompson Webb

John Brown University

David Liefert

University of Wyoming

Philip E. Higuera

University of Montana

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Faculty of 1000 (United States)

106

National University of Tierra del Fuego

101

University of Wisconsin System

University of Wyoming

Centre National de la Recherche Scientifique

University of Arizona

University of Wisconsin–Madison

United States Geological Survey

Chinese Academy of Sciences

University of Minnesota

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Supplementary material to "Climatic history of the northeastern United States during the past 3000 years"

Jennifer R. Marlon Neil Pederson Connor Nolan Simon Goring Bryan N. Shuman

10.5194/cp-2016-104-supplement

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Model systems for a no‐analog future: species associations and climates during the last deglaciation

Annals of the New York Academy of Sciences (2013)

John W. Williams Jessica L. Blois Jacquelyn L. Gill L. M. Gonzales Eric C. Grimm

As the earth system moves to a novel state, model systems (experimental, observational, paleoecological) are needed to assess and improve the predictive accuracy of ecological models under environments with no contemporary analog. In recent years, we have intensively studied the no‐analog plant associations and climates in eastern North America during the last deglaciation to better constrain their spatiotemporal distribution, test hypotheses about climatic and megaherbivory controls, and assess the accuracy of species‐ and community‐level models. The formation of no‐analog plant associations was asynchronous, beginning first in the south‐central United States; at sites in the north‐central United States, it is linked to declining megafaunal abundances. Insolation and temperature were more seasonal than present, creating climates currently nonexistent in North America, and shifting species–climate relationships for some taxa. These shifts pose a common challenge to empirical paleoclimatic reconstructions, species distribution models (SDMs), and conservation–optimization models based on SDMs. Steps forward include combining recent and paleoecological data to more fully describe species’ fundamental niches, employing community‐level models to model shifts in species interactions under no‐analog climates, and assimilating paleoecological data with mechanistic ecosystem models. Accurately modeling species interactions under novel environments remains a fundamental challenge for all forms of ecological models.

Deglaciation

Megafauna

Earth system science

Species distribution

10.1111/nyas.12226

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Subregional variability in the response of New England vegetation to postglacial climate change

Journal of Biogeography (2018)

W. Wyatt Oswald David R. Foster Bryan N. Shuman Elaine D. Doughty Edward K. Faison

Abstract Aim We analysed a dataset composed of multiple palaeoclimate and lake‐sediment pollen records from New England to explore how postglacial changes in the composition and spatial patterns of vegetation were controlled by regional‐scale climate change, a subregional environmental gradient, and landscape‐scale variations in soil characteristics. Location The 120,000‐km 2 study area includes parts of Vermont and New Hampshire in the north, where sites are 150–200 km from the Atlantic Ocean, and spans the coastline from southeastern New York to Cape Cod and the adjacent islands, including Block Island, the Elizabeth Islands, Nantucket, and Martha's Vineyard. Methods We analysed pollen records from 29 study sites, using multivariate cluster analysis to visualize changes in the composition and spatial patterns of vegetation during the last 14,000 years. The pollen data were compared with temperature and precipitation reconstructions. Results Boreal forest featuring Picea and Pinus banksiana was present across the region when conditions were cool and dry 14,000–12,000 calibrated 14 C years before present (ybp). Pinus strobus became regionally dominant as temperatures increased between 12,000 and 10,000 ybp. The composition of forests in inland and coastal areas diverged in response to further warming after 10,000 ybp, when Quercus and Pinus rigida expanded across southern New England, whereas conditions remained cool enough in inland areas to maintain Pinus strobus . Increasing precipitation allowed Tsuga canadensis , Fagus grandifolia , and Betula to replace Pinus strobus in inland areas during 9,000–8,000 ybp, and also led to the expansion of Carya across the coastal part of the region beginning at 7,000–6,000 ybp. Abrupt cooling at 5,500–5,000 ybp caused sharp declines in Tsuga in inland areas and Quercus at some coastal sites, and the populations of those taxa remained low until they recovered around 3,000 ybp in response to rising precipitation. Throughout most of the Holocene, sites underlain by sandy glacial deposits were occupied by Pinus rigida and Quercus . Main conclusions Postglacial changes in the composition and spatial pattern of New England forests were controlled by long‐term trends and abrupt shifts in temperature and precipitation, as well as by the environmental gradient between coastal and inland parts of the region. Substrate and soil moisture shaped landscape‐scale variations in forest composition.

Tsuga

Environmental change

10.1111/jbi.13407

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Detecting Climate Change Impacts on Socio-Hydrological Systems in the Rocky Mountains, USA

David J. Williams Corrine Nöel Knapp Bryan N. Shuman Bart Geerts Melissa Bukovsky

Observation networks established in complex mountain landscapes promise to address critical gaps in understanding of socio-hydrological systems and their process interactions operating at local to regional scales. Knowledge of vulnerabilities and risks founded on observed biophysical and socioeconomic conditions and responses is required to represent realistic scenarios in model simulations of climate change impacts on managed water resources. Socio-hydrological observatories often lack design coordination that consequently constrains the ability to link processes and detect feedbacks across scales and domain boundaries. The goal of the 5-year (2022-2027) project WyACT (Wyoming Anticipating Climate Transitions) is to build adaptive capacity in headwater mountain communities in the Greater Yellowstone Area of of the Rocky Mountains founded on observations, simulation modeling, and driven stakeholder needs and participation. A key feature of WyACT is the development, from the ground up, of a regional observatory network that explicitly coordinates observations of socioeconomic, hydrological, and ecological responses to climate-driven stressors. WY-SEaSON (Wyoming Socio-Environmental Systems Observatory Network) will quantify and monitor the range of responses of snowpack and soil moisture, streamflow, aquatic ecosystems, vegetation stress and fire risk, economic risk perception, and preferred adaptation pathways to a changing climate in a key headwaters region that feeds three major river drainages in western North America. This presentation highlights the structure of WY-SEaSON including the operating principles, goals, mission, and design with examples of emerging and integrated observations.

10.5194/egusphere-egu24-20504

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Vegetation response to wildfire and climate forcing in a Rocky Mountain lodgepole pine forest over the past 2500 years

The Holocene (2020)

Barrie V. Chileen Kendra K. McLauchlan Philip E. Higuera Meredith Parish Bryan N. Shuman

Wildfire is a ubiquitous disturbance agent in subalpine forests in western North America. Lodgepole pine ( Pinus contorta var. latifolia), a dominant tree species in these forests, is largely resilient to high-severity fires, but this resilience may be compromised under future scenarios of altered climate and fire activity. We investigated fire occurrence and post-fire vegetation change in a lodgepole pine forest over the past 2500 years to understand ecosystem responses to variability in wildfire and climate. We reconstructed vegetation composition from pollen preserved in a sediment core from Chickaree Lake, Colorado, USA (1.5-ha lake), in Rocky Mountain National Park, and compared vegetation change to an existing fire history record. Pollen samples ( n = 52) were analyzed to characterize millennial-scale and short-term (decadal-scale) changes in vegetation associated with multiple high-severity fire events. Pollen assemblages were dominated by Pinus throughout the record, reflecting the persistence of lodgepole pine. Wildfires resulted in significant declines in Pinus pollen percentages, but pollen assemblages returned to pre-fire conditions after 18 fire events, within c.75 years. The primary broad-scale change was an increase in Picea, Artemisia, Rosaceae, and Arceuthobium pollen types, around 1155 calibrated years before present. The timing of this change is coincident with changes in regional pollen records, and a shift toward wetter winter conditions identified from regional paleoclimate records. Our results indicate the overall stability of vegetation in Rocky Mountain lodgepole pine forests during climate changes and repeated high-severity fires. Contemporary deviations from this pattern of resilience could indicate future recovery challenges in these ecosystems.

Subalpine forest

Fire ecology

Fire history

Fire regime

Mountain pine beetle

10.1177/0959683620941068

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Wildfire activity in northern Rocky Mountain subalpine forests still within millennial-scale range of variability

Environmental Research Letters (2023)

Kyra D. Wolf Philip E. Higuera Bryan N. Shuman Kendra K. McLauchlan

Abstract Increasing area burned across western North America raises questions about the precedence and magnitude of changes in fire activity, relative to the historical range of variability (HRV) that ecosystems experienced over recent centuries and millennia. Paleoecological records of past fire occurrence provide context for contemporary changes in ecosystems characterized by infrequent, high-severity fire regimes. Here we present a network of 12 fire-history records derived from macroscopic charcoal preserved in sediments of small subalpine lakes within a c. 10 000 km 2 landscape in the U.S. northern Rocky Mountains (Northern Rockies). We used this network to characterize landscape-scale burning over the past 2500 yr, and to evaluate the precedence of widespread regional burning experienced in the early 20th and 21st centuries. We further compare the Northern Rockies fire history to a previously published network of fire-history records in the Southern Rockies. In Northern Rockies subalpine forests, widespread fire activity was strongly linked to seasonal climate conditions, in contemporary, historical, and paleo records. The average estimated fire rotation period (FRP) over the past 2500 yr was 164 yr (HRV: 127–225 yr), while the contemporary FRP from 1900 to 2021 CE was 215 yr. Thus, extensive regional burning in the early 20th century (e.g. 1910 CE) and in recent decades remains within the HRV of recent millennia. Results from the Northern Rockies contrast with the Southern Rockies, which burned with less frequency on average over the past 2500 yr, and where 21st-century burning has exceeded the HRV. Our results support expectations that Northern Rockies fire activity will continue to increase with climatic warming, surpassing historical burning if more than one exceptional fire year akin to 1910 occurs within the next several decades. The ecological consequences of climatic warming in subalpine forests will depend, in large part, on the magnitude of fire-regime changes relative to the past.

Fire regime

Subalpine forest

Fire ecology

Fire history

10.1088/1748-9326/acee16

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Citations (4)

Holocene Lake-Level Changes in Northwest Montana Indicate Substantially Drier than Modern Conditions in the Mid-Holocene

AGU Fall Meeting Abstracts (2020)

L. Mallon Bryan N. Shuman Meredith Parish

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