Water and Carbon Fluxes Along an Elevational Gradient in a Sagebrush Ecosystem

Flerchinger, G. N.; Fellows, Aaron W.; Seyfried, M. S.; Clark, Patrick E.; Lohse, Kathleen A.

doi:10.1007/s10021-019-00400-x

Cited by 37 publications

(58 citation statements)

References 58 publications

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“…Annual net carbon uptake (NEP) at these sites ranged from nearly neutral for the WBS site to 180 g C·m −2 ·year −1 for the MBS site in these years (Flerchinger et al, , Table S2), which roughly corresponded to the magnitude of winter R eco reported here. Despite WBS being nearly carbon neutral for 2015, winter R eco accounted for only 39 to 74% of average annual NEP over the study period; much of the winter R eco from WBS (30%) was attributed to be brief warm periods when the soil warmed above 1 °C.…”

Section: Discussionsupporting

confidence: 64%

“…These reductions corresponded with reduced soil moisture, indicating that water limitations caused much of the decline (Figure ). Moreover, a pulse in CO 2 efflux typical of drylands after rainfall (Huxman et al, ) was observed at the WBS and LoS sites in the summer of 2015 (Flerchinger et al, ), indicating that water availability strongly limited decomposition (Figure S2).…”

Section: Discussionmentioning

confidence: 93%

“…Winter CO 2 efflux was monitored at five sagebrush shrublands situated at sites ranging in elevation from 1,425 to 2,111 m. All sites are located in the RCEW within 13 km of each other. Four of the sites are part of the RC CZO established in late 2014 to monitor long‐term fluxes spanning an elevation/climate gradient across the rain‐to‐snow transition zone (Table ; Flerchinger et al, ); the fifth site is a high‐elevation, snow‐dominated site within RCEW operated from 2004 to 2007 that predates the RC CZO (Fellows et al, ; Flerchinger et al, ; Reba et al, ).…”

Section: Methodsmentioning

confidence: 99%

“…These low elevations support a sparser plant canopy and reduced live and dead carbon stocks. Anticipated changes in warming and snow cover suggest the rain‐to‐snow transition zone will shift upslope, and that the small and intermittent snowpack currently found at low elevation may occur in many snow‐dominated upper‐montane regions with just a few degrees of warming (Flerchinger et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Collectively, these cold winters and dry summers restrict most biological activity to spring and early summer while temperatures are warm but before water limitations become severe (Bowling et al, ; Comstock & Ehleringer, ; Gilmanov et al, ). As a result, the growing season is often short, annual totals of carbon uptake and loss are small (Flerchinger et al, ), and the cumulative impact of even a small continuous CO 2 efflux over a long winter can have an important impact on the annual carbon budget (Brooks et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Winter CO₂ Efflux From Sagebrush Shrublands Distributed Across the Rain‐to‐Snow Transition Zone

et al. 2020

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The projected shifts in winter weather and snowpack conditions are expected to impact carbon storage in western U.S. rangelands. Sagebrush shrublands comprise much of the western United States, yet contribution of winter CO2 efflux to the overall carbon budget of these ecosystems remains uncertain. We explored factors controlling winter CO2 efflux measured using eddy covariance at five sagebrush‐dominated sites along an elevation/climate transect extending from 1,425 to 2,111 m. Results showed that winter CO2 efflux was modest but had important impacts on annual carbon budgets, and its impact increased in high‐elevation, snow‐dominated ecosystems compared to low, rain‐dominated ones. Observed cumulative winter CO2 efflux accounted for 8–30% of annual gross ecosystem production (GEP) and roughly approximated annual net carbon uptake. Omission of winter periods would have increased net uptake by 1.5 to 2.2 times. Within‐site variability in observed 30‐min winter CO2 efflux was related to soil temperature and moisture. Between‐site variability was attributed to available carbon stocks, including soil organic carbon and the previous year's GEP. At low elevations, lack of snow cover to insulate soil from freezing, coupled with lower carbon stocks, limited CO2 efflux. Conversely, large carbon stocks and deep snowpack that prevented soil freezing at high elevation led to increased CO2 efflux. These results show how climate and biota exert strong controls on winter ecosystem respiration and extend our understanding of how state factors influence winter CO2 efflux. Collectively, our findings suggest that an upward climatic shift in the rain‐to‐snow transition elevation may alter the carbon budget of sagebrush shrublands.

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Section: Discussionsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Winter CO₂ Efflux From Sagebrush Shrublands Distributed Across the Rain‐to‐Snow Transition Zone

et al. 2020

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Projected change in rangeland fractional component cover across the sagebrush biome under climate change through 2085

2021

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Climate change over the past century has altered vegetation community composition and species distributions across rangelands in the western United States. The scale and magnitude of climatic influences are unknown. While many studies have projected the effects of climate change using several modeling approaches, none has evaluated the impacts to fractional component cover at a 30-m resolution across the full sagebrush (Artemisia spp.) biome. We used fractional component cover data for rangeland functional groups and weather data from the 1985 to 2018 reference period in conjunction with soils and topography data to develop empirical models describing the spatiotemporal variation in component cover.To investigate the ramifications of future change across the western United States, we extended models based on historical relationships over the reference period to model landscape effects based on future weather conditions from two emission scenarios and three time periods (2020s, 2050s, and 2080s). We tested both generalized additive models (GAMs) and regression tree models, finding that the former led to superior spatial and statistical results. Our results indicate more xeric vegetation across most of the study area, with an increasing dominance of non-sagebrush shrubs, annual herbaceous cover, and bare ground over herbaceous and sagebrush cover in both the representative concentration pathway (RCP) 4.5 and 8.5 scenarios. In general, both scenarios yielded similar results, but RCP 8.5 tended to be more extreme, with greater change relative to the reference period. Results demonstrate that in cool sites some degree of warming to growing season maximum temperature or nongrowing season minimum temperature could be beneficial to sagebrush and shrub growth. However, warming nongrowing season maximum temperature was beneficial to shrub, but not to sagebrush growth. Our results inform rangeland managers of potential future vegetation composition, cover, and species distributions, which could improve prioritization of conservation and restoration efforts.

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Understanding the future of big sagebrush regeneration: challenges of projecting complex ecological processes

et al. 2021

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Regeneration is an essential demographic step that affects plant population persistence, recovery after disturbances, and potential migration to track suitable climate conditions. Challenges of restoring big sagebrush (Artemisia tridentata) after disturbances including fire-invasive annual grass interactions exemplify the need to understand the complex regeneration processes of this long-lived, woody species that is widespread across the semiarid western U.S. Projected 21st century climate change is expected to increase drought risks and intensify restoration challenges. A detailed understanding of regeneration will be crucial for developing management frameworks for the big sagebrush region in the 21st century. Here, we used two complementary models to explore spatial and temporal relationships in the potential of big sagebrush regeneration representing (1) range-wide big sagebrush regeneration responses in natural vegetation (process-based model) and (2) big sagebrush restoration seeding outcomes following fire in the Great Basin and the Snake River Plains (regression-based model). The process-based model suggested substantial geographic variation in long-term regeneration trajectories with central and northern areas of the big sagebrush region remaining climatically suitable, whereas marginal and southern areas are becoming less suitable. The regression-based model suggested, however, that restoration seeding may become increasingly more difficult, illustrating the particularly difficult challenge of promoting sagebrush establishment after wildfire in invaded landscapes. These results suggest that sustaining big sagebrush on the landscape throughout the 21st century may climatically be feasible for many areas and that uncertainty about the long-term sustainability of big sagebrush may be driven more by dynamics of biological invasions and wildfire than by uncertainty in climate change projections. Divergent projections of the two models under 21st century climate conditions encourage further study to evaluate potential benefits of recreating conditions of uninvaded, unburned natural big sagebrush vegetation for post-fire restoration seeding, such as seeding in multiple years and, for at least much of the northern Great Basin and Snake River Plains, the control of the fire-invasive annual grass cycle.

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Water and Carbon Fluxes Along an Elevational Gradient in a Sagebrush Ecosystem

Cited by 37 publications

References 58 publications

Winter CO₂ Efflux From Sagebrush Shrublands Distributed Across the Rain‐to‐Snow Transition Zone

Winter CO₂ Efflux From Sagebrush Shrublands Distributed Across the Rain‐to‐Snow Transition Zone

Projected change in rangeland fractional component cover across the sagebrush biome under climate change through 2085

Understanding the future of big sagebrush regeneration: challenges of projecting complex ecological processes

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Water and Carbon Fluxes Along an Elevational Gradient in a Sagebrush Ecosystem

Cited by 37 publications

References 58 publications

Winter CO2 Efflux From Sagebrush Shrublands Distributed Across the Rain‐to‐Snow Transition Zone

Winter CO2 Efflux From Sagebrush Shrublands Distributed Across the Rain‐to‐Snow Transition Zone

Projected change in rangeland fractional component cover across the sagebrush biome under climate change through 2085

Understanding the future of big sagebrush regeneration: challenges of projecting complex ecological processes

Contact Info

Product

Resources

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Winter CO₂ Efflux From Sagebrush Shrublands Distributed Across the Rain‐to‐Snow Transition Zone

Winter CO₂ Efflux From Sagebrush Shrublands Distributed Across the Rain‐to‐Snow Transition Zone