Evidence for nonuniform permafrost degradation after fire in boreal landscapes

Minsley, Burke J.; Pastick, Neal J.; Wylie, Bruce K.; Brown, Dana R. N.; Kass, M. Andy

doi:10.1002/2015jf003781

Cited by 60 publications

(52 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Five unburned patches of black spruce forest were also sampled, confirming the presence of near-surface permafrost at these locations. Other studies in the study area have documented contrasting permafrost status between burned and unburned areas [18,36]. Permafrost was likely widespread but discontinuous in this study area before fire.…”

Section: Study Area and Designmentioning

confidence: 84%

Landscape Effects of Wildfire on Permafrost Distribution in Interior Alaska Derived from Remote Sensing

Brown

Jorgenson²,

Kielland

et al. 2016

Remote Sensing

View full text Add to dashboard Cite

Climate change coupled with an intensifying wildfire regime is becoming an important driver of permafrost loss and ecosystem change in the northern boreal forest. There is a growing need to understand the effects of fire on the spatial distribution of permafrost and its associated ecological consequences. We focus on the effects of fire a decade after disturbance in a rocky upland landscape in the interior Alaskan boreal forest. Our main objectives were to (1) map near-surface permafrost distribution and drainage classes and (2) analyze the controls over landscape-scale patterns of post-fire permafrost degradation. Relationships among remote sensing variables and field-based data on soil properties (temperature, moisture, organic layer thickness) and vegetation (plant community composition) were analyzed using correlation, regression, and ordination analyses. The remote sensing data we considered included spectral indices from optical datasets (Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operational Land Imager (OLI)), the principal components of a time series of radar backscatter (Advanced Land Observing Satellite-Phased Array type L-band Synthetic Aperture Radar (ALOS-PALSAR)), and topographic variables from a Light Detection and Ranging (LiDAR)-derived digital elevation model (DEM). We found strong empirical relationships between the normalized difference infrared index (NDII) and post-fire vegetation, soil moisture, and soil temperature, enabling us to indirectly map permafrost status and drainage class using regression-based models. The thickness of the insulating surface organic layer after fire, a measure of burn severity, was an important control over the extent of permafrost degradation. According to our classifications, 90% of the area considered to have experienced high severity burn (using the difference normalized burn ratio (dNBR)) lacked permafrost after fire. Permafrost thaw, in turn, likely increased drainage and resulted in drier surface soils. Burn severity also influenced plant community composition, which was tightly linked to soil temperature and moisture. Overall, interactions between burn severity, topography, and vegetation appear to control the distribution of near-surface permafrost and associated drainage conditions after disturbance.

show abstract

Section: Study Area and Designmentioning

confidence: 84%

Landscape Effects of Wildfire on Permafrost Distribution in Interior Alaska Derived from Remote Sensing

Brown

Jorgenson²,

Kielland

et al. 2016

Remote Sensing

View full text Add to dashboard Cite

show abstract

“…Extreme effects such as thermokarst-related subsidence of up to 6 m (e.g., Yoshikawa and Hinzman, 2003) are possible. Catastrophic events such as wildfires can initiate or exacerbate permafrost degradation by combustion of surface organics, thereby increasing soil heat flux (e.g., Yoshikawa and Hinzman, 2003;Minsley et al, 2016b). All of these effects lead to increased ecosystem stress through increased vulnerability and altered long-term forest communities.…”

mentioning

confidence: 99%

“…In this paper, we present the results of borehole nuclear magnetic resonance surveys as part of a larger multiyear interdisciplinary study in Alaska (Minsley et al, 2016b) to investigate water content and porosity characteristics of the permafrost and active layer in situ, without requiring core analysis. We observe significant quantities of liquid water within near-surface (upper 3 m) permafrost and describe the distribution of that water as a function of apparent pore size.…”

mentioning

confidence: 99%

In situ nuclear magnetic resonance response of permafrost and active layer soil in boreal and tundra ecosystems

et al. 2017

Self Cite

View full text Add to dashboard Cite

Abstract. Characterization of permafrost, particularly warm and near-surface permafrost which can contain significant liquid water, is critical to understanding complex interrelationships with climate change, ecosystems, and disturbances such as wildfires. Understanding the vulnerability and resilience of permafrost requires an interdisciplinary approach, relying on (for example) geophysical investigations, ecological characterization, direct observations, remote sensing, and more. As part of a multiyear investigation into the impacts of wildfires on permafrost, we have collected in situ measurements of the nuclear magnetic resonance (NMR) response of the active layer and permafrost in a variety of soil conditions, types, and saturations. In this paper, we summarize the NMR data and present quantitative relationships between active layer and permafrost liquid water content and pore sizes and show the efficacy of borehole NMR (bNMR) to permafrost studies. Through statistical analyses and synthetic freezing simulations, we also demonstrate that borehole NMR is sensitive to the nucleation of ice within soil pore spaces.

show abstract

“…ERT has been widely used for detecting permafrost bodies and estimating permafrost thickness in Canada (Briggs et al, 2016;Douglas et al, 2016;Lewkowicz et al, 2011;Minsley et al, 2016;Way and Lewkowicz, 2015), Scandinavia (Kasprzak, 2015;Sjöberg et al, 2015), the European Alps (Hauck, 2013) and the Tibet Plateau (You et al, 2013). Minimum electrode spacing was 0.5, 1 or 2 m over standard profile lengths of 40-160 m, or longer where roll-along surveys were performed, giving maximum penetration depths of approximately 6 m, 12 m or 25 m, 20 respectively.…”

Section: Methodsmentioning

confidence: 99%

Characteristics and fate of isolated permafrost patches in coastal Labrador, Canada

Way¹,

Lewkowicz²,

Yu³

2018

Preprint

View full text Add to dashboard Cite

Abstract. Bodies of peatland permafrost were examined at five sites along a 300 km transect spanning the isolated patches permafrost zone in the coastal barrens of southeastern Labrador. Mean annual air temperatures ranged from +1°C in the south (latitude 51.4°N) to -1.1°C in the north (53.7°N) while mean ground temperatures at the top of permafrost varied 10 respectively from -0.7°C to -2.3°C with shallow active layers (40-60 cm) throughout. Small surface offsets due to wind scouring of snow from the crests of palsas and peat plateaux, and large thermal offsets due to thick peat are critical to permafrost, which is therefore absent in wetland, forested and forest-tundra areas inland, notwithstanding average air temperatures much lower than near the coast. Most permafrost peatland bodies are less than 5 m thick with a maximum of 10 m with steep geothermal gradients. One-dimensional thermal modelling for two sites showed that they are in equilibrium 15 with the current climate, but the permafrost mounds are generally relict and could not form today without the low snow depths that result from a heaved peat surface. Despite the warm permafrost, model predictions using downscaled global warming scenarios (RCP2.6, 4.5 and 8.5) indicate that perennially frozen ground will thaw from the base up and may persist at the southern site until the middle of the 21 st Century. At the northern site, permafrost is more resilient, persisting to the 2060s under RCP8.5, the 2090s under RCP4.5, or beyond the 21 st century under RCP2.6. Despite evidence of peatland 20 permafrost degradation in the study region, the local-scale modelling suggests that the southern boundary of permafrost may not move as quickly as had previously been thought.

show abstract

Evidence for nonuniform permafrost degradation after fire in boreal landscapes

Cited by 60 publications

References 54 publications

Landscape Effects of Wildfire on Permafrost Distribution in Interior Alaska Derived from Remote Sensing

Landscape Effects of Wildfire on Permafrost Distribution in Interior Alaska Derived from Remote Sensing

In situ nuclear magnetic resonance response of permafrost and active layer soil in boreal and tundra ecosystems

Characteristics and fate of isolated permafrost patches in coastal Labrador, Canada

Contact Info

Product

Resources

About