Increasing elevation of fire in the Sierra Nevada and implications for forest change

Schwartz, Mark W.; Butt, Nathalie; Dolanc, Christopher R.; Holguin, Andrew; Moritz, Max A.; North, Malcolm P.; Safford, Hugh D.; Stephenson, Nathan L.; Thorne, James H.; Mantgem, Phillip J. van

doi:10.1890/es15-00003.1

Cited by 64 publications

(61 citation statements)

References 36 publications

(39 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Drier conditions make higher‐elevation forests available to burn earlier in the fire season, which likely accounts in part for the observed increase in the maximum elevation of fires in the Sierra Nevada since 1900 (Schwartz et al. ). In Sierran mixed‐conifer forests or dry pine forests (75% and 13% of conifer forest in the study area, respectively), fuel moistures are commonly low enough to support high‐severity fire by July or August (Estes et al.…”

Section: Discussionmentioning

confidence: 99%

“…Under extreme conditions such as prolonged drought or high winds, weather may overwhelm bottom-up controls (Perry et al 2011, Cansler andMcKenzie 2014) and lead to widespread high-severity fire, regardless of vegetation/fuels, topography, or previous history of wildfire or prescribed burns (Lydersen et al 2014). Fires occurring during droughts or later in the summer in Mediterranean climates are also more likely to spread to higher-elevation vegetation types and burn at higher severity due to progressive drying of fuels (Lutz et al 2009, Schwartz et al 2015.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Previous burns and topography limit and reinforce fire severity in a large wildfire

Harris

Taylor

2017

Ecosphere

View full text Add to dashboard Cite

Abstract. In fire-prone forests, self-reinforcing fire behavior may generate a mosaic of vegetation types and structures. In forests long subject to fire exclusion, such feedbacks may result in forest loss when surface and canopy fuel accumulations lead to unusually severe fires. We examined drivers of fire severity in one large (>1000 km 2 ) wildfire in the western United States, the Rim Fire in the Sierra Nevada, California, and how it was influenced by severity of 21 previous fires to examine the influences on (1) the severity of the first fire since 1984 and (2) reburn severity. The random forest machine-learning statistical model was used to predict satellite-derived fire severity classes from geospatial datasets of fire history, topographic setting, weather, and vegetation type. Topography and inferred weather were the most important variables influencing the previous burn. Previous fire severity was the most important factor influencing reburn severity, and areas tended to reburn at the same severity class as the previous burn. However, areas reburned in <15 yr burned at lower severity than expected. Previous fire severity and Rim Fire severity were higher on ridges, at intermediate elevations (~750-1250 m), and on slopes <30°, indicating a consistent effect of topography on fire severity patterns in these forests. Areas burned with low severity prescribed fires burned at low severity again in the Rim Fire, and areas with long fire-free periods burned at higher severity. This fire history effect suggests that prescribed burning was an effective management tool, leading to lower fire severity in the previous burns and the subsequent reburn. Our results show that self-reinforcing fire behavior results mainly from effects of vegetation structure and fuels on fire severity and that this behavior is mediated by topographic setting and the time since last fire.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Previous burns and topography limit and reinforce fire severity in a large wildfire

Harris

Taylor

2017

Ecosphere

View full text Add to dashboard Cite

show abstract

“…The link between fire risk and forest mortality is a fundamental function of fuel amount, moisture, weather, and topography (Schwartz et al. ). The pattern of fire regimes and fire behavior is affected by the amount and the continuity of canopy flues and the crown species.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, widespread mortality is likely to amplify other disturbances, such as fire (Bigler et al 2005), that play an important role in determining the structure and function of forests. The link between fire risk and forest mortality is a fundamental function of fuel amount, moisture, weather, and topography (Schwartz et al 2015). The pattern of fire regimes and fire behavior is affected by the amount and the continuity of canopy flues and the crown species.…”

Section: Introductionmentioning

confidence: 99%

What mediates tree mortality during drought in the southern Sierra Nevada?

Paz‐Kagan

Brodrick

Vaughn

et al. 2017

Ecological Applications

Self Cite

View full text Add to dashboard Cite

Severe drought has the potential to cause selective mortality within a forest, thereby inducing shifts in forest species composition. The southern Sierra Nevada foothills and mountains of California have experienced extensive forest dieback due to drought stress and insect outbreak. We used high-fidelity imaging spectroscopy (HiFIS) and light detection and ranging (LiDAR) from the Carnegie Airborne Observatory (CAO) to estimate the effect of forest dieback on species composition in response to drought stress in Sequoia National Park. Our aims were (1) to quantify site-specific conditions that mediate tree mortality along an elevation gradient in the southern Sierra Nevada Mountains, (2) to assess where mortality events have a greater probability of occurring, and (3) to estimate which tree species have a greater likelihood of mortality along the elevation gradient. A series of statistical models were generated to classify species composition and identify tree mortality, and the influences of different environmental factors were spatially quantified and analyzed to assess where mortality events have a greater likelihood of occurring. A higher probability of mortality was observed in the lower portion of the elevation gradient, on southwest- and west-facing slopes, in areas with shallow soils, on shallower slopes, and at greater distances from water. All of these factors are related to site water balance throughout the landscape. Our results also suggest that mortality is species-specific along the elevation gradient, mainly affecting Pinus ponderosa and Pinus lambertiana at lower elevations. Selective mortality within the forest may drive long-term shifts in community composition along the elevation gradient.

show abstract

“…In addition, intensified climate stress will increase the risk of wildfire and drive it to higher elevations than historically (Schwartz et al. , Liang et al. ).…”

Section: Discussionmentioning

confidence: 99%

The impact of climate change uncertainty on California's vegetation and adaptation management

et al. 2017

Self Cite

View full text Add to dashboard Cite

Abstract. The impacts of different emission levels and climate change conditions to landscape-scale natural vegetation could have large repercussions for ecosystem services and environmental health. We forecast the risk-reduction benefits to natural landscapes of lowering business-as-usual greenhouse gas emissions by comparing the extent and spatial patterns of climate exposure to dominant vegetation under current emissions trajectories (Representative Concentration Pathway, RCP8.5) and envisioned Paris Accord target emissions (RCP4.5). This comparison allows us to assess the ecosystem value of reaching targets to keep global temperature warming under 2°C. Using 350,719 km 2 of natural lands in California, USA, and the mapped extents of 30 vegetation types, we identify each type's current bioclimatic envelope by the frequency with which it occupies current climate conditions. We then map the trajectory of each pixel's climate under the four climate futures to quantify areas expected to fall within, become marginal to (outside a 95% probability contour), or move beyond their current climate conditions by the end of the 21st century. In California, these four future climates represent temperature increases of 1.9-4.5°C and a À24.8 to +22.9% change in annual precipitation by 2100. From 158,481 to 196,493 km 2 (45-56%) of California's natural vegetation is predicted to become highly climatically stressed under current emission levels (RCP8.5) under the drier and wetter global climate models, respectively. Vegetation in three California ecoregions critical to human welfare, southwestern CA, the Great Valley, and the Sierra Nevada Mountains, becomes >50% impacted, including 68% of the lands around Los Angeles and San Diego. However, reducing emissions to RCP4.5 levels reduces statewide climate exposure risk by 86,382-99,726 km 2 . These projections are conservative baseline estimates because they do not account for amplified drought-related mortality, fires, and beetle outbreaks that have been observed during the current five-year drought. However, these results point to the landscape benefits of emission reductions.

show abstract

Increasing elevation of fire in the Sierra Nevada and implications for forest change

Cited by 64 publications

References 36 publications

Previous burns and topography limit and reinforce fire severity in a large wildfire

Previous burns and topography limit and reinforce fire severity in a large wildfire

What mediates tree mortality during drought in the southern Sierra Nevada?

The impact of climate change uncertainty on California's vegetation and adaptation management

Contact Info

Product

Resources

About