Characterizing the Spatial Patterns and Spatially Explicit Probabilities of Post-Fire Vegetation Residual Patches in Boreal Wildfire Scars PDF Download
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Author: Yikalo Hayelom Araya
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ISBN:
Category :
Languages : en
Pages :
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Author: Yikalo Hayelom Araya
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Category :
Languages : en
Pages :
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Author: Budhendra Oudesh Singh
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Category :
Languages : en
Pages :
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Author: João Torres
Publisher:
ISBN: 9783330064812
Category :
Languages : en
Pages : 232
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Author:
Publisher:
ISBN:
Category : Forest fires
Languages : en
Pages : 50
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Author: Marc-André Parisien
Publisher:
ISBN:
Category : Nature
Languages : en
Pages : 48
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Resource management in fire-dominated ecosystems requires an understanding of the probability of wildfire occurring & spreading at different points in a landscape. This report describes an approach to evaluating wildfire susceptibility, or burn probability, for fire-prone landscapes such as the boreal forest of North America. The approach involves use of the BURN-P3 (probability, prediction, & planning) landscape-level simulation model, which combines deterministic fire growth based on the Canadian Fire Behaviour Prediction System and spatial data for forest fuels & topography with probabilistic fire ignitions & spread events derived from historical fire & weather data. A case study of the application of BURN-P3 is undertaken for a boreal mixedwood area of central Saskatchewan. The results presented highlight the importance of landscape features to wildfire susceptibility and indicate whether assessments based solely on stand-level characteristics are adequate.
Author: Jacqueline W. Curtis (corresponding author)
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Author: Grant M. Casady
Publisher:
ISBN:
Category :
Languages : en
Pages : 376
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Ecosystem response to disturbance is a function of environmental factors interacting at a number ofspatio-temporal scales. This research explored ecosystem response to wildfire as a function of local and broad-scale environmental factors using satellite based time-series remote sensing data. This topic was explored as a series of three independent but related studies. The first study focused on the evaluation of techniques for the analysis of time-series satellite data for describing post-fire vegetation trends at sites in the US, Spain, and Israel. Time-series data effectively described post-fire trends, and reference sites were valuable for differentiating between post-fire effects and other environmental factors. The use of phenological indicators derived from the time-series shows promise as a monitoring tool, but requires further investigation. The next study evaluated the influence of broad-scale climate factors on rates of post-fire vegetation regeneration across the western US. Rates of post-fire regeneration were higher with increased precipitation and higher minimum temperatures. Changes in climate are likely to result in shifts in post-fire vegetation dynamics, leading to important feedbacks into the climate system. The use of time-series data was a valuable tool in measuring trends in post-fire vegetation across a large area and over an extended period. The final study used time-series vegetation data to measure variations in post-fire vegetation response across an extensive 2002 wildfire. Regression tree analysis related post-fire regeneration to local environmental factors such as burn severity, soil properties, vegetation, and topography. Residuals from modeled rates of post-fire regeneration were evaluated in the context of management activities and site characteristics using expert knowledge. Post-fire rates of regeneration were a function of water availability, pre-burn vegetation, and burn severity. Management activities, soil differences, and shifts in vegetation community composition resulted in deviations from the modeled post-fire regeneration rates. The results of these three research studies indicate that remotely sensed time-series vegetation data provide a useful tool for measuring post-fire vegetation dynamics. Both broad-scale and local environmental factors play important roles in defining post-fire vegetation response, and the use of remote sensing and geospatial data sets can be useful in integrating these factors and enhancing management decisions.
Author: Larry J. Sugarbaker
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ISBN:
Category : Aerial photography in forestry
Languages : en
Pages : 30
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Author: Christine E. Kuntzemann
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ISBN:
Category : Fragmented landscapes
Languages : en
Pages : 0
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In the boreal biome of North America, large wildfires usually leave behind residual patches of unburned vegetation, termed refugia, which can strongly affect post-fire ecosystem processes. While topographic complexity is a major driver of fire refugia in mountainous terrain, refugia and fire severity (the ecological impacts of fire) in boreal landscapes are more likely driven by bottom-up controls affecting the extent and type of fuels. In this study, I investigate the role of hydrological (e.g., peatlands), ecological, and topographic heterogeneity on fire severity and the presence of fire refugia under different spatial and temporal climate moisture conditions in the Alberta boreal region over a 33-year (1985-2018) period. Fire severity was measured using the Relativized Burn Ratio (RBR). Generalized linear models were used to examine relationships of fire severity and probability of refugia as a function of bottom-up (vegetation, topography, site moisture, ecosystem) and top-down (normal and annual climatic moisture) controls. I then developed predictive maps of refugia probability and fire severity under normal and inter-annual climatic moisture conditions. I found that peatlands, stratified as bogs and fens, burned at lower severities and exhibited a higher probability of refugia than uplands, with vegetation (fuel) presenting a stronger control on fire than climate, topography, site moisture, or ecosystem type. In general, locations with wetter regional (normal) climatic moisture, a proxy for fuel amount, experienced increased fire severity and refugia probabilities when surrounded by more peatlands. While the amount of bogs affected both fire severity and refugia at intermediate scales (900-m area), fens affected fire severity most strongly when at a landscape scale (3000-m area) and refugia when at a local-scale (120-m area). Bogs decreased fire severity in adjacent uplands and peatlands under all regional and annual climatic moisture conditions but did not affect refugia probability in uplands. Fens reduced fire severity in adjacent uplands under all conditions and had varying effects on adjacent peatlands depending on moisture availability. Fens also increased refugia probability in adjacent uplands under all conditions, as well as in adjacent peatlands under all regional climatic moisture conditions. Areas of hydrologically-connected peatlands, particularly fens, may be capable of slowing future vegetation transitions, stemming from climate-driven increases to fire severity and post-disturbance moisture stress, in neighboring forests.
Author: Brendan Morris Rogers
Publisher:
ISBN: 9781303810312
Category :
Languages : en
Pages : 202
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Large areas of boreal forest in North America and Eurasia are frequently disturbed by wildfire. These fires alter ecosystem structure and function and affect climate through various biophysical and biogeochemical pathways. Fire-related forcings, however, are highly uncertain, can be opposite in sign, and depend on fire behavior as mediated by meteorology and intrinsic ecosystem properties. Our current understanding of large-scale fire dynamics is inadequate for fully characterizing their role in the climate system. This is particularly pertinent given the sensitivity of high latitudes and the large projected increases in fire frequencies during the 21st century. My dissertation aims to better characterize the controls on and feedbacks from boreal fires so that we may properly account for them in global change projections and potentially mitigate the impacts. I first quantified landscape-scale fire carbon emissions from a 2010 burn in Alaska using field measurements and fine-scale (30 m) remote sensing imagery. Accurate maps of fire emissions are needed to validate larger-scale models and quantify regional carbon fluxes, but are currently lacking due to spatial scaling issues. Here I show that by accounting for plot-level heterogeneity and species effects on spectral signatures, emission models can be generated from non-linear correlations between the differenced Normalized Burn Ratio (dNBR) and field data. Belowground combustion was quantified from soil cores and scaled to the site-level using spruce adventitious root heights. Species-specific allometric equations and visual estimates were used to characterize aboveground carbon losses. Results indicated that fire-wide combustion (1.98 ± 0.19 kg C m−2) was substantially lower than that in the core burning area (2.67 ± 0.24 kg C m−2) and sites (2.88 ± 0.23 kg C m−2) because of lower-severity patches and unburned islands. These areas constitute a significant fraction of burn perimeters in Alaska but are generally not accounted for in regional-scale estimates. This approach may be suitable for other fires in the region. In addition to the positive forcing from carbon emissions, forest fires in boreal North America exert a cooling effect due to relatively large increases in spring albedo from canopy destruction and tree fall. Although this forcing has been characterized at local and regional scales, its climate impacts have not been assessed. I simulated the continental-scale climate footprint of this cooling under various burning scenarios. Forest composition was characterized using a stochastic model of fire occurrence, historical fire data from national inventories, and succession trajectories derived from moderate-scale remote sensing (500 m). When coupled to an Earth system model, younger vegetation from increased burning cooled the high-latitude atmosphere, primarily in the winter and spring, with noticeable feedbacks from the ocean and sea ice. Results from multiple scenarios suggested that a doubling of burn area could cool the surface by 0.23 ±0.09°C across boreal North America during winter and spring months (December through May). This has the potential to provide a negative feedback to winter warming across the domain on the order of 3 - 5% for a doubling, and 14 - 23% for a quadrupling, of burn area. Maximum cooling occurred in the areas of greatest burning and between February and April, reaching feedback potentials of up to 60%. Fire dynamics have been studied much less extensively in boreal Eurasia despite the region containing roughly 2/3rds of the world's boreal forests and displaying unique patterns of fire behavior. I used over a decade of satellite imagery to characterize variations in circumpolar fire behavior, immediate impacts, and longer-term responses. Compared to boreal North America, Eurasian fires were 58 ± 31% less likely to be crown fires, combusted 36 ± 5% less live vegetation, and caused 42 ± 5% less tree mortality. Eurasian fires also generated a 69 ± 9% smaller surface shortwave forcing during the initial post-fire decade, suggesting a near-neutral net climate forcing. Current global fire models were unable to capture the continental differences. I demonstrate that fire weather cannot explain the divergent fire dynamics and climate feedbacks. The primary drivers are shown to be species-level adaptations to fire, making this a preeminent example of species effects on continental-scale carbon and energy exchange.
