Changing climate, vegetation, and fire disturbance in a sub-boreal pine-dominated forest, British Columbia, Canada

2017 ◽  
Vol 47 (5) ◽  
pp. 615-627 ◽  
Author(s):  
Kendrick J. Brown ◽  
Nicholas J. Hebda ◽  
Nicholas Conder ◽  
Karen G. Golinski ◽  
Brad Hawkes ◽  
...  
Keyword(s):  
British Columbia ◽  
Pinus Ponderosa ◽  
Pinus Contorta ◽  
Fire History ◽  
Fire Regime ◽  
Late Glacial ◽  
Fire Frequency ◽  
Fire Disturbance ◽  
Surface Fires ◽  
Climate Niche

Holocene climate, vegetation, and fire history were reconstructed using pollen, molluscs, and charcoal from two lake sediment records (Scum and Norma lakes) collected from the Chilcotin Plateau, British Columbia, Canada. In the late-glacial period, cold steppe prevailed and fire was limited. Artemisia steppe expanded in the earliest Holocene as climate warmed and conditions became dry, with shallow basins drying out. High-frequency surface fires maintained the steppe. An increase in Pinus after 10 200 cal BP signals moistening and the establishment of Pinus ponderosa P. & C. Lawson and Pinus contorta Dougl. ex Loud. stands, with surface fires in the former and higher severity fires in the latter. Cooling around 8500 cal BP favored P. contorta, and a crown fire regime likely prevailed, with intermittent surface fires. Shallow basins began to fill with water. In the mid-Holocene, basins filled further and Picea increased slightly in abundance. Fire frequency decreased, though severity increased. In the last three millennia, modern P. contorta dominated forests were established, with mixed-severity fire disturbance. Considering the future, the results of this study align well with ecosystem climate niche simulations, indicating that non-arboreal and open-forest communities may again prevail widely on the plateau, together with surface fires. Land managers need to develop strategies to manage the upcoming transformation.

Long-term climate, vegetation and fire regime change in a managed municipal water supply area, British Columbia, Canada

The Holocene ◽  
2019 ◽  
Vol 29 (9) ◽  
pp. 1411-1424
Author(s):  
KJ Brown ◽  
NJR Hebda ◽  
G Schoups ◽  
N Conder ◽  
KAP Smith ◽  
...  
Keyword(s):  
British Columbia ◽  
Water Supply ◽  
Fire History ◽  
Management Practices ◽  
Fire Regime ◽  
Late Glacial ◽  
Fire Disturbance ◽  
Municipal Water Supply ◽  
European Settlement ◽  
Municipal Water

Post-glacial climate, vegetation and fire history were reconstructed from a sediment record from Begbie Lake, British Columbia, Canada, located in a municipal water supply area servicing > 350,000 people. Watershed managers have identified wildfire as a threat to water supply and seek to understand how vegetation and fire have varied through time with climate. In the cold late-glacial, open Pinus woodlands, periodically disturbed by fire, transitioned to mixed conifer forests subject to high-severity fire. The early Holocene is of interest to watershed managers because climate was warmer and drier than present. During this interval, low streamflow, abundant fire-adapted taxa, elevated background charcoal and regional increases in biomass burning indicate that fire seasons were longer and that fire was an important disturbance mechanism. Climate moistened in the mid Holocene, facilitating canopy closure and decreased fire disturbance. However, surface fires prevailed in Quercus ecosystems, which were expanding locally. Charcoal increased between 6180–2500 cal yr BP as climate further cooled and moistened, likely reflecting human activity and/or increased climate variability. Modern conditions arose within the last few millennia, impacted most recently by European settlement. In combination with paleoclimate modelling, modern management practices and forecast simulations, the Begbie Lake record informs about ecosystem changes within the watershed, yielding insights for management.

Comparing methods of reconstructing fire history using fire scars in a southwestern United States ponderosa pine forest

2006 ◽  
Vol 36 (4) ◽  
pp. 855-867 ◽  
Author(s):  
Megan L Van Horne ◽  
Peter Z Fulé
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Fire History ◽  
Sampling Methods ◽  
Fire Regime ◽  
Fire Frequency ◽  
Fire Scars ◽  
Fire Scar ◽  
Targeted Sampling ◽  
Fire Intervals

Fire scars have been used to understand the historical role of fire in ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) ecosystems, but sampling methods and interpretation of results have been criticized for being statistically invalid and biased and for leading to exaggerated estimates of fire frequency. We compared "targeted" sampling, random sampling, and grid-based sampling to a census of all 1479 fire-scarred trees in a 1 km2 study site in northern Arizona. Of these trees, 1246 were sufficiently intact to collect cross-sections; of these, 648 had fire scars that could be cross-dated to the year of occurrence in the 200-year analysis period. Given a sufficient sample size (approximately n ≥ 50), we concluded that all tested sampling methods resulted in accurate estimates of the census fire frequency, with mean fire intervals within 1 year of the census mean. We also assessed three analytical techniques: (1) fire intervals from individual trees, (2) the interval between the tree origin and the first scar, and (3) proportional filtering. "Bracketing" fire regime statistics to account for purported uncertainty associated with targeted sampling was not useful. Quantifying differences in sampling approaches cannot resolve all the limitations of fire-scar methods, but does strengthen interpretation of these data.

11 000 years of fire history and climate in the mountain hemlock rain forests of southwestern British Columbia based on sedimentary charcoal

2003 ◽  
Vol 33 (2) ◽  
pp. 292-312 ◽  
Author(s):  
Douglas J Hallett ◽  
Dana S Lepofsky ◽  
Rolf W Mathewes ◽  
Ken P Lertzman
Keyword(s):  
British Columbia ◽  
Lake Sediment ◽  
Fire History ◽  
Fire Regime ◽  
Fire Frequency ◽  
Summer Drought ◽  
Rain Forests ◽  
Independent Evidence ◽  
The Holocene ◽  
Soil Charcoal

Little is known about the role of fire in the mountain hemlock (Tsuga mertensiana (Bong.) Carrière) rain forests of southern British Columbia. High-resolution analysis of macroscopic charcoal from lake sediment cores, along with 102 accelerator mass spectrometry (AMS) ages on soil charcoal, was used to reconstruct the long-term fire history around two subalpine lakes in the southern Coast and North Cascade Mountains. AMS ages on soil charcoal provide independent evidence of local fire around a lake and support the interpretation of peaks in lake sediment charcoal as distinct fire events during the Holocene. Local fires are rare, with intervals ranging from centuries to several millennia at some sites. Overall fire frequency varied continuously throughout the Holocene, suggesting that fire regimes are linked to climate via large-scale atmospheric circulation patterns. Fires were frequent between 11 000 and 8800 calendar years BP during the warm and dry early Holocene. The onset of humid conditions in the mid-Holocene, as rain forest taxa established in the region, produced a variable fire period until 3500 calendar years BP. A synchronous decrease in fire frequency from 3500 to 2400 calendar years BP corresponds to Neoglacial advances in the region and cool humid climate. A return of frequent fire between 2400 and 1300 calendar years BP suggests that prolonged summer drought occurred more often during this interval, which we name the Fraser Valley Fire Period. The present-day fire regime was established after 1300 calendar years BP.

Fire regime shift linked to increased forest density in a piñon–juniper savanna landscape

2014 ◽  
Vol 23 (2) ◽  
pp. 234 ◽  
Author(s):  
Ellis Q. Margolis
Keyword(s):  
Regime Shift ◽  
Fire History ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Climatic Conditions ◽  
Tree Density ◽  
High Severity ◽  
Wide Range ◽  
In Fire

Piñon–juniper (PJ) fire regimes are generally characterised as infrequent high-severity. However, PJ ecosystems vary across a large geographic and bio-climatic range and little is known about one of the principal PJ functional types, PJ savannas. It is logical that (1) grass in PJ savannas could support frequent, low-severity fire and (2) exclusion of frequent fire could explain increased tree density in PJ savannas. To assess these hypotheses I used dendroecological methods to reconstruct fire history and forest structure in a PJ-dominated savanna. Evidence of high-severity fire was not observed. From 112 fire-scarred trees I reconstructed 87 fire years (1547–1899). Mean fire interval was 7.8 years for fires recorded at ≥2 sites. Tree establishment was negatively correlated with fire frequency (r=–0.74) and peak PJ establishment was synchronous with dry (unfavourable) conditions and a regime shift (decline) in fire frequency in the late 1800s. The collapse of the grass-fuelled, frequent, surface fire regime in this PJ savanna was likely the primary driver of current high tree density (mean=881treesha–1) that is >600% of the historical estimate. Variability in bio-climatic conditions likely drive variability in fire regimes across the wide range of PJ ecosystems.

Summary and Synthesis: Past and Future Changes in the Alaskan Boreal Forest

2006 ◽  
Author(s):  
Marilyn W. Walker ◽  
Mary E. Edwards
Keyword(s):  
Boreal Forest ◽  
Bark Beetles ◽  
Fire Regime ◽  
Black Spruce ◽  
Rapid Change ◽  
White Spruce ◽  
Late Glacial ◽  
Fire Frequency ◽  
Tree Resistance ◽  
Forest Sites

Historically the boreal forest has experienced major changes, and it remains a highly dynamic biome today. During cold phases of Quaternary climate cycles, forests were virtually absent from Alaska, and since the postglacial re-establishment of forests ca 13,000 years ago, there have been periods of both relative stability and rapid change (Chapter 5). Today, the Alaskan boreal forest appears to be on the brink of further significant change in composition and function triggered by recent changes that include climatic warming (Chapter 4). In this chapter, we summarize the major conclusions from earlier chapters as a basis for anticipating future trends. Alaska warmed rapidly at the end of the last glacial period, ca 15,000–13,000 years ago. Broadly speaking, climate was warmest and driest in the late glacial and early Holocene; subsequently, moisture increased, and the climate gradually cooled. These changes were associated with shifts in vegetation dominance from deciduous woodland and shrubland to white spruce and then to black spruce. The establishment of stands of fire-prone black spruce over large areas of the boreal forest 5000–6000 years ago is linked to an apparent increase in fire frequency, despite the climatic trend to cooler and moister conditions. This suggests that long-term features of the Holocene fire regime are more strongly driven by vegetation characteristics than directly by climate (Chapter 5). White spruce forests show decreased growth in response to recent warming, because warming-induced drought stress is more limiting to growth than is temperature per se (Chapters 5, 11). If these environmental controls persist, projections suggest that continued climate warming will lead to zero net annual growth and perhaps the movement of white spruce to cooler upland forest sites before the end of the twenty-first century. At the southern limit of the Alaskan boreal forest, spruce bark beetle outbreaks have decimated extensive areas of spruce forest, because warmer temperatures have reduced tree resistance to bark beetles and shortened the life cycle of the beetle from two years to one, shifting the tree-beetle interaction in favor of the insect (Chapter 9).

Using simulation to map fire regimes: an evaluation of approaches, strategies, and limitations

2003 ◽  
Vol 12 (4) ◽  
pp. 309 ◽  
Author(s):  
Robert E. Keane ◽  
Geoffrey J. Cary ◽  
Russell Parsons
Keyword(s):  
Geographical Information Systems ◽  
Fire History ◽  
Fire Regime ◽  
Wildland Fire ◽  
Fire Regimes ◽  
Simulation Modelling ◽  
Fire Frequency ◽  
Geographical Information ◽  
Spatially Explicit ◽  
Eastern Australia

Spatial depictions of fire regimes are indispensable to fire management because they portray important characteristics of wildland fire, such as severity, intensity, and pattern, across a landscape that serves as important reference for future treatment activities. However, spatially explicit fire regime maps are difficult and costly to create requiring extensive expertise in fire history sampling, multivariate statistics, remotely sensed image classification, fire behaviour and effects, fuel dynamics, landscape ecology, simulation modelling, and geographical information systems (GIS). This paper first compares three common strategies for predicting fire regimes (classification, empirical, and simulation) using a 51�000�ha landscape in the Selway-Bitterroot Wilderness Area of Montana, USA. Simulation modelling is identified as the best overall strategy with respect to developing temporally deep spatial fire patterns, but it has limitations. To illustrate these problems, we performed three simulation experiments using the LANDSUM spatial model to determine the relative importance of (1) simulation time span; (2) fire frequency parameters; and (3) fire size parameters on the simulation of landscape fire return interval. The model used to simulate fire regimes is also very important, so we compared two spatially explicit landscape fire succession models (LANDSUM and FIRESCAPE) to demonstrate differences between model predictions and limitations of each on a neutral landscape. FIRESCAPE was developed for simulating fire regimes in eucalypt forests of south-eastern Australia. Finally, challenges for future simulation and fire regime research are presented including field data, scale, fire regime variability, map obsolescence, and classification resolution.

Fire regimes and their correlates in the Darwin region of northern Australia

2007 ◽  
Vol 13 (3) ◽  
pp. 177 ◽  
Author(s):  
Owen Price ◽  
Bryan Baker
Keyword(s):  
Fire History ◽  
Ad Hoc ◽  
Fire Regime ◽  
Negative Impact ◽  
Fire Suppression ◽  
Landsat Imagery ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Dry Season ◽  
Generalized Linear Modelling

A nine year fire history for the Darwin region was created from Landsat imagery, and examined to describe the fire regime across the region. 43% of the region burned each year, and approximately one quarter of the fires occur in the late dry season, which is lower than most other studied areas. Freehold land, which covers 35% of the greater Darwin region, has 20% long-unburnt land. In contrast, most publicly owned and Aboriginal owned land has very high fire frequency (60-70% per year), and only 5% long unburnt. It seems that much of the Freehold land is managed for fire suppression, while the common land is burnt either to protect the Freehold or by pyromaniacs. Generalized Linear Modelling among a random sample of points revealed that fire frequency is higher among large blocks of savannah vegetation, and at greater distances from mangrove vegetation and roads. This suggests that various kinds of fire break can be used to manage fire in the region. The overall fire frequency in the Darwin region is probably too high and is having a negative impact on wildlife. However, the relatively low proportion of late dry season fires means the regime is probably not as bad as in some other regions. The management of fire is ad-hoc and strongly influenced by tenure. There needs to be a clear statement of regional fire targets and a strategy to achieve these. Continuation of the fire mapping is an essential component of achieving the targets.

scholarly journals A Disrupted Historical Fire Regime in Central British Columbia

2021 ◽  
Vol 9 ◽  
Author(s):  
Wesley Brookes ◽  
Lori D. Daniels ◽  
Kelsey Copes-Gerbitz ◽  
Jennifer N. Baron ◽  
Allan L. Carroll
Keyword(s):  
British Columbia ◽  
Prescribed Burning ◽  
Fire Regime ◽  
Spatial Scales ◽  
Fire Frequency ◽  
Dry Forest ◽  
Moderate Severity ◽  
High Severity ◽  
Wide Range ◽  
Fire Exclusion

In the 2017 and 2018, 2.55 million hectares burned across British Columbia, Canada, including unanticipated large and high-severity fires in many dry forests. To transform forest and fire management to achieve resilience to future megafires requires improved understanding historical fire frequency, severity, and spatial patterns. Our dendroecological reconstructions of 35 plots in a 161-hectare study area in a dry Douglas-fir forest revealed historical fires that burned at a wide range of frequencies and severities at both the plot- and study-area scales. The 23 fires between 1619 and 1943 burned at intervals of 10–30 years, primarily at low- to moderate-severity that scarred trees but generated few cohorts. In contrast, current fire-free intervals of 70–180 years exceed historical maximum intervals. Of the six widespread fires from 1790 to 1905, the 1863 fire affected 86% of plots and was moderate in severity with patches of higher severity that generated cohorts at fine scales only. These results indicate the severity of fires varied at fine spatial scales, and offer little support for the common assertion that periodic, high-severity, stand-initiating events were a component of the mixed-severity fire regime in these forest types. Many studies consider fires in the late 1800s relatively severe because they generated new cohorts of trees, and thus, emphasize the importance of high-severity fires in a mixed-severity fire regime. In our study area, the most widespread and severe fire was not a stand-initiating fire. Rather, the post-1863 cohorts persisted due disruption of the fire regime in the twentieth century when land-use shifted from Indigenous fire stewardship and early European settler fires to fire exclusion and suppression. In absence of low- to moderate-severity fires, contemporary forests are dense with closed canopies that are vulnerable to high-severity fire. Future management should reduce forest densities and to restore stand- and landscape-level heterogeneity and increase forest resilience. The timing and size of repeat treatments such as thinning of subcanopy trees and prescribed burning, including Indigenous fire stewardship, can be guided by our refined understanding of the mixed-severity fire regime that was historically dominated by low- to moderate-severity fires in this dry forest ecosystem.

scholarly journals Fire History and Potential Fire Behavior in a Rocky Mountain Foothill Landscape

1990 ◽  
Vol 14 ◽  
pp. 29-29
Author(s):  
Yegang Wu ◽  
Dennis Knight
Keyword(s):  
Fire History ◽  
Fire Behavior ◽  
Grid Cell ◽  
Rocky Mountain ◽  
Fire Frequency ◽  
Stand Age ◽  
Weibull Function ◽  
Peak Period ◽  
Fire Scar ◽  
Surface Fires

A landscape approach was used to study fire history and fire behavior in the Douglas-fir forests and foothill vegetation of the Bighorn Canyon National Recreation Area in southcentral Montana. The 3,976 ha study area was divided into 4-ha grid cells, and traditional fire scar analysis and fuel sampling methods were used for data collection in each cell. There have been 15 surface fires during the last 109 years and 10 canopy fires during the last 360 years. The mean fire interval in the forests as a whole, was 7 years for surface fires and 31 years for canopy fires. Using the Weibull function, the recurrent time for fire in a specific grid cell was 212 and 226 years for surface and canopy fires, respectively. The distribution of the probability density function showed that there was a peak of high canopy fire frequency between 150-250 years of stand age. There was no obvious peak period for surface fires in humid ravines, which suggests that surface fires there are not associated with aging. Employing Rothermel's model, a fire behavior model (FIREMDL) was developed and linked it to a geographic information system (GRASS) to simulate flammability of each grid cell under different conditions of fuel moisture and wind velocity. The results suggest that flammability is highly variable because of differences in vegetation and topographic position.

scholarly journals Fire Histoy Determination in the Mixed Conifer/Aspen Community of Bryce Canyon National Park

1993 ◽  
Vol 17 ◽  
pp. 31-35
Author(s):  
Michael Jenkins
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
National Park ◽  
Fire History ◽  
Fire Regime ◽  
Mixed Conifer ◽  
Major Objective ◽  
Ponderosa Pine Forests ◽  
Fire Scar ◽  
European Settlement

The major objective of this ongoing study is to document vegetative changes resulting from alteration of the fire regime in the mixed conifer/aspen communities of Bryce Canyon National Park. Previous fire history studies have documented fire return intervals using fire scar analysis of ponderosa pine Pinus ponderosa in the park (Buchannan and Tolman 1983: Wight 1989) and for the Paunsaugunt Plateau (Stein 1988). Numerous other studies have similarly documented the fire regime in pre-European settlement ponderosa pine forests in western North America. The study is being conducted in the more mesic mixed conifer communities at the south end of Bryce Canyon National Park and will specifically document vegetative changes suggested by Roberts et al. (1992) resulting from suppression of frequent low intensity surface fires and overgrazing.

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