Holocene climate–fire–vegetation interactions at a subalpine watershed in southeastern British Columbia, Canada

2014 ◽  
Vol 81 (2) ◽  
pp. 228-239 ◽  
Author(s):  
Colin J. Courtney Mustaphi ◽  
Michael F.J. Pisaric
Keyword(s):  
British Columbia ◽  
Fire Regime ◽  
Environmental Gradients ◽  
Forest Biomass ◽  
Fire Frequency ◽  
Ecosystem Responses ◽  
Disturbance Regimes ◽  
Subalpine Lake ◽  
Fuel Accumulation

AbstractVegetation assemblages and associated disturbance regimes are spatially heterogeneous in mountain ecosystems throughout the world due to the complex terrain and strong environmental gradients. Given this complexity, numerous sites describing postglacial vegetation and fire histories are needed to adequately understand forest development and ecosystem responses to varying climate and disturbance regimes. To gain insight into long-term historical climate–fire–vegetation interactions in southeastern British Columbia, Canada, sedimentological and paleoecological analyses were performed on a sediment core recovered from a small subalpine lake. The pollen assemblages, stomata, and macroremains indicate that from 9500 to 7500 cal yr BP, Pinus-dominated forests occurred within the catchment and Alnus was also present. Climate was an important control of fire and fire frequency was highest at this time, peaking at 8 fires 1000 yr− 1, yet charcoal accumulation rates were low, indicative of low terrestrial biomass abundance. From 7500 to 4600 cal yr BP, Pinus decreased as Picea, Abies and Larix increased and fire frequencies decreased to 3–6 fires 1000 yr− 1. Since 7500 cal yr BP the fire regime varied at a millennial scale, driven by forest biomass abundance and fuel accumulation changes. Local scale (bottom-up) controls of fire increased in relative importance since at least 6000 cal yr BP.

Determinants of fire activity during the last 3500 yr at a wildland—urban interface, Alberta, Canada

2016 ◽  
Vol 86 (3) ◽  
pp. 247-259 ◽  
Author(s):  
Emma L. Davis ◽  
Colin J. Courtney Mustaphi ◽  
Amber Gall ◽  
Michael F.J. Pisaric ◽  
Jesse C. Vermaire ◽  
...  
Keyword(s):  
Tree Ring ◽  
Management Practices ◽  
Vegetation History ◽  
Fire Regime ◽  
Fire Suppression ◽  
Fire Frequency ◽  
Sources Of Information ◽  
Fire Activity ◽  
Historical Range

AbstractLong-term records of wildfires and their controlling factors are important sources of information for informing land management practices. Here, dendrochronology and lake sediment analyses are used to develop a 3500-yr fire and vegetation history for a montane forest in Jasper National Park, Alberta, Canada. The tree-ring record (AD 1771-2012) indicates that this region historically experienced a mixed-severity fire regime, and that effective fire suppression excluded widespread fire events from the study area during the 20th century. A sediment core collected from Little Trefoil Lake, located near the Jasper townsite, is analyzed for subfossil pollen and macroscopic charcoal (>150 μm). When comparing the tree-ring record to the 3500-yr record of sediment-derived fire events, only high-severity fires are represented in the charcoal record. Comparisons between the charcoal record and historical climate and pollen data indicate that climate and vegetation composition have been important controls on the fire regime for most of the last 3500 yr. Although fire frequency is presently within the historical range of variability, the fire return interval of the last 150 yr is longer than expected given modern climate and vegetation conditions, indicating that humans have become the main control on fire activity around Little Trefoil Lake.

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 Postglacial Fire Frequency and its Relation to Long-Term Vegetational and Climatic Changes in Yellowstone Park

1992 ◽  
Vol 16 ◽  
pp. 212-218
Author(s):  
Cathy Whitlock
Keyword(s):  
Fire Regime ◽  
Fire Frequency ◽  
Northern Rocky Mountains ◽  
Modern Pollen ◽  
Pollen Rain ◽  
History Of ◽  
Fossil Records ◽  
In Fire ◽  
The Relationship

The primary research objective has been to study the vegetational history of Yellowstone and its sensitivity to changes in climate and fire frequency. To establish a sequence of vegetational changes, a network of pollen records spanning the last 14,000 years has been studied from different types of vegetation within the Park. The relationship between modern pollen rain, modern vegetation and present­day climate in the northern Rocky Mountains has been the basis for interpreting past vegetation and climate from the fossil records. Changes in fire regime during the past 14,000 years have been inferred from sedimentary charcoal and other fire proxy in lake sediments. Calibration of the fire signal is based on a study that measures the input of charcoal into lakes following the 1988 fires in Yellowstone.

Fires in temperate peatlands (southern Quebec): past and recent trends

2007 ◽  
Vol 85 (3) ◽  
pp. 263-272 ◽  
Author(s):  
Claude Lavoie ◽  
Stéphanie Pellerin
Keyword(s):  
Fire History ◽  
Fire Regime ◽  
Fire Frequency ◽  
Time Interval ◽  
Temperate Region ◽  
Forest Expansion ◽  
Short Period ◽  
History Of ◽  
Recent Trends

In this study, we reconstructed the long-term fire history of a set of ombrotrophic peatlands (bogs) located in a temperate region of southern Quebec (Bas-Saint-Laurent). Past and recent fire-free intervals (time interval between two consecutive fires) were compared using macrofossil analyses. During most of the Holocene epoch, fires were relatively rare events in bogs of the Bas-Saint-Laurent region. The fire-free intervals were approximately ten times longer (all sites considered) before the beginning of agricultural activities in the region (1800 AD) than after. This strongly suggests an anthropogenic influence on the fire regime prevailing in the bogs over the last 200 years. However, the shortening of the fire-free intervals was mainly the result of the ignition of one or two fires in almost every site during a relatively short period (200 years), rather than a higher fire frequency in each of the bogs. In some cases, fires had an influence on the vegetation structure of bogs, but it is more likely that a combination of several disturbances (fire, drainage, and drier than average summers) favoured the establishment of dense stands of pine and spruce, a forest expansion phenomenon that is now widespread in temperate bogs.

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.

scholarly journals Intraspecific trait variability shapes leaf trait response to altered fire regimes

2020 ◽  
Author(s):  
Rachel M Mitchell ◽  
Greg M Ames ◽  
Justin P Wright
Keyword(s):  
Species Composition ◽  
Community Composition ◽  
Functional Traits ◽  
Plant Traits ◽  
Fire Regime ◽  
Pinus Palustris ◽  
Fire Frequency ◽  
Fire Intensity ◽  
Dry Matter Content ◽  
Disturbance Regimes

Abstract Background and Aims Understanding impacts of altered disturbance regimes on community structure and function is a key goal for community ecology. Functional traits link species composition to ecosystem functioning. Changes in the distribution of functional traits at community scales in response to disturbance can be driven not only by shifts in species composition, but also by shifts in intraspecific trait values. Understanding the relative importance of these two processes has important implications for predicting community responses to altered disturbance regimes. Methods We experimentally manipulated fire return intervals in replicated blocks of a fire-adapted, longleaf pine (Pinus palustris) ecosystem in North Carolina, USA and measured specific leaf area (SLA), leaf dry matter content (LDMC) and compositional responses along a lowland to upland gradient over a 4 year period. Plots were burned between zero and four times. Using a trait-based approach, we simulate hypothetical scenarios which allow species presence, abundance or trait values to vary over time and compare these with observed traits to understand the relative contributions of each of these three processes to observed trait patterns at the study site. We addressed the following questions. (1) How do changes in the fire regime affect community composition, structure and community-level trait responses? (2) Are these effects consistent across a gradient of fire intensity? (3) What are the relative contributions of species turnover, changes in abundance and changes in intraspecific trait values to observed changes in community-weighted mean (CWM) traits in response to altered fire regime? Key Results We found strong evidence that altered fire return interval impacted understorey plant communities. The number of fires a plot experienced significantly affected the magnitude of its compositional change and shifted the ecotone boundary separating shrub-dominated lowland areas from grass-dominated upland areas, with suppression sites (0 burns) experiencing an upland shift and annual burn sites a lowland shift. We found significant effects of burn regimes on the CWM of SLA, and that observed shifts in both SLA and LDMC were driven primarily by intraspecific changes in trait values. Conclusions In a fire-adapted ecosystem, increased fire frequency altered community composition and structure of the ecosystem through changes in the position of the shrub line. We also found that plant traits responded directionally to increased fire frequency, with SLA decreasing in response to fire frequency across the environmental gradient. For both SLA and LDMC, nearly all of the observed changes in CWM traits were driven by intraspecific variation.

scholarly journals The ghost of disturbance past: long-term effects of pulse disturbances on community biomass and composition

2020 ◽  
Vol 287 (1930) ◽  
pp. 20200678 ◽  
Author(s):  
Claire Jacquet ◽  
Florian Altermatt
Keyword(s):  
Logistic Growth ◽  
Long Term Effects ◽  
Ecological Stability ◽  
Ecosystem Responses ◽  
Disturbance Regimes ◽  
Community Biomass ◽  
Disturbance Frequency ◽  
Disturbance Intensity ◽  
Negative Impacts

Current global change is associated with an increase in disturbance frequency and intensity, with the potential to trigger population collapses and to cause permanent transitions to new ecosystem states. However, our understanding of ecosystem responses to disturbances is still incomplete. Specifically, there is a mismatch between the diversity of disturbance regimes experienced by ecosystems and the one-dimensional description of disturbances used in most studies on ecological stability. To fill this gap, we conducted a full factorial experiment on microbial communities, where we varied the frequency and intensity of disturbances affecting species mortality, resulting in 20 different disturbance regimes. We explored the direct and long-term effects of these disturbance regimes on community biomass. While most communities were able to recover biomass and composition states similar to undisturbed controls after a halt of the disturbances, we identified some disturbance thresholds that had long-lasting legacies on communities. Using a model based on logistic growth, we identified qualitatively the sets of disturbance frequency and intensity that had equivalent long-term negative impacts on experimental communities. Our results show that an increase in disturbance intensity is a bigger threat for biodiversity and biomass recovery than the occurrence of more frequent but less intense disturbances.

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.

scholarly journals Disturbance structures canopy and understory productivity along an environmental gradient

2021 ◽  
Author(s):  
Max Castorani ◽  
Shannon Harrer ◽  
Robert Miller ◽  
Dan Reed
Keyword(s):  
Habitat Quality ◽  
Primary Productivity ◽  
Species Interactions ◽  
Environmental Gradient ◽  
Net Primary Productivity ◽  
Kelp Forest ◽  
High Quality ◽  
Ecosystem Responses ◽  
Disturbance Regimes

Disturbances often disproportionately impact different vegetation layers in forests and other vertically-stratified ecosystems, shaping community structure and ecosystem function. However, disturbance-driven changes may be mediated by environmental conditions that affect habitat quality and species interactions. In a decade-long field experiment, we tested how kelp forest net primary productivity (NPP) responds to repeated canopy loss along a gradient in grazing and substrate suitability. We discovered that habitat quality can mediate the effects of intensified disturbance on canopy and understory NPP. Experimental pulse and press disturbances suppressed total macroalgal NPP, but effects were strongest in high-quality habitats that supported dense kelp canopies that were removed by disturbance. Understory macroalgae partly compensated for canopy NPP losses and this effect magnified with increasing habitat quality. Disturbance-driven increases in understory NPP were still rising after 7–10 years of disturbance, demonstrating the value of long-term experimentation for understanding ecosystem responses to rapidly changing disturbance regimes.

scholarly journals A century of transformation: Fire regime transitions from 1919 to 2019 in southeastern British Columbia, Canada

2021 ◽  
Author(s):  
Jennifer N Baron ◽  
Sarah E. Gergel ◽  
Paul F. Hessburg ◽  
Lori D. Daniels
Keyword(s):  
British Columbia ◽  
Fire Regime ◽  
Fire Suppression ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Burned Area ◽  
Annual Number ◽  
Fire Size ◽  
Climatic Period ◽  
Fire Exclusion

The past 100 years marks a transition between pre-colonial and modern era fire regimes, which provides crucial context for understanding future wildfire behavior. Using the greatest depth of digitized fire events in Canada, we identify distinct phases of wildfire regimes from 1919 to 2019 by evaluating changes in mapped fire perimeters (>20-ha) across the East Kootenay forest region (including the southern Rocky Mountain Trench), British Columbia (BC). We detect transitions in annual number of fires, burned area, and fire size; explore the roles of lightning- and human-caused fires in driving these transitions; and quantify departures from historical fire frequency at the regional level. We found that, relative to historical fire frequency, fire exclusion created a significant fire deficit across 89% of the flammable landscape. Fire was active from 1919 to 1940 with frequent and large fire events, but the regime was already altered by a century of colonization. Fire activity decreased after 1940, coinciding with effective fire suppression influenced by a mild climatic period. After 2003, the combined effects of fire exclusion and accelerated climate change fueled a shift in fire regimes of various forest types, with increases in area burned and mean fire size driven by lightning.

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