The effects of vegetative type, edges, fire history, rainfall, and management in fire-maintained habitat

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.

Download Full-text

Long-term fire history from alluvial fan sediments: the role of drought and climate variability, and implications for management of Rocky Mountain forests

International Journal of Wildland Fire ◽

10.1071/wf07027 ◽

2008 ◽

Vol 17 (1) ◽

pp. 84 ◽

Cited By ~ 37

Author(s):

Jennifer Pierce ◽

Grant Meyer

Keyword(s):

Ponderosa Pine ◽

Fire History ◽

Fire Regimes ◽

Alluvial Fan ◽

Ice Age ◽

Pine Forests ◽

Drought Severity ◽

Ponderosa Pine Forests ◽

Grass Growth ◽

In Fire

Alluvial fan deposits are widespread and preserve millennial-length records of fire. We used these records to examine changes in fire regimes over the last 2000 years in Yellowstone National Park mixed-conifer forests and drier central Idaho ponderosa pine forests. In Idaho, frequent, small, fire-related erosional events occurred within the Little Ice Age (~1450–1800 AD), when greater effective moisture probably promoted grass growth and low-severity fires. This regime is consistent with tree-ring records showing generally wetter conditions and frequent fires before European settlement. At higher elevations in Yellowstone, cool conditions limited overall fire activity. Conversely, both Idaho and Yellowstone experienced a peak in fire-related debris flows between ~950 and 1150 AD. During this generally warmer time, severe multidecadal droughts were interspersed with unusually wet intervals that probably increased forest densities, producing stand-replacing fires. Thus, severe fires are clearly within the natural range of variability in Idaho ponderosa pine forests over longer timescales. Historical records indicate that large burn areas in Idaho correspond with drought intervals within the past 100 years and that burn area has increased markedly since ~1985. Recent stand-replacing fires in ponderosa pine forests are likely related to both changes in management and increasing temperatures and drought severity during the 20th century.

Download Full-text

Variation in fire scar phenology from mixed conifer trees in the Sierra Nevada

Canadian Journal of Forest Research ◽

10.1139/cjfr-2017-0297 ◽

2018 ◽

Vol 48 (1) ◽

pp. 101-104 ◽

Cited By ~ 2

Author(s):

Scott L. Stephens ◽

Liam Maier ◽

Lilah Gonen ◽

Jennifer D. York ◽

Brandon M. Collins ◽

...

Keyword(s):

Sierra Nevada ◽

Fire History ◽

Fire Regimes ◽

Fire Season ◽

Mixed Conifer ◽

Outer Bark ◽

Individual Tree ◽

Fire Scar ◽

The Individual ◽

In Fire

Fire scar based studies have provided robust reconstructions of past fire regimes. The season in which a fire occurs can have considerable impacts to ecosystems but inference on seasonality from fire scars is relatively uncertain. This study examined patterns in the phenology of cambium formation and wounding responses in the five common mixed conifer tree species of the Sierra Nevada. The outer bark was shaved on 35 trees and individual locations within the shaved portions were wounded systematically by applying direct heat using a handheld torch. Most of the trees had not commenced annual ring development by the first burning treatment in late May. By the second treatment, scars were identified mostly within the early or middle earlywood, although variation was high compared with other treatment periods. By late October, all scars were recorded at the ring boundary. Although intra-ring scar positions generally followed a logical temporal pattern, there was high tree to tree variation such as Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) burned on 26 June induced scars in the early, mid, and late earlywood depending on the individual tree. This high variation makes it somewhat challenging to precisely assign past fire season to published fire history studies.

Download Full-text

Fire history and age structure in red fir forests of Sequoia National Park, California

Canadian Journal of Forest Research ◽

10.1139/x87-098 ◽

1987 ◽

Vol 17 (7) ◽

pp. 582-587 ◽

Cited By ~ 21

Author(s):

Donald C. Pitcher

Keyword(s):

Age Structure ◽

National Park ◽

Fire History ◽

Fire Behavior ◽

White Pine ◽

Sequoia National Park ◽

Fire Scar ◽

Forest Age Structure ◽

Negative Exponential ◽

In Fire

The relationship between historical fires and age structure was examined on three plots in red fir (Abiesmagnifica var. shastensis Lemm.) forests within Sequoia National Park, California, U.S.A. All trees greater than 0.1 m in height were mapped and aged. Fire history was determined from 16 fire-scar sections. Red fir trees are more shade tolerant, longer lived, larger, and slower growing than western white pine (Pinusmonticola Dougl.) on the plots. No fires have occurred since 1886, but prior to that time the average fire-free interval was 65 years. Most of the trees on two of the plots originated after fires, but on the third plot red fir regeneration was delayed for at least 60 years following the last fire. Structural differences between the plots were linked to variations in fire behavior. The decrease in fire frequencies in this century may have led to a decrease in red fir establishment. Excluding the most recent period, the forest age structure is in something of a steady state that approximates a negative exponential age-class distribution.

Download Full-text

Improving estimates of savanna burning emissions for greenhouse accounting in northern Australia: limitations, challenges, applications

International Journal of Wildland Fire ◽

10.1071/wf08009 ◽

2009 ◽

Vol 18 (1) ◽

pp. 1 ◽

Cited By ~ 116

Author(s):

Jeremy Russell-Smith ◽

Brett P. Murphy ◽

C. P. (Mick) Meyer ◽

Garry D. Cook ◽

Stefan Maier ◽

...

Keyword(s):

Greenhouse Gas ◽

Fire History ◽

Fire Management ◽

Combustion Efficiency ◽

Management Program ◽

Anthropogenic Sources ◽

Fuel Load ◽

Northern Australia ◽

Savanna Burning ◽

In Fire

Although biomass burning of savannas is recognised as a major global source of greenhouse gas emissions, quantification remains problematic with resulting regional emissions estimates often differing markedly. Here we undertake a critical assessment of Australia’s National Greenhouse Gas Inventory (NGGI) savanna burning emissions methodology. We describe the methodology developed for, and results and associated uncertainties derived from, a landscape-scale emissions abatement project in fire-prone western Arnhem Land, northern Australia. The methodology incorporates (i) detailed fire history and vegetation structure and fuels type mapping derived from satellite imagery; (ii) field-based assessments of fuel load accumulation, burning efficiencies (patchiness, combustion efficiency, ash retention) and N : C composition; and (iii) application of standard, regionally derived emission factors. Importantly, this refined methodology differs from the NGGI by incorporation of fire seasonality and severity components, and substantial improvements in baseline data. We consider how the application of a fire management program aimed at shifting the seasonality of burning (from one currently dominated by extensive late dry season wildfires to one where strategic fire management is undertaken earlier in the year) can provide significant project-based emissions abatement. The approach has wider application to fire-prone savanna systems dominated by anthropogenic sources of ignition.

Download Full-text

Refuges for birds in fire-prone landscapes: The influence of fire severity and fire history on the distribution of forest birds

Forest Ecology and Management ◽

10.1016/j.foreco.2014.01.008 ◽

2014 ◽

Vol 318 ◽

pp. 110-121 ◽

Cited By ~ 35

Author(s):

Natasha M. Robinson ◽

Steven W.J. Leonard ◽

Andrew F. Bennett ◽

Michael F. Clarke

Keyword(s):

Fire History ◽

Fire Severity ◽

Forest Birds ◽

In Fire

Download Full-text

Using bioregional variation in fire history and fire response attributes as a basis for managing threatened flora in a fire-prone Mediterranean climate biodiversity hotspot

Australian Journal of Botany ◽

10.1071/bt17176 ◽

2018 ◽

Vol 66 (2) ◽

pp. 134 ◽

Cited By ~ 10

Author(s):

Erica Shedley ◽

Neil Burrows ◽

Colin J. Yates ◽

David J. Coates

Keyword(s):

Plant Species ◽

Threatened Species ◽

Fire History ◽

Fire Regimes ◽

Biodiversity Hotspot ◽

Fire Response ◽

Relative Level ◽

Threatened Plant ◽

Threatened Plant Species ◽

In Fire

Inappropriate fire-regimes brought about by patterns of human settlement and land-use threaten plant diversity in Mediterranean-type climate (MTC) regions. In south-west Western Australia (SWWA), where there are many threatened plant species distributed across a range of human-modified landscapes, there is a need for approaches to identify where the threat is greatest. This requires knowledge of contemporary fire regimes, how they vary across landscapes, and the sensitivity of threatened species to these regimes. Currently, this information is lacking, and this limits strategic fire management. In this study we compiled fire response information for SWWA’s threatened plant species and undertook a bioregional assessment of variation in fire interval over the last 40 years. We determined the fire response traits of 242 (60%) of the region’s 401 extant threatened species. Over half of the 242 species were obligate seeders and will therefore have population dynamics particularly sensitive to fire interval. Our study highlights large differences in fire interval across nine bioregions in SWWA. The differences were greatest for the heavily cleared and fragmented bioregions compared with more continuously vegetated bioregions. We discuss how variations in the frequency of fire life-history traits and fire interval interact to determine the nature and relative level of threat posed by fire in these landscapes. Survival of many populations of threatened flora in this biodiversity hotspot will depend on developing appropriate fire regimes that match the regeneration requirements of each species.

Download Full-text

A 7600 yr vegetation and fire history from Anthony Lake, northeastern Oregon, USA, with linkages to modern synoptic climate patterns

Quaternary Research ◽

10.1017/qua.2018.124 ◽

2019 ◽

Vol 91 (2) ◽

pp. 705-713

Author(s):

Colin J. Long ◽

Jaqueline J. Shinker ◽

Thomas A. Minckley ◽

Mitchell J. Power ◽

Patrick J. Bartlein

Keyword(s):

High Resolution ◽

Great Basin ◽

Fire History ◽

Fire Occurrence ◽

Charcoal Analysis ◽

Dry Air ◽

Blue Mountains ◽

Climate Patterns ◽

Dry Conditions ◽

In Fire

AbstractWe used pollen and high-resolution charcoal analysis of lake sediment to reconstruct a 7600 yr vegetation and fire history from Anthony Lake, located in the Blue Mountains of northeastern Oregon. From 7300 to 6300 cal yr BP, the forest was composed primarily of Populus, and fire was common, indicating warm, dry conditions. From 6300 to 3000 cal yr BP, Populus declined as Pinus and Picea increased in abundance and fire became less frequent, suggesting a shift to cooler, wetter conditions. From 3000 cal yr BP to present, modern-day forests composed of Pinus and Abies developed, and from 1650 cal yr BP to present, fires increased. We utilized the modern climate-analogue approach to explain the potential synoptic climatological processes associated with regional fire. The results indicate that years with high fire occurrence experience positive 500 mb height anomalies centered over the Great Basin, with anomalous southerly component of flow delivering dry air into the region and with associated sinking motions to further suppress precipitation. It is possible that such conditions became more common over the last 1650 cal yr BP, supporting an increase in fire despite the shift to more mesic conditions.

Download Full-text

Variability in fire - climate relationships in ponderosa pine forests in the Colorado Front Range

International Journal of Wildland Fire ◽

10.1071/wf07029 ◽

2008 ◽

Vol 17 (1) ◽

pp. 50 ◽

Cited By ~ 27

Author(s):

Rosemary L. Sherriff ◽

Thomas T. Veblen

Keyword(s):

Pinus Ponderosa ◽

Ponderosa Pine ◽

Fire History ◽

Southern Oscillation ◽

Primary Objective ◽

Fire Occurrence ◽

Ponderosa Pine Forests ◽

Fire Scar ◽

Montane Zone ◽

In Fire

Understanding the interactions of climate variability and wildfire has been a primary objective of recent fire history research. The present study examines the influence of El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) on fire occurrence using fire-scar evidence from 58 sites from the lower ecotone to the upper elevational limits of ponderosa pine (Pinus ponderosa) in northern Colorado. An important finding is that at low v. high elevations within the montane zone, climatic patterns conducive to years of widespread fire are different. Differences in fire–climate relationships are manifested primarily in antecedent year climate. Below ~2100 m, fires are dependent on antecedent moister conditions that favour fine fuel accumulation 2 years before dry fire years. In the upper montane zone, fires are dependent primarily on drought rather than an increase in fine fuels. Throughout the montane zone, fire is strongly linked to variations in moisture availability that in turn is linked to climate influences of ENSO, PDO and AMO. Fire occurrence is greater than expected during the phases of each index associated with drought. Regionally widespread fire years are associated with specific phase combinations of ENSO, PDO and AMO. In particular, the combination of La Niña, negative PDO and positive AMO is highly conducive to widespread fire.

Download Full-text