Table of Contents

Fire Ecology
Volume 6, Issue 3 - 2010
DOI: 10.4996/fireecology.0603

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Research Articles

Germination Patterns of Soil Seed Banks in Relation to Fire in Portuguese Littoral Pine Forest Vegetation

Authors: Lourdes Santos, Jorge Capelo, and Mário Tavares
Pages: 1-15
DOI: 10.4996/fireecology.0603001

Germination behavior of maritime pine (Pinus pinaster Aiton) forests soil seed banks after fire treatments in controlled laboratory conditions was analyzed. Germination response of all tree and shrub seeds after wildfires in the Leiria National Forest, Portugal, was simulated by treating sample trays of soil seed banks with distinct combinations of: burning time (0 min, 5 min, and 15 min), seed depth (5 cm and 8.5 cm), and presence or absence of ash cover. The design included control samples for null hypothesis testing. During a time span of 20 months after treatments, the maximum number of seedlings observed every 30 day period, their taxonomical identity, the number of destroyed seeds, and the number of non-germinated seeds were analyzed. Six functional species groups, defined by germination response (i.e,. germinated, destroyed, non-germinated), were identified using minimum-variance hierarchical clustering and correspondence analysis. In addition, the influence of the three environmental design factors and three functional species groups based on their general germination response were then analyzed by means of general regression models.

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Impact of Climate Change on Forest Fire Severity and Consequences for Carbon Stocks in Boreal Forest Stands of Quebec, Canada: A Synthesis

Authors: Simon van Bellen, Michelle Garneau, and Yves Bergeron
Pages: 16-44
DOI: 10.4996/fireecology.0603016

The global boreal forests comprise large stocks of organic carbon that vary with climate and fire regimes. Global warming is likely to influence several aspects of fire and cause shifts in carbon sequestration patterns. Fire severity or forest floor depth of burn is one important aspect that influences both carbon emission during combustion as well as postfire ecosystem regeneration. Numerous publications on projections of future area burned exist, whereas scenarios on twenty-first century fire severity are more scarce, and the stand-typical response to severe fire weather is rarely taken into account. This paper aims to synthesize knowledge on boreal forest carbon stocks in relation to changes in fire severity for Quebec, Canada.

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Historic Fire Regime of an Upland Oak Forest in South-Central North America

Authors: Ryan DeSantis, Stephen W. Hallgren, and David W. Stahle
Pages: 45-61
DOI: 10.4996/fireecology.0603045

Prescribed burning is used in upland oak forests of south-central North America to improve wildlife habitat, reduce fire hazard, restore ecosystem integrity, and maintain biological diversity. However, little is known about the frequency, seasonality, and ignition source of historic fires that shaped these forests. In general, it is believed that fire frequency in upland oak forests of south-central North America was influenced by climate and humans, and decreased since Euro-American settlement; yet there is a dearth of scientific evidence to support this conclusion. The objective of this study was to link the fire history of an upland oak forest in east-central Oklahoma with factors controlling the fire regime.

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Fire-Excluded Relict Forests in the Southeastern Klamath Mountains, California, USA

Authors: Carlos M. Leonzo and Christopher R. Keyes
Pages: 62-76
DOI: 10.4996/fireecology.0603062

The rare relict ponderosa pine (Pinus ponderosa C. Lawson) mixed-conifer forests of northern California’s Whiskeytown National Recreation Area (WNRA), USA, present a classic example of fire exclusion. Altered fire regimes in this biologically unique area have been documented, but the resulting changes in forest composition and structure have not previously been described. A fully randomized, park-wide sampling of relict forest structure at WNRA reveals a high degree of topographic variability in tree species composition, but strikingly similar changes in recent structural development. A distinct cohort of encroachment trees initiated approximately 64 yr to 67 yr ago with little age variation (2 yr SE), with distinct strata now distinguishing the relict and encroachment cohorts.

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Burn Severity of Areas Reburned by Wildfires in the Gila National Forest, New Mexico, USA

Authors: Zachary A. Holden, Penelope Morgan, and Andrew T. Hudak
Pages: 77-85
DOI: 10.4996/fireecology.0603077

We describe satellite-inferred burn severity patterns of areas that were burned and then reburned by wildland fire from 1984 to 2004 within the Gila Aldo Leopold Wilderness Complex, New Mexico, USA. Thirteen fires have burned 27 000 hectares across multiple vegetation types at intervals between fires ranging from 3 yr to 14 yr. Burn severity of reburned areas showed sensitivity to the severity of the initial fire. The severity of reburned areas also varied by vegetation type and time elapsed between fires. Initial fires that burned at low severity tended to reburn at low severity, while reburned areas where initial fire was severe showed higher probability of reburning at high severity. Our analysis also suggests that there may be thresholds in the severity of an initial burn above which the severity of the subsequent fire is likely to increase.

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Native Bunchgrass Response to Prescribed Fire in Ungrazed Mountain Big Sagebrush Ecosystems

Authors: Lisa M. Ellsworth and J. Boone Kauffman
Pages: 86-96
DOI: 10.4996/fireecology.0603086

Fire was historically a dominant ecological process throughout mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana [Rydb.] Beetle) ecosystems of western North America, and the native biota have developed many adaptations to persist in a regime typified by frequent fires. Following spring and fall prescribed fires conducted in sites of different ecological conditions at the Lava Beds National Monument, California, USA, we examined the reproductive, density, and cover responses of four native bunchgrasses: bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Löve), Thurber’s needlegrass (Achnatherum thurberianum [Piper] Barkworth), squirreltail (Elymus elymoides [Raf.] Swezey), and Sandberg bluegrass (Poa secunda J. Presl). High rates of survival and fire-enhanced flowering were measured following fires. Thurber’s needlegrass density decreased following spring burns in sites dominated by cheatgrass (Bromus tectorum L.) (from 3.3 plants m-2 to 0.8 plants m-2; P < 0.05). Density of bluebunch wheatgrass decreased following spring fires (from 3.7 plants m-2 to 1.9 plants m-2; P = 0.02) and cover was reduced in both spring and fall burn treatments (P = 0.04) in native dominated sites.

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The Effects of Raking on Sugar Pine Mortality Following Prescribed Fire in Sequoia and Kings Canyon National Parks, California, USA

Authors: Jonathan C.B. Nesmith, Kevin L. OHara, Phillip J. van Mantgem, and Perry de Valpine
Pages: 97-116
DOI: 10.4996/fireecology.0603097

Prescribed fire is an important tool for fuel reduction, the control of competing vegetation, and forest restoration. The accumulated fuels associated with historical fire exclusion can cause undesirably high tree mortality rates following prescribed fires and wildfires. This is especially true for sugar pine (Pinus lambertiana Douglas), which is already negatively affected by the introduced pathogen white pine blister rust (Cronartium ribicola J.C. Fisch. ex Rabenh). We tested the efficacy of raking away fuels around the base of sugar pine to reduce mortality following prescribed fire in Sequoia and Kings Canyon national parks, California, USA. This study was conducted in three prescribed fires and included 457 trees, half of which had the fuels around their bases raked away to mineral soil to 0.5 m away from the stem. Fire effects were assessed and tree mortality was recorded for three years after prescribed fires. Overall, raking had no detectable effect on mortality: raked trees averaged 30 % mortality compared to 36 % for unraked trees. There was a significant effect, however, between the interaction of raking and average pre-treatment forest floor fuel depth: the predicted probability of survival of a 50 cm dbh tree was 0.94 vs. 0.96 when average pre-treatment fuel depth was 0 cm for a raked and unraked tree, respectively.

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Spatially Heterogeneous Estimates of Fire Frequency in Ponderosa Pine Forests of Washington, USA

Authors: James T. Kernan and Amy E. Hessl
Pages: 117-135
DOI: 10.4996/fireecology.0603117

Many fire history studies have evaluated the temporal nature of fire regimes using fire interval statistics calculated from fire scars. More recently, researchers have begun to evaluate the spatial properties of past fires as well. In this paper, we describe a technique for investigating spatio-temporal variability using a geographic information system (GIS). We used a dataset of fire-scarred trees collected from four sites in eastern Washington, USA, ponderosa pine (Pinus ponderosa C. Lawson) forests. The patterns of past fires recorded by individual trees (points) were converted to two-dimensional representations of fire with inverse distance weighting (IDW) in a GIS. A map overlay approach was then used to extract a fine-grained, spatially explicit reconstruction of fire frequency at the four sites.

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Short Communication

Acorn Dispersal of California Black Oak after a Stand-Replacing Fire

Authors: Mark I. Borchert and Claudia M. Tyler
Pages: 136-141
DOI: 10.4996/fireecology.0603136

We investigated California black oak (Quercus kelloggii Newberry) acorn dispersal by rodents and birds in the months after a stand-replacing fire in a mixed conifer forest in the San Bernardino Mountains of southern California, USA. The objective of this study was to compare scatter-hoarding in a high-severity burn to that in an unburned forest. In the fall of 2007, we placed 600 magnet-bearing acorns under trees in the unburned area. Of the 600, we recovered 77 (13 %). Dispersers moved acorns an average distance of 5 m and buried them to an average depth of 30 mm.

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Book Review

Living with Fire: Fire Ecology and Policy for the Twenty-First Century

Author: Neil G. Sugihara
Page: 142
DOI: 10.4996/fireecology.0603142

In Living with Fire, Sara Jensen and Guy McPherson explore the complex, and uncomfortable, intersection of today’s fire policy, fire science, and fire management. They consider the perceived wildland fire “crisis” to be a result of the media deluge presenting a bleak view of wildfires destroying the beloved American West. The public is confronted with the impression that there is a crisis and that must be solved to make our forests and people “fire-safe.” Living with Fire is a thought-provoking book that is not intended to solve the dilemma of our current wildland fire situation but to frame it in way that incorporates the complexities of fire science, policy, communication, information, and land management within our society’s view of fire policy and management.

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