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

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.

2013 ◽  
Vol 22 (8) ◽  
pp. 1021 ◽  
Author(s):  
Calvin A. Farris ◽  
Christopher H. Baisan ◽  
Donald A. Falk ◽  
Megan L. Van Horne ◽  
Peter Z. Fulé ◽  
...  

Fire history researchers employ various forms of search-based sampling to target specimens that contain visible evidence of well preserved fire scars. Targeted sampling is considered to be the most efficient way to increase the completeness and length of the fire-scar record, but the accuracy of this method for estimating landscape-scale fire frequency parameters compared with probabilistic (i.e. systematic and random) sampling is poorly understood. In this study we compared metrics of temporal and spatial fire occurrence reconstructed independently from targeted and probabilistic fire-scar sampling to identify potential differences in parameter estimation in south-western ponderosa pine forests. Data were analysed for three case studies spanning a broad geographic range of ponderosa pine ecosystems across the US Southwest at multiple spatial scales: Centennial Forest in northern Arizona (100ha); Monument Canyon Research Natural Area (RNA) in central New Mexico (256ha); and Mica Mountain in southern Arizona (2780ha). We found that the percentage of available samples that recorded individual fire years (i.e. fire-scar synchrony) was correlated strongly between targeted and probabilistic datasets at all three study areas (r=0.85, 0.96 and 0.91 respectively). These strong positive correlations resulted predictably in similar estimates of commonly used statistical measures of fire frequency and cumulative area burned, including Mean Fire Return Interval (MFI) and Natural Fire Rotation (NFR). Consistent with theoretical expectations, targeted fire-scar sampling resulted in greater overall sampling efficiency and lower rates of sample attrition. Our findings demonstrate that targeted sampling in these systems can produce accurate estimates of landscape-scale fire frequency parameters relative to intensive probabilistic sampling.


Author(s):  
Michael Jenkins

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.


Fire ◽  
2019 ◽  
Vol 2 (4) ◽  
pp. 61
Author(s):  
Thomas Saladyga

Blackgum (Nyssa sylvatica) is a “consummate subordinate” hardwood tree species consigned to the mid-canopy of many eastern North American forests. Despite its wide distribution and ecological amplitude, blackgum is an underutilized tree species in fire history reconstructions within its range. In this study, I analyzed cross-section samples collected from 19 fire-scarred blackgum trees at a dry, nutrient-poor ridgetop study area in northeastern Pennsylvania. All but two of these samples were successfully crossdated, each containing between one and six fire scars. Fires recorded by blackgum occurred frequently, with site-level mean fire intervals between approximately three and five years. There was an increase in blackgum growth within two years following fire events, but this increase was not statistically significant and it was dependent on local fire regime characteristics. In addition, the blackgum fire-scar data increased the temporal and spatial resolution of an existing local fire history. These results provide evidence for the potential use of blackgum in fire history reconstructions, but applications may be limited by tree age, complacent growth that prevents crossdating, and the degree of rot resistance after scarring.


2006 ◽  
Vol 15 (3) ◽  
pp. 439 ◽  
Author(s):  
Peter Z. Fulé ◽  
Thomas A. Heinlein ◽  
W. Wallace Covington

Fire scars and other paleoecological methods are imperfect proxies for detecting past patterns of fire events. However, calculations of long fire rotations in Grand Canyon ponderosa pine forests by Baker are not convincing in methodology or assumptions compared with fire-scar evidence of frequent surface fires. Patches of severe disturbance are a possible hypothesis to explain the relatively short age structure at the park, where ~12% fewer trees were older than 300 years compared with another unharvested northern Arizona site. However, mapped patterns of old trees as well as the evidence for frequent surface fire from fire scars, charcoal deposition studies, and evolutionary history are more consistent with the dominance of surface fire prior to c. 1880. The most relevant available evidence of fire recurrence at a given point, mean point fire intervals, had median values <16 years at all five study sites, close to filtered composite fire interval statistics (~6–10 years), but much lower than Baker’s calculated fire rotation values (55–110 years). The composite fire interval is not a uniquely important statistic or a numerical guideline for management, but one of many lines of evidence underscoring the ecological role of frequent surface fire in ponderosa pine forests.


1989 ◽  
Vol 19 (11) ◽  
pp. 1451-1457 ◽  
Author(s):  
Mark A. Finney ◽  
Robert E. Martin

Fire occurrence data between the 12th and 20th centuries were obtained from analysis of fire scars on coast redwood (Sequoiasempervirens (D. Don.) Endl.) and bishop pine (Pinusmuricata D. Don.). Mean fire intervals were calculated for settlement and presettlement periods from fire scar samples individually (point data) and from composites of samples aggregated within three approximately 200-ha study areas. Mean fire intervals from point data (20.5 to 29.0 years) were more than three times greater than mean intervals from composite data (6.1 to 9.3 years). Mean fire intervals derived from point data compared well with values previously reported, although substantial bias ascribed to point data suggests that these values for mean fire intervals in redwood forest communities are too large. A period of significantly longer fire intervals during the 17th century was suggested by analysis of fire intervals by century and using a moving average.


2008 ◽  
Vol 17 (1) ◽  
pp. 50 ◽  
Author(s):  
Rosemary L. Sherriff ◽  
Thomas T. Veblen

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.


2007 ◽  
Vol 37 (9) ◽  
pp. 1605-1614 ◽  
Author(s):  
Russell A. Parsons ◽  
Emily K. Heyerdahl ◽  
Robert E. Keane ◽  
Brigitte Dorner ◽  
Joseph Fall

We assessed accuracy in point fire intervals using a simulation model that sampled four spatially explicit simulated fire histories. These histories varied in fire frequency and size and were simulated on a flat landscape with two forest types (dry versus mesic). We used three sampling designs (random, systematic grids, and stratified). We assessed the sensitivity of estimates of Weibull median probability fire intervals (WMPI) to sampling design and to factors that degrade the fire scar record: failure of a tree to record a fire and loss of fire-scarred trees. Accuracy was affected by all of the factors investigated and generally varied with fire regime type. The maximum error was from degradation of the record, primarily because degradation reduced the number of intervals from which WMPI was estimated. The sampling designs were roughly equal in their ability to capture overall WMPI, regardless of fire regime, but the gridded design yielded more accurate estimates of spatial variation in WMPI. Accuracy in WMPI increased with increasing number of points sampled for all fire regimes and sampling designs, but the number of points needed to obtain accurate estimates was greater for fire regimes with complex spatial patterns of fire intervals than for those with relatively homogeneous patterns.


2001 ◽  
Vol 10 (1) ◽  
pp. 65 ◽  
Author(s):  
Sandra Bravo ◽  
Carlos Kunst ◽  
Ana Gimenez ◽  
Graciela Moglia

Our objective was to assess the current fire regime of a 600 ha savanna dominated by the grass species Elionorus muticus Spreng., located in Santiago del Estero Province, north-western Chaco region, Argentina. The degree of tolerance of some native woody species to fire, the fire mean fire frequency (FF), and Weibull median probability (WMPI) were evaluated. Sampling sites were located in the ecotone between the savanna and the surrounding forests. A database was developed from fire scars found in cross sections of native tree and shrub species, cut at different heights above ground; that covered the recent 70 years of fire history (1925–1996). Results indicate that the savanna has a mean FF of 0.179 fires year–1 and an FI = 3 years. The mean height of fire scars found in trees and shrubs which indicate medium to high fireline intensities with flame lengths larger than 1 m are frequent in the savanna. Native species have different degrees of tolerance: Aspidosperma quebracho blanco (tree) and Schinopsis quebracho colorado (tree) are more tolerant to fire than Acacia furcatispina (shrub) and A. aroma (shrub). Bark thickness of the tree species (1–1.5 cm in mature individuals) allows them to withstand the frequent, high intensity fires of the savanna.


2013 ◽  
Vol 43 (7) ◽  
pp. 669-675 ◽  
Author(s):  
Aura Piha ◽  
Timo Kuuluvainen ◽  
Henrik Lindberg ◽  
Ilkka Vanha-Majamaa

Determining forest fire history is commonly based on fire scar dating with dendrochronological methods. We used an experimental setup to investigate the impacts of low-intensity prescribed fire on fire scar formation 8 years after fire in 12 young managed Scots pine (Pinus sylvestris L.) stands. Five stands were between 30 and 35 years old and seven were 45 years old at the time of burning. A total of 217 fire scars were recorded in 142 trees. The number of separate scars per tree originating from a single fire ranged from 1 to 6, with 67% of the trees having just one scar. The proportion of fire-scarred trees out of all trees per plot ranged from 0% to 30%, averaging 16.5% in young stands and 2.8% in older stands. Four of the 12 burned plots did not have any trees with fire scars, and these were all in the older age group. This means that in the older stands, in only three of seven plots (43%) did the fire leave scars from which fire can potentially be detected and dated afterwards. Our results suggest that fire scar dating in Scots pine dominated forests may underestimate fire frequency, area, and the importance of historically common low-intensity surface fires in dendrochronological reconstructions of past fire histories.


1988 ◽  
Vol 3 (3) ◽  
pp. 76-80 ◽  
Author(s):  
Stephen W. Barrett

Abstract In south-central Idaho, fire-scar and tree regeneration patterns in the Salmon River Breaks portion of the Frank Church River of No Return Wilderness suggest that primarily surface fires occurred frequently in semiarid ponderosa pine (Pinus ponderosa var. ponderosa)/Douglas-fir (Pseudotsuga menziesii var. glauca) forests. Efficient fire suppression since about 1935 has markedly reduced area fire frequency and has altered fuel succession, contributing to recent crown fire behavior in north- and east-facing stands. Prescribed fires might now be difficult to contain in these communities, but burning would help return fuels to pre-1935 conditions. West. J. Appl. For. 3(3):76-80, July 1988.


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