Fine-scale variation of historical fire regimes in sagebrush-steppe and juniper woodland: an example from California, USA

2008 ◽  
Vol 17 (2) ◽  
pp. 245 ◽  
Author(s):  
Richard F. Miller ◽  
Emily K. Heyerdahl
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Soil Depth ◽  
Spatial Scales ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Big Sagebrush ◽  
Western Juniper ◽  
Fine Fuels ◽  
Fire Intervals

Coarse-scale estimates of fire intervals across the mountain big sagebrush (Artemisia tridentata spp. vaseyana (Rydb.) Beetle) alliance range from decades to centuries. However, soil depth and texture can affect the abundance and continuity of fine fuels and vary at fine spatial scales, suggesting fire regimes may vary at similar scales. We explored variation in fire frequency across 4000 ha in four plant associations with differing soils in which mountain big sagebrush and western juniper (Juniperus occidentalis subsp. occidentalis Hook.) were diagnostic or a transitory component. We reconstructed fire frequency from fire-scarred ponderosa pine (Pinus ponderosa P. & C. Lawson) in one association. The other three associations lacked fire-scarred trees so we inferred fire frequency from establishment or death dates of western juniper and a model of the rate of post-fire succession we developed from current vegetation along a chronosequence of time-since-fire. Historical fire frequency varied at fine spatial scales in response to soil-driven variation in fuel abundance and continuity and spanned the range of frequencies currently debated. Fire intervals ranged from decades in areas of deep, productive soils where fine fuels were likely abundant and continuous, to centuries in areas of shallow, coarse soils where fine fuel was likely limited.

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.

Wildfire Patterns Change in Central Idaho's Ponderosa Pine-Douglas-fir Forest

1986 ◽  
Vol 1 (1) ◽  
pp. 16-18 ◽  
Author(s):  
Robert Steele ◽  
Stephen F. Arno ◽  
Katheleen Geier-Hayes
Keyword(s):  
American Indians ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Prescribed Burning ◽  
Fire Suppression ◽  
Livestock Grazing ◽  
Fine Fuels ◽  
Fire Intervals ◽  
Old Trees

Abstract Study of long-term fire histories (from fire scars on old trees) helps determine if severe fires were characteristic of the ponderosa pine (Pinus ponderosa) forests in central Idaho before the arrival of Euroamericans. Before 1895, all sample sites had average fire intervals of 10 to 22 years, implying a pattern of light to moderate surface fire. After 1895, fire intervals lengthened considerably, and severe fires became relatively common. Factors apparently influencing this change were a reduction in uncontrolled fires started by American Indians and Euroamericans; heavy livestock grazing that removed fine fuels; establishment of a fire suppression program; accumulation of slash from early logging; and development of dense conifer understories (ladder fuels). Applications of prescribed burning might reduce the risk of severe wildfires. West. J. Appl. For. 1:16-18, Jan, 1986

scholarly journals Resilience of the boreal forest in response to Holocene fire-frequency changes assessed by pollen diversity and population dynamics

2010 ◽  
Vol 19 (8) ◽  
pp. 1026 ◽  
Author(s):  
Christopher Carcaillet ◽  
Pierre J. H. Richard ◽  
Yves Bergeron ◽  
Bianca Fréchette ◽  
Adam A. Ali
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Frequency Control ◽  
Regional Scale ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Frequency Changes ◽  
Fire Intervals ◽  
In Fire

The hypothesis that changes in fire frequency control the long-term dynamics of boreal forests is tested on the basis of paleodata. Sites with different wildfire histories at the regional scale should exhibit different vegetation trajectories. Mean fire intervals and vegetation reconstructions are based respectively on sedimentary charcoal and pollen from two small lakes, one in the Mixedwood boreal forests and the second in the Coniferous boreal forests. The pollen-inferred vegetation exhibits different trajectories of boreal forest dynamics after afforestation, whereas mean fire intervals have no significant or a delayed impact on the pollen data, either in terms of diversity or trajectories. These boreal forests appear resilient to changes in fire regimes, although subtle modifications can be highlighted. Vegetation compositions have converged during the last 1200 years with the decrease in mean fire intervals, owing to an increasing abundance of boreal species at the southern site (Mixedwood), whereas changes are less pronounced at the northern site (Coniferous). Although wildfire is a natural property of boreal ecosystems, this study does not support the hypothesis that changes in mean fire intervals are the key process controlling long-term vegetation transformation. Fluctuations in mean fire intervals alone do not explain the historical and current distribution of vegetation, but they may have accelerated the climatic process of borealisation, likely resulting from orbital forcing.

A comparison of targeted and systematic fire-scar sampling for estimating historical fire frequency in south-western ponderosa pine forests

2013 ◽  
Vol 22 (8) ◽  
pp. 1021 ◽  
Author(s):  
Calvin A. Farris ◽  
Christopher H. Baisan ◽  
Donald A. Falk ◽  
Megan L. Van Horne ◽  
Peter Z. Fulé ◽  
...  
Keyword(s):  
Ponderosa Pine ◽  
Fire History ◽  
Spatial Scales ◽  
Fire Frequency ◽  
Landscape Scale ◽  
Pine Forests ◽  
Ponderosa Pine Forests ◽  
Fire Scar ◽  
Targeted Sampling ◽  
Statistical Measures

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.

Effects of fuel morphology on ember generation characteristics at the tree scale

2020 ◽  
Vol 29 (11) ◽  
pp. 1042
Author(s):  
Tyler R. Hudson ◽  
Ryan B. Bray ◽  
David L. Blunck ◽  
Wesley Page ◽  
Bret Butler
Keyword(s):  
Mass Loss ◽  
Pseudotsuga Menziesii ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Douglas Fir ◽  
Biological Factors ◽  
Abies Grandis ◽  
Western Juniper ◽  
Juniperus Occidentalis ◽  
Spot Fires

This work reports characteristics of embers generated by torching trees and seeks to identify the important physical and biological factors involved. The size of embers, number flux and propensity to ignite spot fires (i.e. number flux of ‘hot’ embers) are reported for several tree species under different combinations of number (one, three or five) and moisture content (11–193%). Douglas-fir (Pseudotsuga menziesii), grand fir (Abies grandis), western juniper (Juniperus occidentalis) and ponderosa pine (Pinus ponderosa) trees were evaluated. Embers were collected on an array of fire-resistant fabric panels and trays filled with water. Douglas-fir trees generated the highest average ember flux per kilogram of mass loss during torching, whereas grand fir trees generated the highest ‘hot’ ember flux per kilogram of mass loss. Western juniper produced the largest fraction of ‘hot’ embers, with ~30% of the embers generated being hot enough to leave char marks. In contrast, only 6% of the embers generated by ponderosa pine were hot enough to leave char marks. Results from this study can be used to help understand the propensity of different species of tree to produce embers and the portion of embers that may be hot enough to start a spot fire.

Assessing accuracy of point fire intervals across landscapes with simulation modelling

2007 ◽  
Vol 37 (9) ◽  
pp. 1605-1614 ◽  
Author(s):  
Russell A. Parsons ◽  
Emily K. Heyerdahl ◽  
Robert E. Keane ◽  
Brigitte Dorner ◽  
Joseph Fall
Keyword(s):  
Fire Regime ◽  
Fire Regimes ◽  
Maximum Error ◽  
Simulation Modelling ◽  
Fire Frequency ◽  
Spatially Explicit ◽  
Forest Types ◽  
Fire Scar ◽  
Fire Intervals ◽  
In Fire

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.

Western juniper and ponderosa pine ecotonal climate–growth relationships across landscape gradients in southern Oregon

2008 ◽  
Vol 38 (12) ◽  
pp. 3021-3032 ◽  
Author(s):  
Kevin C. Knutson ◽  
David A. Pyke
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Radial Growth ◽  
Winter Precipitation ◽  
Forest Growth ◽  
Annual Growth ◽  
Growth Responses ◽  
Climate Fluctuations ◽  
Western Juniper ◽  
Tree Ring Data

Forecasts of climate change for the Pacific northwestern United States predict warmer temperatures, increased winter precipitation, and drier summers. Prediction of forest growth responses to these climate fluctuations requires identification of climatic variables limiting tree growth, particularly at limits of tree species distributions. We addressed this problem at the pine–woodland ecotone using tree-ring data for western juniper ( Juniperus occidentalis var. occidentalis Hook.) and ponderosa pine ( Pinus ponderosa Dougl. ex Loud.) from southern Oregon. Annual growth chronologies for 1950–2000 were developed for each species at 17 locations. Correlation and linear regression of climate–growth relationships revealed that radial growth in both species is highly dependent on October–June precipitation events that recharge growing season soil water. Mean annual radial growth for the nine driest years suggests that annual growth in both species is more sensitive to drought at lower elevations and sites with steeper slopes and sandy or rocky soils. Future increases in winter precipitation could increase productivity in both species at the pine–woodland ecotone. Growth responses, however, will also likely vary across landscape features, and our findings suggest that heightened sensitivity to future drought periods and increased temperatures in the two species will predominantly occur at lower elevation sites with poor water-holding capacities.

Buried viable seed in a ponderosa pine community

1984 ◽  
Vol 62 (1) ◽  
pp. 44-52 ◽  
Author(s):  
David W. Pratt ◽  
R. Alan Black ◽  
B. A. Zamora
Keyword(s):  
Seed Bank ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Soil Depth ◽  
Poa Pratensis ◽  
Mineral Soil ◽  
Heat Treatments ◽  
Seed Density ◽  
Viable Seed ◽  
Stellaria Media

The seed bank of a Pinus ponderosa – Symphoricarpos albus stand in east-central Washington was examined with respect to species composition, depth distribution, and germination responses to heat and shade treatments. Seeds of 57 species were present in the seed bank to a depth of 10 cm. Twenty-one of these species were not found in the aboveground vegetation of the study area. Estimated viable seed densities in spring and autumn collections were 13 052 ± 1481 and 14 463 ± 1356 seeds m−2, respectively. Stellaria media and Poa pratensis, both alien species, accounted for 50% of the buried viable seed. Seed density was highest in litter samples. Total seed density decreased with soil depth, although seeds of some pioneer species were more abundant in the mineral soil than in the litter. Species dominating the seed bank were generally unimportant in the aboveground vegetation. Woody species, which dominated the aboveground vegetation, accounted for only 1% of the seed bank. Annual forbs dominated the seed bank (45% of total buried viable seed) but were not dominant in the vegetation. Seeds of several species survived prestratification heat treatments. Poststratification heat treatments inhibited germination or destroyed seed of nearly all species. As shading increased, germination of most species decreased. However, shade did not inhibit germination of species characteristic of mature successional stages.

Fire Suppression's Effects on Forest Succession within a Central Idaho Wilderness

1988 ◽  
Vol 3 (3) ◽  
pp. 76-80 ◽  
Author(s):  
Stephen W. Barrett
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Forest Succession ◽  
Fire Suppression ◽  
Fire Behavior ◽  
Fire Frequency ◽  
Tree Regeneration ◽  
Fire Scar ◽  
South Central ◽  
Central Idaho

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.

scholarly journals The Effect of Seeding Treatments and Climate on Fire Regimes in Wyoming Sagebrush Steppe

Fire ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 16
Author(s):  
Chris Bowman-Prideaux ◽  
Beth A. Newingham ◽  
Eva K. Strand
Keyword(s):  
Fire Regime ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Western United States ◽  
Sagebrush Steppe ◽  
Annual Grass ◽  
Big Sagebrush ◽  
Return Interval ◽  
Arid Steppe ◽  
Wyoming Big Sagebrush

Wildfire size and frequency have increased in the western United States since the 1950s, but it is unclear how seeding treatments have altered fire regimes in arid steppe systems. We analyzed how the number of fires since 1955 and the fire return interval and frequency between 1995 and 2015 responded to seeding treatments, anthropogenic features, and abiotic landscape variables in Wyoming big sagebrush ecosystems. Arid sites had more fires than mesic sites and fire return intervals were shortest on locations first treated between 1975 and 2000. Sites drill seeded before the most recent fire had fewer, less frequent fires with longer fire return intervals (15–20 years) than aerially seeded sites (intervals of 5–8 years). The response of fire regime variables at unseeded sites fell between those of aerial and drill seeding. Increased moisture availability resulted in decreased fire frequency between 1994 and 2014 and the total number of fires since 1955 on sites with unseeded and aerially pre-fire seeding, but fire regimes did not change when drill seeded. Greater annual grass biomass likely contributed to frequent fires in the arid region. In Wyoming big sagebrush steppe, drill seeding treatments reduced wildfire risk relative to aerial seeded or unseeded sites.

Sign in / Sign up

Export Citation Format

Share Document