ArticlePDF Available

Fire history on a desert mountain range: Rincon Mountain Wilderness, Arizona, USA

Authors:

Abstract

Modern fire records and fire-scarred remnant material collected from logs, snags, and stumps were used to reconstruct and analyze fire history in the mixed-conifer and pine forest above 2300 m within the Rincon Mountain Wilderness of Saguaro National Monument, Arizona, United States. Cross-dating of the remnant material allowed dating of fire events to the calendar year. Estimates of seasonal occurrence were compiled for larger fires. It was determined that the fire regime was dominated by large scale (> 200 ha), early-season (May–July) surface fires. The mean fire interval over the Mica Mountain study area for the period 1657–1893 was 6.1 years with a range of 1–13 years for larger fires. The mean fire interval for the mixed-conifer forest type (1748–1886) was 9.9 years with a range of 3–19 years. Thirty-five major fire years between 1700 and 1900 were compared with a tree-ring reconstruction of the Palmer drought severity index (PDSI). Mean July PDSI for 2 years prior to fires was higher (wetter) than average, while mean fire year PDSI was near average. This 490-year record of fire occurrence demonstrates the value of high-resolution (annual and seasonal) tree-ring analyses for documenting and interpreting temporal and spatial patterns of past fire regimes.
... A total of 40 fire-scarred samples were collected, including eight partial crosssections from live trees (Figures 2A,C) and 32 dead tree crosssections from stumps, logs, or standing snags ( Figure 2B). The sampling focused primarily on dead trees to minimize potential damage to live trees (Baisan and Swetnam, 1990). ...
... The quality of the dating was then statistically verified using COFECHA (Holmes, 1983). Once dated, position of each fire-scar within the growth ring was determined based on the methodology proposed by Baisan and Swetnam (1990), using the following categories: EE (beginning of earlywood), ME (middle of earlywood), LE (end of earlywood), L (latewood), and D (dormancy or ring limit). The different categories were grouped into two periods 1) spring (D + EE) and 2) summer (ME + LE + L) (Grissino-Mayer, 2001 ...
... Using a combination of dead and live trees, we were able to reconstruct the fire history the last 278 years at this P. lumholtzii site. Most of the work was conducted using samples from dead wood to minimize damaging living trees, as suggested by Baisan and Swetnam (1990). Likewise, it is corroborated that these forests are longlived and allow us to reconstruct fire regimes over several centuries. ...
Article
Full-text available
To sustainably manage forests, it is important to understand the historical fire regimes including the severity, frequency, seasonal timing of fires as well as the relationship between climate and fire in order to develop management plans that mimic and/or complements the natural disturbance pattern. The objectives of this study were to reconstruct the natural fire regime within a Pinus lumholtzii site in order to understand the fire regimes within this forest type as well as adjacent high timber value mixed-pine forests where historical fire regimes are not available due to past timber harvesting activities. Using 36 fire-scarred trees, we reconstructed the historical fire regimes in San Dimas, Durango, México for the last 238 years. We found a pattern of frequent fires but an absence of fire since 1962, with most fires (98%) being recorded in the spring season. The lack of fire for over six decades within these historically frequent fire forests could result in high fuel accumulation. Such conditions in combination with increasing temperatures and aridity in the region could increase the risk of high severity wildfires that could jeopardize the sustainability of these forests and the human communities that these forests support.
... A total of 40 fire-scarred samples were collected, including eight partial crosssections from live trees (Figures 2A,C) and 32 dead tree crosssections from stumps, logs, or standing snags ( Figure 2B). The sampling focused primarily on dead trees to minimize potential damage to live trees (Baisan and Swetnam, 1990). ...
... The quality of the dating was then statistically verified using COFECHA (Holmes, 1983). Once dated, position of each fire-scar within the growth ring was determined based on the methodology proposed by Baisan and Swetnam (1990), using the following categories: EE (beginning of earlywood), ME (middle of earlywood), LE (end of earlywood), L (latewood), and D (dormancy or ring limit). The different categories were grouped into two periods 1) spring (D + EE) and 2) summer (ME + LE + L) (Grissino-Mayer, 2001 ...
... Using a combination of dead and live trees, we were able to reconstruct the fire history the last 278 years at this P. lumholtzii site. Most of the work was conducted using samples from dead wood to minimize damaging living trees, as suggested by Baisan and Swetnam (1990). Likewise, it is corroborated that these forests are longlived and allow us to reconstruct fire regimes over several centuries. ...
Article
Full-text available
To sustainably manage forests, it is important to understand the historical fire regimes including the severity, frequency, seasonal timing of fires as well as the relationship between climate and fire in order to develop management plans that mimic and/or complements the natural disturbance pattern. The objectives of this study were to reconstruct the natural fire regime within a Pinus lumholtzii site in order to understand the fire regimes within this forest type as well as adjacent high timber value mixed-pine forests where historical fire regimes are not available due to past timber harvesting activities. Using 36 fire-scarred trees, we reconstructed the historical fire regimes in San Dimas, Durango, México for the last 238 years. We found a pattern of frequent fires but an absence of fire since 1962, with most fires (98%) being recorded in the spring season. The lack of fire for over six decades within these historically frequent fire forests could result in high fuel accumulation. Such conditions in combination with increasing temperatures and aridity in the region could increase the risk of high severity wildfires that could jeopardize the sustainability of these forests and the human communities that these forests support.
... The season of fire occurrence was estimated based on the relative position of each fire scar within the annual ring ( Figure 3a): Early Earlywood "EE" (Figure 3c), Middle Earlywood "ME" (Figure 3d), Late Earlywood "LE", Latewood "L", and Dormancy "D" (Figure 3b) [30,31]. The location of fire scars within the annual ring was grouped into two categories for further analysis: (1) spring (EE + D); and (2) summer (ME + LE + L) [9,17]. ...
Article
Full-text available
Understanding the ecological role of fire in forests is essential for proper management and conservation programs. The objectives of this study were: (1) to reconstruct the history of fires in a temperate forest in Sierra Madre Occidental; and (2) to interpret the impacts of fire and climate on forest structure. Sixty tree cross-sections with fire scars were analyzed, and descriptive statistics of fire history were generated. Additionally, growth cores were analyzed, and the ages of trees of different diameter categories were calculated. The synchrony between fire history and tree establishment was determined, and precipitation and Palmer Drought Severity Index (PDSI) values were correlated with the number of trees established per year. The presence of 137 fire scars was determined, which allowed the reconstruction of 41 fire events over the period 1855–2019; however, only the period 1940–2015 was used to compare tree recruitment, as tree establishment was detected in this period. The mean fire interval (MFI) was 2.28 years in general, and 12.17 years for extensive fires. As regards vegetation, a continuous recruitment pattern was observed, typical of a frequent low-intensity fire regime, although peak regeneration occurred after extensive fires. The correlation analysis showed that the number of trees established per year was influenced by the wet conditions that occurred in December of the previous year and the dry conditions in September and October of the previous year. This finding demonstrates the historical influence of fire and climate on the structure of the current stand in the study area. Therefore, the present study highlights the importance of including fire in forest management programs, considering the natural fire regime to which the species in this ecosystem are already adapted.
... Preceding this recent surge of analyses of drought legacy effects in ring-width time series is a much longer history of quantifying growth reductions (or changes in other metrics derived from tree rings) following discrete events, such as volcanic eruptions (Alfaro-Sánchez et al., 2018;Esper et al., 2013;Lough & Fritts, 1987), insect outbreaks (Flower et al., 2014;Peters et al., 2017) or wildfires (Baisan & Swetnam, 1990;Malevich et al., 2018). These studies apply the socalled superposed epoch analysis (SEA) to assess growth following an extreme event and to test the probability that an observed growth anomaly has occurred by chance (Haurwitz & Brier, 1981;Rao et al., 2019). ...
Article
Drought legacies in radial tree growth are an important feature of variability in biomass accumulation and are widely used to characterize forest resilience to climate change. Defined as a deviation from normal growth, the statistical significance of legacy effects depends on the definition of “normal” ‐ expected growth under average conditions – which has not received sufficient scrutiny. We re‐examined legacy effect analyses using the International Tree‐Ring Data Bank (ITRDB) and then produced synthetic tree‐ring data to disentangle four key variables influencing the magnitude of legacy effects. We hypothesized that legacy effects i) are mainly influenced by the auto‐correlation of the radial growth time series (phi), ii) depend on climate‐growth cross‐correlation (rho), iii) are directly proportional to the inherent variability of the growth time series (standard deviation, SD), and iv) scale with the chosen extreme event threshold. Using a data simulation approach, we were able to reproduce observed lag patterns, demonstrating that legacy effects are a direct outcome of ubiquitous biological memory. We found that stronger legacy effects for conifers compared to angiosperms is a consequence of their higher auto‐correlation, and that the detectability of legacy effects following rare drought events at individual sites is compromised by strong background stochasticity. Synthesis: We propose two pathways forward to improve the assessment and interpretation of legacy effects: First, we highlight the need to account for auto‐correlated residuals of climate‐growth regression models a posteriori, thereby retrospectively adjusting expectations for “normal” growth variability. Alternatively, we recommend including lagged climate variables in regression models a priori. By doing so, the magnitude of detected legacy effects is greatly reduced and biological memory is directly attributed to antecedent climatic drivers. We argue that future analyses should focus on understanding the functional reasons for how and why key statistical parameters describing this biological memory differ across species and sites. These two pathways should also stimulate improved process‐based representation of vegetation carbon dynamics in mechanistic models.
... The full treatment was burned with a prescribed surface fire using strip headfires under cool autumn conditions in 1994 and every 4 four years thereafter : 1998, 2002, 2006, 2010, and 2014. The 4-year fire interval is an average of pre-fire-exclusion fire frequencies from the northern Arizona region (Baisan andSwetnam 1990, Fulé et al. 1997). The use of relatively cool fires in autumn differs from pre-1876 patterns but the season and intensity had to be controlled in practical terms as the study area is adjacent to buildings, dense forest, and a highway. ...
Article
Full-text available
We report on survival and growth of ponderosa pines (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) two decades after forest restoration treatments in the G. A. Pearson Natural Area, northern Arizona. Despite protection from harvest that conserved old trees, a dense forest susceptible to uncharacteristically severe disturbance had developed during more than a century of exclusion of the previous frequent surface‐fire regime that ceased upon Euro‐American settlement circa 1876. Trees were thinned in 1993 to emulate pre‐fire‐exclusion forest conditions, accumulated forest floor was removed, and surface fire was re‐introduced at 4‐year intervals (full restoration). There was also a partial restoration treatment consisting of thinning alone. Compared to untreated controls, mortality of old trees (mean age 243 yr, max 462 yr) differed by < 1 tree ha‐1 and old tree survival was statistically indistinguishable between treatments (90.5% control, 92.3% full, 82.6% partial). Post‐treatment growth as measured by basal area increment of both old (pre‐1876) and young (post‐1876) pines was significantly higher in both treatments than counterpart control trees for more than two decades following thinning. Drought meeting the definition of megadrought affected the region almost all the time since the onset of the experiment, including three severe dry years. Growth of all trees declined in the three driest years but old and young treated trees had significantly less decline. Association of tree growth with temperature (negative correlation) and precipitation (positive correlation) was much weaker in treated trees, indicating that they may experience less growth decline from warmer, drier conditions predicted in future decades. Overall, tree responses after the first two decades following treatment suggest that forest restoration treatments have led to substantial, sustained improvement in the growth of old and young ponderosa pines without affecting old tree survival, thereby improving resilience to warming climate. This article is protected by copyright. All rights reserved.
... SEA has been used in a wide range of applications in space and environmental sciences. For example, it is used in studies of climatology [42][43][44], or to determine the correlation between fire events and soil moisture conditions [45][46][47][48][49][50]. ...
Article
Full-text available
The world has entered a compound risk era with multiple crises, and the adverse impact of trade friction and extreme weather disasters on China’s barley import has become increasingly prominent. In this context, this study uses superimposed epoch analysis and partial equilibrium model to evaluate the impact of extreme weather disasters in China’s major barley-exporting countries on China’s barley industry in the course of China–Australia trade friction. The results show that: (1) extreme weather disaster caused barley production in France and Canada to decrease by 7.95% and 18.36% respectively; (2) when the two external shocks occur at the same time, China’s barley import volume tends to decline compared with the basic scenario, the import price rises sharply, there are certain trade-diverting effects in barley import, and China’s imports from countries not affected by extreme weather disasters will increase to a certain extent; (3) China’s barley production remains at a low rate of growth and is vulnerable to external shocks, facing certain import risks. This study provides important policy implications for preventing import risks and ensuring the sufficient supply of domestic barley.
... We also measured bark thickness at seven equidistant points of the cross-sections with an electronic Vernier and estimated the relative bark thickness (ratio of bark thickness to stem radius) of each fire scar sample (Schafer et al. 2015) We determined the number of fire scars and the years or basal diameter from pith to the first fire scar for each tree. The seasonality of fire scars was recorded according to their position within the annual growth ring, classified as follows: D, dormancy; EE, earlywood; ME, middle of earlywood; LE, late earlywood; and L, latewood (Baisan and Swetnam 1990). Following Cerano-Paredes et al. (2015), we determined fire scars occurring during the dry season (March-June) by summing EE + ME fire scars and those occurring in the wet season (July-October), which corresponded to LE fire scars. ...
Article
Fire scar analysis is a fundamental tool for reconstructing fire regimes in conifer forests. However, little is known about fire scar properties in tropical montane conifers, where some assumptions limit dendroecological research. These include that fir species do not exhibit external fire scars and that pines without external fire scars have not experienced past fires. This study describes fire scar patterns in two conifer species growing in Mexican temperate forests: sacred fir (Abies religiosa) and smooth-bark Mexican pine (Pinus pseudostrobus). We extracted cross-sections from 110 trees and measured tree age, basal diameter, bark thickness, fire scar size and seasonality, the number of scars per tree, years and basal diameter from pith to the first scar, and the proportion of external and buried fire scars. Most trees had three fire scars, which appeared during the dry season after the first 15 years measured from the pith. Old and large-diameter trees did not have more fire scars, but the time between fire scars influenced fire scar closure in sacred firs. Bark thickness and the proportion of visible and buried fire scars were similar in both species. Our results suggest that the absence of visible fire scars in smooth-bark Mexican pines does not imply the absence of fire, and sacred firs can exhibit external fire scars like pines.
... We determined the seasonality of fire scars (earlywood, latewood, or dormant; corresponding to spring, summer, or fall/winter fires) based on the intra-ring position of scars (Baisan and Swetnam, 1990). First, we created individual site level composite chronologies based on both regular fire years as years when a minimum of two samples recorded scars and major fire years as years when ≥ 25% of recording samples had fire scars, with a minimum of two samples. ...
Article
In this study, we aimed to use tree-ring based fire reconstruction to understand the spatiotemporal patterns of past fires in different climate types of western Anatolia. We collected fire scarred wood samples from living trees as wedges and remnant woods from ten sites along a transect that represents a continental to Mediterranean climate gradient. We determined fire years and assigned seasonality of fires based on the intraring position of the fire scars. We calculated fire statistics and analysed fire-climate relationships. Breakpoints in our Anatolian regional fire chronology were estimated to determine the regime shifts. A decrease in fire frequency was recorded at most of the sites after the end of the 19th and the beginning of the 20th century. We observed two critical fire regime shift periods. The period between 1853 and 1934 is characterized by highly frequent (a total of 82 fires) and simultaneous fires occurring in multiple sites and this period overlapped with the longest and most severe drought period of the past 550 years. The fire frequency decline after 1934 coincided with the period of the first forest protection law in 1937. Dry, as well as prior wet conditions were main drivers of fires in the black pine forests in western Anatolia. We observed a decrease in fire frequency in the late 19th and early 20th centuries due to fire suppression activities. Continued fire suppression activities may cause fuel accumulation and pose a risk for more intense fires and thus a paradox for forests in the future. Based on future climate projections, we will face prolonged fire seasons as a consequence of increasing drought frequency, which may shift the fire regime from surface to crown fires with the accumulation of combustible material in the understory in black pine forests.
... We processed all samples according to standard dendrochronological methods (Speer 2010), including polishing surfaces with progressively finer grit sand paper until annual rings, cellular structures, and fire scars were clearly visible under magnification. We crossdated samples and assigned a year and season to each scar based on the position of the scar within the ring (Stokes andSmiley 1968, Baisan andSwetnam 1990). Crossdating was verified by two dendrochronologists. ...
Article
Full-text available
Every year, millions of hectares burn across Siberia, driven by a combination of warming temperatures, regional drought and human-caused ignitions. Dendrochronology provides a long-term context to evaluate recent trends in fire activity and interpret the relative influence of humans and climate drivers on fire regimes. We developed a 400-year record of fire-scarred trees from 17 sites in pine-dominated forests located southeast of Lake Baikal. Site-level mean fire return intervals (MFI) ranged from 4 – 27 years for all fires and 8 – 35 years for widespread fires within sites. Sites with the lowest MFI values were located within 1 km of agricultural fields in grassland valleys, suggesting that agricultural burning influenced MFIs at nearby sites. Fire frequency varied over the record, with significantly high values around 1790, from 1865 to 1880, 1948 to 1955 and 1995 to 2005. The increased fire activity corresponded with migration waves to the region and major socio-economic change connected with the establishment and breakdown of the Soviet Union. At broader scales, Superposed Epoch Analysis (SEA) showed that synchronous fire years were associated with regional drought and precipitation deficits. Wet conditions for two to three years prior to the event year were also significant, suggesting that increased moisture promoted growth of understory fine fuels to support more extensive fires across the study area. Although fire frequencies increased during the 20th century, fire-climate relationships weakened, suggesting increased human-caused ignitions may override regional climate drivers. Our dataset presents a continuous record of frequent surface fires over the past 400 years, providing a valuable opportunity to compare dendrochronology-based reconstructions with satellite and documentary records.
Article
Full-text available
Prior research suggests that Indigenous fire management buffers climate influences on wildfires, but it is unclear whether these benefits accrue across geographic scales. We use a network of 4824 fire-scarred trees in Southwest United States dry forests to analyze up to 400 years of fire-climate relationships at local, landscape, and regional scales for traditional territories of three different Indigenous cultures. Comparison of fire-year and prior climate conditions for periods of intensive cultural use and less-intensive use indicates that Indigenous fire management weakened fire-climate relationships at local and landscape scales. This effect did not scale up across the entire region because land use was spatially and temporally heterogeneous at that scale. Restoring or emulating Indigenous fire practices could buffer climate impacts at local scales but would need to be repeatedly implemented at broad scales for broader regional benefits.
Article
Fire scars in 181 scarred Quercus douglasii cross sections were dated from 2 different stands in the Sierra Nevada foothills, California. In the stand with no fires for the last 35 yr, open-scarred trees revealed a shorter fire history, 90% fewer fire dates, and a mean fire interval (MFI) that was shorter than determined from intact trees. In the stand with no fires for the last 15 yr, MFI and length and length of record were comparable but open-scarred trees accounted for 27% fewer fires than intact trees. Open-scarred trees were twice as likely to scar as intact trees, but the average number of scars tree-1 were similar. Time since last fire is critical, as scars may heal before sampling. This suggests that fire history estimates will be most affected by sample restriction in areas with long periods of fire suppression. -from Author
Article
Data on the years in which fires burned, on fire frequency, and on intensity and areal extent of fires were gathered from 935 scars on 220 stumps of mixed conifer forest species in an 1800ha-study area in the Sierra Nevada, California, USA. Before 1875, fires scarred clusters of living trees every 9 yr on west-facing slopes at Redwood Mountain and every 16 yr on east-facing slopes. Mean fire-free intervals between 1700 and 1875 varied by habitat phase from 5 yr in ponderosa pine on a dry ridge to 15-18 yr in more moist sites with white fir. For most 1-ha sites, the maximum time without fire was 14-28 yr. From 1700 to 1875, fires of various sizes were found every 2-3 yr somewhere in a given drainage (not necessarily the same site) and every 5-9 yr in 3to 16-ha sites. This compares with fires every 8-18 yr in 1-ha clusters and every 11-39 yr on individual trees. Scar records of pre-1700 fires suggest intervals fairly comparable to those from 1700 to 1875. Evidence of fires diminished greatly after Indian burning was eliminated in the early 1870's, and such fire records became almost nonexistent after 1900, when fire suppression became more effective. Most of the pre-1875 fires were small and of low intensity. Even the larger fires were usually confined to 1 slope or 1 drainage area. The short mean intervals between fires suggest that pre-1875 mixed conifer forests did not usually have heavy accumulations of litter or dense thickets of understory trees. Instead, small-acreage, low-intensity surface fires must have consumed accumulated litter at frequent intervals and at the same time killed most of the conifer regeneration which had become established since previous fires. Such frequent fires would have led to an intricate mosaic of age classes and vegetation subtypes which, in turn, insured that a subsequent fire would not burn large areas with great intensity. Intense fires which moved from crown to crown were absent in the study area for the past 400 to 2000 yr. If frequency of lightning ignition of fires over the past 50 yr is typical, ignitions by Indians must have augmented lightning-caused fires to yield the pre-1865 frequency of fires in the Sierra mixed conifer forest. Since 1900, the lack of frequent, low-intensity fires has resulted in a major increase in understory forest and fuels.
Article
Tree stems 2 106 yr old (i.e., established before significant European influence in this area) in a 7.3-ha old-growth ponderosa pine (Pinus ponderosa) forest in northern Arizona were aged and mapped. Age structure analysis showed that successful establishment of ponderosa pine was infrequent. The periods without successful establishment could be quite long, as suggested by four consecutive decades in which only two surviving trees were established. The stems were strongly aggregated, as measured with nearest neighbor analysis, and groups were visually distinct in the field. Most of the stems occurred in groups of three or more, with group size ranging from 3 to 44 stems and area occupied by a group ranging from 0.02 to 0.29 ha. Ages of stems within groups were variable, the most homogeneous group having a range of 33 yr and the least having a range of 268 yr. The data are not consistent with the commonly held view that southwestern ponderosa pine occurs in even-aged groups and that each group became established following the demise of the group previously occupying the site. Instead, it seems more likely that seedlings became established when one or two trees within the group died, the additional fuel surrounding the dead trees causing an intensely burned spot in the otherwise low-intensity fires that were frequent in the area. The hot spot would create a potential seedbed for pine by eliminating, at least temporarily, the competing grasses on that small area. This decreased competition, in conjunction with adequate seed production and favorable moisture conditions in the spring and early summer, may well have been critical for pon- derosa pine establishment. The relative infrequency of all these events occuning in the necessary sequence could explain the erratic age structure data from this area.
Article
Prior to the year 1900, firs burned through a mixed conifer stand located in the South Fork of Thomas Creek, in the White Mountains of Arizona, at an interval of 22 years. Small fires burned on the area at more frequent intervals. In the absence of these periodic fires, species diversity remains high but stand composition and structure appears to be changing.