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Burned hillside from recent fire in chaparral in southern California.  Even cactus can be seen burned. The lack of organic materials changed soil moisture and impacts amphibians.
Burned hillside from recent fire in chaparral in southern California. Even cactus can be seen burned. The lack of organic materials changed soil moisture and impacts amphibians.
Robert Fisher USGS
Papers & Reports Prioritizing conserved areas threatened by wildfire for monitoring and management
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Authors: Tracey J A, Rochester C J, Hathaway S A, Preston K L, Syphard A D, Vandergast A G, Diffendorfer J E, Franklin J, MacKenzie J B, Oberbauer T A, Tremor S, Winchell C, Fisher R N | Date: 2018-09-07 | Outlet: PLoS ONE | Format: .PDF
In many parts of the world, the combined effects of habitat fragmentation and altered disturbance regimes pose a significant threat to biodiversity. This is particularly true in Mediterranean-type ecosystems (MTEs), which tend to be fire-prone, species rich, and heavily impacted by human land use. Given the spatial complexity of overlapping threats and species? vulnerability along with limited conservation budgets, methods are needed for prioritizing areas for monitoring and management in these regions. We developed a multi-criteria Pareto ranking methodology for prioritizing spatial units for conservation and applied it to fire threat, habitat fragmentation threat, species richness, and genetic biodiversity criteria in San Diego County, California, USA. We summarized the criteria and Pareto ranking results (from west to east) within the maritime, coastal, transitional, inland climate zones within San Diego County. Fire threat increased from the maritime zone eastward to the transitional zone, then decreased in the mountainous inland climate zone. Number of fires and fire return interval departure were strongly negatively correlated. Fragmentation threats, particularly road density and development density, were highest in the maritime climate zone and declined as we moved eastward and were positively correlated. Species richness criteria showed distributions among climate zones similar to that of the fire threat variables. When using species richness and fire threat criteria, most lower-ranked (higher conservation priority) units occurred in the coastal and transitional zones. When considering genetic biodiversity, lower-ranked units occurred more often in the mountainous inland zone. With Pareto ranking, there is no need to select criteria weights as part of the decision-making process. However, negative correlations and larger numbers of criteria can result in more units assigned to the same rank. Pareto ranking is broadly applicable and can be used as a standalone decision analysis method or in conjunction with other methods.
Otay Fire in 2003 on Otay Mountain.
Otay Fire in 2003 on Otay Mountain.
Robert Fisher, USGS
Papers & Reports Setting priorities for private land conservation in fire-prone landscapes: Are fire risk reduction and biodiversity conservation competing or compatible objectives?
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Authors: Syphard AD, Butsic V, Bar-Massada A, Keeley JE, Tracey JA, Fisher RN | Date: 2016 | Outlet: Ecology and Society 21(3):2. | Format: .PDF
Although wildfire plays an important role in maintaining biodiversity in many ecosystems, fire management to protect human assets is often carried out by different agencies than those tasked for conserving biodiversity. In fact, fire risk reduction and biodiversity conservation are often viewed as competing objectives. Here we explored the role of management through private land conservation and asked whether we could identify private land acquisition strategies that fulfill the mutual objectives of biodiversity conservation and fire risk reduction, or whether the maximization of one objective comes at a detriment to the other. Using a fixed budget and number of homes slated for development, we simulated 20 years of housing growth under alternative conservation selection
strategies, and then projected the mean risk of fires destroying structures and the area and configuration of important habitat types in San Diego County, California, USA. We found clear differences in both fire risk projections and biodiversity impacts based on the way conservation lands are prioritized for selection, but these differences were split between two distinct groupings. If no conservation lands were purchased, or if purchases were prioritized based on cost or likelihood of development, both the projected fire risk and biodiversity impacts were much higher than if conservation lands were purchased in areas with high fire hazard or high species richness. Thus, conserving land focused on either of the two objectives resulted in nearly equivalent mutual benefits for both. These benefits not only resulted from preventing development in sensitive areas, but they were also due to the different housing patterns and arrangements that occurred as development was displaced from those areas. Although biodiversity conflicts may still arise using other fire management strategies, this study shows that mutual objectives can be attained through land-use planning in this region. These results likely generalize to any place where high species richness overlaps with hazardous wildland vegetation.
Papers & Reports Declines revisited: long-term recovery and spatial population dynamics of tailed frog larvae after wildfire
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Authors: Hossack BR, Honeycutt RK | Outlet: Biological Conservation
Drought has fueled an increased frequency and severity of large wildfires in many ecosystems. Despite an increase in research on wildfire effects on vertebrates, the vast majority of it has focused on short-term (<5 yrs) effects and there is still little information on the time scale of population recovery for species that decline in abundance after fire. In 2003, a large wildfire in Montana (USA) burned the watersheds of four of eight streams that we sampled for larval Rocky Mountain tailed frogs (Ascaphus montanus) in 2001. Surveys during 2004?2005 revealed reduced abundance of larvae in burned streams relative to unburned streams, with greater declines associated with increased fire extent. Rocky Mountain tailed frogs have low vagility and have several unusual life-history traits that could slow population recovery, including an extended larval period (4 yrs), delayed sexual maturity (6?8 yrs), and low fecundity (<50 eggs/yr). To determine if abundance remained depressed since the 2003 wildfire, we repeated surveys during 2014?2015 and found relative abundance of larvae in burned and unburned streams had nearly converged to pre-fire conditions within two generations. The negative effects of burn extent on larval abundance weakened >58% within 12 yrs after the fire. We also found moderate synchrony among populations in unburned streams and negative spatial autocorrelation among populations in burned streams. We suspect negative spatial autocorrelation among spatially-clustered burned streams reflected increased post-fire patchiness in resources and different rates of local recovery. Our results add to a growing body of work that suggests populations in intact ecosystems tend to be resilient to habitat changes caused by wildfire. Our results also provide important insights into recovery times of populations that have been negatively affected by severe wildfire.
Papers & Reports Trace Elements in Stormflow, Ash, and Burned Soil Following the 2009 Station Fire in Southern California
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Authors: Burton C, Hoefen T, Plumlee G, Baumberger K, Backlin A, Gallegos E, Fisher RN | Date: 2016-05-04 | Outlet: PLOS One | Format: .PDF
Most research on the effects of wildfires on water quality in streams has focused on suspended sediment and nutrients in streams and water bodies, and relatively little research has examined the effects of wildfires on trace elements. The purpose of this study was two-fold: 1) to determine the effect of the 2009 Station Fire in the Angeles National Forest northeast of Los Angeles, CA on trace element concentrations in streams, and 2) compare trace elements in post-fire stormflow water quality to criteria for aquatic life to determine if trace elements reached concentrations that can harm aquatic life. Pre-storm and stormflow water-quality samples were collected in streams located inside and outside of the burn area of the Station Fire. Ash and burned soil samples were collected from several locations within the perimeter of the Station Fire. Filtered concentrations of Fe, Mn, and Hg and total concentrations of most trace elements were elevated as a result of the Station Fire. In contrast, filtered concentrations of Cu, Pb, Ni, and Se and total concentrations of Cu were elevated primarily due to storms and not the Station Fire. Total concentrations of Se and Zn were elevated as a result of both storms and the Station Fire. Suspended sediment in stormflows following the Station Fire was an important transport mechanism for trace elements. Cu, Pb, and Zn primarily originate from ash in the sediment. Fe primarily originates from burned soil in the sediment. As, Mn, and Ni originate from both ash and burned soil. Filtered concentrations of trace elements in stormwater samples affected by the Station Fire did not reach levels that were greater than criteria established for aquatic life. Total concentrations for Fe, Pb, Ni, and Zn were detected at concentrations above criteria established for aquatic life.
California Red-legged Frog ([I]Rana draytonii[/I])
California Red-legged Frog (Rana draytonii)
Papers & Reports Evolutionary dynamics of a rapidly receding southern range boundary in the threatened California Red-Legged Frog (Rana draytonii)
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Authors: Richmond JQ, Barr KR, Backlin AR, Vandergast AG, Fisher RN | Date: 2013-02 | Outlet: Evolutionary Applications doi:10.1111/eva.12067 | Format: .PDF
Populations forming the edge of a species range are often imperiled by isolation and low genetic diversity, with proximity to human population centers being a major determinant of edge stability in modern landscapes. Since the 1960s, the California red-legged frog (Rana draytonii) has undergone extensive declines in urban-plagued southern California, where the range edge has rapidly contracted northward while shifting its cardinal orientation to an east-west trending axis. We studied the genetic structure and diversity of these front-line populations, tested for signatures of contemporary disturbance, specifically fire, and attempted to disentangle these signals from demographic events extending deeper into the past. Consistent with the genetic expectations of the ‘abundant-center’ model, we found that diversity, admixture and opportunity for random mating increases in populations sampled successively further away from the range boundary. Demographic simulations indicate that bottlenecks in peripheral isolates are associated with processes extending tens to a few hundred generations in the past, despite the demographic collapse of some populations due to recent fire-flood events. While the effects of recent disturbance have left little genetic imprint on these populations, they likely contribute to an extinction debt that will lead to continued range contraction unless management intervenes to stall or reverse the process.
Sierra Madre Mountain Yellow-legged Frog ([I]Rana muscosa[/I])
Sierra Madre Mountain Yellow-legged Frog (Rana muscosa)
Papers & Reports The precarious persistence of the endangered Sierra Madre yellow-legged frog (Rana muscosa) in southern California
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Authors: Backlin AR, Hitchcock CJ, Gallegos EA, Yee JL, Fisher RN | Date: 2013 | Outlet: Oryx - International Journal of Conservation (in press) | Format: .PDF
We conducted surveys for the endangered Sierra Madre yellow-legged frog (Rana muscosa) throughout southern California to evaluate their current distribution and status. Surveys were conducted between 2000 and 2009 at 150 unique streams and lakes within the San Gabriel, San Bernardino, San Jacinto, and Palomar mountains of southern California. Of the 150 survey locations only nine small, geographically isolated, populations were detected across the four mountain ranges. The nine R. muscosa populations all tested positive for the amphibian chytrid fungus (Batrachochytrium dendrobatidis). Our data show that when R. muscosa is known to be present, it is highly detectable (89%) from a single visit during the frogs active season. We estimate there were only 166 adult frogs that remained in the wild in 2009. From our research, it appears that R. muscosa populations in southern California are extremely vulnerable to natural and stochastic events and may become extirpated in the near future without intervention.
Papers & Reports Disease in a dynamic landscape: Host behavior and wildfire reduce amphibian chytrid infection
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Authors: Hossack BR, Lowe WH, Ware JL, Corn PS | Date: 2013 | Outlet: Biological Conservation 157: 293-299 | Format: .PDF
Disturbances are often expected to magnify effects of disease, but these effects may depend on the ecology, behavior, and life history of both hosts and pathogens. In many ecosystems, wildfire is the dominant natural disturbance and thus could directly or indirectly affect dynamics of many diseases. To determine how probability of infection by the aquatic fungus Batrachochytrium dendrobatidis (Bd) varies relative to habitat use by individuals, wildfire, and host characteristics, we sampled 404 boreal toads (Anaxyrus boreas boreas) across Glacier National Park, Montana (USA). Bd causes chytridiomycosis, an emerging infectious disease linked with widespread amphibian declines, including the boreal toad. Probability of infection was similar for females and the combined group of males and juveniles. However, only 9% of terrestrial toads were infected compared to >30% of aquatic toads, and toads captured in recently burned areas were half as likely to be infected as toads in unburned areas. We suspect these large differences in infection reflect habitat choices by individuals that affect pathogen exposure and persistence, especially in burned forests where warm, arid conditions could limit Bd growth. Our results show that natural disturbances such as wildfire and the resulting diverse habitats can influence infection across large landscapes, potentially maintaining local refuges and host behaviors that facilitate evolution of disease resistance.
Papers & Reports Interactive effects of wildfire, forest management, and isolation on amphibian and parasite abundance
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Authors: Hossack BR, Lowe WH, Honeycutt RK, Parks SA, Corn PS | Date: 2013 | Outlet: Ecological Applications 23: 479-492 | Format: .PDF
Projected increases in wildfire and other climate-driven disturbances will affect
populations and communities worldwide, including host–parasite relationships. Research in
temperate forests has shown that wildfire can negatively affect amphibians, but this research
has occurred primarily outside of managed landscapes where interactions with human
disturbances could result in additive or synergistic effects. Furthermore, parasites represent a
large component of biodiversity and can affect host fitness and population dynamics, yet they
are rarely included in studies of how vertebrate hosts respond to disturbance. To determine
how wildfire affects amphibians and their parasites, and whether effects differ between
protected and managed landscapes, we compared abundance of two amphibians and two
nematodes relative to wildfire extent and severity around wetlands in neighboring protected
and managed forests (Montana, USA). Population sizes of adult, male long-toed salamanders
(Ambystoma macrodactylum) decreased with increased burn severity, with stronger negative
effects on isolated populations and in managed forests. In contrast, breeding population sizes
of Columbia spotted frogs (Rana luteiventris) increased with burn extent in both protected and
managed protected forests. Path analysis showed that the effects of wildfire on the two species
of nematodes were consistent with differences in their life history and transmission strategies
and the responses of their hosts. Burn severity indirectly reduced abundance of soil-transmitted
Cosmocercoides variabilis through reductions in salamander abundance. Burn severity also
directly reduced C. variabilis abundance, possibly though changes in soil conditions. For the
aquatically transmitted nematode Gyrinicola batrachiensis, the positive effect of burn extent on
density of Columbia spotted frog larvae indirectly increased parasite abundance. Our results
show that effects of wildfire on amphibians depend upon burn extent and severity, isolation,
and prior land use. Through subsequent effects on the parasites, our results also reveal how
changes in disturbance regimes can affect communities across trophic levels.
Papers & Reports Rapid increases and time-lagged declines in amphibian occupancy after wildfire
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Authors: Hossack BR, Lowe WH, Corn PS | Date: 2013-02 | Outlet: Conservation Biology 27: 219–228 | Format: .PDF
Climate change is expected to increase the frequency and severity of drought and wildfire. Aquatic and moisture-sensitive species, such as amphibians, may be particularly vulnerable to these modified disturbance regimes because large wildfires often occur during extended droughts and thus may compound environmental threats. However, understanding of the effects of wildfires on amphibians in forests with long fire-return intervals is limited. Numerous stand-replacing wildfires have occurred since 1988 in Glacier National Park (Montana, U.S.A.), where we have conducted long-term monitoring of amphibians. We measured responses of 3 amphibian species to fires of different sizes, severity, and age in a small geographic area with uniform management. We used data from wetlands associated with 6 wildfires that burned between 1988 and 2003 to evaluate whether burn extent and severity and interactions between wildfire and wetland isolation affected the distribution of breeding populations. We measured responses with models that accounted for imperfect detection to estimate occupancy during prefire (0–4 years) and different postfire recovery periods. For the long-toed salamander (Ambystoma macrodactylum) and Columbia spotted frog (Rana luteiventris), occupancy was not affected for 6 years after wildfire. But 7–21 years after wildfire, occupancy for both species decreased ≥25% in areas where >50% of the forest within 500 m of wetlands burned. In contrast, occupancy of the boreal toad (Anaxyrus boreas) tripled in the 3 years after low-elevation forests burned. This increase in occupancy was followed by a gradual decline. Our results show that accounting for magnitude of change and time lags is critical to understanding population dynamics of amphibians after large disturbances. Our results also inform understanding of the potential threat of increases in wildfire frequency or severity to amphibians in the region.
The Clark Fire Study Site in the Cascade Mountians of Oregon.
The Clark Fire Study Site in the Cascade Mountians of Oregon.
M. Adams
Papers & Reports Using multilevel spatial models to understand salamander site occupancy patterns after wildfire
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Authors: Chelgren N, Adams M, Bailey L, Bury R | Date: 2011 | Outlet: Ecology 92:408-421 | Format: URL
Studies of the distribution of elusive forest wildlife have suffered from the confounding of true presence with the uncertainty of detection. Occupancy modeling, which incorporates probabilities of species detection conditional on presence, is an emerging approach for reducing observation bias. However, the current likelihood modeling framework is restrictive for handling unexplained sources of variation in the response that may occur when there are dependence structures such as smaller sampling units that are nested within larger sampling units. We used multilevel Bayesian occupancy modeling to handle dependence structures and partition sources of variation in occupancy of sites by terrestrial salamanders (family Plethodontidae) within and surrounding an earlier wildfire in western Oregon, USA. Comparison of model fit favored a spatial N-mixture model that accounted for variation in salamander abundance over models that were based on binary detection/non-detection data. Though catch per unit effort was higher in burned areas than unburned, there was strong support that this pattern was due to a higher probability of capture for individuals in burned plots. Within the burn the odds of capturing an individual given it was present were 2.06 times the odds outside the burn, reflecting reduced complexity of ground cover in the burn. There was weak support that true occupancy was lower within the burned area. While the odds of occupancy in the burn were 0.49 times the odds outside the burn among the five species, the magnitude of variation attributed to the burn was small in comparison to variation attributed to other landscape variables and to unexplained, spatially autocorrelated random variation. While ordinary occupancy models may separate the biological pattern of interest from variation in detection probability when all sources of variation are known, the addition of random effects structures for unexplained sources of variation in occupancy and detection probability may often more appropriately represent levels of uncertainty.