Responses of exotic plant species to fires in <i>Pinus ponderosa</i> forests in northern Arizona

Crawford, Julie; Wahren, Carl-Henrik; Kyle, Sean C.; Moir, William H.

doi:10.2307/3236610

Cited by 125 publications

(127 citation statements)

References 28 publications

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“…Seeds of common mullein can persist in the soil for decades (Kivilaan and Bandurski 1981), thereby enabling it to reestablish in areas long after it has disappeared from the aboveground plant community. Postfire expansion of musk thistle, Canada thistle, and common mullein populations has been documented throughout the western United States (Crawford et al 2001;Doyle et al 1998;Floyd et al 2006;USDA Forest Service 2008).…”

Section: Impacts Of Fire Severity and Time Since Fire On Exotic Specimentioning

confidence: 97%

“…3 Scatterplots depicting the relationship between native and exotic richness in 1,000-m 2 plots, by fire severity. Data were combined across all years because the interaction terms total exotic richness 9 year and total exotic richness 9 year 9 fire severity were not significant in the model For example, Crawford et al (2001) document a dramatic increase in exotic cover with increasing burn severity following three Arizona wildfires. They found that exotic cover jumped from 0% in nearby unburned stands to 59% in moderately burned stands and 116% in severely burned stands.…”

Section: Impacts Of Fire Severity and Time Since Fire On Exotic Specimentioning

confidence: 99%

“…Exotics repeatedly have been found to be least stimulated in lightly burned forests where overstory tree mortality and forest floor consumption are minimal, and most stimulated in severely burned forests where tree crowns and forest floor are largely consumed (Crawford et al 2001;Freeman et al 2007;Hunter et al 2006). The response of exotic plants after fire also often varies with time since fire (Klinger et al 2006;Koniak 1985;Nelson et al 2008).…”

Section: Introductionmentioning

confidence: 96%

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Impacts of mixed severity wildfire on exotic plants in a Colorado ponderosa pine–Douglas-fir forest

2010

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The 2002 Hayman Fire burned with mixed severity across 55,800 ha of montane Colorado forest, including pre-existing plots that were originally measured for understory plant composition and cover in 1997. We examined the influence of the Hayman Fire on exotic plants by remeasuring these plots annually from 2003 to 2007. We found that (1) exotic richness and cover generally increased as fire severity and time since fire increased; (2) the exotic species present in a plot before the fire were also largely present in the plot postfire, regardless of fire severity; (3) most of the new postfire species in a plot were present elsewhere in the study area before the fire, although some new species were truly new invaders that were not found in prefire surveys; (4) lightly burned riparian forests were not more susceptible to exotic invasion than surrounding uplands that burned with similar severity; and (5) native and exotic richness and cover were positively correlated or uncorrelated for all fire severities and years. Our findings indicate that exotics were stimulated by the Hayman Fire, especially in severely burned areas. However, exotic richness and cover remain low as of 2007, and correlations between native and exotic richness and cover suggest that exotics have not yet interfered with native understory development. Therefore, we conclude that exotic plants are not a major ecological threat at present, but recommend that monitoring be continued to evaluate if they will pose a threat in future years.

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Section: Impacts Of Fire Severity and Time Since Fire On Exotic Specimentioning

confidence: 97%

Section: Impacts Of Fire Severity and Time Since Fire On Exotic Specimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Impacts of mixed severity wildfire on exotic plants in a Colorado ponderosa pine–Douglas-fir forest

2010

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“…Even at the two sites dominated by meadow, A1 Mountain and Slaughter Mesa, understory plant cover is still low relative to the >60% cover that Moir and Dieterich (1988) suggest as a generality for full-meadow sites in the region. Studies have found that high-intensity fires in the ponderosa pine system can be implicated in the decline of native grasses, perhaps through negative impacts on duff layer and soil seedbed (Griffis et al 2001;Crawford et al 2001) and suggest that understory cover can remain sparse for decades after severe fire. Without data on prefire understory cover or soil type, however, we cannot assess the degree of recovery in understory vegetation at these sites.…”

Section: Discussionmentioning

confidence: 99%

How resilient are southwestern ponderosa pine forests after crown fires?

Savage¹,

Mast²

2005

Can. J. For. Res.

271

219

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Abstract:The exclusion of low-severity surface fire from ponderosa pine (Pinus ponderosa P. & C. Lawson) forests of the Southwest has changed ecosystem structure and function such that severe crown fires are increasingly causing extensive stand mortality. This altered fire regime has resulted from the intersection of natural drought cycles with human activities that have suppressed natural fires for over a century. What is the trajectory of forest recovery after such fires? This study explores the regeneration response of ponderosa pine and other species to crown fires that occurred in the region from the late 1940s to the mid-1970s. We address two main questions: (1) What is the success of ponderosa regeneration and establishment, and (2) Can these sites, burned in stand-destroying fires, be "captured" by other species on the scale of decades? Two main trajectories of recovery were found: (1) establishment of unnaturally dense ponderosa pine stands vulnerable to further crown fire and (2) establishment of nonforested grass or shrub communities.

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“…Low-intensity fire creates conditions suitable for early successional species by increasing bare ground for germination sites, increasing short-term nutrient availability, and removing dominant competitors (Denslow 1983;Collins and Gibson 1990;Whelan 1995;Crawford et al 2001). Bottlebrush squirreltail is an early and rapid colonizer of disturbed sites (Jones 1998) and generally increases following low-intensity fall burns (Young and Miller 1985).…”

Section: Fire Effectsmentioning

confidence: 99%

Herbaceous Vegetation Responses (1992-2004) to Restoration Treatments in a Ponderosa Pine Forest

Moore¹,

Casey²,

Bakker³

2006

REM

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Ecological restoration treatments are widely applied in southwestern ponderosa pine forests to convert them to an open canopy structure similar to that found at the time of Euro-American settlement. An experiment was initiated in northern Arizona in 1994 to evaluate long-term ecosystem responses to 3 restoration treatments: 1) thinning from below (thinning), 2) thinning from below plus forest floor manipulation with periodic prescribed burning (composite), and 3) an untreated control. Results focus on total herbaceous and functional-group standing crop response to these restoration treatments. Pretreatment data were collected in 1992 and posttreatment responses were measured from 1994 through 2004. Total herbaceous standing crop was significantly higher on the 2 treated areas than on the control over the entire posttreatment period, but did not differ between the thinning and composite treatments. Plant functional groups responded differently to treatments and to drought. In general, the graminoid standing crop responded within several years after the initial treatments and continued to increase through time, until a series of severe droughts reduced standing crop to pretreatment levels. C 3 graminoids dominated the standing-crop response, of which bottlebrush squirreltail (Elymus elymoides (Raf.) Swezey ssp. elymoides) was the primary contributor. C 4 graminoids had a minimal response to restoration treatments, possibly because they were less abundant before the experiment began or because they were adversely affected by autumn burning. Legumes and forbs exhibited a 4-5 year lag before responding to the thinning and composite treatments. Annual and biennial plants showed a large biomass increase approximately 5 years after implementation of the composite treatment. The restoration goal of optimizing herbaceous standing crop must be weighed against the competing goals of increasing the abundance of specific functional groups, increasing biodiversity or rare plants, and managing invasive plant species. ResumenLos tratamientos de restauració n ecoló gica son ampliamente aplicados en los bosques de ''Ponderosa pine'' del sudoeste para convertirlos en una estructura de cobertura abierta similar a la que se encontró en el tiempo de la colonizació n Euroamericana. En 1994, en el norte de Arizona, se inicio un experimento para evaluar las respuestas a largo lazo del ecosistema a tres tratamientos de restauració n: 1) aclareo desde abajo (aclareo); 2) Aclareo desde abajo mas manipulació n del piso del bosque con fuego prescrito perió dico (compuesto) y 3) control sin tratar. Los resultados se enfocaron en la respuesta de la biomasa total herbá cea y de grupos funcionales a estos tratamientos de restauració n. Los datos pre-tratamiento fueron colectados en 1992 y las respuestas post-tratamientos fueron medidas de 1994 a 2004. Durante todo el periodo post-tratamiento la biomasa total herbá cea de las dos á reas tratadas fue significativamente mayor que la del á rea control, pero no difirió entre los tratamientos d...

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Responses of exotic plant species to fires in Pinus ponderosa forests in northern Arizona

Cited by 125 publications

References 28 publications

Impacts of mixed severity wildfire on exotic plants in a Colorado ponderosa pine–Douglas-fir forest

Impacts of mixed severity wildfire on exotic plants in a Colorado ponderosa pine–Douglas-fir forest

How resilient are southwestern ponderosa pine forests after crown fires?

Herbaceous Vegetation Responses (1992-2004) to Restoration Treatments in a Ponderosa Pine Forest

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