Tree mortality in drought-stressed mixed-conifer and ponderosa pine forests, Arizona, USA

Ganey, Joseph L.; Vojta, Scott C.

doi:10.1016/j.foreco.2010.09.048

Cited by 139 publications

(129 citation statements)

References 38 publications

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“…Our specific objectives were to: 1) Estimate trends in various parameters used to describe log populations, including log density, log volume, area covered by logs, and total log length; and 2) evaluate trends in decay-class, size-class, and species composition of log populations. These data document trends in log populations in mixed-conifer and ponderosa pine forest during a period of rapid forest change mediated by climate (Breshears et al, 2005;Allen et al, 2010;Ganey & Vojta, 2011). Results thus may provide a glimpse of trends in log populations likely under future climate in the southwestern United States, which is predicted to be both warmer and drier (Seager et al, 2007;Seager & Vecchi, 2010), and may aid managers in planning for and mitigating the effects of climate change.…”

Section: Introductionmentioning

confidence: 68%

“…Observed mortality from 1997 to 2007 was far greater in mixed-conifer than in ponderosa pine forest (Ganey & Vojta, 2011), and is creating a large pulse in log creation in mixed-conifer forest. Stephens and Ruth (2005) also noted that fuels accumulate more rapidly in productive mixedconifer forests than in ponderosa pine forests, even though those pine forests typically have missed more fire cycles.…”

Section: Discussionmentioning

confidence: 98%

“…The changes documented here represent only the initial changes resulting from a drought-mediated pulse in tree mortality (Ganey & Vojta, 2011), however, because many of the dead trees are still standing. As these trees fall, we anticipate greater increases in log abundance and related parameters in both forest types (Ganey & Vojta, 2010;Hoffman et al, 2011;StevensRumann et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

“…As a result, we sampled a wide range in forest structural conditions in each forest type. For example, density of trees ≥20 cm diameter at breast height in 2004 ranged from 78 to 489 (mean = 274.8 ± 13.1 [SE]) trees·ha -1 in mixed-conifer forest and from 11 to 689 (mean = 237.6 ± 18.1) trees·ha -1 in ponderosa pine forest, and basal area ranged from 7 to 52 (mean = 25.8 ± 1.4) and from 1 to 44 (mean = 20.8 ± 1.2) m 2 ·ha -1 in mixed-conifer and ponderosa pine forest, respectively (Ganey & Vojta, 2011 …”

Section: Study Areamentioning

confidence: 99%

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Rapid Increase in Log Populations in Drought-Stressed Mixed-Conifer and Ponderosa Pine Forests in Northern Arizona

Ganey¹,

Vojta²

2012

OJF

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Down logs provide important ecosystem services in forests and affect surface fuel loads and fire behavior. Amounts and kinds of logs are influenced by factors such as forest type, disturbance regime, forest management, and climate. To quantify potential short-term changes in log populations during a recent globalclimate-change type drought, we sampled logs in mixed-conifer and ponderosa pine (Pinus ponderosa) forests in northern Arizona in 2004 and 2009 (n = 53 and 60 1-ha plots in mixed-conifer and ponderosa pine forests, respectively). Over this short time interval, density of logs, log volume, area covered by logs, and total length of logs increased significantly in both forest types. Increases in all log parameters were greater in mixed-conifer than in ponderosa pine forest, and spatial variability was pronounced in both forest types. These results document rapid increases in log populations in mixed-conifer forest, with smaller changes observed in ponderosa pine forest. These increases were driven by climate-mediated tree mortality which created a pulse in log input, rather than by active forest management. The observed increases will affect wildlife habitat, surface fuel loads, and other ecosystem processes. These changes are likely to continue if climate change results in increased warmth and aridity as predicted, and may require shifts in management emphasis.

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Section: Introductionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

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Rapid Increase in Log Populations in Drought-Stressed Mixed-Conifer and Ponderosa Pine Forests in Northern Arizona

Ganey¹,

Vojta²

2012

OJF

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“…Catastrophic forest damage resulting from extreme drought and heat is increasingly being reported from around the world (Ganey and Vojta 2011;Granzow-de la Cerda et al 2012). A recent review by Allen et al (2010) outlined 88 documented episodes of forest damage resulting from drought and/or heat events since the early 1970's, illustrating the vulnerability of forests to extreme climate conditions worldwide.…”

Section: Introductionmentioning

confidence: 99%

Sudden forest canopy collapse corresponding with extreme drought and heat in a mediterranean-type eucalypt forest in southwestern Australia

et al. 2013

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Drought and heat-induced forest dieback and mortality are emerging global concerns.Although Mediterranean-type forest (MTF) ecosystems are considered to be resilient to drought and other disturbances, we observed a sudden and unprecedented forest collapse in a MTF in Western Australia corresponding with record dry and heat conditions in 2010/2011.An aerial survey and subsequent field investigation were undertaken to examine: the incidence and severity of canopy dieback and stem mortality, associations between canopy health and stand-related factors as well as tree species response. Canopy mortality was found to be concentrated in distinct patches, representing 1.5% of the aerial sample (1,350 ha).Within these patches, 74% of all measured stems (> 1cm DBHOB) had dying or recently killed crowns, leading to 26% stem mortality six months following the collapse. Patches of canopy collapse were more densely stocked with the dominant species, Eucalyptus marginata, and lacked the prominent midstorey species Banksia grandis, compared to the surrounding forest. A differential response to the disturbance was observed among cooccurring tree species, which suggests contrasting strategies for coping with extreme water stress. These results suggest that MTFs, once thought to be resilient to climate change, are susceptible to sudden and severe forest collapse when key thresholds have been reached.

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Canopy effects on snow sublimation from a central Arizona Basin

Svoma

2017

JGR Atmospheres

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Guided by 30 m terrain and forest cover data, snow sublimation from the Salt River basin in the Southwest U.S. is simulated for years 2008 (wet year) and 2007 (dry year). Downscaled meteorological input correlates well (r~0.80) with independent observations at AmeriFlux sites. Additionally, model correlation and bias with eddy‐covariance vapor flux observations is comparable to previous localized modeling efforts. Upon a 30% reduction in effective leaf area index, canopy sublimation decreases by 1.29 mm (27.0%) and 1.05 mm (23.0%) at the basin scale for the 2008 and 2007 simulations, respectively. Ground sublimation decreases 0.72 mm (4.75%) in 2008 and only 0.17 mm (1.5%) in 2007. Canopy snow‐holding capacity and frequent unloading events at lower elevations limit the variability in canopy sublimation from wet year to dry year at the basin scale. The greater decrease in snowpack sublimation in the wet year is partly due to decreased longwave radiation from the canopy reduction over a more extensive snowpack than the dry year. This decrease overcomes the increased solar radiation and wind speed during winter. A second factor is that a greater extent of the snowpack persisted into spring in 2008 than 2007, and the large increase in shortwave flux upon canopy reduction increases melt rates, reducing duration. Only in heavily forested high elevations (>2900 m above sea level) in 2008 does the snowpack persist long enough into spring to result in increased ground sublimation upon canopy reduction. As forest cover change can occur rapidly, these results are critical from water resource and ecosystem function perspectives.

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Tree mortality in drought-stressed mixed-conifer and ponderosa pine forests, Arizona, USA

Cited by 139 publications

References 38 publications

Rapid Increase in Log Populations in Drought-Stressed Mixed-Conifer and Ponderosa Pine Forests in Northern Arizona

Rapid Increase in Log Populations in Drought-Stressed Mixed-Conifer and Ponderosa Pine Forests in Northern Arizona

Sudden forest canopy collapse corresponding with extreme drought and heat in a mediterranean-type eucalypt forest in southwestern Australia

Canopy effects on snow sublimation from a central Arizona Basin

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