New exposure-based metric approach for evaluating O3 risk to North American aspen forests

Percy, Kevin E.; Nosal, M.; Heilman, Warren E.; Dann, Tom; Söber, J.; Legge, A.H.; Karnosky, David F.

doi:10.1016/j.envpol.2006.10.009

Cited by 34 publications

(10 citation statements)

References 54 publications

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“…There are many investigations in the literature indicating that plants may acclimate over time to added CO 2 (Kö rner, 2006), but this does not appear to be so for O 3 . The effects of O 3 found in the present study are generally consistent with previously reported reductions in overall growth under added O 3 at the site and the improved relative performance of the O 3 -resistant aspen clone 8L in the presence of added O 3 Percy et al, 2007).…”

Section: Discussionsupporting

confidence: 82%

“…The decreases attributed to elevated O 3 are consistent with the generally observed reduction of growth. The increases other than that for branch magnitude were probably due to the increased relative performance of relatively O 3 -tolerant clones in the presence of competition with less O 3 tolerant genotypes, although Percy et al (2007) mentions the possibility of hormetic O 3 effects.…”

Section: Discussionmentioning

confidence: 98%

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Environmental Pollution

2006

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Canopy architecture and stem flow are affected by elevated CO 2 and tropospheric O 3 . a r t i c l e i n f o a b s t r a c tThe forest hydrologic budget may be impacted by increasing CO 2 and tropospheric O 3 . Efficient means to quantify such effects are beneficial. We hypothesized that changes in the balance of canopy interception, stem flow, and through-fall in the presence of elevated CO 2 and O 3 could be discerned using image analysis of leafless branches. We compared annual stem flow to the results of a computerized analysis of all branches from the 2002, 2004, and 2006 annual growth whorls of 97 ten-year-old trees from the Aspen Free-Air CO 2 and O 3 Enrichment (Aspen FACE) experiment in Rhinelander, WI. We found significant effects of elevated CO 2 and O 3 on some branch metrics, and that the branch metrics were useful for predicting stem flow from birch, but not aspen. The results of this study should contribute to development of techniques for efficient characterization of effects on the forest hydrologic budget of increasing CO 2 and tropospheric O 3 .

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 98%

Environmental Pollution

2006

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“…Current and projected [O 3 ] are sufficient to cause chronic changes in trees [for reviews see Chappelka & Samuelson (1998); Skarby et al (1998); Karnosky et al (2007); Matyssek et al (2007)], most notably reductions in photosynthesis (Long & Naidu, 2002; Wittig et al , 2007), accelerated leaf senescence (Pell et al , 1999; Karnosky et al , 2005; Nunn et al , 2005) and decreased productivity (Percy et al , 2007). Forests are one of the most important global sinks for carbon (Geider et al , 2001; Houghton, 2003; Sitch et al , 2007).…”

Section: Introductionmentioning

confidence: 99%

“…We have shown previously that the rise in [O 3 ] since the Industrial Revolution has already resulted in a significant decrease in tree leaf photosynthesis (Wittig et al , 2007), but does this translate into a loss in biomass and production? Percy et al (2007) estimated a maximum 31% loss in productivity of Populus tremuloides in parts of its North American range between 2001 and 2003 due to O 3 . How widespread are such decreases and can we assess whether there has been an overall loss and by what amount?…”

Section: Introductionmentioning

confidence: 99%

Quantifying the impact of current and future tropospheric ozone on tree biomass, growth, physiology and biochemistry: a quantitative meta‐analysis

Wittig

Ainsworth

Naidu

et al. 2009

Global Change Biology

505

370

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The northern hemisphere temperate and boreal forests currently provide an important carbon sink; however, current tropospheric ozone concentrations ([O 3 ]) and [O 3 ] projected for later this century are damaging to trees and have the potential to reduce the carbon sink strength of these forests. This meta-analysis estimated the magnitude of the impacts of current [O 3 ] and future [O 3 ] on the biomass, growth, physiology and biochemistry of trees representative of northern hemisphere forests. Current ambient [O 3 ] (40 ppb on average) significantly reduced the total biomass of trees by 7% compared with trees grown in charcoal-filtered (CF) controls, which approximate preindustrial [O 3 ]. Above-and belowground productivity were equally affected by ambient [O 3 ] in these studies. Elevated [O 3 ] of 64 ppb reduced total biomass by 11% compared with trees grown at ambient [O 3 ] while elevated [O 3 ] of 97 ppb reduced total biomass of trees by 17% compared with CF controls. The root-to-shoot ratio was significantly reduced by elevated [O 3 ] indicating greater sensitivity of root biomass to [O 3 ]. At elevated [O 3 ], trees had significant reductions in leaf area, Rubisco content and chlorophyll content which may underlie significant reductions in photosynthetic capacity. Trees also had lower transpiration rates, and were shorter in height and had reduced diameter when grown at elevated [O 3 ]. Further, at elevated [O 3 ], gymnosperms were significantly less sensitive than angiosperms. There were too few observations of the interaction of [O 3 ] with elevated [CO 2 ] and drought to conclusively project how these climate change factors will alter tree responses to [O 3 ]. Taken together, these results demonstrate that the carbonsink strength of northern hemisphere forests is likely reduced by current [O 3 ] and will be further reduced in future if [O 3 ] rises. This implies that a key carbon sink currently offsetting a significant portion of global fossil fuel CO 2 emissions could be diminished or lost in the future.

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“…The authors were careful to note that none of the O 3 parameters examined showed a statistically significant relationship to growth and should not be used alone to predict growth [24]. Percy et al [25] combined the fourth highest 8-h average concentration experienced in their high exposure chambers with other parameters and found a statistically significant result. It is important to note that those study conclusions were derived with data from fumigation exposures with high hourly average concentrations in the experimental chambers and the 8-h average concentrations may be highly correlated with the frequent occurrences of these elevated levels.…”

Section: Critical Loads/levels In the Us And Canadamentioning

confidence: 99%

The Use of Critical Levels for Determining Plant Response to Ozone in Europe and in North America

Musselman

Lefohn²

2007

The Scientific World JOURNAL

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Critical levels to determine plant response to ozone (O3) have been used in Europe since the 1980s, utilizing the concentration-based AOT40 to relate plant response to ambient O3 exposure. More recently, there has been progress in Europe toward utilizing flux-based critical levels, because plant response is more closely related to O3 uptake than to the amount of O3 in ambient air. Flux-based critical levels are plant species specific; data for parameterization of flux-based critical levels models are lacking for most plant species. Although flux-based critical levels are now being used for a limited number of agricultural crops and tree species where data are available, the use of flux-based critical levels is limited by the lack of adequate consideration and incorporation of plant internal detoxification mechanisms in flux modeling. Critical levels have not been used in North America; however, recent interest in the U.S. and Canada for using critical loads for nitrogen and sulfur has generated interest in using critical levels for O3. A major obstacle for utilization of critical levels in North America is that ambient air quality standards for O3 in the U.S. and Canada are concentration based. It appears that cumulative exposure-based metrics, particularly when implemented with a quantification of peak concentrations and environmental variables, such as a drought index, are currently the most useful to relate O3 to vegetation response. Because data are unavailable to quantify detoxification potential of vegetation, effective flux models are not available to determine plant response to O3.

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New exposure-based metric approach for evaluating O3 risk to North American aspen forests

Cited by 34 publications

References 54 publications

Environmental Pollution

Environmental Pollution

Quantifying the impact of current and future tropospheric ozone on tree biomass, growth, physiology and biochemistry: a quantitative meta‐analysis

The Use of Critical Levels for Determining Plant Response to Ozone in Europe and in North America

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