Ozone fluxes and epidemiology of forest injury

Transcription

1 Ozone fluxes and epidemiology of forest injury Elena Paoletti (CNR Florence Italy), Alessandra De Marco (ENEA Rome Italy), Pierre Sicard (ACRI-ST Sophie Antipolis France), Silvano Fares (CRA Rome, Italy) Ozone concentrations Northern Hemisphere Present annual rate: % (Paoletti, 2007) Emission of ozone precursors Europe 32 countries Since 1990 to 2005 : -36% -42% (EMEP, 2008)

2 Past trends Reduction of peaks over the last years and increase of background levels (faster in the cities than at rural areas) Annual peak (P98) Annual average (M24) (Sicard et al., 2013; Paoletti et al., in press)

3 Future trends Uncertainty in future scenarios depends on efficiency of control measures over precursors (Young et al., 2013)

4 The Mediterranean climate as an hot spot (EEA, 2013)

5 Is ozone a concern for health in the cities? It is a secondary pollutant Elevated urban pollution (NO) favours O 3 depletion Biogenic VOCs favour O 3 formation (Gregg et al., 2003)

6 Effects on health PEOPLE Lung inflammation Reduced lung function Degenerative diseases e.g. atherosclerosis, heart attacks, chronic inflammatory diseases (rheumatoid arthritis), cataract, central nervous system disorders (Parkinson s and Alzheimer s disease), age related disorders and finally cancer 0.7 M/yr respiratory mortalities worldwide, corresponding to 6.3 M/yr of lost life. > 75% of O3-induced mortalities estimated to occur in the densely populated and heavily polluted Asian continent PLANTS Pinus halepensis Acer campestre Stomatal conductance Control on water loss (Kampa & Castanas, 2008; Anenberg et al 2010) (Paoletti, 2007; Ainsworth et al. 2012)

7 (Tuovinen et al. 2007) From exposure to ozone flux Fagus sylvatica PODy= S [(gsto y) [O 3 ] CF] gsto = gmax * [min (fphen, fo3) * flight * max [ fmin ( ftemp, fvpd, fswc ) ] DO 3 SE model (Emberson et al 2000, Jarvis 1979)

8 g s (mmol m -2 s -1 ), VPD (hpa) Avoidance CO 2 O 3 H 2 O Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec O3 (nl l -1 ) Daytime Mean daily trend of ozone, leaf-level stomatal conductance, and vapor pressure deficit in a Quercus ilex forest in central Italy Source: Matyssek, Bytnerowicz, Karlsson, PAOLETTI, Sanz, Schaub, Wieser, 2007, Environ Pollut, 146:

9 Epidemiology of ozone injury Epidemiology is the study of the patterns, causes, and effects of ozone on health conditions in defined populations, to identify risk factors and targets for preventive healthcare. Epidemiology has helped developing methodology used in clinical research, public health studies and, to a lesser extent, basic research in biological sciences (see biomonitoring) Epidemiological investigations where large-scale biological responses are studied under realistic environmental conditions in the field may provide useful information for establishing the best standards and thresholds for protecting plants from O 3 Epidemiology of ozone injury may be very helpful in particular when forests are investigated, as large trees require expensive experimental facilities for realistic ozone simulation and a few individuals can be usually investigated The majority of previous epidemiological assessments used ambient O3 exposure as a metric of injury (e.g. Arbaugh et al 1998, Karlsson et al 2006, Braun et al 2007, McLaughlin et al 2007, Bussotti & Ferretti 2009, Baumgarden et al 2009, Fishman et al 2010, Sun et al 2012, Kefauer et al 2013) A NEW FACILITY FOR OZONE EXPOSURE IN FREE AIR

10 How to derive large-scale stomatal ozone fluxes Modelling (hourly met & O3 data) Micrometeorology Sap-flow measurements

11 Which plant-response indicators? Growth, yield and their proxies Ozone visible injury Crown transparency Spectral indices

12 Work in progress: AOT40 vs POD Both AOT40 and POD1 exceeded the critical levels in the entire domain AOT40 overestimated O 3 risk as compared to PODY The use of AOT40 significantly changed ozone risk assessment for vegetation relative to PODY, while no spatial and temporal differences occurred when using POD1 rather than POD0

13 Selection of the best standards Triticum durum Creso cv: Ambient concentrations of 45 ppb (conc. ambiente) lead to a 10 % yield reduction in comparison with pre-industrial period (10 ppb) [-18% ontriticum aestivum, Feng et al. 2008] US metrics predicts losses better than Europeans, but with the high legally accepted threshold (75 ppb) only 39% of sites are protected. We propose a POD metric of 22 mmol m- 2 in order to cover 97% of sites.

14 pidemiology of yield reduction in durum wheat using geostatistics Precipitation explains most of the regression variance, as wheat in central Italy is not irrigated. Several ozone indices were tested. The best one was stomatal flux. Overall the ozone indices explained ab. 5% of total variance. De Marco A., Screpanti A., Paoletti E.: 2010, Geostatistics as a validation tool of ozone standards for durum wheat protection. Environmental Pollution 158:

15 Ozone impact on GPP (1) Long-term continuous eddy-covariance measurements (>9 years at 30 min resolution) at three Mediterranean-type sites The relative importance of factors in affecting GPP is site(species)-specific. Up to 12 19% of the carbon assimilation reduction in P. ponderosa and in the Citrus plantation is explained by higher stomatal ozone flux. Random Forest Analysis of the effects on GPP at three Mediterranean-type ecosystems: Pinus ponderosa, Citrus sinensis, Quercus ilex Fares et al. Global Change Biology (2013)

16 Ozone impact on GPP (2) Reduction in carbon assimilation was more related to stomatal ozone flux than to ozone concentration. The negative effects of ozone occurred within a day of exposure/uptake O3 concentration Stomatal O3 flux Fares et al (2013) GCB

17 Testing Canopy Moisture Content as a plant response indicator of ozone injury Results on the relative importance of predictors using the random tree analysis Importance Fagus sylvatica Pinus halepensis 1.2 a) 2010 c) 2010 Importance CMC response to ozone was speciesspecific, being negligible in F. sylvatica and significant in P. halepensis, and explained by linear and non-linear interactions with relevant ecological drivers. Importance Longitude Latitude b) Longitude Latitude Ozone RH Temperature Solar R Fagus sylvatica Ozone RH Temperature Solar R SWC SWC POD0 POD0 POD1 POD1 AOT40 AOT Longitude Latitude Longitude Latitude Ozone RH Temperature Solar R Pinus halepensis 2011 d) 2011 Importance Ozone RH Temperature Solar R SWC SWC POD0 POD0 POD1 POD1 AOT40 AOT40

18 Crown transparency and growth at CONECOFOR sites Only 14 sites with availability of: Meteo data from the closest (comparable) station (source: UCEA) Ozone from passive monitors at the sites (source: CFS) Crown transparency from annual assessments ( ) (source: CFS) Growth increments from 5-yr assessments ( , ) (source: CFS, CRA-SEL) Calculation of AOT40 and POD0 Meteo Forest

19 5-yr mean, m3/ha*y 5-yr mean, m3/ha*y % trees with >25% transparency % trees with >25% transparency Crown transparency increases with increasing POD0, but no effects on growth increments 100 R² = 0, R² = 0, AOT40, ppb h 20 R² = 0,026 ns POD0, mmol/m2 20 R² = 0,003 ns yr AOT40 average, ppb h 0 0, , , , yr POD0 average, ppb h

20 Conclusions Epidemiological studies may help to fill the gap between field conditions and lab studies Modern approaches must focus on stomatal ozone flux as a metric Among the tested metrics, we recommend the use of POD0 in the assessment of ozone risk for vegetation, because it has both biological significance and practicality in usage

21 Thanks! Financial support: LIFE10 ENV/FR/208 Technical support: Grand Site Sainte-Victoire, Mercantour National Park, ONF (National Office of Forests), CFS (Corpo Forestale dello Stato) and JRC (Joint Research Centre).