life10 env/fr/208 adapting mediterranean forests to climate change and air pollution camille renou,...

7-10 Apri l 2014 , Rome, I ta ly24th CCE workshop and 30th Task Force meet ing of the ICP M&M

LIFE10 ENV/FR/208

Pierre Sicard (ACRI-ST, France)

Adapting Mediterranean forests to climate change and air pollution

Camille Renou, Romain Serra (ACRI-ST, France)Alessandra de Marco, Augusto Screpanti, Giovanni Vialetto (ENEA, Italy)

Elena Paoletti, Giulia Carriero, Sara Pignattelli, Yasutomo Hoshika (IPP-CNR, Italy)Nicolas Vas, Laurence Dalstein-Richier (GIEFS, France), Francesco Taglaferro (IPLA, Italy)

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Background & Context

24th CCE workshop and 30th Task Force meeting of the ICP M&M:7-10 April 2014, Rome, Italy

The Mediterranean region is the most exposed to O3 pollution in Europe, and the climate change is expected to be more pronounced in the Mediterranean Basin.

In the Western European Mediterranean area, the O3 control measures are effective at rural sites, while O3 levels are still increasing in the cities (Sicard et al., 2013).

The current O3 ground-levels are high (annual mean > 40ppb; hourly max > 100ppb) enough to cause health problems, affecting trees, biodiversity and well-being of citizens.

To date, the O3 pollution appears as a major air quality issue in urban, suburban and rural areas.

Main objectives:

(1) To assess the current European standards AOT40 (external exposure)(2) To refine the criteria for Mediterranean forest protection against O3 and climate change(3) To propose proper standards & thresholds based on the quantity of O3 absorbed by plants

FO3REST - Ozone and Climate Change Impacts on French and Italian Forests: Refinement of criteria and thresholds for forest protection

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Description of the works

Activities in 2012 & 2013:

(1) In field campaign : O3 visible injury (stippling/mottling, crown dicoloration & leaf loss) was evaluated.

Protocol and macroscopic observations

In agreement with the European protocol defined by the ICP-Forests. Samplers & microscopic analyses to confirm the O3-induced symptoms.

(2) Meteorological data, soil data and O3 concentrations were obtained from the coupled WRF-CHIMERE modelling system.

(3) Spearman test (based on ranks, robust, suitable for non-normally distributed data) was carried out to understand the relative contribution of O3 to visible injury occurrence.

(4) Validation of DO3SE outputs by Eddy-covariance campaigns

In FO3REST, stomatal O3 fluxes were modelled & correlated to real-world forest impacts in terms of visible injury to define more realistic thresholds for vegetation protection.


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Location of experimental plots

24 plots in Piedmont region28 plots in South-eastern France

The survey was based on 1040 trees over 52 plots (20 trees per plot).


Distributed at different altitudes & main ecological zones to consider climate impact on the symptoms occurrence.

O3 produces characteristic symptoms on needles of Pinus cembra & P. halepensis: valuable bioindicator species for O3 stress.

P. halepensis: widely distributed in the Mediterranean area & has an important role in maintenance and reforestation due to its good regenerative potential.

France: 14 plots with Pinus cembra & 11 with Pinus halepensis.

Italy: 19 deciduous (e.g. Fraxinus exc., Fagus syl., Quercus sp.) & 5 conifers (e.g. Pinus sylvestris, Pinus cembra).

Visit of the experimental plots in the Mercantour National Park in 2013

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In-field ozone-induced assessment


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Fagus sylvatica: no symptoms Bronzing + stippling

Carpinus betulus: no symptoms

Deciduous: Ozone-induced symptoms

For broadleaf plants Symptoms observed on 5 trees / 5 branches (> 30 leaves) and scored.

- Upper leaf surface interveinal stipple

- Red or brown spots between the leaf veins

- Chlorosis: non-green pigmentation = loss of chlorophyll

- Flecking: brown or black areas on the upper surface (death of cells)

- Bifacial necrosis


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Pinus halepensis: no symptoms

Conifers: Ozone-induced symptoms

Mottling (diffuse) + insect

For conifers: 5 trees are chosen per plot & 5 branches are removed from the upper third of the crown layer.

- Tipburn : death of cells (red or brown) spreading from the tip of needles downwards- Chlorotic mottle: discrete patches of yellow tissue on needles

Symptoms scored on 30 one-year-old needles (C+1) and two-year-old needles (C+2) in % of total surface affected.

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Microscopical analysis

First visible effects of O3 appear on the palisade mesophyll chloroplasts.

* Lysis: disintegration of a biological cell membrane by a physical, chemical or biological agent, leading to cell death

O3 damages palisade mesophyll inducing chloroplasts lysis* and cells collapse.

Sometimes anthocyanins** (red pigments) appear in the palisade. Epidermis and spongy mesophyll remain intact in the first steps of the injury.

Leaf section and O3-induced injury into the palisade mesophyll

** Anthocyanins: water-soluble vacuolar pigments


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Microscopical analysis

Pinus cembra: 2-year old needles

Large intercellular spaces

Necrosing chlorotic spots with mesophyll lysing and collapsing

Chloroplasts lysis

Tannins and/or anthocyanins presence


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Results of visible injury 2012-2013


NumberMain tree

specie

Survey 2012Leaf Loss(%)

Discoloration

scoring

O3 induced damages

C+1 (%)

C+2(%)

1 Robinia pseudoacacia 7 0.2 0

2 Fraxinus excelsior 2 0 1.84

3 Robinia pseudoacacia 12 1 1.52

4 Fraxinus excelsior 2 0.4 18.85 Quercus cerris 3 0 06 Fagus sylvatica 9 1.4 1.87 Fraxinus ornus 16 1 6.88 Robinia pseudoacacia 4 0.2 09 Pinus cembra 7 0 0.12 2.36

10 Fraxinus excelsior 4 0.4 1.411 Pinus sylvestris 15 0 0.72 2.5612 Pinus sylvestris 14 0 0 013 Fagus sylvatica 21 1.4 6.3214 Fagus sylvatica 3 0.2 015 Robinia pseudoacacia 18 0 016 Fraxinus ornus 2 0.2 5.817 Quercus petraea 14 0.8 018 Fagus sylvatica 5 1 0

19 Robinia pseudoacacia 15 0.2 0

20 Fraxinus excelsior 19 0.2 021 Picea excelsa 10 0 0 022 Fraxinus excelsior 15 0.4 16.623 Fraxinus excelsior 20 0.2 2.824 Abies alba 4 0 0 0

NumberMain tree

specie

Survey 2013Leaf Loss(%)

Discoloration

scoring

O3 induced damages

C+1(%)

C+2(%)

1 Robinia pseudoacacia 9.8 0.35 1.60

2 Fraxinus excelsior 4.5 0.05 10.803 Robinia pseudoacacia 6.0 0.05 0.04 Fraxinus excelsior 11.8 0.20 38.505 Quercus cerris 17.8 0.30 4.306 Fagus sylvatica 7.5 0.40 21.407 Fraxinus ornus 33.5 0.15 17.108 Robinia pseudoacacia 20.7 0.80 31.409 Pinus cembra 4.0 0.30 0.00 2.92

10 Fraxinus excelsior 7.8 0.10 7.6011 Pinus sylvestris 10.0 0.15 0.24 7.0812 Pinus sylvestris 12.2 0.05 1.56 4.7613 Fagus sylvatica 26.8 0.45 6.3214 Fagus sylvatica 13.3 0.40 2.0815 Robinia pseudoacacia 13.8 0.35 0.0016 Fraxinus ornus 10.8 0.30 14.8017 Quercus petraea 9.3 0.60 0.6018 Fagus sylvatica 25.5 0.80 0.0019 Robinia pseudoacacia 7.8 0.00 0.0020 Fraxinus excelsior 10.5 0.25 0.0021 Picea excelsa 18.2 0.20 0.00 0.0022 Fraxinus excelsior 15.8 0.30 24.023 Fraxinus excelsior 46.5 2.00 1.2024 Abies alba 1.75 0.15 0.00 0.00

Increase of defoliation, discoloration and the surface affected by ozone-induced symptoms between 2012 and 2013

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Estimation of PODY

PODY (nmolO3.m-2.s-1): accumulated stomatal ozone uptake above a species-specific threshold Y:

Estimation of PODY: DO3SE model

DO3SE model was applied with 2 hourly thresholds:

1 nmolO3.m-2.PLA.s-1 as recommended by UNECE (2010) 0 nmolO3.m-2.PLA.s-1 - Any O3 molecule entering into leaves may induce a metabolic response

(Musselmann et al., 2006)

DO3SE model was applied for:

Whole day Day hours from 08:00-20:00 (CET) Day hours with a global radiation > 50 W.m−2


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Species-specific parameterization

gmax: maximum stomatal conductance

fmin : minimum stomatal conductance

fphen , flight, ftemp, fVPD, fSWC are the variation in gmax with leaf age, irradiance, temperature, water vapour pressure deficit and soil water content.

Leaf-level stomatal conductance to water vapour (gsw) was estimated using the multiplicative model (Emberson et al., 2000) and the parameters suggested in UNECE (2010):

Estimation of PODy


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Results: Spearman’s coefficients

Analysis of exposure and flux-based ozone approaches

PODY is correlated with the occurrence and the severity of O3-induced symptoms.

AOT40 is stronger correlated with discoloration and defoliation, i.e. typical aspecific indicators.

Pinus cembra AOT40 A-POD0 A-POD1 B-POD0 B-POD1 C-POD0 C-POD1

C+1 0,285 0,671 0,539 0,567 0,497 0,569 0,470

C+2 0,269 0,650 0,552 0,545 0,482 0,553 0,466

Leaf loss 0,495 0,509 0,561 0,527 0,546 0,451 0,453

Discoloration 0,300 0,585 0,442 0,089 0,468 0,493 0,383A - Whole day; B - 08:00-20:00; C - hours with a GR > 50 W.m−2

Pinus halepensis AOT40 A-POD0 A-POD1 B-POD0 B-POD1 C-POD0 C-POD1

C+1 -0,167 0,332 0,436 0,230 0,331 0,233 0,270

C+2 -0,067 0,498 0,622 0,404 0,520 0,384 0,430

Leaf loss 0,187 0,218 0,145 0,241 0,186 0,252 0,261

Discoloration 0,375 0,498 0,504 0,477 0,496 0,477 0,489

Analysis of the best threshold

For all tree species, POD0 is better correlated with the occurrence and the severity of visible symptoms, except for Pinus halepensis (Y=1, detoxification capacity)

Analysis of the best time window

For all species, O3-symptoms are stronger correlated with PODY calculated for the whole day - Night-time O3 uptake may be physiologically stressful.


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Derivation of Clef from aspecific symptoms

Critical levels were derived as either the lowest PODY that induced an effect that was statistically different from the effect at zero PODY.

The CL is rounded up or down to the nearest whole number (functions are statistically significant p < 0.01).

A tree is considered as damaged when leaf loss exceeds 25% and the discoloration scoring higher than 2.

As an example:

A POD0 of ~ 15 mmol.m-2 PLA over one growing season has been provisionally identified for conifers.


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Derivation of Clef from specific symptoms

For the ozone-induced symptoms, we considered a tree as damaged when the affected surface of needles/leaves exceeds 25%.

As an example, a POD0 target value of 12 mmol.m-2 over one growing season has been identified for deciduous.

For the one-year old needles, a POD0 of 8 mmol.m-2 has been identified and of 12 mmol.m-2 for ozone sensitive conifers represented by Pinus cembra and Pinus halepensis.



A new automatic tool to map PODY

WRF-CHIMERE8 distribution maps (EUFORGEN)

Second step: the program extracts useful hourly data from the meteorological (WRF) and multi-scale chemistry-transport model (CHIMERE): ozone, meteorology and landuse data between 8am to 8pm, whole day or for global radiation > 50W.m-² over the domain.

Third step: for each tree species, the program applies the proper parameterization among 15 parameterizations (ICP manual, UNECE, 2010).

First step: from the distribution maps, the program extracts X,Y for 8 tree species.


For Fagus sylvatica, we have implemented a pre-selection to select grid points to apply two different parameterizations (Continental Central European beech & Mediterranean Europe beech).

A new automatic tool to map PODY

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Mapping POD0 in 2012 & 2013


POD0 (daily) in 2012POD0 (8-20h) in 2012

POD0 (daily) in 2013

Night (21h-7h) relative to the daily POD0

Fagus sylvatica = 14%Robinia pseudoacacia = 13%Fraxinus excelsior = 17%

Fagus sylvatica

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Mapping POD0 in 2012 & 2013


POD0 (daily) in 2012POD0 (8-20h) in 2012

Pinus halepensis

POD0 (daily) in 2013

Night (21h-7h) relative to the daily POD0

Pinus halepensis = 11%Pinus sylvestris = 17%Pinus cembra = 15%

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Validation of DO3SE parameterization


The measured ozone fluxes are compared with modelled stomatal fluxes (DO3SE model).

DO3SE model has not been extensively tested under Mediterranean conditions.

It was imperative that further evaluations should be performed.

FO3REST provides an opportunity to infer an evaluation of the DO3SE model parameterisation under “Mediterranean style” conditions for Mediterranean tree species. 4 locations: San Rossore & Castelporziano (Italy) and Puéchabon & Fontblanche (France)

Mediterranean tree species: Pinus halepensis, Quercus ilex and Pinus pinea.


Validation of DO3SE by EC campaigns

We measured vertical fluxes between vertical wind speed and gas concentration (O3, CO2, H2O) with observations 10 times per second:

'' ii CwF

Measurements of O3 fluxes by the micrometeorological Eddy covariance approach at forest canopy level.



Campaign at Castelporziano (Poster by Silvano Fares et al.) & Excursion

The Estate of Castelporziano covers 6000 ha, close to urban areas (25 km from Rome) exposed to polluted plumes loaded with tropospheric ozone.

This place is covered by natural Mediterranean vegetation: macchia and forest ecosystems (holm oak, mixed oaks, stone pine) distributed along the sea-inland belt.

Conditions compatible for micrometeorological work: flat area with homogeneously distributed vegetation.

A tower was equipped for flux measurements with stations for meteorological and plant physiological parameters.



A good agreement was found between the DO3SE outputs and measurements by Eddy-covariance.

The DO3SE parameterization was included in the new version of the UNECE mapping manual for ozone-risk assessment.

Continuous campaign during 4 months in 2011.

The study allowed a first validation of the stomatal flux model DO3SE (Fares et al., 2013).

The forest canopy is a relevant ozone sink with total ozone fluxes up to 10 nmol.m-2.s-1.

Comparisons of measured & modelled stomatal conductance showed that DO3SE underestimated of about 10 %.

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Conclusions & discussions

PODY is well correlated with O3-induced symptoms whereas AOT40 is stronger correlated with discoloration and defoliation, i.e. typical aspecific indicators (multiple causes).

An assessment based on phytotoxic O3 dose (PODY) and on real plant damage is more appropriate.

First observation in field at large scale of the better performance of PODY relative to AOT40.

The stomatal flux-based approach would be a useful tool for O3 risk assessment.

POD0 & POD1 were provisionally identified for sensitive forest trees.

Further field-based validation of O3 flux-effect relationships is required via epidemiological studies.

AOT40 inconsistent with forest condition: does not account for the different kinds of tree species, genotypes, forest types and site conditions.

To date, most experiments to establish biologically relevant plant responses have been performed under controlled conditions not representative of actual field conditions and the results may not provide realistic results for developing standards for protecting vegetation.

The main conclusions of this work:


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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 the JRC (Joint Research Centre).

life10 env/fr/208 adapting mediterranean forests to climate change and air pollution camille renou,...

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