VILLA ADA URBAN PARK (ROME, ITALY)

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removed by trees in a historical urban park in the centre Rome, Italy (Villa .... [2] Buccolieri R., Mohamed Salim S., Leo L.S., Di Sabatino S., Chan A., Ielpo P., ...
UNIVERSITA’ DEGLI STUDI DE L’AQUILA

Ecosystem services: removal of particulate matter by trees in an urban park of Rome, Italy F. Manes*1, E. Salvatori1, V. Silli12, G. Incerti1, C. Ricotta1, S. Mereu1, L. Fusaro1 1 Department of Environmental Biology, La Sapienza University of Rome, Italy. 2 Department of Environmental Sciences, University of L’Aquila, Italy [email protected]

RATIONALE AND OBJECTIVES In the last few hundred years, there has been a relevant shift of people away from rural areas into cities, that have resulted in increased urbanization. Human activities in urban conurbations are inevitably concentrated in a relatively small area, and most of them are accompanied by emissions of air pollutants and greenhouse gases, which posing a significant risk to human health and wellbeing [1]. Among these air pollutants, particulate matter (PM) represents one of the most important and widespread treat, responsible for a relevant impact both on health and on the whole environment (including plants and cultural heritage). There is, therefore, the need for targeted, effective actions aimed at reducing PM concentrations at the urban and regional scale. Some studies of CFD (Computational Fluid Dynamic) describing metodologies to model PM distribution in urban environment, show the inconsistencies between model results and real case measures [2]. In this context, urban forests are particularly important because, beside their well known aesthetic and recreational benefits, they provide a series of important ecosystem services, such as improvement of air quality by removal air pollutants [3] [4]. Many studies have provided quantitative estimates of air pollutant removal by trees and shrubs in different urban areas [5] [6]. As an example, in Rome a significant positive impact on human health (reduction of mortality and morbidity) has been estimated as a result of tropospheric ozone removal by woody vegetation (evergreen broadleaves, deciduous broadleaves and conifers) [7]. Here we present the results of a study implemented in the frame of the Project HE.R.E.P.L.U.S. (HEalth Risk from Enviromental Pollution Levels in Urban Systems, EU FP7). Our aim was to provide a first estimate of the amount of Particulate Matter (PM10) removed by trees in a historical urban park in the centre Rome, Italy (Villa Ada) and to assess experimentally the concentration of the PM in selected vegetated and bare soil areas within the park, at the same distance from the SS4 road.

a) Municipality of Rome, Italy

STUDY AREA: VILLA ADA URBAN PARK (ROME, ITALY) Legend Evergreen broadleaves (Quercus ilex prevalent) Deciduous broadleaves (Quercus spp prevalent) Conifers (Pinus pinea prevalent)

b) Detail: Villa Ada Urban Park

The Villa Ada Urban Park is located in the centre of Rome (Fig. 1). It is an historical Villa, in which woody vegetation covers 116.37 ha: 38.5 ha are represented by evergreen broadleaves (Q. ilex prevalent), 35.7 ha by deciduous broadleaves (Quercus spp. prevalent) and 42.2 ha by conifers (Pinus pinea prevalent). The distribution of these main tree functional groups has been derived by supervised classification of a Landsat 5 TM image (from 21 July 1999), with a spatial resolution of 30 x 30 m, as described in Manes et al. (2012) FIELD CAMPAIGNS FOR THE ESTIMATION OF VEGETATION REMOVAL CAPACITY (Villa Ada, Rome , 2012)

Fig. 1. Urban vegetation of the Municipality of Rome (city limits outlined in black): a) distribution of the three tree functional groups analyzed in this study within the metropolitan area; b) position and tree cover of the Villa Ada urban park.

ESTIMATION OF PM10 REMOVAL BY URBAN TREES

Particles concentration measurements were carried out by two OPCs (Optical Particles Counters, Aerocet 531, MetOne, USA). Micrometeorological parameters, in particular wind speed and wind direction, were recorded by a dedicated weather station (WS2800, LaCrosse, Swiss). The experimental campaign was carried out in the eastern part of Villa Ada, near the road SS4 characterized by high levels of vehicular traffic. Measures were carried out in vegetated and bare soil areas, at the same distance from the SS4 road. PM data were corrected for air water content [8] and processed by Statistica software, in order to perform descriptive and ANOVA analyses (STATISTICA, Statsoft, USA).

(HEREPLUS Project, 2003)

Wind speed (ms-1)

2 1.5 1 0.5 0 17.05 17.07 17.09 17.11 17.13 17.15 17.17 17.19 17.21 17.23 17.25 17.27 17.29 17.31 17.33 17.35 17.37 17.39 17.41 17.43 17.45 17.47 17.49 17.51 17.53 17.55 17.57 17.59 18.01 18.03 18.05 18.07 18.09 18.11 18.13

The seasonal PM10 deposition to the main tree functional groups in the Villa Ada park (“real case”), was estimated for the year 2003 following the equations of Nowak (2004). For each functional group, the Leaf Area Index data of the HEREPLUS Project were used. The seasonal PM10 deposition that would have occurred if bare soil would replace woody vegetation in all locations (“bare soil scenario”) has been also estimated. The ratio between vegetation/bare soil PM10 deposition show a conspicuous contribution of all the three vegetation leaf-types in removing PM10 from the urban atmosphere. In particular, during the extremely dry year 2003, evergreen broadleaves played the most effective role, overcoming conifers and deciduous broadleaves in removing PM10

2.5

a) Wind speed, during measurements campaign 0.04 0.035

(conifers)

PM10 concentration (mgm-3)

0.03

vegetated soil bare soil

0.025

Deciduous broadleaves

Conifers

0.02 0.015 0.01

16

0.005 0 17.05 17.07 17.09 17.11 17.13 17.15 17.17 17.19 17.21 17.23 17.25 17.27 17.29 17.31 17.33 17.35 17.37 17.39 17.41 17.43 17.45 17.47 17.49 17.51 17.53 17.55 17.57 17.59 18.01 18.03 18.05 18.07 18.09 18.11 18.13

Vegetation/Bare Soil PM10 deposition

18

Evergreen broadleaves

14

Sample time

b) Trend of PM10 measurements

12 10

100

8

% abatement by vegetation (PM10)

80 60 40

6

20 0

4

-20 -40 -60

2

-80 -100

0 Winter

Spring

Summer

Fall

YEAR 2003

Fig. 3. Ratio between PM10 deposition to each tree functional group (“real case”), and PM10 deposition to bare soil (“bare soil scenario”), in the Villa Ada urban park, simulated for winter, spring, summer, fall, and the whole year 2003.

Aerocer 531 and weather station, LaCrosse WS2800

Results of the experimental campaign point out the higher capability of the vegetated soil (characterized by trees -mainly conifers- and hedges) to abate airborne particulate, compared to the bare soil (with only herbaceous plants). ANOVA analysis, performed on concentration data of PM10 showed significant differences between the two data series (bare and vegetated soil). The percentage of abatement due to vegetated soil ranges from 12.5% to 66.6 %, according to our other studies on PM distribution carried out in Mediterranean Forest (Castelporziano Estate, Italy). Wind speed, in the site of the campaign, ranged from 0 to 2 ms1; in some cases it is interesting to observe a drop down of PM10 concentration at wind peaks.

c) Percentage of PM10 abatement Fig. 2. Concentrations of PM10 measured in the experimental site: a) trend of wind speed measured during the campaign; b) trend of measured PM10 concentrations in bare and vegetated soil; c) percentage of PM10 reduction (vegetated compared to bare soil)

CONCLUSIONS The results of this study confirm the effective potential of trees and green barriers (shrubs and hedges) in limiting and removing particulate matter, thus highlighting the functional role of the urban forest, and the need to preserve, as well as to increase, urban vegetation. These consideration may be useful also for a sustainable urban planning, since regional and municipal environmental planning officials require innovative, reliable and effective tools in reducing urban air pollution, to be integrated with the standard regulatory measures such as traffic limitation. In the EC political context, Green Infrastructures represent a multifunctional resource capable of delivering a wide range of environmental benefits and services. Further studies are in progress in aim to deepen the potential role of vegetation (in particular trees and green barriers as shrubs and hedges) in removing air pollutants, improving air quality and corresponding ecosystem services, especially in high populated metropolitan areas.

REFERENCES [1] Martuzzi M., Mitis F., Iavarone I. and Serinelli M. Health impact of PM10 and ozone in 13 Italian cities. Wold Health Organization, Regional Office for Europe, Copenhagen, Denmark (2006) [2] Buccolieri R., Mohamed Salim S., Leo L.S., Di Sabatino S., Chan A., Ielpo P., de Gennaro G., Gromke C.. Analysis of local scale tree-eatmosphere interaction on pollutant concentration in idealized street canyons and application to a real urban junction. Atmos Environ, 1702-1713, 45 (2011). [3] Manes, F., E. Salvatori, G. La Torre, P. Villari, M. Vitale, D. Biscontini, and G. Incerti. Urban green and its relation with air pollution: ecological studies in the Metropolitan area of Rome. Italian j Pubblic Health-UK, 278–283, 5 (2008) [4] Jim C.Y., and Chen W.Y.. Assessing the ecosystem service of air pollutant removal by urban trees in Guangzhou (China). J Environ Manage, 665–676, 88 (2008) [5] Alonso R., Vivanco M.G., González-Fernández I., Bermejo V., Palomino I., Garrido J.L., Elvira S., Salvador S., and Artíñano B.. Modelling the influence of peri-urban trees in the air quality of Madrid region (Spain). Environ Pollut, 2138-2147, 159 (2011) [6] Tallis M., Taylora G., Sinnett D., Freer-Smith P.. Estimating the removal of atmospheric particulate pollution canopy of London, under current and future environments Landscape and Urban Plan, 129– 138, 103 (2011) [7] Manes F., Incerti G., Salvatori E., Vitale M., Ricotta C., Costanza R.. Urban ecosystem services: tree diversity and stability of tropospheric ozone removal. Ecol. Appl, 349–360, 22 (2012) [8] Sioutas C., Kim S., Chang M., Terrell L. L., Gong Jr. H.. Field evaluation of a modifed DataRAM MIE scattering monitor for real-time PM2.5 mass concentration measurements. Atmos Environ, 4829-4838, 34 (2000)