Combining the Conservation of Biodiversity with The
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sustainability Article Combining the Conservation of Biodiversity with the Provision of Ecosystem Services in Urban Green Infrastructure Planning: Critical Features Arising from a Case Study in the Metropolitan Area of Rome Giulia Capotorti, Eva Del Vico *, Ilaria Anzellotti and Laura Celesti-Grapow Department of Environmental Biology, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy; [email protected] (G.C.); [email protected] (I.A.); [email protected] (L.C.-G.) * Correspondence: [email protected]; Tel.: +39-06-4991-2420 Academic Editors: Karsten Grunewald and Olaf Bastian Received: 5 August 2016; Accepted: 15 December 2016; Published: 23 December 2016 Abstract: A large number of green infrastructure (GI) projects have recently been proposed, planned and implemented in European cities following the adoption of the GI strategy by the EU Commission in 2013. Although this policy tool is closely related to biodiversity conservation targets, some doubts have arisen as regards the ability of current urban GI to provide beneficial effects not only for human societies but also for the ecological systems that host them. The aim of this work is to review the features that should be considered critical when searching for solutions that simultaneously support biodiversity and guarantee the provision of ecosystem services (ES) in urban areas. Starting from a case study in the metropolitan area of Rome, we highlight the role of urban trees and forests as proxies for overall biodiversity and as main ecosystem service providers. We look beyond the individual functional features of plant species and vegetation communities to promote the biogeographic representativity, ecological coherence and landscape connectivity of new or restored GI elements. Keywords: biogeographic representativity; connectivity; ecological coherence; European Green Infrastructure Strategy; urban forests; urban trees 1. Introduction The European GI Strategy defines green infrastructure (GI) as a “strategically planned network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services” [1]. GI consists of “spatially or functionally connected areas which maintain ecological coherence as an essential condition for healthy ecosystems”, and contemporarily presents an added value that derives from the potential to attract investments in natural capital to strengthen the ability of ecosystems to deliver multiple goods and services that benefit human societies [2]. Since its adoption in 2013, the European GI Strategy has attracted great interest across EU Member States, stimulating the proposal, planning and implementation of a large number of GI projects at both the landscape and the local scale [3], with the latter involving above all urban and peri-urban areas [4–7]. Unlike landscape scale designs in rural settings, those conceived for local scale GI in urban contexts have been addressed mainly at enhancing the provision of ecosystem services (ES) and the cost-effectiveness of such interventions, while considering the health of ecosystems, i.e., biodiversity in its multiple aspects, just a secondary and/or approximate goal [5,8,9]. This applies to several case studies that have focused on ways of greening grey infrastructures, e.g., by means of green roofs and green walls, or on increasing the provision of green spaces without considering the environmental setting within which the cities lie [10,11]. Sustainability 2017, 9, 10; doi:10.3390/su9010010 www.mdpi.com/journal/sustainability Sustainability 2017, 9, 10 2 of 17 Theoretical frameworks that effectively incorporate biodiversity conservation into GI are being promoted to overcome these restrictions. They are drawing the attention of researchers, practitioners Sustainability 2017, 9, 10 2 of 17 and decision-makers to structural and functional connectivity [12], to the quality of the surrounding urban matrixTheoretical [13], to frameworks native biodiversity that effectively [14], andincorporate to species, biodiversity habitats conservation and ecosystems into GI of are conservation being importancepromoted [15 to]. overcome The need these remains, restrictions. however, They toare build drawing the the evidence attention base of researchers, required topractitioners ensure that GI projectsand aredecision-makers effectively biodiversity-oriented to structural and functional and aptlyconnectivity fitted to[12], local to the environments quality of the [ 16surrounding]. Inurban keeping matrix with [13], to an native operational biodiversity perspective, [14], and to the species, aim of habitats this work and ecosystems is to provide of conservation an overview of the concreteimportance features [15]. The that need should remains, be consideredhowever, to buil whend the searching evidence forbase solutions required to that ensure simultaneously that GI projects are effectively biodiversity-oriented and aptly fitted to local environments [16]. support biodiversity and guarantee the supply of ES in urban areas. In particular, the results of this In keeping with an operational perspective, the aim of this work is to provide an overview of overview represent the basic ecological knowledge underlying the ongoing development of pilot urban the concrete features that should be considered when searching for solutions that simultaneously GI projectssupport in biodiversity the metropolitan and guarantee area of th Rome.e supply These of ES projectsin urban haveareas. been In particular, commissioned the results by of the this Italian Ministryoverview for the represent Environment the basic to ecological start implementing knowledge theunderlying European the GIongoing Strategy, development and consequently of pilot the relatedurban Action GI projects 6 of the in EUthe Biodiversitymetropolitan area Strategy, of Rome. at the These national projects level. have Onbeen the commissioned one hand, we by providethe an overviewItalian Ministry of the literaturefor the Environment regarding theto varyingstart implementing performance the ofEuropean urban forests GI Strategy, and trees and in ES provision;consequently on the the other related hand, Action we highlight 6 of the EU the Biodiversity evidence availableStrategy, at regarding the national the level. features On the that one play a criticalhand, role we in provide the conservation an overview of of urban the literature plant diversity. regarding Accordingly, the varying performance we also identify of urban and forests discuss an arrayand of differenttrees in ES actions provision; that on allow the plantother hand, diversity we highlight values and the theevidence provision available of ES regarding to be combined. the features that play a critical role in the conservation of urban plant diversity. Accordingly, we also The conclusions point to the actual and expected impact of these findings at the broader national and identify and discuss an array of different actions that allow plant diversity values and the provision European levels. of ES to be combined. The conclusions point to the actual and expected impact of these findings at the broader national and European levels. 2. Materials and Methods As2. Materials recently and proposed Methods for the implementation of the European Biodiversity Strategy for 2020 [17], actual vegetationAs recently cover proposed can befor consideredthe implementation as an effective of the European operational Biodiversity proxy Strategy whenoutlining for 2020 [17], overall ecosystemactual complexityvegetation cover [18]. can Concurrently, be considered plant as an communities effective operational and plant proxy species when are outlining widely overall recognized as beingecosystem among complexity the main [18]. providers Concurrently, of ES in plant urban communities areas, especially and plant in species the form are widely of forests recognized though also as isolatedas being trees among [19 the–21 main]. For providers these reasons, of ES in urban we analyzed areas, especially specific in featuresthe form of forests trees andthough forests also that may,as besides isolated being trees [19–21]. able to For deliver thesemultiple reasons, we ES, analyzed be critical specific to the features quality of trees of natural and forests and that semi-natural may, besides being able to deliver multiple ES, be critical to the quality of natural and semi-natural ecosystems in urban contexts. The city of Rome, a metropolis in Mediterranean Europe, was adopted ecosystems in urban contexts. The city of Rome, a metropolis in Mediterranean Europe, was adopted as a case study (Figure1). The city covers an area of 345 km 2 and represents the central urban sector of as a case study (Figure 1). The city covers an area of 345 km2 and represents the central urban sector 2 the municipality,of the municipality, which which covers covers an area an area of approximately of approximately 1300 1300 km km.2. FigureFigure 1. Study 1. Study area. area. Location Location ofof thethe urbanurban sector of of Rome Rome (central (central Italy) Italy) within within the municipal, the municipal, metropolitanmetropolitan and and regional regional administrative administrative boundaries. boundaries. Sustainability 2017, 9, 10 3 of 17 Sustainability 2017, 9, 10 3 of 17 The overall approach adopted in the present work is shown in Figure 2. The overall approach adopted in the present work is shown in Figure2. Figure 2. OverallOverall approach approach adopted