Guidelines suistainable urban forestry ROMA_Eng

23 / 55

21
in the Villa dei Quintili, in the Regional Park of Appia Antic ). In addition to the aesthetic value
these interventions also favour the preservation of germplasm and genetic resources .
Following some general principles to consider when choosing species so that the intervention is
aimed for: capture of CO2, mitigation of air and noise pollution, increase of biodiversity. Indications
regarding the species that can cause allergy problems, and the use of which must therefore be carefully
evaluated, will be also provided.
1.4.1 Criteria for the selection of species appropriate to carbon sequestration
The creation of new forest areas is one of the measures envisaged to contrast climate chang .
Forests are in fact big sink where carbon accumulates naturally. Private companies that plants a certain
number of trees, especially in urban and periurban areas, to offset emissions from some of their
activities are increasin .
A key aspect for the fixation of carbon in the urban environment is therefore the choice of species
that are suited to perform this function as well as the environmental conditions of the site where they
will be planted. Specifically to maximize carbon sequestration the following criteria should be
adopted:
• to favour fast-growing and long-lived species;
• to favour species that reach large dimensions at maturity;
• to favour species resistant to disease and, in urban areas, to the stress related to pollution. In
any case it is important to keep the tree cover, replacing quickly dead individuals;
• to favour species that can reproduce itself and then to renew economically the plantation or to
expand spontaneously in areas around;
• to favour fast-growing pioneer species in areas with anthrosols rich in detritus or otherwise
thin soils;
• choose different species, but with the same management needs (irrigation, pruning,
fertilization, etc.). In particular to give preference to species with low maintenance
requirements and which require minimal pruning;
• to preserve the carbon sequestered in the soil reducing conditions affecting the roots: the
amount of carbon stored in the soil is in fact 3 times higher than that present in the
vegetation; then even small changes can significantly impact the ability to sequester carbon;
• to achieve forestation interventions on surfaces as wide as possible, so as to be planted a
greater number of plants.
Species which can be used to maximize the role of CO2 sequestration are:
• poplars (in Rome Populus alba, P. nigra , P. canescens are indigenous), thanks to their rapid
growth. But they may not be suitable in urban environment both as a source of allergies and
because potentially subject to collapses. Again they require a large supply of water (therefore
it is advisable to plant them in proximity of watercourses );
• white willow (Salix alba), a fast-growing species suitable for installations in proximity of
watercourses. But it can cause allergies;
• linden (Tilia cordata, T. platyphyllos , T. x vulgaris), species typically large and long-lived.
Especially the common lime tree (T. platyphyllos), not indigenous in Rome, is widely used in
the tree-lined road , as well as being aesthetically pleasing, has very fragrant flowers;
• birch (Betula pendula), other fast-growing species, but more suited to temperate climates.
Moreover, it is not among the native species in Rom and can cause allergies;
• maples (Acer campestre, A. monspessulanus , A. platanoides, A. pseudoplatanus), for their
growth rate, especially curly maple ( A. platanoides) which is not native to Rome and is
demanding about condition of soils. While A. campestre and A. monspessulanus are more
31 See:
32 The Kyoto Protocol provides the possibility for signatory countries to use carbon absorption owing to implementation of activities of Land
Use, Land Use Change and Forestry for the achievement of objectives established by the Protocol.
33 Examples include the Life project GAIA ("Green Areas Inner -city agreement") in Bologna, which involves the planting of trees in
existing areas and the creation of new green spaces and tree-lines through the contribution of private companies; they will use this
contribution to offset emissions resulting from their activities; the aforementioned project Life "Rome for Kyoto" which provided for the
reforestation of public green area of 12 hectares falling within the Riserva Naturale della Valle dei Casali; the LIFE + Carbomark
(Improvement of policies toward local voluntary carbon markets for climate change mitigation ) in Veneto and Friuli Venezia Giulia, whose
overall objective is to promote a local market for carbon credits, on a voluntary basis, to strengthen policies EU concerning the fight against
climate change, including the planting of trees in urban areas.
34 Paci M., 2011. Ecologia forestale. Elementi di conoscenza dei sistemi forestali applicati alla selvicoltura. Edagricole.
35 For example “cupresdsine” poplars were planted in the Aniene Valley Nature Reserve.
36 A spontaneous formation lives in the SIC Caldara di Manziana, near Rome, but it is linked to particular soil and microclimate conditions.