Dimensional and genetic characterization of the last oriental plane trees (Platanus orientalis L.) of historical sites in Lazio (central Italy)

Abstract

In central Italy, Platanus orientalis L. specimens characterize many gardens in urban and suburban villas. In this research, centuries-old oriental plane trees were studied in different historical sites of Lazio according to the COVE (COnservation of VEteran trees) multidisciplinary model. Historical sources, morphological and dendro- metric aspects, crown quality, genetic traits of each specimen, as well as their susceptibility to the canker stain disease, were investigated. Platanus orientalis was clearly distinguished from P. occidentalis and their hybrid P. acerifolia through molecular tools. UPGMA analysis based on SSR and ISSR molecular markers clustered the plane trees in different sub-groups, probably according to the different sites of sampling. These findings, sup- ported by historical and morphological data collected in the considered sites, showed that almost all the trees studied are a small remnant of those planted in the period running from the second half of XVI century to the first decades of XVII century. Plant health conditions diverge within and among the sites inspected. Past-prolonged severe pruning treatments of trees located near the main monuments affected their growth, causing faster and premature senescence. However, the management of historical gardens has so far led to an efficient prevention of Ceratocystis platani introduction, spread and establishment. This study highlights the importance of a multidis- ciplinary approach to interpret the present status of the ancient tree asset within historical sites and let the past become a lesson for the future in a broader scenario of conservation and management of cultural heritage. 1. Introduction Platanus orientalis L., commonly named oriental plane tree (OPT), is a tertiary flora relict species spreading from the Caucasus to the Himalaya as up to the Mediterranean; in southern Italy, there are small patches of forest stands (Campania, Calabria and eastern Sicily) (Rinaldi et al., 2019), while Rosati et al. (2015) consider this species as an archaeophyte. During the Roman era, in the Italian landscape the OPT was widely cultivated as an ornamental tree of particular value in urban and peri- urban context. Neglected during the medieval period, when the life was marked by difficulties and calamities including famine, plague, and war, OPT was reintroduced in the Italian peninsula only in the XIV century (Di B ́erenger, 1965), making this species one of the protagonists of gardens within Italian villas until the XVII century. In this period, its fortune mirrored the widespread use during classical Greek and Roman times, once again for their beauty and shadow. In addition, for the owners, OPT represented a real status symbol (Grimal, 1990; Schieve- nin, 2014; Tosco, 2018). It is worth mentioning that in several historical sites OPTs were planted according to geometric patterns in harmony with the architectural elements, as Pliny the Elder already recom- mended in his Naturalis historia (Tosco, 2018). Today, due to various events, in some sites those trees no longer exist (i.e., Horti Farnesiani in Rome and Palazzo Giardino in Parma) (Cogotti, 2018; Mambriani, in verbis). Nevertheless, ancient specimens within monumental complexes, set up between the XVI to the XVII century, are still present in Lazio region. Probably, the pedoclimatic characteristics of these areas enabled this hygrophilous and fast-growing species to reach majestic shapes (Rix and Fay, 2017). Today the conservation of ancient or rare germplasms is shared as a pivotal challenge for cultural assets (Abbate et al., 2020; Mattioni et al., 2020; Petruccelli et al., 2021). No specific management protocols have been designed for veteran trees in these historical sites. * Corresponding author. E-mail addresses: ciaffi@unitus.it (M. Ciaffi), vettrain@unitus.it (A.M. Vettraino), enrica.alicandri@unitus.it (E. Alicandri), antonio.tomao@unitus.it (A. Tomao), francesca.adducci@studenti.unitus.it (F. Adducci), elkuz@unitus.it (E. Kuzminsky), agrimi@unitus.it (M. Agrimi). Contents lists available at ScienceDirect Urban Forestry & Urban Greening journal homepage: www.elsevier.com/locate/ufug https://doi.org/10.1016/j.ufug.2022.127506 Received 18 November 2021; Received in revised form 25 January 2022; Accepted 7 February 2022