Conservation of veteran trees within historical gardens (COVE): a case study applied to Platanus orientalis L. in central Italy

Abstract

Many veteran trees characterize the landscape of Mediterranean historical parks and gardens, representing unique values from ecological, cultural, social and historical points of view. The absence of natural regeneration is one of the main limits for their conservation. The main purpose of this research was to combine theoretical reasoning and practical solutions to maintain this rich tree heritage. A protocol based on an interdisciplinary approach was developed and applied to the plane trees (Platanus spp.) within the formal garden of Villa Lante of Bagnaia (Viterbo, Italy). The COVE analysis consisted of the following four phases: i) selection of veteran tree species after gathering and comparing historical information; ii) taxonomic identification based on morphological and molecular analyses; iii) tree inventory in GIS environment; and iv) vegetative propagation by woody cuttings and micropropagation. The plane trees surveyed grow on three level terraces and significantly differ in size and phytosanitary conditions according to their topographic position. Molecular analyses indicated a genetic uniformity for the plane trees studied and their memberships to P. orientalis species. This evidence suggests that all specimens belong to the original planting dating back to 1576. All individuals showed a high susceptibility to the pathogen Ceratocystis platani even though so far there is no evidence of canker stain attack. Woody cuttings from the most vigorous individual showed 80% rooting rates. In vitro micropropagation using node culture approach provided healthy plants, maintaining the genetic fidelity respect to mother plant after three years of culture. The obtained results represent a successful example of integrated research for germplasm conservation and management of veteran trees within historical villas in Central Italy.