Archaeological-environmental issues

The problematic coexistence of the botanical features of the Oppian Hill and the underground archaeological structures of Trajan’s Baths and the Domus Aurea is well known.

The plants on the Trajanic Terrace date to the arrangement designed in several stages by A. Munoz in the 1930s and include:

Ulmus campestris (elms) facing the Colosseum, rows of Pinus pinea (umbrella pines), Quercus ilex (holm oaks) and Cupressus sempervirens (cypresses) flanking the wide avenue which cuts the Trajanic bath complex in two, completely ruining the visual unity of the archaeological system.

Elevation – SSBAR Archive

Elevation – SSBAR Archive

The area’s vegetation is currently in an extremely poor condition and some of the trees present pathogenic alterations with the consequent risk of problems to the plant or the detachment of dead branches. It was therefore essential to monitor the situation in detail. The botanical recording of 2011 showed the significant changes that had taken place over a period of six years and allowed us to identify interventions that could no longer be put off for the safety of visitors to the park, the trees and the monument. The 2012 update shows the most recent interventions.

Excerpt from the botanical recording – SSBAR Archive

Excerpt from the botanical recording – SSBAR Archive

The layer of earth weighing on the archaeological structures beneath

Interaction between plants and masonry – SSBAR Archive

Interaction between plants and masonry – SSBAR Archive

is on average 1.70 m thick: this entails a significant weight but is at the same time insufficiently thick to avoid the problems caused by the presence of the roots of the trees planted on the terrace. The older trees, which have reached their maximum aerial growth and root system expansion are extremely dangerous given the weight of the plant biomass, an added weight of several hundredweight only partially distributed by the roots.

Tree-felling work – SSBAR Archive
Tree-felling work – SSBAR Archive

These penetrate into the structures, creating cracks or enlarging those already present, in part due to the chemical action of the root exudates which can dissolve mortars. Exudates – chemical compounds released by roots especially in proximity to the root tips and older parts – react with mortar, causing it to dissolve and disintegrate, a situation worsened by the inevitable erosion by atmospheric agents. Over the years, in a slow but inexorable process, the mortar holding the monument together is lost, and thus the monument itself as well.

Tree-felling work – SSBAR Archive

Tree-felling work – SSBAR Archive

One of the first interventions carried out, in collaboration with the Rome Ufficio Giardini (Parks Authority), was to fell an Ulmus campestris (elm) affected by Dutch elm disease, a disease caused by a fungal parasite that was compromising its stability.

On the wall faces and tops, spontaneous plants become weeds.

In the West Wing of the Domus Aurea, above the rooms running north-south and forming the edge of the building complex – the so-called Little Barracks” – the presence of invasive plants was particularly serious. This made it necessary to carry out a mechanical and chemical weeding intervention.

Detail of the analysis of plants and rehabilitation interventions in the area of the so-called “Little Barracks” – July 2011 – SSBAR Archive

Detail of the analysis of plants and rehabilitation interventions in the area of the so-called “Little Barracks” – July 2011 – SSBAR Archive

Before interventions – SSBAR Archive

Before interventions – SSBAR Archive

We can speak of weeds in accordance with the definition

“objectionable plants in the sense of plant species growing where they are not desired”

Terminology Committee of the Weed Science Society of America

This is a particularly appropriate definition of plants in archaeological areas where, if not adequately controlled, weeds may seriously compromise the delicate equilibrium and create situations of conflict: between the need to safeguard the most significant features of the flora

During interventions – SSBAR Archive

During interventions – SSBAR Archive

from an environmental point of view or that of their historical significance, and the need to conserve unique archaeological structures, on which the flora has a detrimental effect. In these contexts, plants that in other cases might be important landscape features become “weeds”.

Mechanical removal (mowing) is neither fully practicable given the impossibility of extracting roots from walls nor effective since, with rare exceptions, regrowth is fairly rapid.

After interventions – SSBAR Archive

After interventions – SSBAR Archive

The cutting operation itself may be damaging and should be carried out with the necessary precautions to avoid causing trauma due to tears. Chemical interventions present other difficulties: the need to use effective products that do not interfere with the lithotypes making up the archaeological mortars, that are safe for operators to use and that do not cause environmental pollution.

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L'autrice

Gabriella Strano

Gabriella Strano

Landscape architect. She has worked for the Soprintendenza Speciale per i Beni Archeologici di Roma since 1978 on the maintenance and enhancement of green areas on behalf of the Parks Authority. She was director of the works in the green areas in the Natural and Archaeological Park at Portus and participated in the planning of landscape projects. In 2011, she became a member of the Domus Aurea’s technical staff.

8 thoughts on “Archaeological-environmental issues

  1. Egr. dr.ssa Strano,
    Frequento il parco del Colle Oppio da 30 anni e capisco dal vs. sito le problematiche relative alle infiltrazioni e ai danni causati dalle piante. Ho peraltro notato che in tutta la zona molti tombini di scolo delle acque piovane sono da anni per mancanza di manutenzione otturati o completamente ricoperti dal fango. Quando piove l’acqua e il fango si spargono dapertutto. Da profano chiedo: oltre agli interventi massicci per risolvere il problema delle infiltrazioni, non sarebbe il caso di ripristinare la funzionalità di questi scoli? Vi sarebbe certamente meno acqua passibile di colare giù nel monumento.
    Saluti,
    Andrea Pepe

  2. Sono il ragazzo della foto che ha abbattuto l’olmo sopra in foto.
    mi piacerebbe ricevere da lei se e’ possibile altre foto.
    per il momento la ringrazio. il giardiniere.

  3. Gentile signor Pepe, il problema che Lei pone è di grande importanza. Il piano di campagna della terrazza Traianea, con le sottostanti presenze archeologiche, si trova ad una quota più bassa rispetto a quella della strada e delle aree circostanti. Questo determina che il percolamento delle acque reflue di superficie, se non opportunamente convogliate in un sistema fognario, ovviamente si riversino verso i punti più bassi. Solo in parte queste vengono assorbite dal manto erboso e, soprattutto nel periodo invernale, quando l’evapotraspirazione è inferiore, aumentano l’indice di infiltrazione d’acqua nel sito archeologico sottostante. Questo è stato anche il motivo per cui è stato eliminato il sistema di irrigazione del prato del parco del Colle Oppio sovrastante la domus Aurea. Nel progetto di isolamento igrotermico è previsto anche un confinamento perimetrale dell’area per ovviare all’incidenza di tali fattori “esterni” e una rete di smaltimento immediato dell’acqua eventualmente in esubero in seguito ad accadimenti metereologici.
    Ci auguriamo anche noi il risanamento del sistema di captazione delle acque di superficie, tombini e caditoie stradali per intenderci, annoso problema della città di Roma.

  4. Pingback: ROMA ARCHEOLOGIA: Fernando Lucchese & Erika Pignatti, “La vegetazione nelle aree archeologiche di Roma e della Campagna Romana,” Quad. Bot. Amb. Appl., 20-2 (2009), [PDF] pp. 3-89. | Rome - The Imperial Fora - Archaeological News & Rel

  5. complimenti ed auguri di buon lavoro.
    ho letto l’articolo sul national geographic di questo mese e da lì mi sono incuriosita e mi è piaciuto molto leggere del lavoro che state facendo e che sicuramente porterà grandi soddisfazioni per voi, ma anche per l’Italia.

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