River floods
The destructive flood caused by the river Sûre, which suddenly devastated the historic park on July 15, 2021, is far from being exceptional. Memorable floods have been well recorded for a long period, from the 16th to the 20th century. Those floods that occurred on February 4, 1892, and on January 16, 1918, destroyed the enclosure walls of the garden.
Climate change is likely to increase the frequency of flooding, while periods of prolonged drought might intensify at the same time, thus affecting the park’s oldest and weakest trees.
Indeed, many beeches, hornbeams, chestnuts and ash trees begin to show signs of weakening or dieback.
Phytosanitary conditions
The recent appearance of new fungal pathogens and invasive parasites is an alarming challenge for the park’s phytosanitary condition in the 21st century.
Ash dieback disease (Chalara fraxinea), a phytopathology native to East Asia, currently causes necrosis and dieback of nearly all the ash trees of the park.
The chestnut leaf miner (Cameraria ohridella), a devastating caterpillar that has recently appeared, causes early drying of the foliage by the end of summer.
Adding to that, fungal diseases (Cylindrocladium buxicola, Volutella buxi) and a caterpillar imported from Asia in the early 21st century (Cydalima perspectalis) have infested all the boxwood plantations.
Plant stratification and microclimate
Except for the two parterres the park essentially consists of formal groves, structured by alignments of trees and low hedges along the paths. Apart from a few old specimen trees dating back to the 1920s most trees were planted in the late 1940s. They present a loose and uniform layer, which results from thinning wood cuts, - a type of forestry practice which consists in lowering the density of the trees in favor of those left in place.
The dense underwood layer which initially was formed by thickets of shrubs has disappeared due to annual clearing which has prevented natural regeneration. The herbaceous layer of the undergrowth (e.g. Anemone nemorosa, Anemone ranunculoides, Ranunculus ficaria, Arum maculatum, Corydalis cava) has likewise declined following the regular removal of dead leaves in autumn, which are nutritious and protective for the bulbs, rhizomes and tubers. The microclimate of the park has thus decreased in freshness and humidity.
Horticultural, ecological and sustainable park management
The historic park of Echternach faces multiple challenges concerning ways of preserving, maintaining and transmitting this precious heritage to future generations.
On an ecological level focused and selective interventions should be henceforth made in order to encourage spontaneous and natural regeneration of the flora, as well as to foster the biodiversity of the fauna.
On a horticultural and aesthetic level replanting trees, shrubs and hedges becomes paramount to redefine the structural pattern of walks and vistas, and to densify the vegetation of the groves. It will also be necessary to prune and progressively replace a certain number of trees for the sake of visitors’ security, and in the interest of the historic park’s restoration. All these interventions are bound to be made with respect to the environment and the architectural and archeological value of the park, which is listed a national monument of cultural significance.
Slate plaque, (pavilion side facing the Sauer River)
The box tree moth (Cydalima perspectalis)
The horse-chestnut leaf miner (Cameraria ohridella)
Yellow anemone (Anemone ranunculoides)
Hollowroot (Corydalis cava)