engleski

HORTICULTURAL HERITAGE PRESERVATION ON LOKRUM ISLAND, A SPECIAL RESERVE OF FOREST VEGETATION: VALUES AND PRESSURES?

The introduction of alien species of plants that have always attracted attention because of their attractiveness is a very old tradition in the Dubrovnik area. The first record was left by Filip de Diversis in the “Description of Dubrovnik” from 1440. On the island of Lokrum most alien species were planted during the time of Emperor Maximilian (1832-1867), who then formed ornamental gardens in the part of the island that today, according to the National Classification of Habitats, includes habitat types: intensively maintained parks within the settlement, extensively maintained parks within the settlement, parks and arboretums outside of populated areas. This is evidenced in the inventory of species by botanist Robert Visiani in 1863 who listed 99 species planted up to that year, including some palm species. The proclamation of the island of Lokrum as a protected area in 1948 prohibited the “maintenance” without the prior approval of the competent institutions, which have become increasingly stringent given the increasing threats to biodiversity conservation such as the spreading of quarantine and invasive species. The occurrence of invasive pests on Lokrum represents pressure for a special reserve and is closely related to the selection of allochthonous plant species that have been used as ornamental dendroflora in the past. A quarantine pest, the red palm weevil, Rhynchophorus ferrugineus, was first recorded in Croatia in Zadar County in 2011, and the Public Institution “Special Reserve of forest vegetation Island Lokrum” started applying preventative palm tree treatment in December 2013 in accordance with the Action plan for the eradication and prevention of the expansion of the red palm weevil, Rhynchophorus ferrugineus, on palm trees for 2013 using plant protection products authorized for use on palm trees. On the island of Lokrum, the palm trees of the Arecaceae family are primarily treated as they are the most common hosts of pests such as Phoenix canariensis, Trachycarpus fortunei and Washingtonia filifera. Despite the application of preventative treatment measures, the occurrence of the red palm weevil on Phoenix canariensis was recorded in 2017 on the island of Lokrum. Seven individuals of Phoenix canariensis and one Phoenix dactylifera have been removed since the beginning of the infection. The box tree moth, Cydalima perspectalis, is a foreign, highly harmful invasive species, as it can cause complete defoliation of the boxwood Buxus sempervirens. In Croatia this pest was first recorded in Istria in 2012, while its presence on the island of Lokrum was established in August 2014, since the Lokrum Reserve has been applying chemical measures to control the said pest (curative treatment), based on the recommendations of the Ministry of Agriculture. The treated sites are shown as well as the proportion removed in relation to the number of palm trees being treated. You can also see the boxwood during the period of intensive pest attack and its current state of conservation. Palm trees and boxwood on the island of Lokrum represent a valuable horticultural element in the area of historic gardens, and as such need to be protected and phytosanitary measures should be implemented in accordance with the conservation measures of the basic phenomenon of protection of the Lokrum Reserve.

phytosanitary measures, palm weevil, boxwood

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