Croatian Journal of Forest Engineering (Apr 2011)
Dendrological and Horticultural Value of Lisičine Arboretum
Abstract
An arboretum is a collection of living woody plants. Apart from scientific research and education, arboreta serve public welfare, contribute to the popularization, planting and maintenance of trees and shrubs, but also have a horticultural value, i.e. they ennoble the area on which they are set. An important endeavor of Croatian Forests Co. Ltd. Zagreb is to renew and arrange theArboretum Lisičine, located on the area of the Forestry Office Voćin, Forest Management Unit Našice. The broader area of the Arboretum amounts to 45 ha, of which about 18 ha is beech forest; outside the fenced area there are about 2 ha of land around the building, whereas the remaining, a little less than 25 ha, make up for the Arboretum area in the narrower sense of the word, on which trees and shrubs, as well as many cultivars from various parts of the world are planted. According to Vidaković (1986), until 1985 about 1100 different taxa of trees and shrubs (species, subspecies, varieties, hybrids and cultivars) were planted. During the Homeland War the Arboretum area was occupied and devastated, and the documentation about the grown plants disappeared. The narrower Arboretum area is divided in 3 parts: 1. horticultural part, 2. area with European and Asian plants, 3. area with American plants. In the horticultural part of theArboretum,which is partially arranged, 416 different taxa have been determined, from 113 genera (Idžojtić et al. 2010). To obtain good results in arranging an area, it is necessary to apply a series of principles: unity and harmony, simplicity, balance, proportion, gradual and natural change, repetition, harmony of colors and forms, etc. In addition, there are many criteria according to which plants for ornamenting an area are selected: size; form; life-span of leaves; leaf shape, size and color; flower shape, size, color and scent; fruit shape, size, color, scent and structure; bark color and texture; twig color and shape; foliation, flowering and fruit-bearing period; edibility and aromaticity of certain plant parts; negative effects; growth speed; maintenance demands; resistance to diseases and pests; ecological demands, etc. Unlike the Arboreta Trsteno and Opeka, theArboretum Lisičine has no cultural-historical value, because it was planted on a former orchard and forest area in the 2nd half of the 20th century. In addition, speaking of its horticultural value,we need to keep in mind that it was primarily planted as a collection of trees and shrubs. The criteria for selecting plants are different when setting an arboretum than when an area is horticulturally shaped. However, if – apart from the scientific and educational function – care is also taken about aesthetics, the arboretum will be a pleasant area to stay in every season, and will not only be a collection of experimental plants. In this work the dendrological and horticultural value of the Arboretum Lisičine is analyzed. The analysis is presented for each of the 12 fields in the horticultural part, with an area of about 9 ha accessible to visitors. The plants growing in the Arboretum today can be considered adjusted to the existing ecological conditions, since they have survived without care ever since they have been planted until the present day. Ifwe look at theArboretum as a park and horticultural unit, it can be said that it is a freely shaped area, with fields of irregular shapes, separated by pathways, walkways or natural borders. The fields are at 150 to 250 m height above sea level, of richly diverse terrain reliefs, and of different exposures. For each field themost important plants are presented, indicating the visual characteristics which make them specific and recognizable. From the list of 416 plants published in the work of Idžojtić et al. (2010), it is evident that in the Arboretum Lisičine there are numerous, very valuable samples or groups of individual woody plants, unique or rarely present on plantations, i.e. plant collections in Croatia. The following can be pointed out as the most valuable ones: Abies bracteata (D. Don) A. Poit., A. mariesii Mast., Acer macrophyllum Pursh, Aesculus glabra Willd., A. × neglecta Lindl., Asimina triloba (L.) Dunal, Cephalotaxus harringtonii (Knight ex J. Forbes) K. Koch var. drupacea (Siebold et Zucc.) Koidz., Chionanthus virginicus L., Colutea × media Willd. 'Copper Beauty', Daphne laureola L., Euonymus planipes (Koehne) Koehne, Jasminum parkeri Dunn, Metasequoia glyptostroboides Hu et W. C. Cheng, Microbiota decussata Kom., Picea alcoquiana (Veitch ex Lindl.) Carrière, P. engelmannii Parry ex Engelm. 'Glauca', P. glehnii (F. Schmidt) Mast., P. jezoensis (Siebold et Zucc.) Carrière, P. × mariorica Boom 'Machala', Pinus banksiana Lamb., P. cembra L., P. contorta Douglas ex Loudon, P. ponderosa Douglas ex C. Lawson, P. × schwerinii Fitschen, Prunus sargentii Rehder, Quercus coccifera L., Q. macrocarpa Michx., Rhododendron spp., Sarcococca saligna (D. Don) Muell. Arg., Sciadopitys verticillata (Thunb.) Siebold et Zucc., Stephanandra tanakae (Franch. et Sav.) Franch. et Sav., Torreya californica Torr., Tsuga heterophylla (Raf.) Sarg. and others. There is special value in numerous conifer cultivars (spruce, falce-cypress, arborvitae, Japanese red cedar and yew), so that it can be stated that the Arboretum Lisičine is one of the richest living collections of different conifer taxa in Croatia. Significant are also taxa collections of individual deciduous and evergreen genera, e.g. Prunus L., Berberis L., Viburnum L., Spiraea L., Acer L., Cotoneaster Medik., Cornus L., Ilex L., Sorbus L. and others, which can also be considered as the most numerous ones in Croatia. Regarding the diversity of flower colors, the Arboretum as a whole can be said to be most beautiful in April, May and June, when the majority of ornamental trees and shrubs are flowering. At the same time, like elsewhere in nature or on similar plantations, the most noticeable and diverse leaf colors occur in autumn, which for deciduous species range from golden-yellow, orange and red to dark red-violet. Color changes throughout the seasons are especially apparent in fields I, IV, VIII and IX on which plants with scenic colored flowers are represented the most, as well as plants with colored leaves during the vegetation period or in autumn. The form, i.e. the constant exchange of higher and lower plants, in combination with different shapes that the plants make up on the ground, considerably contribute to the visual impression. Ageneral problem of this Arboretum is that on some fields the plants were planted too close to each other; this refers to trees and shrubs as well, and was particularly present on fields V, VI and VIII, where a lot of work had to be done for the plants to become accessible. Conifers that were planted thickly in groups had a green crown only on the outer side, and it repeatedly occurred that while the Arboretum was being arranged, due to the removal of only one damaged or dry plant, the appearance of thewhole group was ruined. If possible, it is always good to leave enough space for the crown to develop, thus preventing the collection to turn into a forest with high crowns, which will no longer be accessible for close observation or sample collecting. Of course, specimen fields can always be planted according to plan,which will evoke the ambience of a natural forest, with closed crowns and high, straight trunks. In the horticultural part of the Arboretum there are somewhat more evergreen (214) than deciduous taxa (202). Such a significant representation of evergreen trees and shrubs, especially conifers, gives certain constancy to the Arboretum, particularly in winter. Among the evergreen plants there is a large number of cultivars of different shapes, colors and textures, whichmake up for the recognizability and visual value of individual fields, especially if we can look at them undisturbed from a remote place, as is the case with fields VI and XII. On several fields in the Arboretum some old grafted apple, pear and cherry trees have been left over from the previous orchard. Apart from them, numerous plants have edible fruits, so that the Arboretum is a very desirable stand for various animals, thus contributing to the overall biodiversity of the larger area. Unfortunately, bringing in of new plant species can also have negative consequences. In the Arboretum Lisičine, in addition to the widespread common locust (Robinia pseudoacacia L.), the autumn elaeagnus (Elaeagnus umbellata Thunb.), spread by birds around the whole Arboretum, has proved to be a very invasive species. The rule is that for each taxon to be planted, apart from ecological demands, the invasiveness, i.e. potential invasiveness should be checked. The horticultural value of an arboretum does not only depend on the plants, their appearance and arrangement, but also on other infrastructural elements. Thus, it can be stated that quite a lot needs to be done in the Arboretum Lisičine to improve these elements, putting in order the pathways and walkways, adding new content and improving maintenance and promotion. Each field in the horticultural part of the Arboretum is specific and has a significant dendrological and horticultural value. The dendrological value is more important and recognizable for scientists and experts, whereas the horticultural value is something that will bring joy and ennoble all people who visit the Arboretum and who are open for the beauty of plants and the space they live in.
