Architectural design of buildings is usually a composition made up of inanimate traditional or modern materials, whereas landscape designs are composed mainly of plants, i.e. materials which are animate, breathing, growing, aging and dying. Trees in an architectural composition form a mass, volume and inner space. Like buildings, trees are long-lasting objects, which carry cultural heritage of generations and the country.
Tree alleys as a specific composed linear spatial formation of trees in rows provide an unusual architectural, aesthetic and landscape forming potential. They are usually a part of a road in the country or settlement. Intentional planting of trees along the roads is known from several historic periods and cultures. A rich tradition of tree alleys can be also observed in our region. In the 18th and 19th centuries tree alleys became a significant element of landscape and a component in urban structures. In a contemporary urban structure with emphasis on economic aspects, tree alleys and their space requirements compete with spatial needs of traffic, infrastructure, street lightning, and exposure of buildings to the sun, etc. Tree alleys along the roads are often perceived as a burden for road maintenance and traffic safety.
Historical tree alleys are a part of cultural heritage, which can be proved by many examples in Slovakia. The ways of their protection is an essential issue in the area of preservation of their cultural, historic and aesthetic values. Heritage Regulation and Nature and Landscape Protection Regulation are major legal documents that regulate protection and development of cultural and natural heritage, and set conditions for their identification, registration and preservation. In the interest of protecting diverse values of tree alleys it is appropriate to involve various instruments for setting conditions of their identification, registration and preservation, e.g. through land use planning. The methodology dealing with characteristic appearance of the landscape and the impact of its elements on the landscape scene has been rather unsuccessful in Slovakia. The mentioned examples of outstanding tree alleys in Slovakia and the described possible ways of their protection bring about the need to pay more attention to the issues of protection, maintenance and renovation of old tree alleys within the protection concepts of cultural, historic and aesthetic values of settlements and landscape greenery.
Tree alleys are a significant phenomenon of landscape character and a hallmark of civilised landscape. They also carry a unique aesthetic, historic and cultural value; and they are a substance of the ambience. However, they are not only a “spiritual element”. They present a physical component, which requires not only an identification of their values, but also a clearly defined set of proceedings for their preservation.