Plane Trees (Platanus sp.) as Non-Native Compositional Landmarks in Historical Gardens and Parks in Rural Landscapes of Slovakia

Plane trees (Platanus sp.) are distinctive non-native elements of European historic gardens and parks, valued for their monumental dimensions, longevity, and compositional significance. However, their spatial and compositional roles within historic designed landscapes remain insufficiently documented. This study investigates these roles across 16 historic manor gardens and landscape parks in southwestern Slovakia, comprising 111 documented plane trees. Field surveys, dendrometric measurements, historical cartographic research, and spatial and landscape-compositional analyses were combined to assess tree groupings, geometric arrangements, and relationships with principal landscape elements. Based on the empirical findings, a classification framework comprising 15 categories of spatial and compositional relationships, including geometric planting arrangements, was developed. Solitary specimens predominated, accounting for 74.60% of documented grouping occurrences, while relationships with principal compositional axes (75% of parks), circulation routes (68.75%), and important views and vistas (56.25%) were particularly frequent. Formal geometric arrangements, including circular and semicircular groupings, were comparatively rare. The findings demonstrate that plane trees contribute to historic landscape compositions not only as monumental individual specimens but also through their integration into wider spatial structures. The proposed evidence-based classification provides a methodological foundation for further comparative research and supports the conservation and restoration of historic designed landscapes.