Short Communication: A method for comparing the tree species composition of Estonian historic manor parks and forests

The following short communication article presents a method for comparing the species composition of Estonian forests and parks, giving an overview of the data that is currently being gathered and underlining how these two datasets can be compared. Even though both forest and park inventories are carried out throughout the country, to this day there have been no comparative studies on how the species composition of parks and forests differ from each other. This stems from the fact that the park and forest inventories are carried out using different methods. Forest inventories classify most of the trees according to their genera, but also differentiate between the species composition of the forest canopy and sub-canopy layers. The park inventories classify all dendrological plants by their species, also measuring several other individual parameters. The main difference being that park inventories do not differentiate between different canopy layers, rather providing species composition charts that include all the dendrological plants growing in the park. In order to compare the two datasets, it is necessary to transfer the data derived from manor park inventories to match that of the Estonian forest inventory. The first step in implementing the method is to divide the inventory data from parks into the forest canopy and sub-canopy layers. The canopy layer of parks was determined to consist of old trees (>100 years). The age of the trees in parks was modelled after growth charts compiled from the data from Estonian forests, which was then extrapolated to reach 120 years. These growth charts were compared to the breast height diameter of park trees, to determine their age. The canopy layer of parks was then analysed to provide an overview of species composition that corresponds to the same level of generalisation as the forest inventories. The results showed that the species composition of old manor parks differs significantly from most Estonian forests with the majority of the trees in parks being broad-leaved. The proposed method is suitable for comparing forests and parks on a generalised level.