This repository contains files of spatial environmental data layers which were used as predictors of nesting habitat suitability for six biodiversity indicator bird species in Finland: (i) three hawk species, the European honey buzzard (Pernis apivorus), the northern goshawk (Accipiter gentilis) and the common buzzard (Buteo buteo), and (ii) three woodpecker species, the white-backed woodpecker (Dendrocopos leucotos), the lesser spotted woodpecker (Dryobates minor) and the Eurasian three-toed woodpecker (Picoides tridactylus). These six bird species have been shown to provide useful indicators of different conservation and biodiversity values of boreal forests, such as occurrences of red listed polypores, and indicative of forest characteristics related to old-growth forests such as representative occurrences of dead wood. The modelling spesifically targetted the nest sites of the bird species where the role of critical suitable environmental conditions is elevated. The data of nesting sites of the bird species are not open access data due to its sensitivity, but can be requested for research purposes by sending a query to the head of the Zoology unit at the Finnish Museum of Natural History. However, the Maxent results of the nesting habitat suitability for bird species across the whole of Finland are available in Zenodo (https://doi.org/10.5281/zenodo.4779108).
Please also note that the environmental data is split - due to its large size - into two repository locations, this one containing the local site variables and 500 m buffer variables, and the other containing the 1 km buffer variables and the two climate variables.
Taken together, 40 different environmental data layers were developed and their information sampled for a 96 x 96 m resolution lattice system covering the whole Finland. These 40 data layers were organised for the modeling into the following groups of predictor variables: (1) Data on forest structure and other forest stand characteristics (96 x 96 m cell) (8 variables), (2) Data on land cover at the forest stand (96 x 96 m cell) (8 variables), (3) Data on forest characteristics in the 500 m landscape buffer area (3 variables), (4) Data on forest characteristics in the 1 km landscape buffer area (3 variables), (5) Data on land cover in the 500 m landscape buffer area, (6) Data on land cover in the 500 m landscape buffer area, and (7) Climate data (2 variables).
These data were used to examine what are the key determinants of the nesting site suitability of the six indicator bird species and to developed predictive maps across the whole Finland for the locations of most optimal nesting forest areas. The nesting habitat suitability modelling was done using the MaxEnt model. The forest structure and habitat quality predictor variables were developed based on national forest data gathered from three sources: (i) Finnish Forest Center (FFC), (ii) Metsähallitus Parks & Wildlife (MPW), and (iii) the multi-source national forest inventory carried out by the Natural Resources Institute Finland (LUKE). The land cover variables were measured using the CORINE Land Cover 2018 system, from the database produced, maintained and distributed by SYKE. The two climate variables were initially for the SUMI project by the Finnish Meteorological Institute and further applied in this modelling study.
The environmental variables, the six indicator bird species and the processses, steps and choices included in the MaxEnt modelling are described in full detail in the following publication: Virkkala, Raimo, Leikola, Niko, Kujala, Heini, Kivinen, Sonja, Hurskainen, Pekka, Kuusela, Saija, Valkama, Jari and Heikkinen, Risto K.: Developing fine-grained nationwide predictions of valuable forests using biodiversity indicator bird species, Ecological Applications, in press. The details of the environmental data are also described in the read_me.doc file uploaded into this repository.