Question: Can the pattern and pace of spontaneous Fagus forest expansion from 1975 to 2003 be accurately detected with mid-resolution satellite imagery? Can the historical Fagus expansion be modelled on the basis of environmental predictors? If so, where are the highest probabilities for future Fagus expansion? What are the implications for park management?
Location: Majella National Park, Italy, > 1000 m a.s.l.; municipalities of S. Eufemia and Pacentro.
Methods: Fagus cover change was detected by overlaying three classified sequential satellite images. Historical Fagus expansion was related to environmental variables using ordinary logistic and autologistic regression models. Fagus expansion probabilities were generated with the best predictive model.
Results: From 1975 to 2003 Fagus advanced into abandoned farmland and subalpine pastures from the contiguous, mid-altitudinal Fagus forest and from Fagus outliers, at a rate of 1.2 % per year. Substantial spatial and temporal variations in expansion rates were detected. The ordinary and autologistic models based on the single predictor Distance-from-Fagus-1975 forecasted the Fagus expansion well (AUC 0.81 resp. 0.88). Multiple logistic models, including the topo-climatic and substrate predictors, improved prediction insignificantly. The strong predictive power of proximity to historical Fagus presence is explained by the dispersal biology of Fagus combined with the shading impact of the Fagus canopy at the forest fringe.
Conclusion: Decade-long Fagus expansion patterns might be reliably forecasted by proximity to historical Fagus distribution. Consequences for park management options are outlined.
Nomenclature: Pignatti (1982).