A new method for quantifying treeline-ecotone change based on multiple spatial pattern dimensions

Treeline-ecotone spatial patterns and their dynamics reflect underlying processes. Changes in ecotone pattern may changes natural drivers or land-use practices. However, characterizing these presents a major challenge, limiting our ability to map, understand predict the upper limits of mountain forests. This paper proposes new method using multiple dimensions describe treeline-ecotone shifts. standardized protocol should be able (i) distinguish different types within large study area, (ii) characterize temporal shifts between two more dates. We mapped alpine treeline ecotones (ATE) at 648 sites eastern French Pyrenees aerial images from ~ 1955 2015, identifying forest non-forest areas hillslope scale. Extracted patch metrics were summarized Principle Component Analysis (PCA) change was quantified shift PCA space compared elevational Three clusters distinguished: diffuse, discrete island-forming ATEs. Between about half changed one cluster another. Shifts into ATEs associated with smaller negative shifts, while diffuse coincided highest positive The proposed allows repeatable quantification vegetation based on historical imagery. Seeing importance for biodiversity, we encourage use this better treelines globally.