A new method for alpine timberline peaks extraction based on remote sensing and inverted digital elevation model

The alpine timberline is a crucial ecological boundary for dividing the landscape, but a method to accurately extract it over a large region remains elusive. In this study, we propose a method for identifying the timberline over a large scale and use it to explore the distribution of the timberline in the Altai Mountains in Asia. The elevation of the timberline peaks was determined by extracting the margin of forest land, obtaining the peaks based on the maximum accumulation of flow, and calculating the shortest distance between the peaks and the margin of forest land. The slope of linear fit between the calculated and actual values was 0.96 and the correlation coefficient between them was 0.87 (p < 0.01), indicating a high accuracy of recognition. The timberline of the Altai Mountains had a range of elevation of 2400–3000 m, and is the lowest timberline in China. The overall elevation of the timberline in the northern basin was higher than that in the southern basin, and was mainly distributed on ramps and abrupt slopes, but rarely on plains and vertical slopes. The distribution of the timberline was clearly characterized by its western aspect being higher than its eastern aspect, and its northern aspect being higher than its southern aspect such that the orientation of its aspect was evident. The elevation of the timberline exhibited a continuous trend of increase with the latitude. Our method for extracting the timberline can systematically reveal the spatial pattern and characteristics of its landscape in the Altai Mountains.