Fisherman's Cottage, Harold Sohlberg, 1906
Mature trees can play an important role in slope stability. The large root systems hold soil and can stitch through horizontal plains of weakness. Evergreens also intercept a fair bit of precipitation reducing the frequency and extent of saturated soils. On eroding shoreline bluffs, large trees can reduce long term erosion rates. When a bluff slope fails, the presence of large trees within the landslide material can create a large natural shoreline bulkhead at the toe of the slope slowing erosion for many years. This is particularly true at locations without large ocean sized waves such as much of Puget Sound and the Salish Sea.
When I saw the above painting at a museum recently the role of large trees on slope stability came to mind. In particular, the painting shows that a view can be maintained by limbing the trees so the water and the view can be viewed through the trunks. Besides the slope stability benefits, the trees provide habitat and enhance the view. An added benefit of a canopy of large evergreens it that they reduce the rate of growth of under story trees that would otherwise block the view. The painter liked the view through the tree trunks enough to paint it. The painting is Norwegian, a landscape that has similarities to the glaciated and forested shorelines of western Washington.
Large wood in landslide deposit on beach