Drunken Trees - Permafrost

Permafrost

Permafrost, which is soil (or rock) that remains below 0 °C for at least two consecutive years, forms a solid matrix in soil which can extend to a depth of hundreds of meters. The permafrost prevents trees from developing deep root systems; for example, the Black Spruce that has adapted to permafrost soils has no significant taproot. In areas where the permafrost temperature is near the melting point of water, climate variations, or loss of surface vegetation from fire, flooding, construction, or deforestation, can thaw the upper extents of the permafrost, creating a thermokarst, the scientific name for a ground slump caused by melting permafrost. The thermokarst undermines the shallow root bed of these trees, causing them to lean or fall. Thermokarst lakes are surrounded by a ring of drunken trees leaning toward the lake, which makes these land features easily identifiable.

Drunken trees may eventually die from their displacement, and in ice-rich permafrost, the entire drunken forest ecosystem can be destroyed by melting. Tilted trees that do not topple over may recover by using gravitropism to resume vertical growth, thereby taking on a curved shape. The reaction wood formed by this process can be studied using dendrochronology using annual growth rings to determine when the tree was subjected to tilting.