Effectiveness of Reforestation in Prevention and Control of Landsliding during Large Cyclonic Storms

1990

S. 340-350

3 Abb., 1 Tab.

Unselbständiges Werk

200085654

The effectiveness of a reforestation project in the eastern North Island, New Zealand, in Prevention and control of landsliding during large cyclonic storms proved difficult to quantify. However, earthflow movement rates under forest were less than those under grass. Onset of movement of the forested earthflows lagged several weeks behind the response of grassed earthflows during large storms, but both returned to pre-storm rates in about the same time interval. Pine plantations <6 years old gave a similar level of protection against landsliding as grass cover on slopes of similar aspect, steepness, and rock type. Slopes under these young stands had a landslide density of 0.62/ha as a result of Cyclone Bola, a severe cyclonic storm event in 1988. Plantations 6-8 years old provided an intermediate level of protection from Cyclone Bola, with a landslide density of 0.21/ha. Plantations older than 8 years gave 10 times the protection of younger stands, with a landslide density of less than 0.06.