Plantation forestry on erodible land — Fact sheet

This fact sheet is based on research from Scion. It looks at the benefits of planting trees on unstable land, types of erosion and the potential for forestry on different types of erodible land.

Why plant trees on erodible land?

Plantation forestry can potentially reduce soil erosion by up to 95%.

Benefits of planting trees on vulnerable and unstable landscapes include:

  • reductions in soil erosion
  • storing carbon dioxide from the atmosphere (carbon sequestration)
  • environmental benefits, like cleaner water and increased biodiversity
  • reduced damage to downstream land and infrastructure.

Trees protect landscapes from erosion, especially during severe storms, by:

  • providing a canopy that intercepts rainfall and reduces the amount of water in the soil
  • having roots that bind the soil together, making it less likely to wash away.

Types of erosion you might see on your land

Rill erosion

Soil on a slope with multiple rills caused by rain going down the slope. The rills look like very small dried up streams.
Happens when water from rainfall doesn’t soak into the soil, but runs across it instead. Image: Environment Canterbury

Gully erosion

Grassy land surrounds a large, deep gully. The top soil has been eroded by water and the land has caved in. Water, soil and grass are in the gully.
Gully erosion is caused by flowing surface water. Image: Bay of Plenty Regional Council Toi Moana

Sheet erosion

A grassy, sloping hill with a large section of soil covering most of the hill where the surface has eroded and become detached.
Sheet erosion happens when rain falls on bare or sparsely covered soil, loosening fine particles that are carried downhill in surface runoff.

Soil slip

A large, steep grassy hill with multiple streaks of soil running down the hill, caused by landslides.
Soil slip – shallow landslides after heavy rain. Image: Peter Scott

Earthflow erosion

Grassy, hilly landscape with multiple slips of soil causing ridges in the land.
Earthflow - large slow-moving slips. Image: Taranaki Regional Council

Land type and forestry

As land gets steeper it tends to have:

  • decreasing versatility
  • increasing vulnerability to erosion
  • declining soil quality
  • fewer ways to help prevent erosion.

Climate conditions at higher altitudes become harsher and less suitable for growing grass or trees.

Types of erodible land and options for use

Limitations of planting erodible land

After harvest, there’s a 6-8 year timeframe where land is vulnerable to erosion. This happens until a planted crop grows up and the canopy (the branches and leaves you see when you look up in a forest) closes.

Some vulnerable landscapes at risk from extreme and/or frequent storms will always struggle to maintain commercial plantations. This is because of:

  • rainfall intensity and runoff
  • the amount of moisture already in the ground
  • slope and slope length
  • soil type and geology
  • vegetation cover (how many plants and trees are already on the land)
  • previous extreme storms
  • whether the land faces the direction of frequent intense storms.

Further reading

This fact sheet is based on research from Scion supported by funding awarded to the Hawke’s Bay Regional Investment Company by the One Billion Trees Partnership Fund, Te Uru Rākau – New Zealand Forest Service/Ministry for Primary Industries.

Read the full reports on the Ministry for Primary Industries' website.

  • Summary report – Planting eroding hill country in the Hawke’s Bay region.
  • Technical report – Planting eroding hill country in the Hawke’s Bay Region: Right tree, right place, right purpose (page 34).


This work was completed in 2019. Since then, devastating weather events have affected the North Island in 2023. The Government is doing more work on species for erodible land in this region, so this material may no longer be accurate or up to date.