The magnificent and historical terraced gardens in the Kalalau Valley are being threatened and destroyed by the introduced and invasive trees.

This scale of damage may help to minimise the numbers of seeds produced and thus the spread of this invasive tree.

Acacia mearnsii is a fast-growing, extremely invasive leguminous tree native to Australia.

The new fence, along with removal of invasive trees and shrubs, restored the panoramic views of the Park and Manhattan skyline.

Considerable efforts have been made to control the rapid spread of these invasive alien trees.

SANParks have been criticized for their programme of removing invasive non-indigenous trees.

The invasive trees were originally planted as commercial plantations for timber, once most of the indigenous afro-montane forests had been felled.

The park's current programme is to allow for the re-growth of the indigenous forests, while slowly removing the plantations of invasive trees.

However, the lower part of the river flows through developed areas as well as past fynbos and plantations of invasive alien trees.

The invasive trees then gradually outgrow and kill these surrounding ecosystems.