Before humans settled in New Zealand around 1250–1300 CE, the Whanganui region was covered by forest, except for small areas of red tussock and scrub in the Moawhango River headwaters in the southern Kaimanawa Mountains. The forest was mostly conifers, particularly podocarps such as tōtara, mataī and rimu, and broadleaf trees such as tawa and kāmahi. Beech trees also grow in the Kaimanawa Mountains and the Kaweka and Ruahine ranges.
Māori impact on forests
By 1840, Māori had cleared the forests by fire in much of the high country between Karioi and the Kaweka Range, and along the coastal lowland. The lowland was subsequently covered with bracken, toetoe, flax and mānuka. In the north-east, forest remained on the Kaweka and Ruahine ranges, along with remnants of kaikawaka and beech on abutting plateaus – but large tracts were dominated by tussock.
Outside these two areas, Māori impact on forests was mostly in the larger valleys.
European settlement saw the coastal lowland progressively sown with pasture grasses and various crops. From the mid-20th century pine trees were planted near the coast at Maxwell (Pākaraka) and Nukumaru, and south of Whanganui town. Planting of pines between the Turakina and Rangitīkei rivers began in 1956, in conjunction with marram grass to stabilise adjoining dunes.
From 1867 runholders in inland Pātea, in the upper Rangitīkei district, burnt off native tussock and converted large areas into pasture. By the early 2000s, fire was no longer used, and scrub had taken over many areas.
Hill country clearance
From the late 1870s, settlers began burning and felling hill-country forest to turn it into grassland for farming. Between 1880 and 1910, dense clouds of smoke were often seen rolling down the Waitōtara, Whanganui, Whangaehu and Turakina valleys.
Erosion has been a constant problem on cleared hills, but since the Second World War land has been rehabilitated through aerial topdressing and better pasture and stock management. Pine forests have been planted in some steeper areas.
Forest was felled from around Rātā to north of Taihape, ahead of the construction of the main trunk railway line between 1885 and 1905. In the 2010s, the land was mostly used for sheep and cattle farming, and some dairying, with extensive pine forests west of Hunterville.
Waimarino and the Whanganui River
Dense podocarp forest on the Waimarino plain was progressively felled after Raetihi and Ohakune were founded in the 1890s. A major bush fire swept though the district in March 1918, destroying several settlements and killing three people.
Over 50 sawmills operated there in the mid-1920s, with the last closing in 1955. In the 2010s the plain comprised farmland and market gardens, with native forest on its northern boundary.
One of the North Island’s largest remaining tracts of intact conifer–broadleaf forest lies within Whanganui National Park (which was established in 1986). The region’s first pine forest was planted at Karioi in 1927.