Arnold Hansson played a major role in New Zealand forestry during the 1920s and 1930s. Born Arnold Maria Hansen in Drammen, Norway, on 10 November 1889 to Hans Arnold Hansen, a chemist, and his wife, Marie Christine Ahlers, he was the only boy in a family of five. After leaving secondary school he gained a BA from Kristiania (Oslo) university and then studied at the state forestry school, Kongsberg, completing his course in 1912. Because there was a shortage of forestry jobs in Europe, he sailed for Canada in 1912; about this time he changed the spelling of his surname to Hansson. Settling at Grand-Mère in Quebec, he was employed by Laurentine and Company, pulp and paper manufacturers, on arduous forestry survey and reconnaissance duties. In 1916 and 1917 Hansson studied for a master of forestry at Yale University, and from 1917 until 1919 he served in France as a sergeant major in a Canadian ambulance unit.
After the war he returned to Laurentine and Company, then set up as a forest consultant. In 1920 Hansson applied for and obtained the position of first chief inspector in the proposed New Zealand State Forest Service, which was officially established in March 1921. Arriving in 1920, he lived first in Auckland, where on 23 May 1922 he married Alice Bell, an Englishwoman to whom he had become engaged after the armistice. A son was born in 1926 in Wellington, where the Hanssons settled.
Initially Hansson was sent to the West Coast to organise the Westland Forest Conservation Region. His attempts to raise professional standards were sincerely offered but not always well received. Tall and bespectacled, he was undoubtedly experienced, hard-working and very well qualified, but he had a rigid outlook. Moreover, he was seen as a foreigner: although naturalised in 1922, he remained self-consciously Norwegian. These problems, and the fact that he had little in common with his director, L. M. Ellis, caused their working relationship to become strained. Unhappy with the conditions, Hansson was to apply (unsuccessfully) for the position of professor of forestry at Auckland University College in 1925.
Despite unsatisfactory circumstances, Ellis made good use of Hansson's abilities. A national inventory of forest resources, managed by Hansson from the Wellington office and completed in 1923, provided the first accurate information about the extent of indigenous forest resources. Hansson completed the measurements and calculations for the volume and yield tables, which were essential before timber sales could be placed on a tender basis. He also made the growth-rate calculations that allowed Ellis to set a 300,000-acre afforestation target in 1925.
In 1924 Hansson began to contemplate setting up a technical association to improve forestry standards. Discussions with F. E. Hutchinson and Professor H. H. Corbin led directly to the establishment of a New Zealand Institute of Foresters in 1928. Ellis served as the first president very briefly, but after his resignation as director in March 1928, Hansson was elected president. His address to the second annual general meeting in 1929 stressed the importance of professionalism, research and public education. He became upset when the institute wanted to broaden its membership to include non-professional foresters and did not serve on the executive in 1930, letting his membership lapse in 1934. Another reason for his withdrawal was the need to save money: throughout the 1920s he had remitted money to Norway to help support his sister and her family.
Office politics continued to concern Hansson. He was unhappy that E. P. Turner, who lacked forestry qualifications, had replaced Ellis as director, and in 1930 accepted an appointment as silviculturist at the Waipoua Forest Experimental Station. The National Expenditure Commission of 1932 successfully recommended the closure of the Waipoua station and in the following decades Hansson convinced himself that Kaipara MP Gordon Coates had engineered his dismissal. He believed Coates had objected to his evidence in the case of a petition relating to the Rotorua–Taupo railway in 1929, which revealed questionable business practices by Dr F. J. Rayner.
Hansson was appointed to the newly established position of forester with New Zealand Railways in 1933, at a much-reduced salary. Here he built up his staff to 12 by 1947 and managed the Pokaka timber sale and the Athenree planting programme. He was now free to implement his ideas about professionalism, which because of his exacting nature led to internal frictions and staff resignations. He became resentful that his responsibilities were in excess of his grading in the department and made several appeals before his retirement in 1950.
Hansson enjoyed a long and active retirement, taking up hobbies such as jewellery making and archery. He continued a correspondence with family and forestry associates from Norway and North America well into the 1950s. He also remained watchful of events in forestry and protested strongly to the minister of forests about omissions in the account of forestry in the 1920s, which was published in New Zealand Forestry in 1964. By this time his own contribution was largely forgotten. His wife died in 1978; he died in Wellington on 5 September 1981, aged 91.