68 | FORESTRY City Forests T T Hugh de Lacy Forests play huge role in water quality The environmental challenges facing New Zealand today because of global warming have an uncanny similarity to those that prompted the Dunedin City Council to go on a pine-planting spree 120 years ago – landslides, dirty water and floods – according to City Forests Manager Grant Dodson. Global warming wasn’t an issue back then but the denuding of the hills to make way for settler farms, especially following the Otago gold rushes of the 1860s, left Dunedin facing the same weather-bomb threats as the East Coast of the North Island in 2023, he says. City Forests was established to prevent that in the Edinburgh of the South. “The gold rushes saw Dunedin’s population go from 5000 to 50,000 virtually overnight, and the city struggled to get sufficient fresh water because the catchments had been denuded of trees to make way for farmland. “The city water department had issues with flash flooding, the water to humans and livestock suffered, then gorse and broom problems started to emerge, so they started to establish pine plantations in 1906. “Their goal was to provide even flows of fresh and clean water free from farm effluent, to reduce the incidence and effects of flooding, to suppress gorse and broom and other weeds, and also produce a crop of timber.” Today that enterprise has flourished into the Dunedin City Council-owned City Forests, an industrial-size business with 20,000ha of productive forest land across coastal Otago, selling 350,000m3 of logs a year, employing 80 people full-time, and delivering an annual dividend of around $8 million to the city ratepayers. All of which makes Grant all the more convinced that, in the face of the negativity towards forestry that followed the East Coast North Island slash-floods of 2023, forestry has a huge role to play – even bigger than when City Forests was launched – in mitigating the environmental damage brought on by environmental changes. “Just in terms of water quality, it’s been proven that the water flowing from pine- forested soils is of similar quality to native forest – which is significant given that the water from the soils in native forests is logically as clean as it can be, because it’s never been interfered with chemically or otherwise,” Grant says. “Forest soil is slightly acidic, is reasonably porous and has quite a lot of organic matter in there. “That’s opposed to soils under pasture which need to be slightly alkaline to grow ryegrass and clover, and are usually subjected to animal wastes and fertilisers, not to mention nitrates and phosphates which are considerable pollutants if they escape into the waterways. “So if you look at the issues New Zealand faces today with its land and water, forestry is still the solution it was 120 years ago. “That doesn’t mean the whole country has to be forested, but it demonstrates that forestry has strong environmental credentials amongst our matrix of rural land use, of which farming is obviously the predominant one,” he says. On top of that is forestry’s positive impact on climate change compared with farming. “Farming has some very significant emissions coming from livestock and fertiliser: sheep and beef farming releases 3.6 tonnes of greenhouse gas equivalents per hectare per year, while with forestry the opposite occurs: forestry sequesters carbon. “Wood itself is around 40% carbon, and when combined with oxygen one tonne of wood equals one tonne of CO2,” Grant says. On top of all that, forestry is a productive and profitable business for its owners, and in City Forests’ case it’s been doing that for the ratepayers of the Dunedin for over a century. Your Complete Engineering Services Workshop 100 Ravensbourne Road, Dunedin, Ph: (03) 471-0516 www.palmersmech.co.nz for further information Proud to provide support services and equipment to City Forests Ltd - Hydraulic and pneumatic service/sales/repairs/design - EWP certified / maintenance/ servicing /compliance - Full mechanical workshop and breakdown service - Full machining workshop - Heavy and light fabrication - Hydraulic hose and fittings 100 Ravensbourne Road, Dunedin, Ph: (03) 471-0516 www.palmersmech.co.nz for further information
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