Nelson City Council is retiring more than a fifth of its forestry blocks and building a wetland along the Maitai River, in response to concerns about the environmental impact of forestry practices locally and nationwide. Source: Stuff NZ
The council released Niwa research, linking pine plantations to environmentally-damaging fine sediment in the Maitai River, amid calls for stronger controls on forestry companies operating in the Maitai catchment.
The report said while forestry only accounted for about a quarter of land used in the watershed, the main source of sediment in half of the river samples taken came from pine forests, mostly harvested or newly replanted blocks.
Excessive fine sediment in fresh and sea bed environments has been linked to adverse effects, including clogging the gills of fish, and is suspected of having led to the demise of the local scallop fishery.
While the Niwa research was helpful, pastoral land, bank erosion and urban development were also known contributors of sediment in the region’s catchments, the council’s group manager for strategy and environment, Clare Barton, said.
“It helps in terms of our Nelson plan and what we might need to focus on around controls.
“We have over the last two to three years been working with forestry companies to look at lifting their game which they’re already signed up to, both in Nelson and nationally.”
The council itself was estimated to own about 322 hectares of forestry in the Maitai and Brook catchments; or around 12%.
The council planned to retire some of its steep hillside forestry plantations based on independent assessments undertaken about two years ago, group manager for infrastructure Alec Louverdis said.
“We’ve got about 640 hectares of forest, and we’re going to be retiring roughly about 140 hectares of that.”
The land would be replanted with permanent species, other than pine, he said.
“We’ll be looking at alternative uses, of which, a large proportion potentially will be native bush.
Included in the land that would not be replanted in pine, was a steep council forestry block, singled out in the Niwa research as contributing 20 per cent of the sediment in the lower Maitai River.
The company that managed the council’s forestry land, PF Olsen, had been involved “at the highest levels” in the national forestry rules that came into effect this month, Louverdis said.
The National Environmental Standards on Plantation Forestry require forestry operators to assess the environmental risks of their operations, submit their harvesting plans to councils, and install measures like sediment control.
Councils can impose stricter rules in unique and sensitive environments.
The standards were “more stringent” than the current rules in the Nelson resource management plan, Barton said. “What we’re doing as part of our Nelson plan review is saying … if there are particular waterways that we’re concerned about, that we can potentially be more stringent.”
The council was looking at introducing an “in-stream limit” for sediment in new rules for freshwater in the Nelson plan.
It was also building a trial wetland at the bottom of Groom Creek, designed to interrupt the pathway of the sediment to the river, which it hoped would work as a blueprint for other forestry operators.