An article that appeared in the Marlborough Express 5 December 2015
Marlborough District Council considers tightening forestry rules
Sedimentation at Hitaua Bay in the Marlborough Sounds.
The Marlborough District Council needs to consider more stringent rules around forestry, its coastal scientist has advised.
Forestry activities in the Marlborough Sounds causes sediment to wash down steep slopes into coastal waters clogging the seabed, the council’s environment committee has heard.
Scientist Steve Urlich examined more than 12 scientific papers and reports from the last 35 years of the effects of plantation forestry on coastal water quality and seabed habitats in the Marlborough Sounds.
The environmental effects were first identified in the late 1970s, Urlich said.
A report by marine biologist Rob Davidson in June said significant ecological marine site Hitaua Bay estuary in the Sounds was smothered with sediment because of forestry earthworks causing a slip.
The sedimentation had resulted in loss of habitat for shellfish and young fish, Urlich said.
“Something needs to change, as these issues keep recurring and are likely to be causing ongoing negative effects to marine life.
“If the Sounds ecosystems are in good health, they provide a range of benefits including greater fish and shellfish abundance.”
The Government’s proposed national environment standard [NES] for plantation forestry did not go far enough, he said.
The council had expressed serious concerns on how the effects of harvesting operations and earthworks in steepland soils would be appropriately managed in the standard, given the high erodibility of Marlborough’s soils.
Given the uncertainty around the final outcome and timing of the standard, council should develop its own rules, Urlich said.
“The proposed national environment standard for plantation forestry does not currently afford the iconic Marlborough Sounds the protection they require.”
There was nearly 17,500 hectares of permitted forestry in the Marlborough Sounds at different stages of harvesting.
“We can expect ongoing effects from forestry for the next 30 years in Tory Channel, Port Underwood and Croisilles Harbour.”
The generation of fine sediment from forest harvesting was inevitable no matter how many and how stringent the controls, Urlich said.
This was because of periodic high rainfall intensity events, the high erodible bedrock and clay-rich soils which clumped together in contact with seawater and settled close to the shore.
Fine sediment production was also caused by the ‘window of vulnerability erosion’, typically five to eight years after harvest.
“Everything is working against us as a land use in the Sounds.”
Mitigation measures needed to be implemented, Urlich said.
Proposals included coastal setbacks of 30 metres, 100m or 200m – a protective vegetation buffer to help reduce soil erosion and sediment entering coastal waters.
Riparian setbacks of 10m from streams to mitigate exposed soils and controls on replanting on slopes more than 30 degrees.
A mandatory replanting plan that showed how sensitive erodible areas were to be avoided.
Removal of logging debris from gullies and stream sides and stricter engineering standards for forestry related earthworks.
The recommendations received a supportive peer review from Landcare research scientists.
“These options have not be constructed as a Trojan horse to force forestry from the Sounds.
“There is no magic bullet. It is up to us to find a solution that works for us.”
Environment committee chairman Peter Jerram wanted action taken in the new Marlborough Environment Plan.
“I don’t want this report to go on a shelf and gather dust. If we had a report like this 30 years ago we would have had different replanting programmes in the Marlborough Sounds.”
Councillor Trevor Hook, who headed the committee looking at the revised plan, said he did not want forestry to turn into “us and them”.
“There needs to be more work done around consultation.”
– The Marlborough Express
Forestry areas in the Sounds (source MDC)