Concerns are being raised about Meridian Energy's ability to successfully revegetate areas of the Lammermoor Range, where it proposes to develop a 176-turbine, $2 billion wind farm.
Emeritus professor Alan Mark, of Dunedin, gave evidence about the hurdles of revegetating native snow tussock at an Environment Court appeal hearing for the Project Hayes development yesterday.
Prof Mark said trials of revegetation on site had so far produced less than satisfactory results, and he was concerned about whether it was possible to appropriately rehabilitate areas damaged during a five-year construction of the wind farm.
He said tussock could not successfully be revegetated by planting individual tussock plants, or by seeding land.
What he described as whole sections of tussock communities would need to be uplifted and immediately transferred to an area in need of revegetation, or to an appropriate storage site where they should be watered and cared for before being permanently placed in the ground.
Of all the land to be disturbed on the 92sq km site, about 250 acres was solely covered in native snow tussock, which meant about 50 acres of land would have to be revegetated with such tussock during each year of the construction phase.
Other areas would be revegetated in exotic grasses.
To displace and relay 50 acres of snow tussock annually for five years was a massive undertaking, and would challenge Meridian, Prof Mark said.
The 900m elevation of Project Hayes would further prohibit tussock revegetation, as would times of the year it was proposed revegetation take place, he said.
Prof Mark said from an environmental point of view, construction and subsequent disturbance of land should take place during winter to allow for spring revegetation, which would give struggling plants the best chance of strengthening over summer before another cycle of construction began.
Meridian had planned to stop construction in winter due to harsh working conditions and access constraints, and revegetation was to be accordingly scheduled during that time.
When cross-examined by Judge Jon Jackson and commissioner Heather McConachy, Prof Mark said any stock grazing on revegetated land would either prevent or slow tussock growth.
The proposed Project Hayes site incorporates aspects of five farming properties, and to date only one farm owner has registered their preference for tussock to be revegetated.
Prof Mark recommended stock should be kept clear of any areas subject to revegetation or rehabilitation for at least one year, and preferably two.
He said in general, the more stock which grazed, the more likely tussock would be eaten, opening up bare areas of land for weeds to flourish.