LiDAR reveals drainage risks to wetlands have been under-estimated

Drainage is a recognised cause of wetland loss worldwide, and New Zealand is no exception. In the last 200 years drainage has reduced the natural extent of wetlands in New Zealand by c. 90%. Avoiding further loss is a national priority. Despite recent reform to restrict new drains within 100 m of existing wetlands in New Zealand, little is known about the extent and effect of existing drains in and near wetlands.

A Chionochloa/Sphagnum/cushion valley bog in east Otago, New Zealand

A valley mire was sampled on the flanks of Swampy Hill, east Otago, New Zealand. It formed in a narrow valley, apparently originally comprising two basins. The end of the mire nearest the outlet contained species typical of fens (i.e., rheotrophic mires). At the head of the valley there was a section of the mire with mixed vegetation cover comprising the tussock grass Chionochloa rubra, Sphagnum species, and cushion/herb/shrub cover.