Environment, composition and conservation of coastal turfs of mainland New Zealand

Abstract

Coastal turfs are communities of tightly interlaced, ground-smothering, short-statured herbs, grasses and sedges occupying shoreline rock landforms exposed to persistent salt-laden onshore winds. They are recorded from eight mainland New Zealand regions along the west and south coasts of North and South Islands. They display regional compositional distinctiveness best explained by geographic location, landform shape and substrate type. There is evidence that the predominant direction of onshore winds delivering aerial salt is aligned obliquely and not perpendicular to the coastline, and that the topographic aspect of turfs is correspondingly skewed in the opposing direction. Significant differences in soil salinity and pH were found between turfs of native herbs and those of exotic grasses and herbs on the same uniform landform. Turfs support 9 threatened and 24 uncommon plants, with all but 1 of the 33 being herbs, and 21 being recorded from just one region. Turfs exposed to ungulate (mostly farm stock) disturbance showed greater vegetation cover than those without ungulates. Conservation priorities should mostly be set intra-regionally and cautiously view ungulate disturbance as a beneficial management tool.

Keywords:

• coast
• exotic plants
• halophytes
• littoral zone
• salinity
• threatened plants
• ungulate disturbance
• vegetation–environment relationships

Acknowledgements

We warmly thank Carol West, Brian Rance, Shannel Courtney, Brian Patrick, Peter de Lange, Bill Lee, Colin Ogle, Peter Johnson, David Norton, Albert Rebergen, Lisa Sinclair, Graeme la Cock, Jim Clarkson, Greg Rine, Simon Walls, Don Neale, Phil Knightbridge, John Barkla, Betty and Eric Rogers and Mary Bruce for planning advice and/or field help. We thank Andrew Tait and NIWA for wind run data. Two anonymous journal referees made helpful comments on the manuscript. This research was funded, in part, by the New Zealand Foundation for Research, Science and Technology Contract C09X0503. The data from this study are archived in the National Vegetation Survey Databank: http://nvs.landcareresearch.co.nz/.