Wider recognition urged for verge habitats

Press, 14 July 1987, Page 21

Wider recognition urged for verge habitats

“A little bit of gentle neglect” may be all that is required to turn road verges in many parts of the country into important habitats for remnant populations of dwindling native species, according to Dr Peter Wardle, deputy director of the Botany Division, D.S.I.R. Dr Wardle is one of a number of New Zealand botanists and environmentalists who have for some time been quietly pressing a case for wider recognition of the value of roadside habitats. These areas are, he says, generally undervalued as refuges for relict populations of native species — particularly in intensively farmed land and within urban boundaries.

Scope for re-establishment

Roadsides also, according to another of the division’s scientists, Dr Colin Meurk, offer scope for re-establishing populations of native species in areas where they have been eliminated by urban or rural “development.” There pre, says Dr Meurk, two

possible approaches to the question: regionally, through individual local authorities, few of whom have the expertise to recognise rare or unusual native species; and nationally, through the Roads Board. Both approaches have merit, says Dr Meurk, citing, as an example a case where local knowledge would have been important, a small population near Geraldine of Coprosma intertexta, a native shrub now very rare on the Canterbury Plains. During road widening, spoil was thrown on the plants, burying some of them. “You can’t,” says Dr Meurk, “attach any blame to the local authority for this. The council workers were simply not aware that the plants had any value.” In seeking ways to avoid further incidents of this type, Dr Meurk has been in touch with the Roads Board and the Ministry of Works and Development, and is compiling a list of roadside areas with significant natural values. With Di Lucas, a Geraldinebased landscape architect and member of the Environmental Council, he has prepared a paper, as yet unpublished, setting out a strategy for the “greening

of our roadsides” by encouraging, and where necessary reestablishing, native species. As areas particularly worthy of revegetation, Dr Meurk and Ms Lucas cite the dryland regions of the eastern South Island, Central Otago, and the Southland plains, areas which at one time supported extensive tussock and scrub. In most of these areas, they say, the road network has the potential to provide "corridors” through farmland from which native vegetation has been eradicated. But at present the verges are largely dominated by introduced grasses and weeds.

Cabbage trees and flaxes only

“Perhaps the saddest commentary on our taming of the land is in the fact that on the busiest route in the South Island (State Highway One, between Christchurch and Timaru) the only native plants that leaven the monotonous flatness and tidy paddocks are occasional cabbage trees, planted flaxes (which do both have a uniquely defiant

character) and kowhai, rare toetoe and pohuehue (on fence posts), and a few ferns and sedges along the water-races. The gem is a strip of scattered silver tussocks in the Chertsey area. "Where are the kanuka, manuka, matagouri, olearia, coprosma, and porcupine scrub woodlands that once characterised the Canterbury Plains? Where are the silver tussock, hard tussock, blue grass and speargrass flats of the more stony soils?” Road verges, the two say, have immense potential value as refuges and gene banks for native species. As examples of native communities surviving on roadsides in areas where they have been eliminated from fanned land, Dr Meurk lists red tussocks on the Southland Downs, bluegrass stands in the Manuherikia, and matagouri, native brooms, and speargrass in the Mackenzie Country. On the Canterbury Plains, he says, many wetland plants — including ferns, sedges, raupo, flaxes, and some small grasses and herbs — now survive only in the ditches and water-races that take the place of the natural

seepages and waterways. Water-races also provide habitat for remnant populations of native insects and fish — habitats that are increasingly coming under threat as the difficulties and costs of maintaining the ageing water-race network prompt counties, one by one, to pipe the water supplies.

Not blanket promotion

Road verges with reconstituted natural communities could, say Dr Meurk and Ms Lucas, ultimately provide one of the few glimpses of the primeval landscape for both the local community and the bus tourist Rest areas could feature plants that could safely be examined pt close hand. The authors emphasise that they are not promoting a blanket replacement of one monotonous type of roadside for another. -- “We would encourage diversity and mosaic,” they say. “There is perhaps a place for the lupins, for verges cut and rolled into cylindrical haybales, for the areas roped off with electric fencing and grazed.”