envirohistory NZ

Continuing with the theme explored in the previous post, the role of semi-managed nature in supporting biodiversity, this post explores how land development can sometimes lead to the enhancement – rather than the degradation – of an environment’s ability to support biodiversity.

This may seem counter-intuitive, but one example of a land-use change (and in many respects, intensification) is pastoral farmland converted to a residential estate. Generally, this kind of land-use change will either have a negative or neutral effect on the land’s ability to support biodiversity. However, a case where this has led to the creation of habitat for indigenous (as well as  non-indigenous) wildlife, is the Waterstone subdivision in northern Paraparaumu.

Here, housing has been concentrated in “clusters”, surrounded by  parklands. Extensive grass areas slope inwards towards small lakes, acting as “wetlands”, so that in the case of high rain-fall, water is processed by being cycled through the landscape itself rather than going into the stormwater system and out to sea (carrying contaminants with it). The lakes are surrounded by native plantings, which provide food and habitat for a growing number of species.

Though a few kilometres from the coastline now, about five millennia ago, this area was coastal dunes. When the climate warmed after the last Ice Age, the sea level increased to its highest point. As the sea retreated to the west, it left a sea wall a few kilometres inland and, between that and the current coastline, sand dunes and swamp lands. Over time, coastal swamp forest established itself on the swamp lands. The traces of these ancient sand dunes remain evident in Waterstone, while the peat swamp, though now stripped of all traces of its original vegetation, still poses problems for road and rail construction, due to its unstable, waterlogged composition.

While an urban housing development, no matter how sustainably designed, can never restore the swamp forest environment that once supported a multitude of species in a complex, interlinked and self-sustaining ecosystem. However, a well-designed development can certainly enhance the biodiversity value of the environment.  It also provides highly accessible opportunities for children to engage and learn about nature – literally in their own back yards. This mixing of residential land-use and nature can only be a step in the right direction for New Zealand’s natural heritage.

Photo top: View of the southern lake at Waterstone, with the regenerating Waikanae hills in the background. Above left: a pair of royal spoonbills resting by the side of the southern lake. Spoonbills return to the lakes in spring each year. Other indigenous wildlife found at Waterstone are pukeko, paradise shelducks, kingfishers, shags, tui, white-faced heron, moreporks and eels. Above right: a white-faced heron feeding at the northern lake (Photo: Bev Cooper). Bottom left: A nest discovered under a tree. A subdivision like Waterstone provides many opportunities for children to learn about nature. (All photos except herons by C. Knight.)