World Wetlands Day – what can you do?
Swamps, marshes, fens and bogs. These are our wetland areas, crucial buffer zones at the boundaries between land and water. Wetlands act as giant sponges in the landscape, soaking up rainfall which helps prevent flooding during storms. They also help protect rivers and lakes from runoff from the land during heavy rain by trapping sediment that can choke a stream and absorbing surplus nutrients like nitrogen that can lead to the explosion of algal blooms. Wetlands are a toxin sink, storing environmental pollutants as well as nitrogen and carbon in its wet, airless soil and in the deep roots of the plants that grow there.
In Zealandia’s valley, before the forest was cleared and the stream dammed in the 1870s, the wetland habitat would have been scant. But the valley’s previous use as the source of Wellington’s water supply left behind dams and reservoirs, along with some flat land ideally suited to wetland development and restoration.
Zealandia’s lower wetland and lake edges have been restored with plants that are representative of a typical Wellington wetland, including grasses, sedges and rushes. At the same time riparian (streamside) planting of wetland trees and shrubs like cabbage trees, tree fuchsias, swamp maire, kahikatea and pukatea has enhanced the freshwater stream habitat further up the valley. The wetland area around the lower dam now boasts shags, pateke, and New Zealand scaup, and the streams and lower lake now support shortfin and longfin eels and banded kokupu fish. The lower lake itself is often cloudy from algal blooms, but the streams that feed into it are usually clean, containing a high diversity of freshwater invertebrates. The variety and abundance of these invertebrates indicate the health of a freshwater system.
What can you do?
Wetlands help keep our freshwater fresh, but they can’t do it all on their own, (especially if we keep draining them). If you have a creek at the bottom of your garden, look after it! Avoid disturbing the ground around it. Excavations and earthworks produce loose sediment, which only washes one way: into the nearest stream. Consider planting shade trees, flaxes, sedges and toetoe to keep the water cool and protect the banks. And don’t necessarily remove established shrubs and grasses at the margins, even if they’re exotic species, because for the invertebrates, eels and other fish in your creek, an established habitat is better than no habitat at all.
Native plants for streamside planting in Wellington (DOC)
Common native wetland plants (Wellington Regional Council)
It’s World Wetland Day 2 Feb & Wonders of Wetlands Month at Zealandia
Feb 2: World Wetlands Day
All month: ask our guides & hosts about the wonders of our wetlands!
Article by volunteer Liz Hibbs.
Looking out over the Keith Taylor wetlands at Zealandia (main image).
The cool green of a wetland stream at Zealandia.
Photos by volunteer Janice McKenna