If you live in the upper North Island, mangrove forests may be a familiar sight.
The coastal trees get a bit of a bad rap but Dr Sharon De Luca, a marine ecologist and partner at environmental planning firm Boffa Miskell believes mangroves are misunderstood.
She explains that there’s one species of mangrove in New Zealand, which is native, and has been in the country for around 19 million years based on dating from petrified wood.
“Some people think they’re a pest or an invasive species, but they are native, so we need to respect that and look after them.”
De Luca says mangrove habitats are in salt-water which is unusual for a tree species like theirs and they breath through their pencil-like roots which exchange gases in sediment as the tides go in and out.
Mangroves prefer warm muddy environments such as estuaries and harbours in Northland and they use their waxy leaves to protect themselves from salt in the water.
“They regularly drop leaves to help reduce the salt content, they’re quite clever plants.”
Unlike many other species of trees, human habitation has actually helped mangroves with our creation of muddy harbours and estuaries. Eventually they would become land, but not in our lifetime, De Luca says.
Nonetheless, mangroves obtained a bad reputation as an invasive species and it’s a view still held by many to this day.
“That’s just not the case. Unfortunately, with the mangrove removal that has gone on in the past, that’s had quite adverse effects on ecology. It’s really the only native plant that we’ve treated this way.
“A lot of people have villainised them and put forward the fact that they have lost their views, that sand flats have become mangrove habitats in their lifetime. I don’t think people really understand that ecology doesn’t stand still. It changes and evolves and it’s natural for harbours and estuaries to fill with sediment and be colonised by mangroves, it’s just that it’s been happening so much faster with the sediment that’s been running off.”
