Cheri van Schravendijk-Goodman tells us why we need to consider the function of exotic trees during repo restoration.
PB3 is a planter bag made from black polythene. PB stands for pint bag, so a PB3 will hold 3 pints or approximately 1800 ml of soil. Native plants grown in PB3 bags tend to be about 30–60 cm tall. It will likely take many decades until the native tree seedlings are the size of the old exotic trees the ruru use for roosts.
Our poor ruru. They grew up in a land that had mighty conifers – our rimu, our mataī, our miro and our kauri, our other podocarps and of course our kahikatea swamp forests, and these are the types of trees that would have provided really good roosting cover. Pukatea have natural little holes, so our ruru generally like to nest at the bottom of trees but also use holes in bigger and older trees as well.
After 1840, with huge tracts of forest and swamp forest being cleared out, all of that habitat was taken away from them. And so it would have pushed them into the areas where that bush still remained until the bigger exotic trees like macrocarpas and pines, gums were planted and got to a decent size that these birds are used to interacting with. As a result, they tend to be the trees now that our ruru are using.
We have this huge push now for restoration and everyone’s super keen to get natives back – and I totally tautoko that – but at the same time we’re in our rush to re-indigenise everything, we are taking out those very things that our animals have had to adapt to. It takes a very, very long time for a PB3 native of this size to get to the size of a macrocarpa or a pine that’s a hundred years old. And so, in the meantime, we’ve got to ask ourselves, if you’re going to take those trees down, where are our birds going to go?
We even have the same challenges with willows. We don’t like willows, but at the moment, some of them are providing habitat for our tuna until such time as we can get the natives to come back and replace them.
So we are going ahead with much fervour, you know, much energy into the restoration space, but we’re forgetting that it’s not just about us, there’s a bigger whakapapa. And that’s why we keep saying you’ve got to understand the whakapapa of the system to then identify and best plan for how you make the shifts and changes towards the overall dream that you have. You don’t have to give the dream up, you’ve just got to recognise that it’s going to take time for some things to shift and change as well.
Photo of Manurewa forest remnants, Auckland Council
Photo, kahikatea at Lake Brunner, Steve Attwood
Footage of pīwakawaka and ruru, and close up of ruru, courtesy of Neil, a visiting English bird lover
Series of photographs of ruru chick and ruru eggs in tree hollows, Sarah Busbridge
Photo of macrocarpa tree, Jon Sullivan, CC BY-NC 2.0
Photo, close-up of macrocarpa tree trunk with holes, Whatsallthisthen, CC BY-NC-ND 2.0
Close-up footage of curious ruru, Nick Bradsworth
Illustration, ruru whakapapa, Cheri van Schravendijk-Goodman, sourced from Te Reo o Te Repo – The Voice of the Wetland