Source: Department of Conservation
Erosion-prone banks, sedimented estuaries and waterways smothered with all the worst weeds. This is the confronting riverscape in Doubtless Bay on Northland’s east coast.
Scratch below the surface though and you find secretive native fish, kōura and insects thriving in little pockets, excellent swimming holes, hapū who care deeply for their awa and whenua, and a community that totally supports work to restore the rivers. It’s for their children, mokopuna and future generations.
Climate change effects in the bay
DOC’s Ngā Awa river ranger Maddy Jopling lives in the area and has seen issues with flooding, erosion and pollution after storms and heavy rain first-hand. She’s not alone.
Farmers have come to fear heavy rain warnings, knowing they will be faced with costs to move and repair fences. Slips destabilise plantation forests and add to fine sediment being carried downstream. Hapū have noticed the loss of prime cockle beds near the Taipā River mouth in the last 20 years. Lifestyle block owners are concerned about the rivers nibbling away at their land and its value diminishing.
“We’re already seeing climate change happening here with more intense weather and more frequent, damaging floods,” says Maddy.
“And sadly, there are other things we’ll have to contend with in the future, such as worse droughts, increased risk of wildfires and sea-level rise affecting land around the coast.”
Healthy rivers need healthy land
Maddy’s job as river ranger for Doubtless Bay is to work with hapū and community to restore the biodiversity of the rivers from source to sea. The bay’s three rivers and their tributaries are treated as a single catchment, so there’s a big area involved.
“It’s critical to think about the future when planting or restoring habitat for native species in Doubtless Bay. Otherwise we won’t get the improvements in river health and biodiversity that we all want.”
A local hapū collective and many local landowners, groups and agencies are interested in or are already involved in restoration work. There is also support from industry representatives.
“The hapū collective wanted to know more about how climate change is likely to affect their rohe and what they could do now to build resilience. I’d also heard a lot of people talk about how the trees they’d put in had collapsed or fencing that had been washed away by floods.”
Equipping the community with best practice revegetation information
Maddy says she saw an opportunity for DOC to support future work by providing best-practice, practical information to help advise and prioritise restoration planting in the catchment.
“We wanted to help people make the best decisions about what to plant where and how to tackle the really difficult issues.
“People also told me about what had worked for them in the past. So when we were setting up the project, we knew it was going to be important to visit a whole range of different places, especially those that are typical of many places here. It makes sense that local people know their land better than anyone.”
Drawing on ecology and mapping expertise
The project started with hapū, community members and DOC science and technical staff taking forest ecologist Dr Adam Forbes and mapping specialist Dr Brad Case on a tour of the catchment. The group visited more than 20 diverse sites in the in the Awapoko, Oruru and Oruaiti subcatchments over 3 days in late summer.
Based on this information and the site visits, the pair have created treatments for 12 different types of habitat in the catchment. The treatments outline possible changes to the vegetation to take climate change and human preferences into account, protect the coast and freshwater and restore wetlands.
Adam says visiting all the different sites in Doubtless Bay was really important.
“I couldn’t have done this without going to the sites and talking to everyone. It enabled me to find out what’s out there and what the issues are.”
He has mined a range of databases to create the treatments, drawing on list of plants for the area, planting densities, flammability ratings and listed options to tackle some of the catchment’s big issues.
“I’ve included a list of species that are relevant for restoration in these catchments for both the pioneer stage and the enrichment stage, once the canopy has been established. There are some neat regionally specific endemic species included, which provide options for people.”
Adam has helpfully provided information on timing, risks, management, maintenance and avenues of support.
Some examples of revegetation treatments
One suggested treatment is for sites in the lower rivers where īnanga spawn. The areas are currently open and weedy with willows and poplars that can keel over into the river during floods. Adam suggests getting light native forest established, including species that īnanga favour for spawning.
Another treatment is for steep hill country with a tendency to slip. These areas are currently in pasture but establishing native vegetation would stabilise the hillsides and reduce erosion downstream.
Mapping reveals hotspots for priority work
Brad has created a series of catchment maps that show different information about the catchment such as susceptibility to erosion and flooding. Overlaying the maps highlights hotspots where multiple issues overlap.
Adam has included many of these areas in his 12 revegetation treatments.
Maddy continues, “When I saw the catchment mapping, I was really excited about the fact that it will help us prioritise restoration as a community at a landscape scale.”
“When you’re going out and doing your restoration work, the scale can be quite overwhelming. There’s so much to do! But the way Brad’s done the modelling makes it really obvious where we need to focus a bit more effort from a climate change perspective.”
Sharing the findings
The report is now available from our website: Doubtless Bay rivers webpage (or download Doubtless Bay revegetation options)
“Adam and Brad have shared the report and discussed their findings with the community already. We’re really interested in feedback though and will continue to work with the community to put the information into practice.”
About Ngā Awa river restoration programme
Taking a whole catchment approach, Ngā Awa is working in partnership with iwi, hapū and communities to restore the biodiversity of 12 rivers from mountains to sea. The three rivers in Doubtless Bay are one of the restoration catchments.
The programme’s goal is to see river ecosystems and species thriving from mountains to sea, which enrich people’s lives. This is achieved by collaborating with others, co-designing and co-leading with iwi, hapū and whānau and recognising climate change. Planning the restoration work is underpinned by sound technical and scientific advice.
