Waikereru Ecosanctuary Seed Island Project
Project Status: Current
Tane’s Tree Trust is part of a team working with the Longbush Ecological Trust to demonstrate how to speed up succession of kānuka scrub into a diverse native forest in the Tairawhiti region. This project is in collaboration with landowner Dame Anne Salmond and other research providers and practitioners. It is aimed at tackling the expected impacts of climate change, biodiversity losses and restoration of waterways within steep marginal pastoral hill country typical of Tairawhiti. The Waikereru Ecosanctuary is over 100 ha of mostly regenerating hill country adjacent to the Longbush Reserve in the Waimata River valley approximately 10km north of Gisborne.
The project comprises several components with our main role in setting up a demonstration area of planted “seed islands” of selected native trees and shrubs to rapidly increase biodiversity targeting gaps of various sizes within the regenerating kanuka. Other components managed by other researchers and practitioners include:
- Survey and mapping of the landforms to provide a context for monitoring natural regeneration and establishment of a network of seed islands;
- Establishing a network of permanent plots to monitor natural regeneration, including a comprehensive botanical survey;
- Carrying out pest animal (both browsers and bird predators) and selective weed control as necessary to support the regeneration; and
- Sharing the findings of this work with the wider community.
Establishing ‘seed islands’ across landscapes is a method for large-scale establishment of native forest. It is a pragmatic and cost-effective option, given the high cost of planting natives ($20,000 or more per ha), and the impracticality of intensive blanket planting on a large scale. The aim is to plant intensively managed small groves of native trees and shrubs to provide greater diversity of wind- and bird-dispersed seed across the wider regenerating landscape such as at Waikereru Ecosanctuary.
This allows for the re-introduction of a range of native tree and shrub species that were once common in the area and will help accelerate the regeneration process to a complex high forest with a diverse mix of species. Seed islands will become like stepping stones, attracting birds to roost, feed and fly between groves and assist in spreading seed across the wider regenerating or planted landscape. This concept works with nature, enlisting the help of birds and wind as agents of seed dispersal.
Work to date
Twenty seed islands have been established in the first year focusing on two categories of sites:
1. Canopy gap – open grass site with surrounding edge kanuka.
2. Partial shade gap – a light covering of scattered kanuka within plot.
While consideration was given to cutting gaps, this site already has a wide range of natural gap sizes to set up and test the concept of seed islands by planting a range of species.
Gap size was governed by the natural openings in the kanuka-dominated shrubland, with 15-50 seedlings (a mixture of tree and shrub species) planted randomly in each seed island to provide a diverse local seed source to supplement the kanuka. The planting site at Waikeruru Ecosanctuary has been registered as a Trees That Count planting site and seed island locations mapped and baseline measurements completed in May 2022.
Funding and next steps
The project is funded by the Lotteries Board with support from owner Anne Salmond, Trees That Count, research associates from Manaaki Whenua, NZ Landcare Trust, and Waimata River Restoration Landcare Group. Nursery seedlings were supplied by the Native Garden Nursery at Matawhero and funded by Trees That Count.
The second year will see a further 20 seed island locations identified and planted with a minimum of 50 selected tree and shrub species.