I first met Katherine de Silva online, she was asking a question on the 'Wild Plants of Wellington' Facebook group.
She came along to one of the Manawa Karioi working bees and we all met her.
Since then, Katherine has chosen Manawa Karioi as a research site and because of its age, she has made two research plots on the site.
She gave me a tour of the two plots she has measured at Manawa Karioi and she talked me through how she is collecting data to help other restoration projects in the future.
Katherine is now on the road in a campervan, studying forty-five restoration plots throughout the country as part of her Master's Degree with Victoria University.
Tell me a bit about yourself?
I finished my bachelor in Environmental Science in 2010 and since then I have been contracting in a variety of roles - field technician, herpetologist, trapper, ecologist, biocontrol officer etc. I decided at the end of 2016 that I would start my Masters in Ecology and Biodiversity which I’m now half way through. I began my field season conducting research into urban restoration through the VUW on 1 December and will be working full time in the field in the South Island until probably April 2018.
Why did you choose this field of research?
I’ve had experience doing vegetation surveys before and I have thoroughly enjoyed spending these days in our forests working with and learning about our native flora. So, I took on a thesis project that would allow me to improve my skills in plant identification, which is a very important skill set in ecology, and that would allow me to spend time working in ecosystems I really enjoy. I also understand how important the implementation of urban forest restoration activities has become, as it is a key tool to improve ecosystem services, function, resilience and biodiversity. So, to be part of a project that will help us understand how we can improve the trajectory and success of restoration activities in degraded urban environments is exciting.
What is the purpose of your Masters study?
The goal is to understand the factors that constrain or promote plant regeneration in urban forests planted up from scratch. This work directly addresses many key restoration questions such as “what are the microhabitat requirements for the missing plant species we aim to reintroduce?” and “what natural succession is happening in urban forests?”. Restoration planting activities are common practice across New Zealand, where bare, degraded land is re-planted in order to improve biodiversity, ecosystem function and social benefits. While establishment of the initial canopy has been relatively successful, the regeneration of late-successional native trees, shrubs and epiphytes beneath the planted canopy, a key process in forest succession, is generally lacking. This research will hopefully assist practitioners to understand factors limiting or triggering natural regeneration, a key indicator of success.
Tell me about the methodology behind the research, how is your study structured?
I will be installing permanent plots across 5 cities (Wellington, Nelson, Christchurch, Dunedin and Invercargill), spanning a large climate gradient within NZ. 45 research sites have been selected to have the structure, composition and environmental conditions measured. Our sites will sit within age categories (young, intermediate, old), providing an understanding of the short-term (1-10 years) to medium-term (10-60 years) successional dynamics of restoration plantings, processes that are virtually unknown in New Zealand cities. Understanding how light, microclimate, and understorey conditions change over the first 60 years of development will provide Councils with critical information for long-term planning to maximise efficiency of resource allocation.
What kind of preparation did you undertake before starting this study?
To find out if the methodology we chose to undertake the vegetation surveys were appropriate, we did a small pilot study at two sites in Wellington (Tawatawa Reserve & Manawa Karioi). We set up two permanent plots and conducted surveys, tweaking techniques and processes to find out what would work best. This was really helpful to set us on the right path, however we continue to fine-tune processes and efficiencies in the field as often things are highlighted once we start working, which we hadn’t thought of previously. to edit.
Why did you choose Manawa Karioi as a site?
Manawa Karioi is the oldest planted forest site we could find in Wellington City, so we really wanted to get it in our research programme. In fact, because we had such strict criteria for our site selection, we couldn’t find any others over 25 years, so we ended up putting two research sites at Manawa Karioi.
How have your field trips been going so far?
Fantastic! I have finished surveying all nine sites in Wellington. And as of today, we have finished site number 2 in Nelson – so 34 more sites to go in total! I have had some great experiences already, visiting the oldest restored site in Wellington was a highlight, with the plot being placed underneath a canopy of puriri, ngaio and Ti Kouka (cabbage tree). It was a very peaceful and relaxing site to work in, with lots of birdsong to keep us company while we crawled along the ground counting seedlings. Another highlight here in Nelson has been seeing a weka the first time myself in the wild - we were sitting on the ground next to the plot and the coolest curious weka came right up to us to check out what we were doing.
What value do restoration projects have in ecological terms?
Restoration activities in New Zealand started during the 1970’s and 80’s; initially seeking to undertake revegetation and weed control programmes on off-shore islands, mainland reserves and national parks. However, restoration programmes have since expanded into urban environments, with a shifted focus to repair biodiversity and ecosystem processes.
Restoration of ecologically functioning plant communities is a skill that has been refined through a few decades of lessons learned. Restoration practitioners now realise the importance of historical and ecological knowledge of the local landscape, to establish the most suitable composition of plant species, and have improved planting practices such as the planting of appropriate species to mimic the stages of forest and the use of eco-sourced seeds to improve planting survival and local genetic diversity. For many people, restoring degraded landscapes and especially those with little local seed source available, is due to the intrinsic value that we place on the living things and processes within forest ecosystems. It is also of high value to humans in order to provide resources and ecosystem services such clean water, fertile soils and purified air.
What outcomes are you expecting?
The results will be combined with a comparable study of cities within the north island, as part of a nationwide assessment under the People Cities & Nature (PCAN) Programme. We don’t yet know what we will find exactly, once we collect the data across all five cities and 45 sites, we will look at the data and see what it tells us. But we may get insight into some of the following areas:
· The composition, structure, regeneration, invasions dynamics in restored urban forests
· The micro-climate and regional climate influences on plant survival within restored urban forests
· Effect of canopy composition on understory plant assembly and natural regeneration of native seedling propagules
· Changes to dominant functional plant groups regenerating along a successional chronosequence at planted urban forest sites.
Our results will provide improved management recommendations and restoration guidelines for urban forest restoration in Wellington & other NZ cities.
How will you share the outcomes of your research?
Communications on progress will take place between all PCAN research groups and other stakeholders including WCC, GWRC, VUW, UoW & regional Botanical Societies. The results will be distributed to all stakeholders in the format of reports, journal publications, talks and other stakeholder engagement activities. Results will also be submitted for publication in peer-reviewed journals and presented at conferences in 2019.
For more Information, a link to programme website and my own details:
Photography and introduction by Vanessa Patea