Throughout February and March the Biodiversity Transformation team have been undertaking vegetation survey work in the Waingake Waterworks QEII bush, with the final survey plot being completed in the last week of March.

Back in the spring and early summer of 2019, 8 permanent vegetation monitoring plots were established at random locations throughout the nationally significant 1100ha forest. Each plot consists of a permanently marked 20x20m quadrat, within which tree species are recorded, trees are tagged and measured and saplings are recorded. 24 individual subplots are marked within each plot, and these are used to record understory species and their height classes. This enables factors such as recruitment, growth, and mortality rates to be measured.

Permanent vegetation plots are an established and robust approach for monitoring forest structure and composition, following a standard methodology. The presence of any fauna (birds, animals and insects) is also recorded, along with signs of pests- such as droppings or damage to plants.

Once established, the plots are ideally resurveyed every 5 years to note the growth of the trees, record any losses and measure any changes in the canopy and understory.

The plots can give us a snapshot of any changing trends to the health of the forest through noting visible pest sign and measuring species abundance and diversity. Changes in native forests can be very slow to observe, but the team were hoping to see a decrease in pest sign and damage and possibly some increase in the numbers of highly palatable understory species from the 2019 survey, thanks to the extensive pest control that has been undertaken in both Waterworks Bush and the wider Waingake area in the interluding years.

At the first plot of the 2025 resurvey, the team were pleased to note there was no visible pest damage at the plot. The 2019 survey had noted recent pig (rooting) damage to the forest floor and some significant ungulate (goats and deer) browse damage to certain palatable understory plants. This downward trend in visible pest-sign largely continued throughout the rest of the plots, with a notable reduction in the occurrence of “fresh” pest signs (droppings, fresh rub marks on trees, freshly disturbed soil etc.) and browsing damage in most locations.

Data from the re-survey will be entered into the National Vegetation Survey Databank (NVS) managed by Manaaki Whenua Landcare Research. The NVS is a repository for ecological data in New Zealand and also supports several tools and services to assist with the management and analysis of datasets. Once data has been entered to NVS, comparisons between 2019 and 2025 data can be analysed to determine if any change can be detected.

The next re-survey of the 8 plots will occur in 2030.