Better management of forest felling waste has gained new impetus in Cyclone Gabrielle’s wake, with the sector firmly in the spotlight for the impact such waste has had on communities, ecosystems, and farmland downstream from harvest areas.
Rotorua-based forest management company Interpine Innovation has taken a long-used means of measuring forest residue waste and turned it into a highly accurate, digitised means to help companies lower post-harvest waste levels.
The tool promises to ensure forest felling does not turn sites into time bombs ready to detonate in the wake of future Gabrielle-like events.
The “Wagner Waste method” has been used for almost half a century to estimate volumes of remaining forest waste by sampling along transect lines. It is accurate, simple and quick to use, but its role has been largely to assess felling completeness and reconcile yield estimates.
“But Gabrielle came along, and the focus has now become more on compliance and what we need to do better as an industry,” says Interpine CEO Te Kapunga Dewes.
The recent release of forest slash rules limiting pieces to no more than 2m long, 10cm wide and under 15 cubic metres total per hectare has put the onus on the sector to help protect downstream land.
Anticipating the need the sector will have for accurate assessment, Interpine has developed a technology package that will take a “whole of site” approach to measuring forest residue waste and evaluating it against the new National Environmental Standards.
“The 15 cubic metre requirement is particularly subjective when you just use a sample-based method, with a high level of variability between sample areas, meaning estimates of volume do not always represent the entire site,” says Dewes.
Utilising drone based LIDAR (light detection and ranging) remote sensing with photogrammetry tech linked to deep learning software enables Interpine’s solution to measure forest waste across the entire logged site, rather than rely on a variable sample estimate.
“The tech can compare the compliance requirement against what is actually there on site, right down to specific pieces of timber, identifying those that may exceed the regulations. You can walk over and touch the particular piece of timber the technology identifies.”
The technology goes a step further: incorporating slope, soil and watercourse inputs enables it to render a risk profile for the site, highlighting specific areas within its footprint that may require more attention.
Such debris risk mitigation could be required by a company as part of its quality parameters, or by councils that have control requirements over and above the baseline mitigation regulations.
Two large forestry companies are already trialling the technology, going as far as using the risk mitigation profile to also provide information on the stability and safety of skid site slash piles.
Three other companies are in the wings, while a trial with a regional council is also pending.
Dewes says the technology is a progressive move by his company, recognising the industry has needed to improve the way it cleans up sites, and be more accountable.
“And we are proud that this is home-grown technology and is based on a stand level approach to the site, not a sampled approach. It’s using locally developed tools for local problems.
“It means operators can go out, hand on heart, and say they are 100% meeting their compliance requirements and can step up further from there.”