Forest monitoring

Our annual growth and yield monitoring programme has progressed well in 2020-2021 with the following activities completed or near-completion:

  • A 383 sample plot inventory of near-harvest forest stands.
  • A 313 sample plot inventory of mid-rotation forest stands.
  • Remeasurement of the majority of permanent sample plots (PSPs) due for reassessment.
  • Updated and reconciled GIS mapping of all harvesting for the 2020/21 year using satellite imagery, orthophotography, small-scale aerial photography, GPS surveys, and UAV footage.
  • Physical yield reconciliation of all major completed Harvest Units.
  • Re-casting of the company’s extensive set of physical and financial yield tables based on the latest available inventory, PSP, and reconciliation data.
  • An annual revision of the company’s 10-year physical and financial harvest plan using Remsoft’s Woodstock planning software integrated with the company’s proprietary financial models. Note that this plan is based on an approximate two-rotation (i.e. 60 years) planning cycle, and uses the very latest available mapping and yield projection data to test for sustainable production levels.
  • An annual survey of the Forest Health of the company's forests was completed in September 2020 by SPS Biosecurity Ltd.  The major findings from the 2020 survey were that several parts of the forest appear to be deficient in nitrogen,  the presence of significant possum damage in Nobleburn forest, and the presence of goat damage in young trees in the Silverpeaks. Further incursions of Red Needle Cast were discovered some distance from the initial find in 2017, and unfortunately, it appears that the disease is now well established in Otago.  To date, it seems unlikely to become a major health issue for our forests, but we will continue monitoring.  No other significant issues have been discovered to date.

By winter 2021, 75% of the company’s forest area older than 20 years of age had been measured, including 92% of radiata stands.

Since 2001 actual harvest volumes have been within 2% of prediction overall, which is well within an acceptable margin of error.

Clearfell coup size monitoring

A coup is an area of forest harvested.  The average clearfell coup size is monitored as part of the company’s commitment to the principles of FSC®. Recent results of this exercise are as follows:

Year (ending) Min (ha) Max (ha) Average (ha)
2005 0.1 53.7 11.4
2006 0.9 82.0 17.9
2007 0.9 59.0 22.1
2008 2.0 104.7 23.1
2009 1.1 84.8 24.1
2010 0.5 148.4 28.7
2011 2.7 66.6 23.4
2012 1.5 109.6 18.0
2013 0.2 94.7 28.2
2014 0.5 65.4 20.1
2015 3.2 115.0 32.3
2016 0.6 109.0 18.4
2017 3.4 124.3 27.1
2018 1.4 93.0 29.7
2019 8.0 100.0 27.0
2020 5.5 110.9 32.1
2021 5.2 96.9 40.8

City Forests has largely reached its sustainable levels of harvesting now.  Most current harvesting is taking place in the company’s larger Waipori and Tokoiti forests.

Chemical use

All chemicals used during the 2020/21 year were checked for compliance with FSC® 's 'highly hazardous' pesticides list (Annex 6.1 of the National Standard) as part of our risk assessment process. One chemical used for weed control during the year is on the current list (Picloram).  This is a fairly recent addition to the list, and City Forests uses small quantities for post-planting weed control. It is an important tool in certain situations for us, and there is currently no other chemical available which is as effective.  No other chemicals used by the company appear on the 'Highly Hazardous" list.

TBfree/Ospri animal pest control chemical operations have been conducted in our Waipori forest during 2019 and Silverpeaks in 2020.  (TBfree's operations are authorised by a variety of Acts and Regulations.)

City Forests actively participates in research into chemical and non-chemical alternatives, and is continually evaluating its management practices for ways in which to minimise Highly Hazardous chemical use.