Using the Field Measurement Approach

If you have 100 hectares or more of post-1989 forest land registered in the Emissions Trading Scheme (ETS), you must use the Field Measurement Approach (FMA) to calculate your forest's carbon stocks. We've created a step-by-step process so you can see what's involved.

Using the Field Measurement Approach (FMA)

The Field Measurement Approach (FMA) is a method used to calculate how much carbon is in post-1989 forest land (the 'carbon stock') from information you collect about your forest. The information you collect is used to calculate a set of look-up tables specific to your forest.

You must use the FMA if you:

  • have 100 hectares or more of post-1989 forest land registered in the ETS at any time during a mandatory emissions return period, or
  • hold a covenant in the Permanent Forest Sink Initiative (PFSI) subject to the FMA, and have a forest sink area of 100 hectares or more at any time during a mandatory emissions return period.

Owners of smaller forest land areas (less than 100 hectares) must use the look-up tables in the Climate Change (Forestry Sector) Regulations 2008 to assess their carbon stocks.

Why you have to use the FMA

The look-up tables in the Regulations give values for forest carbon stocks based on forest age and regionally- or nationally-averaged growth factors. They don't reflect New Zealand's diverse growing conditions at the individual forest level. Variation in forest growth affects how much carbon a forest stores. The participant-specific tables provide the estimated carbon stock levels of the specific forests subject to the FMA.   

How the FMA works

MPI assigns post-1989 forest owners who are subject to the FMA a set of sample plot locations for their forest. Using rules in the FMA Standard and the FMA Information Standard, you must then collect information which characterises the forest at these plot locations.

MPI uses this information to create participant-specific look-up tables for the carbon stocks on your forest land. You then use these tables to calculate the carbon stock of your forest.

Follow the steps

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Step 1: Decide whether to assign a forest class

Categorise your final intended forest land as either exotic or indigenous.

You can choose to classify your forest land as either exotic or indigenous – depending on what it will be at harvest or maturity. You don't have to do this, but if you have indigenous forest land it can reduce measurement costs because you can choose to sample half the number of plots (compared to exotic forest land).

Note, once a forest class has been assigned to your existing land, it cannot be changed unless you are being issued a new set of sample plots.

See section 2 of the FMA guide to learn more about choosing a forest class.

FMA guide [PDF, 2 MB]

You can assign forest class by:

  • asking MPI for an Assign forest class form.  We will send you a form with details specific to your forest land, or
  • submitting it electronically in our ETS online transaction system when uploading your mapping information.

To request an Assign forest class form:

Find out more

For help submitting your FMA information online:

Step 2: Request sample plots

You must ask MPI for sample plot locations for your forest land.

Requesting sample plots from MPI

Request sample plots by asking MPI for a Request to allocate permanent sample plot locations form.  A form with details and choices specific to your forest land will be sent to you.

To request a form:

You can ask MPI for either:

  • the required minimum number of sample plots – as set out in the Climate Change (Forestry Sector) Regulations 2008
  • a larger number of plots – if you want a more accurate assessment of carbon stocks on your forest land.

Climate Change (Forestry Sector) Regulations 2008 – NZ Legislation website

Step 3: Locate and mark sample plots
Use a global positioning system (GPS) receiver to locate sample plots provided by MPI.

The FMA Standard and FMA guide give instructions on:

  • how to locate sample plots using an approved GPS
  • how to mark the location of sample plots
  • how to relocate plots, if you need to
  • collection of information from part of a plot instead of the whole (when required or allowed). 
Step 4: Collect FMA information
You must collect information about trees in each sample plot.

You must collect information about trees with a diameter at breast height of 25mm or more in each sample plot. You can choose to collect information about smaller trees and shrubs.

Information you must collect includes:

  • tree species
  • tree diameters and heights
  • shrub type, and crown cover and height information (if collecting shrub information)
  • past and planned silvicultural activities for trees (pruning, thinning)
  • adverse events (such as fire, wind or disease).

Information you need to provide is detailed in the FMA Standard and checklist.

If you have trouble collecting information

If you are unable to collect FMA information from a particular sample plot because it's too difficult or dangerous, you can apply for a permanent waiver. You will need to justify why FMA information can't be collected, and may be required to estimate FMA information.

Recording FMA information

Part 5 of the FMA Information Standard tells you how to record information.  Simpler versions of the information requirements are provided in the FMA guide appendices and the FMA information checklist to record information in the field.  

Step 5: Submit information to MPI
How you submit information from your sample plots.

You can submit FMA information to MPI:

  • online, as manually entered data
  • by uploading the information as an electronic file (in XML format as specified in the FMA Information Standard).

Log in to the ETS online system

Once your FMA information is loaded in the ETS online system you can check it and correct any errors.  MPI will further check your data and may contact you for extra information.

Step 6: Calculate carbon stocks
Use your specific carbon tables to calculate carbon stocks.

After accepting your FMA information, MPI uses local and international forest growth and carbon allocation models to create your specific carbon tables. These give the average carbon stocks for each forest type on your forest land. 

Once you've received your carbon tables, you can use them to prepare and submit your emissions returns. You will also use them for future emissions returns, unless your set of sample plots change (for example if you request a new set). This would require a new set of carbon tables. 

Other obligations for land subject to the FMA

If your land is subject to the FMA, you must meet specific requirements when adding or removing land to your ETS registration. For example, you may need to reapply for sample plots, or get an updated set of specific carbon tables. For more information, see section 5 of the FMA guide.

Download the FMA guide [PDF, 2 MB]

Temporary exemptions from the FMA process

You can apply for a temporary waiver from FMA requirements if – for reasons beyond your control – you can't comply in time to get your specific carbon tables. You will need to justify why FMA requirements can't be met.

Find out more

The legal requirements relating to the FMA for post-1989 forests in the ETS are set out in:

Who to contact

To contact MPI about the FMA:

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