Users enter a range of parameters including:
- A site quality index (poor, average, good),
- Initial stand stocking at planting (stems/ha),
- List of species planted including an option of mixed shrubs,
- Planting mix expressed as the percentage of each species, and
- Survival if known within the first 2 years after planting.
The calculator will predict growth of each species to age 80 years taking account of expected mortality. These predictions are based on average growth rates recorded in the Tāne’s Tree Trust Indigenous Plantation Database.
Users can also elect to calibrate growth for a particular stand by entering a stand measurement consisting of stand age, percentage stocking by species, height and diameter. In this case, the calculator will adjust predicted growth and mortality taking account of the measured growth recorded in the stand.
Submitting data and results
Once data is entered press the “Submit” button to provide predictions of growth over time. Graphs and tables provide various stand parameters annually over time to age 80 years based on the data entered by users using predictions based on assumptions built into the growth and yield models:
- Stocking that decreases over time from expected natural mortality (stems/ha)
- Mean height of trees in the stand over time (m)
- Mean DBH (diameter at breast height) of trees in the stand (cm)
- Basal area (m2/ha)
- Total stem volume inside bark (m3/ha)
- Carbon in stems, branches, foliage and roots (tCO2 eq/ha)
Users can then request a one-page summary report of their stand based on the data entered. This includes:
- Planting age and area of the stand
- Stocking – total for site
- Height and DBH – average per tree
- Basal area and volume – total for site
- Carbon – tonnes of CO2 equivalent, total for site