NCGS-M004 — Canopy and shade measurement at T4 or later
- Code: NCGS-M004
- Version: NCGS-2026-09-24
- Approval status: Approved
Measurement of each living tree’s crown from the two canopy axes recorded on a monitoring visit at T4 or later: the crown area as an ellipse, the shade area of a site as the sum over its living trees, the usable-shade subset as the sum over crowns wide enough to sit under, and the canopy cover change at the site as the shade area minus the site’s baseline canopy. Claims shade only once trees are old enough for a crown to mean something.
underlying principles and assumptions
Shade is measured, never projected from a count of trees planted; the horizon is the hinge (ADR-0012); a dead tree casts no shade; usable shade is the crown area of trees whose long axis reaches the stated threshold, a stated simplification of what a person can sit under, not a model of the sun; the baseline is what the site had before the project: its shade area at T0, or at the site’s first canopy visit for trees that predate the project, and zero for trees the project planted where no earlier visit measured them.
methods and procedures
On a visit at T4 or T5 whose activity applies NCGS-M004, for every living tree measure the longest crown axis and the axis perpendicular to it at the widest point, in metres, and record them on the observation with the photograph; crown area is pi/4 times the product; shade area of the site is the sum over living trees; usable shade is the same sum over trees with a long axis of at least 2 metres; canopy cover change is the shade area minus the baseline canopy.
data requirements and inputs
A registered design whose plan reaches T4 for the monitored stratum; conformant planting records; monitoring visit records at T4 or T5 whose activity applies NCGS-M004, with both canopy axes on every observation of a living tree; the site’s T0 visit, or its first canopy visit for trees that predate the project, where a baseline is claimed.
calculation and transformation rules
For each living tree i with axes l_i and s_i in metres, crown area c_i = pi/4 × l_i × s_i. Shade area of the site at the horizon SA = sum over living trees of c_i. Usable shade area USA = sum of c_i over living trees with l_i >= 2. Canopy cover change CC = SA minus B, where B is the site’s shade area at T0, or at the site’s first canopy visit for trees that predate the project, and zero for trees the project planted without an earlier visit. All roll up by summing over sites.
outputs and units of measure
Shade area of living trees (M2) by horizon, species, site and census place, with the usable-shade subset (M2) reported alongside; canopy cover change at site (M2) by horizon, site and census place.
validation and verification approach
Verification with the visit: the reviewer of the visit checks that both axes are present on every living tree, plausible against the photograph and the species’ mature canopy, that the horizon is T4 or later, and recomputes the sums and the usable subset.
limitations and applicability boundaries
An ellipse from two axes, not a crown projection; the usable-shade threshold is a convention, not a measure of comfort, and the sun’s path is not modelled. Meaningless before T4, when crowns are seedlings. Defined for the monitoring visit activity type only.
rationale
KIA-Adapt derived shade area from two axes (A4 I.A.3.2.3 and I.A.3.2.4); the visit already captures the axes, so the measurement exists before the first T4 visit and a 2026 design cannot claim it (ADR-0012).
Applicability
- NCGS-M004: canopy and shade are measured at T4 or later; a visit applying the methodology declares T4 or T5 (ADR-0012).
- NCGS-M004: every living tree observed on a canopy visit carries both canopy axes in metres above zero.
Indicators it serves
Activity types
- Monitoring visit
Knowledge domains a reviewer needs
- Field survey and data capture
- Tree establishment and stewardship
Variables
| Variable | Role | Unit | Description |
|---|---|---|---|
| Canopy cover change at site (CC) | DerivedOutput | M2 | CC = SA minus the site’s baseline canopy B: the shade area at T0, or at the site’s first canopy visit for trees that predate the project, and zero for project trees without an earlier visit. |
| Shade area of the site (SA) | DerivedOutput | M2 | SA = sum over living trees of pi/4 × l_i × s_i. |
| Usable shade area of the site (USA) | DerivedOutput | M2 | USA = sum of c_i over living trees with l_i >= 2 metres; the subset of SA a person can sit under, reported alongside shade area. |
| Canopy long axis (l_i, m) | MeasuredInput | M | |
| Canopy short axis (s_i, m) | MeasuredInput | M | |
| Tree alive on the canopy visit (a_i) | MeasuredInput | UNITLESS |
Monitoring requirements
- NCGS-M004 monitoring requirement: canopy axes on every living tree at T4 or later: On a visit at T4 or T5 applying the methodology, both canopy axes and the photograph on every living tree reached; a T0 visit where a baseline is claimed.