Instructions

A plot holds every tree in a stand. Scan the stems that are large enough, place the small ones by hand, add attributes as you go, and export when you are done. All of it stays on the phone until you export.

Before you start

• Allow Location when asked. The GPS fixes taken during a scan place the stems on the earth; without them the plot is mapped in the scan's own frame, north up.
• Under Settings, choose whether tape readings are in centimetres or inches and heights in metres or feet. Stored values are always metric; the export is metric.
• LiDAR works to about 5 m. Stand two to three metres from the trunk when you measure.

Plots

The home screen lists the plots on the phone. New plot asks for a name and who is measuring. A plot can be scanned again on a later visit, and a stem measured in a later scan can be tied to its earlier record so the plot keeps one history per tree.

Measuring a stem

1. Tap Scan. Walk around the tree so the LiDAR sees as much of the bark as possible; the mesh is drawn as it builds.
2. Aim the crosshair at the trunk and tap Measure, or tap the trunk. The default slice is at breast height, 1.37 m above the ground the LiDAR has seen at the base of the tree. The Height button offers other heights, and Tap height measures where the crosshair sits.
3. Read the fit. A ring is drawn on the fitted circle with two bars at the edges of the bark as seen from where you stand. Green means more than half the circle was seen, orange a third to a half, red less. If the ring does not sit on the bark, tap Undo, scan more of the trunk and tap again.
4. Tapping a measured stem at another height adds a taper slice to it instead of a new tree.

Each stem keeps three diameters: the fitted circle, the functional DBH from the area of the traced outline, and the tape-equivalent from the outline's perimeter. The exported diameter is the tape reading when one was typed, else the tape-equivalent when the outline is complete, else the circle, and a column says which.

Double stems and vegetation

Cut splits a double stem or trims foliage off a fit. Stand where the two stems sit side by side, tap Cut, then tap the groove between them. Each side is fitted again and both stems are kept.

Attributes

The Attributes button opens the stem sheet for the last tree measured; any stem in the Map or Stems tab opens its own. The sheet takes species, the tape DBH and readings from other instruments for validation, tag number, status, health, damage, competition, foliage affected, total height and crown base, a leaf sample, an increment core and notes. Every edit is saved as it is made. Save closes the sheet and Done closes the number pad. Hold the Attributes button to have the sheet open after every measured tree.

Increment core

With the tree the last one measured, aim the crosshair at the spot where the core is taken and tap Core. The stem records the height of the core above the ground and its azimuth round the stem. Bark and sapwood thickness are typed on the sheet. For coast redwood the sheet shows the projected leaf area from the sapwood area.

Small trees and hand-placed stems

Above either map, tap Add stem, then tap where the tree stands. A pin appears; tap again or drag to adjust, then Place. The sheet opens for the tape diameter or, for a seedling, the root-collar diameter, height by ruler, planting date and condition. Nothing is added until Place.

Fixed-radius plot

Tap Plot centre above either map and place the pin. The circle sheet takes the plot size, from the standard sizes or any radius in metres or feet, with the plot number, slope, aspect and notes, and shows the plot summary: stems per hectare and per acre, seedlings, basal area, quadratic mean diameter, the range of diameters, heights when entered, and the species split by basal area. Stems outside the circle stay in the file, marked as outside, and are left out of the summary.

Maps

Plan shows the stems in metres with their outlines, north up, with a scale bar. Imagery shows them on satellite imagery once the scan has a GPS fit. If the phone's GPS placed the plot off its tree tops, tap Shift stems, drag the stems onto the imagery, and Apply; the offset is kept with the plot and written to the export.

Export

Export writes one CSV per plot with a row per stem and a column for every attribute, the three diameters, the fit diagnostics, the outline as a polygon, the plot circle, and the georeferencing method. A second file lists taper slices when any were taken. The files open in any spreadsheet or GIS.

Requirements

iPhone 12 Pro or any later Pro model, or an iPad Pro with LiDAR. iOS 17 or later.