The savings model
A conservative model — every assumption named and sourced
Vancouver as the worked example, built from public Park Board data and peer-reviewed literature, with every assumption at the floor of what the evidence supports. The pilot replaces these modelled values with measured ones.
What Vancouver's own numbers say
The gap between the published cadence and the operational one is the mortality driver. A standard surface bag empties in 5–9 hours; Tree Guardian meters the same fill across the full window between visits.
One fill, ten days — where the water goes
Both systems get the same fill on day zero. A standard surface bag empties in 5–9 hours and the soil dries by day two. Tree Guardian meters the same water into the root zone: seven days inside the target band, then a three-day buffer above the stress threshold.
Two levers, added together
Lever 1 — Watering labour
Lever 2 — Mortality reduction
How the $440K moves under different assumptions
The conservative case sits in the bottom third of the realistic envelope: the $15/visit rate is well below the Park Board's loaded crew-and-truck cost, and even the pessimistic floor clears $244K a year.
Where the need is greatest
Dot size = trees planted per year; colour = estimated young-tree mortality. Click any dot for its numbers — estimates apply city canopy and heat data from Vancouver's 2025 Urban Forest Strategy and are illustrative.
Highest-priority neighbourhoods
The lowest-canopy neighbourhoods are the hottest, the driest, and the hardest on a newly planted tree — the same places the 2021 heat dome hit hardest. They are where the pilot starts, and where every saved tree counts double.
The break-even math
One failed street tree costs the City about $3,250 — $2,000 of establishment (planting plus two years of watering) and $1,250 to remove the failure and replant the site. At pilot pricing of $250 per kit, a single avoided failure covers thirteen trees' worth of kits.
The replacement tree's own watering is counted in its own establishment, so nothing is double-counted. Pilot kits $250 per tree; volume pricing $150.
Heat is the stress test
During the 2021 heat dome BC recorded 619 heat-related deaths (BCCDC) and Vancouver lost 800+ trees. Peer-reviewed analysis found every 5% of added canopy cuts heat-death risk by 9% (Henderson et al. 2022). Tree Guardian holds root-zone moisture through multi-week heat events — exactly when crews can't reach every tree.
Put the model to the test — the pilot measures every one of these numbers.