One tree, to scale
The City measures the trunk of most of its street trees and publishes nothing else about them. These drawings show exactly that much: the trunk at true scale, the root zone a planning rule protects around it, and a person for comparison.
The trees these are drawn from
- 43,051street trees in the City's layer
- 35,619carry a measured trunk diameter
- 7 inmedian trunk diameter
- 89 inlargest trunk measured
Owned by City 33,161 · Harvard 5,139 · MIT 2,276 · DCR 1,796. Ownership is an institution, never a household: a street tree stands in the public way, which is why it can be drawn at all.
Three sizes from the city's own distribution
The median street tree — 7 inches
Both views at one scale. Bar is 10 feet. · Thicker than 49% of the city's measured street trees
- Measured
- trunk diameter, 7 in
- Planning rule
- root protection radius, one foot per inch of trunk diameter — not a survey of this tree's roots
- Modelled
- height and crown for Gleditsia triacanthos, from published growth equations fitted in this region (adjusted R² 0.81) — not a measurement of this tree
- Not published
- height, crown, crowndiameter
Where the ordinance starts protecting — 6 inches
Both views at one scale. Bar is 10 feet. · Thicker than 44% of the city's measured street trees
- Measured
- trunk diameter, 6 in
- Planning rule
- root protection radius, one foot per inch of trunk diameter — not a survey of this tree's roots
- Modelled
- height and crown for Gleditsia triacanthos, from published growth equations fitted in this region (adjusted R² 0.81) — not a measurement of this tree
- Not published
- height, crown, crowndiameter
The largest measured — 89 inches
Both views at one scale. Bar is 50 feet. · Thicker than 100% of the city's measured street trees
- Measured
- trunk diameter, 89 in
- Planning rule
- root protection radius, one foot per inch of trunk diameter — not a survey of this tree's roots
- Not published
- A 89 in trunk predicts a tree ht outside the range this equation was fitted over, so it is refused rather than extrapolated.
Age, and how long a replacement takes
How long a replacement Honeylocust takes to catch up
Years from planting. The tree that was here, and the one planted in its place.
- Age parity
- about 44 years, modelled from trunk diameter — a replacement is as old as the removed tree when it is that old.
- Canopy parity
- Not published. It would need this tree's crown area and the replacement's growth curve on the same basis, and nobody publishes the pair.
- Service parity
- Not published, and refused rather than estimated. A single number would be wrong in principle: shade, interception and cooling return on different curves, and the ordinance settles what is owed rather than when function returns.
What this tree does
2 modelled from its trunk · 4 nobody has measured for Cambridge
- 7,266 sq ftLeaf surface, one sideModelled for Honeylocust from published growth equations for this region (adjusted R² 0.94). It is the input every other service estimate starts from, which is why it is the one that can be shown.
- 2,570 sq ftShade footprint at middayThe crown's own area, from its modelled diameter. Geometry rather than a model of shading: it is the ground the crown covers with the sun overhead, not the cooling that follows from it.
- Carbon storedNeeds an i-Tree Eco study or equivalent for Cambridge, and none is published. The model's inputs are exactly what the record lacks: the canopy assessment holds crown and height but states it has no species, trunk diameter or health, and the permit feed stopped publishing species and diameter in 2021.
- Oxygen producedIn every standard tool this is a stoichiometric restatement of net carbon sequestration rather than an independent measurement. Showing the two side by side would count one estimate twice.
- Runoff avoidedThe City did model retention, with the InVEST urban flood module, and published the result as a unitless index rather than a volume. There is no defensible conversion from that index to gallons, and inventing one would be a false engineering claim about the City's own model.
- Cooling deliveredRefused rather than unavailable. A single tree's contribution to air temperature cannot be stated as a degree figure without a matched control area and pre-and-post observation, and it is the number a reader most wants — which is exactly why it must not be estimated here.
Where removals happen
Removal permits by neighbourhood
Thirteen neighbourhoods, shaded light to dark by removal permits, 2019 to 2025.
The year is the year the permit was issued, not the year the tree came down — the record publishes no removal date at all, so a count of trees removed in a year cannot be built from it. A count, not a rate. The neighbourhood with the most removals also holds the city's densest canopy — a removal count largely tracks how many trees a neighbourhood has, so reading this as where the harm lands reads it backwards. The specification asks for every removal drawn as its own crown polygon; no crown diameter is published for any removed tree, and a removal maps to one household, so this is the finest resolution the record supports.
Below ground, and what the tree exchanges
The space below
Every distance in feet from the trunk centre. Nothing here is a survey of this tree's roots.
- Measured
- the trunk, and only the trunk. It is the one dimension the City publishes.
- Modelled
- the crown, from published growth equations for this species in this region.
- Planning rule
- the protection radius and the feeder range. Both are conventions applied to this tree, not observations of it — which is why the range fades outward instead of ending at a line.
- Not surveyed
- the roots themselves. No excavation, air-spade or radar survey exists for this tree, so no root is drawn. A drawn root is indistinguishable from a scanned one at a glance, and that is the confusion this diagram refuses to create.
What a tree exchanges
Energy crosses the boundary and does not come back. Matter circles inside it.
- Three arcs, one ray
- the asymmetry is the argument. Carbon, water and nutrients return to where they started; sunlight does not. A reader sees that before reading a word.
- No quantities
- the annual figures a diagram like this usually carries — carbon stored, oxygen released, runoff avoided — are not published for Cambridge. They are named gaps on this tracker with the offices that hold them. Numbers on a cycle diagram are the most persuasive way to publish a figure nobody measured.
Why a street tree, and not the removal record
The Tree Tracker specification builds this screen around removal permit 1176407, described as a Northern Red Oak of 34 inches and 90 feet. That permit is real and public. It carries no species, no diameter and no height — only a flag saying the tree was over six inches. Diameters stopped being recorded on removal permits after 2021: none of the 269 permits issued in 2024 carries one.
So a true-scale drawing cannot be made from that record. It can be made from this one, where 35,619 trunk diameters are measured and published.
It also settles a question the specification leaves open. A removal permit maps a tree to a household, and this site does not publish household locations. A street tree belongs to the City, Harvard, MIT or the state, stands in the public way, and identifies nobody — so nothing had to be relaxed to draw it.
Street Trees — Cambridge Open Data, retrieved 2026-08-18.
