Short answer

Notable individual trees get their own asset. Similar trees standing together as a group can be modelled as a single polygon asset (a "clump"). Either approach works for the routine recurring jobs (e.g. annual 5-foot pruning) — the difference is granularity of record.

Detail

When to make a tree its own asset:

  • It's notable on its own — a memorial tree, a particularly old or large specimen, a named tree.
  • It has a different inspection or maintenance regime to the trees around it (e.g. it's a fruit tree managed jointly with volunteers).
  • The council is likely to want photo / condition history specific to that tree.
  • It's at risk and you want a defensible inspection trail.

When a clump is fine:

  • A row or cluster of similar trees that are always treated together (e.g. "the line of poplars by the car park").
  • Trees alongside a road or boundary where the council inspects "all of them" rather than each one.
  • Bulk imports of woodland where individual records are not yet justified.

If you go with a clump, draw a polygon around the group and use a name like "Jubilee Park — Trees by Car Park". Routine pruning, leaf clearance, and the like can target the clump in the same way they'd target an individual tree.

Some councils — particularly those with active tree-officer roles — eventually move from clumps to individual trees as their record-keeping matures. That's fine; it's a one-way upgrade and easy to do incrementally.

Watch-outs

  • Don't add every tree on day one — it's a lot of effort and a lot of map clutter for marginal benefit. Start with the notable ones plus clumps, then promote individuals as the council's needs grow.
  • Trees in cemeteries, churchyards, and play areas are usually worth individual records because of the safety implications of falling branches.