Municipal tree management: how a local authority runs it

What municipal tree management involves

Municipal tree management is all the work needed to keep a local authority's trees safe, healthy and up to number. That is more than pruning. You know which trees you have, you inspect them, you plan maintenance and have it carried out, you replace what is lost, and you record what you did. This article describes how Dutch municipalities organise it; the terms and rules are those of the Netherlands.

The recording is part of it because the municipality owns the trees on its land. Whoever owns a tree has a duty of care: you have to take reasonable measures to prevent damage, and you have to be able to show afterwards that you did. How that works in Dutch law is explained in the article on the duty of care for trees.

Tree management is also a financial and political task. Trees give shade and cooling, they cost maintenance every year, and residents watch every felling closely. A municipality that knows its trees well can explain why it does something, and what it costs not to.

From policy to management plan

Tree management usually sits in a few documents, from general to specific. The names differ per municipality, the layers do not:

Tree policy (bomenbeleidsplan)

The long-term vision, usually adopted by the council: how many and which trees the municipality wants, where it protects trees, and how it deals with felling, replanting and trees on building sites.

Tree management plan (boombeheerplan)

The policy worked out for the tree manager: which trees there are, how often you inspect which group, what maintenance each group gets, and what that takes in work and money per year.

Felling rules

When felling a tree needs a permit. Inside the bebouwingscontour houtkap, the built-up area boundary for felling, the Dutch municipality decides that itself, in its omgevingsplan (the local environment plan). Outside it the national rules apply, with the province as the competent authority.

Specification or contract

The agreements with the contractor who carries out the work: which work, at what price, which quality requirements it has to meet and how you check that.

The felling rules under the Dutch Environment and Planning Act (Omgevingswet) are explained by the Informatiepunt Leefomgeving (in Dutch). For the quality requirements of the work itself, many municipalities refer in their specification to Handboek Bomen, the Dutch reference work for tree care and tree inspection published by the Norminstituut Bomen (in Dutch).

A management plan is as good as the tree inventory it rests on. If half the trees are missing from it, or listed with a condition from ten years ago, you are planning by feel. In IDA Bomen that inventory sits on one map, and every value knows its date and its source.

The tree management cycle

Tree management is cyclical: the same round, again and again, with each step feeding the next.

1. Inventory

   You record which trees there are, with species, dimensions and location. After that you keep the inventory up to date: new planting in, felled trees out.

2. Inspect

   A tree safety inspection, BVC in Dutch, gives every tree a safety class and an advice. How often you inspect is set in your management plan, per group of trees and by risk.

3. Plan

   The advice and the regular maintenance produce the work for the coming year: formative pruning of young trees, maintenance pruning, felling, closer examination. Urgent measures come first.

4. Carry out

   An in-house crew or a contractor carries out the work and reports per tree what was done.

5. Review and update

   You check the work, process the outcome in the inventory and close the measure. Only then is the tree up to date again.

6. Replace

   For trees that are lost you plant new ones, with aftercare in the first years. The new tree goes into the inventory, and the cycle starts again.

In IDA every round in this cycle is a project: a group of trees, a type such as BVC, pruning or planting, and a form. What exactly is recorded during the inspection is covered in what a tree safety inspection is. How you get to a reliable inventory is covered in creating a tree inventory.

Who does what

In a small municipality it is one person with a contractor, in a large one a team. The roles are the same:

• The tree manager owns the inventory and the management plan. They decide which work is coming and review what comes back.
• The tree inspector carries out the inspections, employed by the municipality or by a consultancy.
• The contractor carries out pruning, felling and planting, often under a specification that runs for several years.
• The supervisor checks the work outside on behalf of the municipality.
• Executive and council set policy and budget, and get the questions from residents.

In IDA the contractor works in your inventory, with access to their own projects only. How to set up that cooperation is covered in working with a contractor.

Where it goes wrong in practice

On paper it is often fine. It grinds in the execution, and usually in the same places:

• The inventory lags behind. Trees have been felled and planted, but the register does not know. The next inspector looks for trees that are no longer there.
• Findings are left lying. The inspection is done and the report is in, but nobody sees which risk trees (risicobomen) have not had a measure yet. Legally that is the weakest spot: you knew, and you did nothing.
• The knowledge is in people's heads. One colleague knows why that avenue is pruned differently. When they leave, it leaves with them.
• Every contractor delivers differently. A spreadsheet here, a PDF there. Processing it takes time, and meanwhile the inventory is out of date.
• The budget has no underpinning. Without figures on condition, age and backlog, every budget round is a negotiation by feel.

Accounting for what you did

Sooner or later the question comes: from a councillor, a resident, an insurer or a court. A municipality that has its tree management in order can show four things without searching:

• Per tree: when it was inspected, by whom, what was seen and what was done next.
• For the whole inventory: how many trees there are, in what condition, and how many measures are open.
• Over time: whether the backlog is growing or shrinking.
• About the money: what maintenance costs, and what postponing means.

The first is for the damage claim, the other three are for the budget and the council. For the first, IDA exports a tree's timeline as a PDF, with photos and approved deviations. After a storm all four come together. What is expected of you then is covered in the article on storm damage to trees.

Tree management in IDA

IDA is tree management software for municipalities and their contractors. It follows the cycle above. We migrate your existing tree inventory for you, whether it is a shapefile from your GIS or an Excel list. That is part of onboarding. The inspector or the contractor fills in the form of their project in the field, on a phone or tablet.

What comes back, you review. New trees from an inventory round and deviations from the register go into a queue, and only enter the register after your approval. Every value of a tree keeps its provenance: which inspection or project it comes from, by whom and when.

To account for your work you colour the map by follow-up, so open risk trees stand out. Saved selections appear as charts on the dashboard: the course of the backlog, or the distribution per district. In the planning view you see the projects per type on a timeline, with what is overdue. And with an imported RAW-bestek, the Dutch standard form of specification, IDA calculates the cost of a selection of trees against the prices in your contract.

You set the frequency in your management plan. With a saved selection, such as all trees whose last inspection is older than the interval in your management plan, you see which trees are due.

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