How to tell a peat fire scar from a heather burn in satellite imagery

A dark patch shows up on this year's pass over a restoration compartment. Before it goes in a report as fire damage, someone has to answer a simpler question first: was that patch put there on purpose?

Managed burning is still part of how a lot of moorland gets handled, and a rotation block that was burned last winter will look, from above, a lot like a patch that burned out of control in a dry spring. Both are dark. Both show reduced vegetation cover. The difference between "accounted for in the plan" and "needs a site visit" comes down to a handful of things you can check in the imagery, not a guess.

Shape and timing tell you more than colour

Muirburn follows a plan. Estates and keepers burn in blocks, usually strips or patches sized to a rotation schedule, with edges that tend to be straight or follow natural breaks like tracks, fence lines and burn breaks cut for exactly that purpose. The burn season itself is narrow, generally running through the cooler, wetter months when fire stays controlled and the moor isn't tinder-dry, and it stops well before ground-nesting birds are back on site. If you overlay a few years of annual passes, a rotation shows up as a sequence: last year's block next to this year's block, moving across the compartment in order.

A wildfire or an uncontrolled peat fire doesn't follow any of that. The scar shape tracks wind direction and fuel load instead of a plan, so it's irregular, often with fingers running up gullies or along drier ridgelines. It isn't confined by compartment boundaries the way a managed burn is, it can cross into areas that were never scheduled to burn, and it's far more likely to turn up in a dry summer than in the standard burn window. If a scar appears outside the burn season and ignores the block boundaries on the management plan, that's the first flag.

Depth of burn is the real tell

Shape gets you most of the way, but the clincher is how the ground recovers, because that tells you how deep the fire actually went. A cool surface burn, which is what a well-managed muirburn aims for, takes off the heather canopy and litter but leaves the duff and the peat body underneath largely intact. Vegetation indices drop sharply the year of the burn, then climb back as heather and cottongrass regrow, usually showing clear recovery within the next annual pass or two.

A peat fire behaves differently because peat itself can smoulder and combust, not just the vegetation sitting on top of it. Where that's happened, the scar doesn't bounce back on the same timeline. Bare peat stays exposed, the signal stays suppressed across multiple years instead of recovering, and the patch often sits in a wetter part of the compartment where surface burns don't normally spread, drains, haggs, or already-bare ground that's lost its vegetation buffer. That combination, slow or absent recovery plus a location that shouldn't have carried a hot fire, is what separates a scar worth flagging from a block that's simply mid-rotation.

Why the distinction matters for reporting

A restoration programme funded against a management plan has to account for scheduled burning as expected land use, not treat it as degradation. Flagging every rotation block as fire damage buries the signal that matters, the uncontrolled losses that expose peat, open new drainage pathways, or push a site further from its restoration targets. Getting the two apart cleanly means the annual change list you hand to funders says something true: this block was burned to plan, this one wasn't, and this one needs a look on the ground before next year's report is due.

That's the kind of year-over-year read Peatland Monitoring is built to produce, flagging the areas where the signal doesn't recover like a managed burn should, so you know which scars to check in person and which ones are simply next in the rotation.

If your restoration area carries both burn history and drainage that needs tracking from year to year, it's worth getting an early look at how the annual condition layer handles your ground.