Planners walk a cold-loving fir uphill before the valley warms past it

Begin at the old treeline, where the frost still holds in the ridge's shadow an hour after the sun clears it. The air up here smells of resin and cold stone, and underneath that, faintly, of the diesel the planting crews aren't supposed to burn on the switchbacks but burn anyway. This is Cascade Basin 61. This is a subalpine fir — Abies, the foresters say, then correct themselves and use the local name, which means nothing to a ledger and everything to the people who gave it. The Mandate intends to move it. Not the old trees, which are too settled to travel, but the stand's future: seedlings grown from this ground, planted three hundred meters upslope, onto ground that is cold now and will be, by the Gaia Ledger's basin model, the only cold left to this mountain inside the lifetime of a child born this season.

"The tree can walk," said Dr. Imani Reyes, who runs the assisted-migration cell for the Terran Restoration Mandate's mountain division, standing at the upper planting line with a seedling tray balanced on her hip. "It just walks at the speed of seeds and wind — a few meters a year, if the year is kind. The warming walks faster. So we carry it." She has carried this one eleven thousand seedlings so far, and lost, by her own count, a third of the first planting to a late melt that fooled them into breaking dormancy early.

The arithmetic is simple and it is brutal. A species survives if it reaches suitable ground faster than its old ground stops being suitable. For most of the recovery the Mandate trusted plants to move themselves, reseeding corridors to help them along. But a mountain is a trap. There is only so much up, and above a certain line there's no more mountain at all. Reyes's cell has decided that for the high conifers, patience is a death sentence dressed up as principle.

The gardener's quarrel

Not everyone in her own guild agrees. At the basin field station I watched two foresters argue over a map until the argument turned theological. "If we choose the elevation, choose the genotype, water it through its first drought — that is not a wild forest," said Teodor Vaught, who has worked restoration in these mountains for thirty years and looks, under the longevity therapies, no older than the seedlings' first stewards. "That is a garden we've agreed to call wilderness because the word comforts us. And who remembers that the whole point was to take our hands off?"

Reyes didn't flinch. "The hands-off version ends with a bare ridge and a true number in Henrik Vantaa's ledger," she said. I'll confess my own interest here. I've argued with my colleague Vantaa, at length, about whether any ledger can hold what a stand of old firs means to the slope beneath it. But he's right about one thing, and it galls me to write it down: when the Mandate moves a population by hand, the Gaia Ledger logs a gain in the upper basin and a planned loss in the lower, and the two numbers balance so neatly that no one auditing them later will see the grief folded into the subtraction.

Because there is grief. The lower stand — the one the model now wants abandoned to its warming — wasn't wild either. It was planted two generations back by people who'd retreated upslope from the drowned coast and needed something living to mark that they'd arrived. "My father put those in," said Nadia Okonkwo, who farms the bench below the old treeline and came up to watch the crews work. "He planted them the year they unbuilt our town on the water. Now you tell me they're in the wrong place." She didn't raise her voice. "Everything my family planted was in the wrong place once. We moved it. We're tired of moving it."

And who remembers the trees that won't make the climb? Not the model. The model only remembers what it's told to carry.

The Mandate's position is that the lower stand won't be cut, only left — allowed to live out its decline while its children grow on higher ground. Reyes calls this continuity. Okonkwo calls it a funeral with a long date on it.

Up at the planting line, the crews work through the short cold morning, setting seedlings into ground that has never grown this tree and, if the model holds, soon will be the only ground that can. Reyes counted the last tray out loud as she emptied it. Eleven thousand and forty. Then she knelt and firmed the soil around the last one with both hands, the way you'd tuck in something you meant to come back for.