Sustainable Forestry

A forest can supply timber indefinitely if the annual cut never exceeds the annual growth. Growth rate is usually given per hectare per year, in cubic meters of new wood. Multiply that rate by the total forest area and you get the sustainable yield: the ceiling on how much can be cut each year while the standing volume of wood stays constant over time. Cut less than that and the forest grows denser; cut more and you draw down the forest's wood the way overdrafting draws down an aquifer.

Three cutting patterns try to hit that ceiling without collapsing the forest. Selective cutting removes only mature or marked trees here and there, leaving the canopy mostly intact and letting natural regeneration fill gaps. Strip cutting clears narrow bands and leaves neighboring strips standing, so seeds from the uncut strips reseed the cleared one, and after a few years the pattern rotates to the next strip. Rotation cycles schedule each section of forest to be cut on a fixed interval long enough for full regrowth, so at any moment different sections sit at different ages. All three spread the harvest in space or time instead of clear-cutting everything at once.

The resilience problem shows up after harvest, in how the forest is replanted. A natural stand carries many species and ages, so a drought, beetle, or blight that kills one species leaves others standing. A plantation of one fast-growing species is efficient to harvest but genetically and structurally uniform, so one pest or storm can take the entire stand. This connects directly to carbon storage: old-growth forests hold huge amounts of carbon in large trees and soil, and converting that stand to a plantation releases stored carbon and resets the site's carbon storage to near zero.