concept

Keystone structure

A physical feature of a landscape that carries biodiversity out of all proportion to the small area it occupies — here the word "keystone" attaches to a structure rather than a species, so the disproportion is genuine. Manning, Fischer and Lindenmayer argued the case in 2006 for something that sounds trivial: the single old tree left standing in a cleared paddock. That one tree becomes a stepping stone for birds crossing the gap, a focal point where seeds rain down and germinate, an island of canopy invertebrates, and a nutrient hotspot.