| TRANSECT | Sample line across a habitat used for standardised surveys, as of plant distribution, animal populations etc. (8) |
| RECONNAISSANCE | Survey, as of land (14) |
| SCANS | Surveys, as a crowd |
| WILDING | Restoring a habitat to a more natural state, as a gardener might do on a small scale (7) |
| INDICATOR | A blinker; or, a species, such as the Adonis blue, barn owl, English bluebell, oakmoss or turtledove, whose absence, abundance or presence reflects a specific environmental condition in a habitat (9) |
| NEOPHYTE | Term for a plant recently introduced to a habitat or region (8) |
| STONE | Unit of mass based on the weight of a rock that was standardised by Edward III as 14 lbs; or, a sarsen or megalith forming part of a prehistoric monument (5) |
| DIA | Line across a cir. |
| DIAMETER | Line across a circle through the centre (8) |
| RAILS | Line across a billiard table (5) |
| BIOTOPE | Subdivision of a habitat, often small, associated with a particular ecological community (7) |
| ONCEOVER | A quick survey as soon as it's finally done (4-4) |
| CHORDS | Lines across a circle |
| KELP | Growing in underwater forests and absorbing carbon, a seaweed whose holdfast provides a habitat for seahorses, sea stars, jellyfish, anemones and other marine life (4) |
| TERRITORIAL | Defending a habitat (of an animal) (11) |
| TREELINE | The edge of a habitat beyond which, due to cold, altitude, aridity,exposure to wind or other cause, |
| HEDGE | Word linking with row to make a habitat forming part of the countryside (5) |
| NOLINA | Covering around one-third of the UK's terrain, a habitat often with blanket bog (6) |
| GAUGE | Distance between the rails of a line of railway track, standardised in Britain and elsewhere as 4ft 8.5 in (5) |
| CARAT | A measure of the weight of diamonds now standardised as 0.20 grams (5) |
