CoachThe conditions of an environment are its measurable physical characteristics:
- temperature, measured with a thermometer, in degrees Celsius;
- humidity — how damp the air or soil is;
- light — from full sun to deep shade.
Conditions change from spot to spot — often sharply within metres — and through the day and the year.
示例
Example 37.5 (The yard, measured)
The July noon survey, with instruments: south wall foot — , dry, full sun; north corner — , damp soil, deep shade. Three metres of distance, sixteen degrees of difference. The two worlds of the opening paragraph are now two rows in a table — and that is progress, because tables can be compared.
Example 37.11 (The stone, above and below)
One stone in the cool corner: on top, lichen and a sunning fly — lit, dry, warm. Beneath, woodlice, a centipede, pale rootlets — dark, damp, cool. Two complete microhabitats separated by five centimetres of rock, each inhabited by exactly those living things whose ranges its conditions match.