Cue Column | Notes Column
| Cue | Notes |
|---|---|
| Who described the species-area relationship? | Alexander von Humboldt — observed species richness increases with area during South American explorations |
| What is the equation? | log S = log C + Z log A (where S = species richness, A = area, Z = coefficient, C = y-intercept) |
| What does Z represent? | The slope of the log-log species-area curve — steeper = species decline faster with area reduction |
| Z value for continents? | 0.1 to 0.2 (gentle slope — immigration rescue effect buffers loss) |
| Z value for islands? | 0.6 to 1.2 (steep slope — isolation, no recolonisation) |
| Why do islands have higher Z? | Isolated — no immigration rescue from mainland; species lost cannot be replaced |
| NEET trap | Students reverse Z values — continents = 0.1–0.2; islands = 0.6–1.2 |
Summary (Bottom):
The species-area relationship (Humboldt) shows richness increases with area: log S = log C + Z log A. Z is the key value — 0.1–0.2 for continents (gentle), 0.6–1.2 for islands (steep). Higher Z = steeper slope = greater species loss with habitat reduction. This underpins the importance of large, connected conservation areas over small, fragmented ones.