Which of the following statements regarding the species-area relationship is correct?

Statements:

1. The Z value typically ranges from 0.1 to 0.2 for smaller areas.
2. For large areas like entire continents, the Z value ranges from 0.6 to 1.2.
3. A higher Z value indicates a more rapid increase in species richness with increasing area.
4. A Z value of exactly 1.0 means species richness doubles with each doubling of area.