A species-area curve typically shows the relationship between the size of a habitat (usually measured as area) and the number of species found within that habitat.
Initially, the species-area curve would rise steeply as the forest area increases, indicating a high diversity of species in the primary forest.
Primary forests are characterized by complex, mature ecosystems with a long evolutionary history, leading to a high number of specialized species adapted to specific ecological niches.
As the area increases, you may see a gradual tapering off of the curve, suggesting that many of the common and widespread species have already been sampled.