The observation that "within a region, species richness increases with increasing exploratory area, but only up to a limit" was made by which scientist?

According to the concept of species-area relations $-$

According to ecologists,what is the value of $Z$ in the species-area relationship equation $\log \, S = \log \, C + Z \, \log \, A$?

Species diversity is bountiful in the tropics near the equator because of the following factors $EXCEPT$ . . . . . .

Why do the tropics have greater biological diversity?

Given $S =$ species richness,$A =$ area,$Z =$ slope of the line,and $C =$ $Y$-intercept. If area is on the $X$-axis and species richness is on the $Y$-axis,what will the graph of $\log S = \log C + Z \log A$ look like?