Which concept did Alexander von Humboldt describe for the first time?

species-area relationships

The correct answer is Option (3) - species-area relationships

During his extensive explorations in the South American jungles, the renowned German naturalist and geographer Alexander von Humboldt made an intriguing observation. He noticed that as the explored area increased within a region, the species richness also increased, but only up to a certain limit. In fact, this relationship between species richness and area, observed across various taxa such as angiosperm plants, birds, bats, and freshwater fishes, follows a rectangular hyperbola. On a logarithmic scale, this relationship is represented by a straight line described by the equation:

log S = log C + Z log A

where: S = Species richness

A = Area Z = Slope of the line (regression coefficient)

C = Y-intercept

In summary, Alexander von Humboldt's findings led to the understanding of the species-area relationship, which demonstrates how species richness varies with the size of the explored area in a particular region.