State two observation made by German naturalist, Alexender von Humboldt during extensive explorations in South American Jungles.
German naturalist and geographer Alexander von Humboldt during his extensive explorations in South American jungles made two observations-
(i) within a region species richness increased with increasing explored area, but only up to limit.
(ii) The relationship between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) turns out to be a rectangular hyperbola.