Q. Alexander von Humboldt observed that, within a region species richness......... with increasing explored area. The most appropriate word to fill the blank is

 445  146 Biodiversity and Conservation Report Error

Solution:

Alexander von Humboldt was a German naturalist and geographer who described species-area relationship for the first time. He did extensive explorations in the wilderness of South American forests and observed that within a region, species richness increases with increasing explored area, but up to a certain limit.