Final answer:
The location most diverse in terms of tree species would be tropical wet forests such as those near the Amazon River in Madre de Dios, Peru, due to their high species diversity.
Step-by-step explanation:
If diversity were solely a measure of the number of trees, the location with the most diverse ecosystem would be the one with the highest count of different tree species. According to biodiversity studies, tropical wet forests like those in Madre de Dios, Peru, near the Amazon River, exhibit very high species diversity. This is supported by research, such as Barlow et al. (2007), which looked at different groups of biodiversity, including terrestrial vertebrates and a range of invertebrates, as well as the work by Whittaker (1972), who proposed measuring β diversity as the proportion by which the species richness of a region exceeds the average richness of a single locality. These studies demonstrate that areas like the Amazon, with their complex ecosystems, are often much more diverse compared to other regions.