Final answer:
Richness is highest with greater habitat diversity, most notably in diverse landscapes with varied land uses and in regions closer to the equator where tropical conditions prevail, fostering high biodiversity and ecosystem complexity.
Step-by-step explanation:
Richness is highest where there is greater habitat diversity. This can be seen in different regions where species richness is notably correlated with the variety and complexity of the landscape, such as the mix of cultural and natural habitats in the Madrid region of Spain. The number of different land uses can significantly affect the richness of certain assemblages, like birds, amphibians, reptiles, and butterflies.
Moreover, latitude plays a critical role in species richness, with the greatest diversity often found in tropical regions, but with a peak usually slightly north of the equator. Factors such as climate predictability, island biogeography, and the extent of woodland cover in a landscape can also influence species richness. For instance, woodland-dependent birds in fragmented landscapes show a strong response to the total amount of wooded area available.
Biodiversity and species richness are also affected by ecosystem complexity and the rate of endemism, with biodiversity hotspots often being located in the tropics. However, this great diversity leads to challenges in species identification and a high risk of biodiversity loss. Hence, conservation efforts are paramount to maintain this richness.