Final answer:
Emergent trees in the top layer of dense canopies in rainforests grow over 70 meters tall, reducing sunlight penetration and creating diverse habitats.
Step-by-step explanation:
The top layer of dense canopies in rainforests has emergent trees that grow to heights of 70 meters or more, which limits the sunlight entering the canopy.
Tropical rainforests have immense biodiversity due to high net primary productivity supported by warm temperatures and abundant rainfall throughout the year. The nutrient-poor soils result in a competition for light, leading to a vertically layered vegetation structure.
The closed upper canopy forms an overhead layer that creates distinct habitats. This includes tall emergent trees that tower above the canopy, allowing them to access more sunlight. The complexity of this environment supports a wide array of life, including epiphytes like bromeliads, ferns, and orchids that thrive high in the canopy where light is plentiful.