Does the edge effect promote biodiversity?

Question

I define the edge effect as: *A term used to describe what occurs at habitat boundaries where two bordering communities influence one another.* My question is whether it generally leads to an increase or decrease in biodiversity (both evenness and richness) and why. Also, what are the biogeographic factors that impact biodiversity relating to this edge effect? I believe that species diversity would increase, as at such habitat boundaries species that inhabit the bordering habitats and those that can also be found in habitat boundaries would be present. I do remember reading that light intensity increases due to the edge effect and thus also allows for shade-intolerant species to thrive, but I do not understand why.

Answer 1

Assuming the two habitat regions are physically adjacent, can expect some species overlap making for a higher biodiversity in the overlap regions.

Regarding more light due to the change in dominate tree species, the switchover should leave some gaps in the top canopy. This lets more light reach the ground. The undiminished sunlight allows some shade-intolerant species to survive. In areas where there is only dim filtered sunlight such shade-intolerant plants would not be able to grow enough to compete against shade tolerant species.