An area with a lot of species diversity is generally considered to be less affected by human interaction because such an area is more likely to have a more complex interactions, including a more complex food web, than an area with less species diversity. In a simple food web, any given species has only one or a few choices of food source. As species diversity increases, generally individual species will have more choices for food.
When humans interact with an ecosystem, some species are impacted more than others. If an important food species is negatively impacted, the diversity of the ecosystem dictates whether there are alternatives for predator species to switch to.
In some cases it is a species' niche, rather than its position in the food web, that matters. In low-diversity systems, one species is more likely to serve as a keystone species, having a disproportionately large effect on the ecosystem overall. If human interaction negatively impacts a keystone species, the entire ecosystem may collapse. Systems with high levels of diversity are, on the other hand, less likely to have a keystone species.