Aaron T.

A keystone species can be defined as one whose impacts on its community or ecosystem are large and greater than would be expected from its relative abundance or total biomass. Based upon scientific observation, certain species have such an impact on a biological community or ecosystem that the remove of that species from it's habitat can create an instability within that ecosystem changing the dynamics of which species becomes dominate. In other words the removal of a that species would allow other species to take over a given population because they are not longer checked by the keystone species. As this theory applies to humans and agriculture, humans may be seen as keystone species. Take for example many of the planted rice fields in Asia. Year after year, the same wetlands are continuously being planted with rich and maintained to maximize the total yield of crops from those areas. This maintenance includes the removal of invasive species competing for the resources that the rice plants do. If humans for some reason decided to not try and cultivate the rice, other species would then move in and compete for the rices resourses and may eventually even replace the rice plants as a dominate species. In this sense man is a keystone species in man maintained environments.