ScienceDaily reported on a study by the Univeristy of Miami that the abundant deer population (which is now four to ten times what it was prior to Europeans coming to North American is detrimental to native plant communities. Here is a summary of their findings:
There is a link between disruption of the native animal community and invasion by non-native plant species, according to new research, and a co-author of a new study suggests that “similar links maybe found in other ecosystems between disrupted fauna and declining diversity of flora.” Deer density in the U.S. is about four to 10 times what it was prior to European settlement of North America, and the researchers make a link between this and the declining plant biodiversity in some regions.
To learn more you can read the article at: Excessive deer populations hurt native plant biodiversity — ScienceDaily
Natural History Wanderings 
Overgrazing is always an issue, but in Sweden scientists have as well recently praised the pooh of Deers as spreading meadow flowers etc.
LikeLike
By: narhvalur on April 25, 2014
at 9:00 AM
Controlled grazing can sometimes be helpful to flowers as well. It is overgrazing that is the issue. What is the right amount is well beyond my knowledge level.
LikeLike
By: Sandy Steinman on April 25, 2014
at 9:04 AM