I can tell you from experience that this is true: we have a nesting pair of heron's in our little watershed, mostly due to the cattle keeping things trimmed to the point where the birds can spot predators more readily. But the key word here is "landowner"...
A landowner has an economic incentive to keep his pastures productive. A landowner will not overgraze his property, to the point where it burns out. However, much of the cattle on grass in this country are on public lands (mostly out West), where no such incentive exists, and a reverse incentive may apply (to "get all you can while the gettin's good", as they say). In the absence of strong governmental management this inevitably leads to a tragedy of the commons.
The fight between cattle-grazing landowners and environmentalists may be a false dichotomy.
(link) [EurekAlert!]00:00 /Agriculture | 0 comments | permanent link