the ones edging fields and lanes) have been in place for a thousand years and maybe more. Apparently they are of great historic value, though I don't know the details as to why.

To a practitioner of landscape history (which is a small, but vital, part of the study of local history) the constitution of a hedgerow can help him to estimate the age of the hedge, therefore the minimum age of the lane it borders, as well as that of the field. This, in turn, can give clues as to historic land use and transport routes.

Even a lay-person can make rough estimates as to hedge-age by counting the number of different vrieties of plant used to make the hedge. As a rule of thumb, you can reckon 100 years for every variety used. (This is obviously not fool-proof, but it works well enough for most of the time.)