This is the second time that we have found growths of ivy which have been deliberately killed by someone sawing through the ivy stems. We do not know why people do this, but we can only assume that they think ivy damages trees in some way. Everyone needs to understand that ivy does no harm whatsoever to healthy trees and removing it does nothing but damage to the natural environment.
Ivy provides abundant and irreplaceable nesting habitat for small birds, it provides food and habitat for numerous insect species on which the birds depend. And it provides a late season nectar resource for bees and other flying insects. Ivy has no effect on tree health but removing it will certainly damage the health of other species. We manage this wood for the benefit of everything that lives in it and we are naturally upset by this form of vandalism, however well-intentioned people believe themselves to be.
In some countries with different ecosystems ivy might be considered an invasive species, for example, there are numerous American websites advising the removal of ivy. In this country no such problems exist and removing ivy does nothing but harm. If you are visiting woodlands and removing ivy you should desist immediately. If you know anyone who does this tell them to stop.