In "Death By Landscape" loss and isolation are inextricably linked. Indeed, the main theme of Margaret Atwood's short story is arguably the way in which loss, if not properly dealt with, can lead to a profound sense of isolation.
Loss of one kind or another is a permanent fixture in Lois's life. Her husband Rob has passed away; her children have grown up and flown the nest; she finds herself constantly haunted by the memory of her lost childhood friend, Lucy. All alone in her apartment, Lois is also isolated from nature, her only experience of which is a view of Lake Ontario from the window.
However, something inside her constantly draws her back to the wilderness, even though it cannot bring her any semblance of peace. She adorns her walls with wilderness landscapes, despite the fact that these paintings fill her with a sense of unease. As an adult, Lois now attempts to do something she could never do as a child: reconcile herself to the wilderness to which Lucy was lost all those years ago. Sadly, the very nature of that landscape has now changed completely. No longer is it seen as a place of beauty, fun or recreation; now it takes on a truly sublime appearance, at once majestic and terrifying.
On the face of it, it may appear that Lois's behavior is masochistic. Why on earth would she surround herself with paintings depicting an environment which so unnerves her and evokes such deeply traumatic childhood memories? On closer inspection, however, we see that the overall picture is much more complicated. By hanging so many wilderness landscapes on the wall, Lois is attempting to create her own little world, a world of artificial nature which, unlike the wilderness of Camp Manitou, she hopes to control.
Unfortunately, she does not. Lois's admission that the paintings make her feel uneasy would seem to suggest that the artificial landscapes exert as much control over her as the real one continues to do.
At the same time, Lois looks upon her painting collection as a way of keeping Lucy alive. We never find out exactly what happened to Lucy, but Lois is so profoundly affected by her friend's disappearance that she grieves over her loss as if she were dead. Additionally, she can never fully come to terms with her loss. Why? She cannot because she has isolated herself from reality, meaning that she will never be able to confront the traumas of her troubled past and achieve some measure of peace.
So long as Lois fails to confront her demons, she will remain forever trapped in a dark place between a real wilderness and a fake one. Whichever way she turns, the painful loss she suffered and the debilitating isolation that goes with it will forever endure.