I know that feeling too. Our garden is sheltered mostly by elms. They haven't been dying off for many years, but this last couple of years Dutch Elm Disease has started to take them again. This year I've also lost my favourite apple tree, one which I planted thirty years ago when we first moved in, and I haven't worked out what it was that got it. Nothing to be done. I've just planted some stone pine seeds. That's the umbrella pine that you see all over Italy and the one we get our pine nuts from. At 66 I'm being a little optimistic that I'll ever harvest my own pine nuts, but hey!