To remember what is gone

   I took the picture below of what I believe was a tree in Golden Gate Park. When I came upon this scene and decided to take a photo of it, I was confident that I was correct in my assumption that a tree had been there, though I couldn't really recall it. I found it strange that my memory was so nonspecific in this case, as I walk here daily, pass this spot at least a couple of times as I complete my laps, and consider myself to possess a strong visual memory.
   As I began to think about my poor recall on this occasion, I realized  that changes that occur in my visual field, such as objects I've seen in specific locations, are sometimes striking in their absence, while on other occasions, like this one, seem to disappear both physically and from my brain.
   While I know well about myself that I tend to best remember the things that I find most important, in this case I can't figure out if this tree, or the area where it was located, was any more or less important than any other area of the park to me. I feel like I would normally be able to visualize quite well things that I choose to see often, it seems that in this case that I am just having difficulty seeing the absence.

It was a tree, wasn't it?