Lyric discussion by fez5 

Cover art for Let It Slide lyrics by No Use For A Name

I think it has to do with loneliness. Metaphor "When theres no one in my tree" is asking "Why I should i care, or why do I matter because no one else notices me?" Then he says let his time or life just "waste away in time. It deacribes a feeling of purposelessness(if that is a word, but u get the drift)