Fall (new) leaves on Sitka Alder

Yesterday I noticed several Sitka Alder with new leaves. Some of them were clearly still developing, and given the lateness of season, I thought this seemed odd. I am guessing the warm August/September (so far – though it seems to be cooling off now) had something to do with it.

I found myself wondering what the break even point for a leaf is. It seems like it would take a fair amount of energy to grow a leaf. Clearly over the course of a leaf’s life, it must generate more energy via photosynthesis than it too to grow (or at least it must on average for a tree). So I wonder what the break even point is. My guess is these new leaves aren’t going to bring in as much as they cost due to the lateness of season, but I don’t really know.

If anyone knows of research into the break even point of leaves, I would be curious to see it.

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