A Gray Morning in Portland: Managing Carbon Falling From the Sky

AN ADDENDUM: Thanks to information provided by two colleagues, I am now able to estimate, with almost no precision, that our three trees produced round about 327,000 leaves. Thanks to Henry and Barbara for providing quantitative backing for my attempted carbon budget.

Our yard has three large big-leaf maples (probably more than you want to know about Acer macrophyllum at that link, by the way). They provide a lot of great shade in the summer, and of course, readers of this page know that Sheryl Crow found refuge in those trees this past summer as she was recovering from injuries sustained in a pre-mature fledging from her nest. But now, it's fall. And "fall" has taken on new meaning. Seems like about a million leaves have come down. They have no respect for us. Yesterday, we spent hours raking and removing leaves from other shrubs. This morning, I looked out the window, and the camellias were covered again. Even as I raked and bagged today, they continued to fall, and not into existing piles, but right back where I had just raked.

I estimate that, from the number of bags and carts we've raked up, somewhere around 75 cubic feet of compacted leaves hit the ground. At, and I'm just guessing here, 15 pounds per cubic foot, that's a little over a half a ton of leaves. What's left in leaves this time of year is cellulose and lignin, with very little water and nutrients. So, that means about 50% of the dry weight is carbon, taken from the atmosphere last spring and summer, and soon to be released through decay. It's too bad that we don't have a place to compost those pesky yellow fellas as we could sure use more carbon in our garden soil. But, they will be composted at a nearby facility and reused next year.

As the trees leafed out last spring, I tried to imagine the yard in the fall. I'll have a better idea next year. Where's that chain saw...