broadleafication of mixed forests

Hey Eric,

A guy I talked with a few years ago was working on his PhD in forestry. He mentioned that in French Canada (and likely in New England I would guess) there has been a trend since colonization toward replanting/favoring broadleaf trees over conifers. Around here a maple forest for syrup production is seen as a status symbol, which may be part of why conifers aren't favored.

My question for the professional plant geek (self-proclaimed, no malice here) is, what is the difference in the rate of carbon sequestration of conifers on average vs. angiosperm trees? And would this broadleaf favoritism make a significant difference in the northern forests' ability to sequester carbon?

Cheers

Hi Everett,

Great question. I'm not aware of the distinction in the carbon sequestration rate of broadleaf versus conifer per se. Slower growing trees tend to be denser and sequester more in the long term, but faster growing trees sequester more in the first 10 years or so as a general global trend. It may be that what they're looking at is albedo, which refers to the reflectivity of the Earth's surface. A dark surface like asphalt absorbs heat from the sun and warms up, while a lighter surface heats up less. The same is true of a northern forest in winter. A bunch of evergreen trees are darker than a snow-covered field. Deciduous trees are somewhere in between. In high latitudes like much of Canada, the carbon sequestration impact of planting coniferous trees is offset or even worse by their albedo impact. This should be a good reason to plant deciduous trees at high latitudes.

Eric

"Conifer species exhibited greater wood C content than angiosperm species (50.8 ± 0.7% (95% C.I.) and 47.7 ± 0.3%, respectively), a trend that was consistent among all biomes. "

Carbon Content of Tree Tissues: A Synthesis
Sean C. Thomas and Adam R. Martin *
Faculty of Forestry, University of Toronto, Earth Sciences Building, 33 Willcocks Street,
Toronto, ON, M5S 3B3, Canada; E-Mail: sc.thomas@utoronto.ca


Sorry, I can't get a link to work to this pdf, but you should be able to find it by searching.

Thanks Eric and Tyler. I ask this question partially because I took an ecology course that explained that conifers fix more carbon, at least in cold climates, partially because of the longer period they have to photosynthesize relative to broadleaves. My father-in-law is a forester up here and explained to me that most conifers (with exceptions, notably Larix spp.) drop about 30% of their needles/scales, which leaves them with weeks more than angiosperms to photosynthesize in the shoulder seasons.

So Eric, the conclusion in favor of planting deciduous trees in high latitudes because it increases albedo relative to conifers and reflects more solar radiation thereby decreasing temperature locally (or regionally)?