Northern Woodlands

One of the most interesting environmental magazines around today is Northern Woodlands:A New Way of Looking at the Forest. Its main focus is how good forestry practices can enhance the environment something we will be talking about more during the summer. It's regular features add a lot to the knowledge base of anyone interested in the outdoors. For instance, in the Calendar feature for the second week in June I learned that female hummingbirds are now building their nests using bud scales lashed together with spider silk camouflaged with lichens and lined with soft plant down. Sounds cozy.

I also learned that newly emerged female mosquitoes and all males feed on plant nectar and are important plant pollinators. Somehow that doesn't make me want to swat them less, but it does make me wonder even more about the environmental impact of widespread spraying, both pro and con. Given the way the year has started with dozens of mosquitoes waiting at my door every morning for breakfast, I bet we'll be hearing a lot about West Nile and EEE.

Michael Synder in the Wood Whys section has an interesting article on leaves. Turns out the leaves on any individual tree are different depending on whether they are mostly in the sun near the top of the tree or mostly in the shade near the interior of a branch or the base of the tree.

Shade leaves are bigger, thinner, and hang from a branch horizontally. These are all adaptations to gather as much light as possible from a dim environment. Extra size and the horizontal orientation provides more surface area to catch whatever light is available. The thinness is the coolest adaptation. It allows the dim light to penetrate to the photosynthesis cells inside while keeping the trees investment in cells that need to be fed to a minimum. The purpose of the shade leaves is insurance. While the sun leaves provide the energy needed for growth in height and diameter, the sun leaves insure that a tree in the shade of another has the energy to hang on season after season.

Sun leaves risk drying out in the sun so they have special adaptations as well. Overheating can also reduce photosynthesis. Sun leaves tend to be smaller, thicker and held vertically, almost parallel to the sun's rays. The smaller size and often additional waxy layers and hairs reduce water loss. The thickness also comes from multiple layers of photosynthetic cells because the suns rays can penetrate deeply into an exposed leaf. The orientation also minimizes overheating and water loss, but because so much light hits a sun leaf the orientation of the leaf does not limit its ability to photosynthesize.

Find the nearest tree and test this out!