Shaping leaves.
Trees have adapted ways to maximize how the leaf captures the sunlight without compromising tree health.
Trees that grow in the lower canopy often have large leaves to capture the sunlight and will often distribute the leaves in such a way as to minimize the shade on the next layers of leaves. This is called mono-layering. In trees that appear in the upper canopy, the leaves are in a multi-layer arrangement where the leaves are above and below other leaves.
Where light is compromised some trees have developed needles that on mass increase the surface area exposed to light so photosynthesis can occur even in winter. A study in Germany compared Beech Trees (with broad leaves) and Spruce, (with needles). The results showed that Spruce was 58% more productive than Beech by photosynthesizing for 260 days compared to 176 days in Beech per year. Needles also reduce the chances of breaking under snow, retain moisture and survive for 3-4 years.
Some studies suggest trees may even adjust their leaf shape as the tree matures to compensate for different levels of light in the forest as the tree grows taller. Trees with leaves in the upper canopy may be damaged by too much sunlight and so the arrangement of the leaves may be on a sharper angle thus limiting the leaf to too much sunlight exposure.
Deciduous trees dump their leaves over winter entering dormancy during low light and have the ability to absorb and store sugars more efficiently than evergreen trees do.
Waxy leaves have developed to reduce moisture loss where water is at a premium.
Leaves are also designed to encourage water to run off the leaf and not sit where breakdown or decay of the leaf could begin.
When you look at your garden and observe all the different leaf shapes and textures, it’s pretty cool to realize it’s not by accident.