I recently had the pleasure of meeting a GLOBE student named Aspen. I was excited because my favorite type of tree is Aspen (Quaking Aspen to be more specific, Populus tremuloides to be even more specific), and I was able to tell her some of the fun facts about her namesake.
My favorite thing about aspens is their bark. The white powder on it can act as sunscreen. It’s only about an SPF of 5 but it’s still pretty cool. The bark also contains chloroplasts which means it can photosynthesize, making it one of the few deciduous trees that do not solely rely on leaves for photosynthesis. They can even live up to two years without leaves! The bark also has salicylic acid, which is similar to aspirin and can act as a pain reliever. This is why you will often see deer and elk munching away on it during the painful months of antler growth. As well, it contains quinine, which is a chemical that used to be used to be the primary treatment for malaria (strange since malaria carrying mosquitos are not found where aspens grow).
In Utah’s Fishlake National Forest, aspens comprise the heaviest known organism in the world at about 6,600 short tons. Considering aspens are typically less than 15m high (though they can range from 5-30m) and only 0.3-0.5m in diameter, it is hard to imagine that they can become so heavy. This is because an entire grove of aspens is only one organism. So, even though there are about 47,000 “trees” in the Utah grove named Pando, nicknamed the Trembling Giant, they all comprise a single organism (goo.gl/mLQ1ck).
The roots of aspens have an incredible evolutionary advantage. Once a single tree becomes established, usually by seed, they will send out root shoots that grow into clones, or ramets. Therefore, a grove of aspens is actually hundreds or thousands of clones that are all connected by their roots. After a disturbance, like wildfire, avalanche, clearing, or rockslide, aspens can quickly recover by shooting up more ramets, often making them the first tree species to grow after a disturbance. However, as they are very shade intolerant, they are often succeeded by conifers.
A view of the shared root system of aspens (goo.gl/UUEw1n). These connected trees are genetically identical to one another. Aspens that grow from seeds (seedlings) are genetically different.
The Quaking aspen is the most widely distributed tree in North America. It extends across all Canadian provinces, the western and northern US, and down through the sierras of Mexico. It can exist at a large range of elevations, but most often is associated with the montane forests of Colorado between 1500-3650 meters. Here in Colorado, they stand out because they are one of few deciduous trees in the dominantly coniferous forests, which makes their yellow to orange green-down in the fall appear especially spectacular. They are a part of the Willow family (Salicaceae) which also includes willows, poplars, and cottonwoods (National Audubon Society Field Guide to North American Trees--W: Western Region).
Aspens in the spring and autumn.