It’s autumn here in the Pacific Northwest, and many of the trees around are displaying their beautiful assortment of leaf colors in reds, yellows, oranges, and golds. The leaves shine their stunning colors until they take their final tumble to the ground. Some trees, however, stay green all year, and they typically have green needle-shaped leaves in place of colorful leaves.

You may find yourself wondering what makes one tree have such a different appearance and life cycle than another? The differences can be explained by the type of trees, whether they are coniferous trees or deciduous trees. Your arborist experts at Mr. Tree can explain why they differ so much from one another in appearance and how they respond to the changing seasons.

Why Do Trees Need Leaves?

Trees require leaves to help sustain their lives. Leaves provide a surface on the tree to absorb carbon dioxide and to release its buildup of oxygen. This “exhaling” of oxygen through tiny pores in the leaves, called stomata, provides clean oxygen for us to breathe. The absorption of carbon dioxide through the same stomata helps remove the carbon dioxide buildup that occurs naturally from humans and animals exhaling it as part of their normal life functions.

Leaves also absorb sunlight to assist in the photosynthetic process to help provide nutrition for trees. By absorbing sunlight and allowing the carbon dioxide to enter through the leaves, the trees are able to produce sugars that become nutrition for them. In an ideal world for trees, the weather would be sunny and humid year-round. This isn’t the case in most places across the globe, and so trees have adapted to survive.

Deciduous Trees

Deciduous trees are best identified by their broadleaves, as opposed to the pine needles found on conifers. These trees are mostly found in areas with nutrient-rich soils, as they will rely on their roots to provide nutrition during the cold months, when they don’t have leaves to provide nutrition for them. Deciduous trees survive the cold winter weather by dropping their leaves during the fall season, in preparation for dormancy during the colder months ahead. Before the leaves fall away for the winter, they display their magical colors for an amazing fall experience each year.

Having such broad leaves absorbing sunlight and carbon dioxide during the warm months allows these trees to provide a substantial nutrient boost in preparation for the colder winter months. Once the leaves drop to their roots below, they break down into compost to provide nutrition to the same trees by enriching the soil.

Deciduous trees are dormant in the cold winter, which means they have much less need for nutrients since they won’t produce new growth until the warmer weather returns. Once the springtime weather arrives, the trees start showing new growth, and the cycle continues.

Deciduous trees reproduce by producing flowers and fruits that contain seeds that spread when animals and birds ingest the fruits and pass the undigested seeds in their waste, often away from the parent tree. This helps spread the species to new locations. Deciduous trees are known for having hardwood, which can be used for building.

Some native deciduous trees in the Pacific Northwest include the vine maple, bigleaf maple, red alder, and white oak. If you would like to know more about which deciduous trees would be best for your yard, contact Mr. Tree.

Coniferous Trees

Coniferous trees are known for their pine cones and needle-like or scaled leaves in place of broadleaves. Coniferous trees stay green all year and are therefore known as evergreens. However, there are a few evergreen trees that don’t produce cones and are therefore not considered coniferous trees. Coniferous trees reproduce by dropping their cones to spread seeds that grow into new conifers. This is why conifer trees are found naturally grouped together in forests.

The needle-like foliage found on coniferous trees has a waxy finish, making these leaves more waterproof and windproof than their deciduous counterparts. They are also less prone to bites from bugs, birds, and other animals. The thin surface and waxy coating help reduce evaporation from the water stored inside the needles.

Coniferous trees continue to photosynthesize during the colder winter months, but they do slow their rate of growth in the colder climates due to the reduced sunlight during the winter. Conifers that grow in warmer climates tend to have yellow-green needles compared to the darker needles of colder zones.

Some commonly known conifer trees are pine, spruce, and fir trees. Christmas trees are often from one of these species because they remain green during the winter months when the deciduous trees have all dropped their leaves.

You can easily identify the species of conifer tree by looking at the needle growth patterns. For example, pine needles tend to grow in bundles of two to five needles per stem, whereas spruce and fir trees grow single needles without any bundling on the stems. Some conifer trees will have stiffer needles, like spruce trees, and some will have softer needles, such as the fir trees. Coniferous trees are known for having softwood, which is typically used in paper production.

The Odd Bunch: Deciduous Conifers

There are a few trees that have characteristics that fall in both the deciduous and conifer categories. Deciduous conifers grow cones and needle-like leaves like the coniferous trees, but they also change colors and drop their leaves in the cold months like deciduous trees do. The western larch and the alpine larch are both deciduous conifers that grow in the Pacific Northwest.

If you’re looking to plant trees in your yard; need regular upkeep, trimming, or pruning; or have questions about your trees, contact your Pacific Northwest arborists at Mr. Tree.