Conifers: Evergreen Trees and Shrubs

 

Evergreen pine trees line the face of Champlain Mountain from the Schooner Head Trail in Acadia National Park Wednesday, November 17, 2020. (Photo by Ashley L. Conti/Friends of Acadia)

Acadia’s iconic trails wind through a dark, dense forest, where wooden walkways protect a thick carpet of moss underfoot. Evergreens trees like red spruce, white spruce, and balsam fir characterize the canopy of this coastal forest. These trees, along with co-occurring white pine, eastern hemlock, and northern white cedar, are all conifers—a related group of trees that produce cones. In the winter, evergreen trees and shrubs provide color to the grateful human eye and essential food and homes to animals.

Many of Acadia's conifers are currently under threat from various pests and diseases including the red pine scale and hemlock woolly adelgid. Unfortunately, many of Acadia's once evergreen mountainsides are now grey due to the large die off of red pines due to this disease. Rapid environmental change, such as climate change, is stressing many of Acadia's trees which leaves them more susceptible to disease and insects. You can help protect Acadia's conifers by not disturbing them during your visit and reducing your carbon footprint during your visit by riding the island explorer, and walking or biking whenever possible.

 

What is (and isn't) a Conifer?

A conifer is a cone bearing plant. Conifer trees are also called a softwood trees, as opposed to deciduous trees which drop their broadleaves and are known as hardwood trees. Confers typically have a distinctive leaf shape called 'needles,' and cones that fall to our feet. Those cones, if they are female, produce seeds, which either grow a new tree where they fell or are eaten by birds and other animals and are therefore carried to new areas to germinate. The male cones, which are much smaller, only contain pollen.

Common coniferous trees in Acadia includes spruce, pine, fir, cedar, and hemlock. Other conifers such as common juniper and Bar Harbor juniper are shrubs, and other evergreen shrubs such as black crowberry can be found here as well.

During your visit to Acadia you may also come across what looks to be a mini-forest of evergreens on the ground. Commonly known as ground pine or creeping cedars, these are not actually confiers at all, nor are they pines or cedars. They are actually more closely related to ferns and they join mosses, lichen, and mushrooms, as the wonderful world of organism that make the forest floor at Acadia so beautiful and diverse.

 

Sap collects on the peaks of the pinecones of a spruce tree near the summit of Cadillac Mountain along the Cadillac North Ridge Trail on Wednesday, July 7, 2021 in Acadia National Park. (Sam Mallon/Friends of Acadia)

Acadia's Common Conifer Trees

Spruce

Spruce needles are single needles emanating around a branch and have four sides. Because of the four sided structure they can be easily rolled between your fingers. Normally they feel spikey to the touch. Red spruce (Picea rubens) is the more common spruce species you will see here at Acadia followed by White spruce (P. glauca) and Black spruce (P. mariana).

Spruces grow on well-drained, rocky upland soils, and particularly on the north side of our mountain slopes where it may be the major tree type present. Spruce trees mostly drop their cones in the autumn or early winter.

 

A white pine with some needle dieback due to winter weather. NPS Photo.

Pines

Pine needles are in groups of 2, 3 or 5 and are longer and softer than spruce and fir needles. The Eastern White Pines is the state tree of Maine and for good reason. They grace the forest with their tall, straight trunks and, growing at up to 1 foot per year, are often the tallest tree in Acadia's forest. White pine occurs in all environments including moist environment, uplands, and on sandy soil, but develops best in fertile, well-drained soils.

Pitch Pine are named after a past use of the tree sap to create turpentine and pitch to coat wooden ships as a preservative. Today they are used as paper pulp, lumber and “fat wood” kindling for fire starting. The sap is used in soap, paint, and varnish. They can grow up to 40 feet, but are usually less than ten feet in Acadia and can be found on mountain ridges. Good locations to find them are Cadillac Mountain and Champlain Mountain.

Jack Pine are also called Grey Pine and usually located in sandy, rocky areas. The best place to find them in Acadia is on Schoodic Peninsula. Their cones stay on tree branches for 12 to 15 years unlike cones of other trees that stay on the branches for up to a few years. Its primary use is for pulp. At maturity this tree can reach 50-60 feet, however in coastal regions they are shorter and knarled.

 

Threats to Acadia's Conifers

Trees and other forest plants have always been under threat by people, diseases, and pests such as insects. The white pine weevil is an insect that kills the topmost shoot and often causes the tree to have multiple stems and a round profile. The hemlock woolly adelgid (Adelges tsugae) are non-native, invasive, aphid-like insects that inevitably kill Eastern hemlock trees. With warming temperatures, the adelgid is moving north and has now been confirmed in Acadia.

The invasive red pine scale (Matsucoccus matsumurae), also known as Japanese pine bast scale, was detected near Norumbega Mountain in the town of Mount Desert and Acadia National Park in September, 2014 . This was the first known occurrence in the State of Maine. The red pine scale insect is native to Japan but arrived in the United States in 1946. The scale insect is about the size of a pin-head and covers itself with a protected white woolly substance that is visible on branches. While red pine trees are a minor component of Acadia’s forests, they provide value for wildlife. Today, many hillsides in Acadia can now seem barren due to the amount of dead red pine in the park.