UPDATE: See note at bottom.
Invasive species are non-native plants, bugs and beasts that for various reasons, usually lack of predators, spread so quickly after being introduced that they overwhelm native species. They’re a huge problem all over the world because they disrupt ecosystems, causing harm to other species that have evolved to depend on the natives that are being killed off.
But not always. An interesting study reported by the USDA Forest Service (details here) says that Norway spruce which were planted by foresters in western Massachusetts a century ago seem to do as good a job as native hemlocks in supporting birdsong populations: “Norway spruce share characteristics with eastern hemlocks, such as short needles and dense canopy cover, and could possibly serve as surrogate habitat for native wildlife.” This is important because hemlocks, as you probably know, are threatened by the hemlock wooly adelgid, an invasive insect that is slowly killing them off; the Norway spruce might provide an ecosystem replacement.
I love hemlock forests in the winter; they hold the snow better than any other conifer creating the perfect Currier & Ives effect. New Hampshire is on the edge of wooly adelgid territory because of our cold winters – but, of course, winters are getting less cold, so the sap-sucking monsters are going to become established here, too.
Readers more knowledgeable about forestry than I say that Norway spruce isn’t “invasive.” It’s non-native, yes, but it doesn’t spread fast enough to overwhelm native species, which is what makes invasive species so bad for the ecosystem. This is a good thing, because my wife pointed out that the two gorgeous conifers along our driveway that we planted years ago (partly to my regret – I blew out my back planting one of them with their big root ball and my back has never been the same since) are Norway spruce. They are loaded with songbirds when we put out the bird-feeder on the opposite side of the driveway; they do seem to like hiding among the thick foliage, perhaps because there’s a resident red hawk in our woods.
Norway spruce are suffering from widespread and ongoing loss of the most current year’s new growth. Abcision of tips occurs always at the nodes then they drop to the ground. There is no evidence of squirrels causing this. Over the last 20 years the canopies of most Norway spruce have thinned significantly and mortality is increasing.
It’s not listed on invasive species lists except for with non-existent sources cited on invasive.org.
I read in research articles that Norway Spruce seed spread is limited to about 60 meters and it grow more slowlt for the first 40 years or so, during which time it doesn’t reproduce. While it’s shade tolerant and will grow in poor soils (which is where it might be getting misunderstood as invasive), it will be stunted in growth. It can’t outcompete in deciduous forests or more drought tolerant trees. Open pollinated strains tend to be slower growing.
It’s researched for its importance for winter bird and mammal habitat as a food sources for shelter and as a key species to mitigate the loss of eastern hemlock to the invasive pest, hemlock wooly adelgid. North american hemlocks have poor resistance to the adelgid. Norway Spruce provide a similar forest biome to hemlock and habitat, uncommon to other native conifers.
Do you have links available for your sources on how Norway Spruce is NOT invasive?
On the invasive plant atlas it is reported as an invasive tree.
U.S. National Parks where reported invasive:
Great Smoky Mountains National Park (North Carolina & Tennessee)
Haleakala National Park (Hawaii)
Monocacy National Battlefield Park (Maryland)
Invasive Plant Atlas is a collaborative project between the National Park Service and the University of Georgia Center for Invasive Species and Ecosystem Health.
Norway Spruce is being considered as a replacement for Eastern Hemlock habitat lost to the invasive hemlock wooly adelgid. The canopy is similar and songbirds adapt to the trees. It also provides food supply and shelter for native species. The NPS has the Norway Spruce listed as rare in a wide range of elevations meaning it hasn’t invaded any significant amount of forest. At the time I wrote my comment the NPS had a list of species it considered invasive in Smoky Mountains NP and it wasn’t listed. I’ll post it if I find it again.
It’s not listed in the PLANTS database of Invasive/Noxious Species. The “I” in the PLANTS database means introduced. Introduced species are not always invasive and many are beneficial. It’s also naturalized or near-native in 9 states meaning it’s integral to local eco-systems.
In it’s native range, Norway Spruce is disappearing.
Where are your sources it’s invasive?
There were links in an old PLANTS database record were outdated and unsubstantiated. I see one article online without a verifiable source, that several point back to.
Norway Spruce as Hemlock Habitat alternative
The Great Smoky Mountains Park current data shows its rare in a wide range of elevations
The Knox News notes that the NPS only manages about 60 exotic species and some are beneficial.
I need some evergreens to plant in the yard at my new house in Albany NY and I can’t find a native that isn’t threatened by the changing climate in some way. I want to plant natives but if they will not survive and the norway spruce will, maybe i should plant it. The deer ruin the arborvitae, hemlock are doomed and even White pine are succumbing. Virginia pine is the only native pine that seems to have a chance. What other trees will survive our messed up new climate?