| Information | Longleaf Pine Tree | Ips Pine Engraver Beetles |
|---|---|---|
| Scientific name | Pinus palustris | Ips calligraphus Ips grandicollis Ips avulsus |
| Common name | Longleaf pine; long-leaf pine; southern pine | eastern six-spined engraver eastern five-spined engraver southern pine engraver |
Top photo by C. Peek at Carvers Creek State Park
In last month's newsletter, while talking about the sassafras tree, we also talked about succession in plant communities. Imagine looking at an area of a forest that has had all the trees cut down. Only scrub and small plants would remain, surrounded by bare soil and tree stumps. But if you waited a few weeks, and the temperature and weather were right, you would see different young plants shooting up. Wait even longer and it will change even more, as the plants will begin competing for sunlight and other resources. The change over time in plant and animal life is succession.
Although succession is an ongoing natural process, sometimes we can identify specific events that jumpstart visible succession. Sometimes it's large manmade events, like clear cutting for timber or the prescribed fires necessary to maintain healthy longleaf pine systems. But it can also be a result of a natural process, like a disease or insect infestation, that results in changes in the habitat. Succession can occur on a smaller scale also. Something as simple as a tree falling in the forest will open up the canopy, allowing more sunlight to reach the ground and encouraging different plants to grow in the newly open area. Small-scale succession is happening all the time.
Here at Carvers Creek, small succession events happen as part of the natural cycles in the various types of plant communities in the park. We also routinely conduct prescribed burns to protect the longleaf pine life cycle. Sometimes, unusual events trigger changes in the plant and animal communities within the park. For instance, right now in the park, you can see the indicators of a small infestation of bark beetles in some of the longleaf pine trees along the edge of East Manchester Road, near the Long Valley Farm entrance.
Bark Beetles and Carvers Creek
This summer was a particularly hot and dry season in North Carolina. Water levels in the small ponds at the park dropped significantly, and the average daily temperature in July was about 2 degrees warmer than last year. In addition, East Manchester Road is one of the busiest roads that borders the park, exposing the trees along the road to great vehicle exhaust. Drought, high heat, and high pollution place extra stress on trees like the longleaf pine, and that stress makes them more susceptible to damage from insects and diseases. This year, that resulted in several longleaf pine trees becoming host to an outbreak of a species of bark beetle known as a pine engraver beetle, or Ips beetle (so-called after the beetle's scientific classification in the Ips genus).
Ips beetles typically breed and live in fallen trees and small trees left over from logging operations, and they play an important role in processing the dead and dying trees. However, when conditions are right, such as periods of tree stress resulting from the drought and high heat, they can infest apparently healthy trees. The Ips life cycle begins when the male beetle bores an entrance hole through the other bark and creates a small chamber inside. Female beetles then use the chamber as a starting point for cutting out a series of galleries that are used for egg laying.
We first suspected we had an outbreak of beetle activity because several of the trees along East Manchester Road were showing signs of stress. Brown or yellowing pine needles and dying branches in the upper part of the tree were indicators something was wrong. The park superintendent and scientists from the Division of Parks and Recreation met to examine some of the trees and found the remains of galleries (pictured in the newsletter PDF), and multiple entrance holes bored through the outer bark, which led them to conclude that it is an Ips beetle infestation.
How Are We Addressing the Bark Beetles?
Bark beetles are a native species and not invasive, and it's important to let the natural cycle of life continue with minimal interference. And because the outbreak is small and contained, with a large strip of ground without host trees between the affected trees and other areas in the park, we do not expect this outbreak to spread. Park staff are currently monitoring the condition of the trees. Most of the trees will probably recover, and any trees that die off will start the natural succession process we talked about at the beginning of this article. We are also experiencing a cooler than normal October, which may help reduce the activity of the bark beetles and limit the damage they can do.
Additional Links
Carvers Creek State Park home page
NC State Extension plant page for longleaf pine trees
NC State Extension PDIC fact page about pine engraver beetles