Mike Schira - WKTV Journal

Sentinel tree tag for identification of a tree entered into the Eyes on the Forest program. | Photo by Michigan State University Extension

By Mike Schira, Michigan State University Extension

Supported by expanding international imports into the country, new and potentially devastating tree pests, both insects and disease, are being introduced to our woodland and landscape trees. Many of these new exotic species won’t find suitable host species or conditions and will simply die off, a few will be successful in becoming established.

Newly established exotic species, having been introduced from other regions of the globe, have no natural enemies or pathogens to hold their numbers down. Unchecked, these new pest species can spread rapidly thereby being labeled as invasive with the potential of devastating their host species.

Examples of past impacts are the losses of American chestnut and elm from both our urban landscapes and forest stands. The loss of the American chestnut and elm affected not only the trees, but also the wildlife that was dependent on the trees for food and shelter. The lost trees may have been shading stream and river waterways. The loss of shade is contributing to increased water temperatures, which reduces the available dissolved oxygen and causes a reduction of fish populations.

Currently beach bark disease, emerald ash borer and oak wilt are examples of exotic species that have become established and are working their way through many of our forest stands, leaving dead skeletons of once healthy trees as they move through.

Spotted lanternfly was first detected in Pennsylvania in September 2014. It feeds on a wide range of fruit, ornamental and woody trees.

In an effort to enable early detection of new invasive tree pests, Michigan State University Extension has developed the Eyes on the Forest program. With initial funding from a Michigan Department of Natural Resources grant, this ongoing program is an effort to establish a network of sentinel trees across the state. Volunteer enthusiasts select the sentinel tree of their choosing and report on the trees overall general health using the online Midwest Invasive Species Network.

Hopefully, with a strong enough network of sentinel trees, we can achieve early detection of new tree pests and work to eliminate them before they can become established. For more information on the program, visit the MSU Extension Eyes on the Forest website.

This article was published by Michigan State University Extension. For more information, visit http://www.msue.msu.edu. To have a digest of information delivered straight to your email inbox, visit http://www.msue.msu.edu/newsletters. To contact an expert in your area, visit http://expert.msue.msu.edu, or call 888-MSUE4MI (888-678-3464).

Artist’s Conk (Ganoderma applanatum) fungi in a sugar maple. (Photo by MSU Extension)

By Mike Schira, Michigan State University Extension

Usually, when we see or hear news items regarding tree and forest fungus, it is being presented as bad or something that is killing trees. Sadly in many instances it’s true that newly introduced fungal pathogens, like Dutch elm disease and oak wilt for example, are a major issue resulting in the death of healthy trees.

The majority of fungi we find in the forest are beneficial to the overall health of the stands they are living with. It is inevitable that trees are going to get old, slowdown in growth and eventually die. These life cycle processes can be rather short in some species; for example aspen, jack pine and white birch or quite long stretching to over hundreds or even thousands of years in the longest growing species like northern white cedar in the Lake States region or sequoia and bristle cone pine in the west.

Regardless of how or when a tree dies, the process of decomposition begins. Tree cell walls contain lignin, a compound that strengthens the cells assisting trees to grow tall. Lignin is tough and fungi are thought to be the only major organism that can break it down. This is important to the remaining trees as well as for the newly established seedlings that depend on the nutrients in the dead and dying trees to allow them to grow and remain healthy. Without the decaying action of fungi, wood would not break down to supply the nutrients for the remaining stand in a timeframe that will sustain growth.

The process of plant growth, decline and decay followed by reabsorption of the released compounds is generally referred to as nutrient cycling. Although there are other organisms that aid in the breakdown of plant matter for this process, it is fungi that preforms the important first step by breaking down the lignin. These processes may be at work above ground in the tree stems and branches, or below ground in the roots and stumps. There are many different species and kinds of fungi that are at work in forest stands and vary depending on tree species, soil type and moisture conditions.

For a more detailed explanation of how the complex processes work to help sustain a healthy forest ecosystem Michigan State University Extension has a series of bulletins that covers this topic; Forest Terminology and Ecological Systems Extension Bulletin E-2635 through E-2641.