Forests are complex ecosystems comprised of biotic (living) and abiotic (non-living) components. Forests change constantly due to the interrelationships of different ecosystem components and the timing of environmental events. Some forest changes are dramatic, while most are quite subtle.
Germination is the process whereby stored energy in a plant seed is reactivated. The resulting metabolic activity leads to the development of a seedling. For germination of specific plant species to be successful, certain environmental conditions need to exist. Consequently, some seeds may lie dormant in the soil for years, only to be reactivated when appropriate environmental conditions arise. Seed storage in the soil is referred to as the “seed bank.”
Different tree species have different sizes of seed. Some tree species are termed “heavy-seeded” because their seeds are large and require the assistance of dispersal agents. American beech and red, white, black, and northern pin oaks are local examples. Blue jays and many other bird species can move acorns a long way. Rodents, such as gray, fox, and red squirrels, also disperse seeds farther from the parent tree than would otherwise occur.
Other tree species are termed “light-seeded” and produce very small seeds that can be dispersed significant distances by wind. For some light-seeded tree species that hold their seed into the winter, dispersal can be enhanced when seeds are blown across the crust that forms on top of snow; these tree species also function as natural winter bird feeders. Local examples of light-seeded tree species include paper birch, yellow birch, and ironwood.
Soil scarification is the process of preparing a site for seed germination by exposing mineral soil. And scarification can occur by different means. For instance, windthrow is the process in which whole trees are blown down. The result is exposed mineral soil where the roots once held the tree vertically in place. Windthrow is common on wetter or rockier sites because tree root depth is limited. Conversely, on drier sites with deep sands, fire can scarify the soil by removing the litter layer through the consumption of leaves (needles) and other organic matter. The resulting ash may function as fertilizer for seeds that germinate on the exposed mineral soil.
For some light-seeded tree species, such as paper birch, fire is critical. While fire may kill adult trees, it also prepares the soil for the next generation. Because paper birch seeds are small, they have little energy reserves and can desiccate quickly and become unviable if they fall on leaf litter. Fire removes the leaf litter and prepares a seedbed and increases seed viability. Not surprisingly, many natural fires occur in late summer and paper birch has evolved to drop seed in the fall or early winter when mineral soil is still exposed and moisture is abundant. Because of this, paper birch is one of the more fire-dependent tree species in Michigan. Fire suppression, along with climate change and secondary succession, has been reducing the abundance of paper birch in Michigan forests for decades.
Scarification can also be accomplished mechanically. Logging operations during the growing season can disturb the top layer of the soil when tracked machinery moves across the forest floor. And scarification can be enhanced when tree tops are dragged around the site. However, logging operations are not conducted during the growing season in many Michigan forests in an attempt to limit the spread of oak wilt. Oak wilt is a fungal pathogen that affects red, black, and northern pin oaks in our area. The pathogen moves below ground via comingled roots and above ground by beetles that respond to injured trees and carry fungal spores from tree to tree. To limit above ground spread of oak wilt, oak forests are often managed when snow covers the ground and beetles are inactive. During this time, soil scarification and its benefits are virtually nonexistent.
Forest landowners should consider the important role of soil scarification in some forest types. When done during logging operations, soil scarification can aid the development of diverse forests by promoting the establishment of many underrepresented tree species. Besides birch trees and ironwood, many pine species also regenerate better when scarification occurs. While eastern white pine seeds have the ability to regenerate across a range of soil types and even in the presence of a significant litter layer, red pine and jack pine benefit from exposed mineral soil.
The role of soil scarification in promoting successful tree germination is but one way in which the integration of biological and ecological concepts are incorporated into recommendations for managing for complex forests that are resilient and resistant.
Greg Corace is the forester for the Alpena-Montmorency Conservation District. For more information, including sources used in this article, Greg can be contacted via email (email@example.com) or phone (989.356.3596 x102).
An in-depth conversation on the practicalities of implementing natural climate solutions through forest management
RFF Live featuring Robert Bonnie, Jimmy Bullock, Christine Cadigan, Sam Cook, Paul Trianosky, and Laurie Wayburn — June 9, 2020
Successful forest conservation starts with a detailed knowledge of the land, its history, and its capabilities and limitations. Such information is the basis of forest planning. While winter in northern Michigan is a wonderful time for planning, spring is a good time for planting vegetation that enhances composition (plant species on a property) and structure (the vertical and horizontal arrangement of vegetation). The type and abundance of wildlife in a forest are largely determined by vegetation composition and structure. Site capabilities and limitations are based on soil type, water availability, and light levels. After these factors are known, and preferably documented, the next step is to identify wildlife species or communities of interest and whether woody plantings are to provide food, cover, or both. Although some plants benefit many species of wildlife, plantings will be most successful if they are customized according to the food preferences and cover requirements of the target species or community. Browsing is defined as the eating of leaves and twigs of woody vegetation. Browsing differs from grazing which is the eating of herbaceous vegetation. Browsing can be a significant impediment to forest regeneration and is a reason why some forests are not as compositionally or structurally complex as they should be. The park-like conditions that we see around us are often the result of browsers limiting age classes of trees and other woody plants. Rodents, lagomorphs (rabbits and hares), and cervids (deer and elk) are all browsers, but different species of browsers impact plants differently. Rabbits and hares, as well as deer and elk, work from above and browse the terminal end of young stems at different heights. Rodents often eat woody plants below the snowline in the winter and tend to girdle plants. Young woody plants (seedlings and saplings) need to be protected from browsers. For large plantings, fencing the entire area may be required. Where fewer plants are involved, such as apple trees, fences can be constructed around each tree with stakes and welded wire fencing. Seedlings need protection for 5 years or more. To protect woody plantings from deer, tree shelters should be 6’ tall; to protect from elk, tree shelters should be 8’ tall. Barriers 2’ high may deter rabbits and hares. The best protection against rodent browsing is the elimination of taller vegetation near the planting. This reduces food and shelter for the animals and has the additional benefit of suppressing competing vegetation. Alternatively, tree guards can be put around the main stem of the planting. Several sizes and types of tree shelters, including cone-shaped models for conifers, are also available. Homemade models can be constructed with stakes, staples, and construction grade plastic. In addition to protecting seedlings, tree shelters can, under certain circumstances, serve several other functions: increase seedling survival and growth rate through moisture retention and a greenhouse effect, improve growth form of seedling planted for timber production, protect seedlings from herbicide drift and mowing machinery, and help managers locate seedlings. It is important to note, however, that shelters do not eliminate the need for weed management. Problems that are encountered with tree shelter include trapping of other wildlife (now preventable with netted tops), possible attraction of insect pests, winter die-back of terminal shoots, and the continued need to support stems for 1-2 years after they grow above the shelter. Regardless of the type of shelter used, frequent inspection is needed to detect possible problems and to repair or replace damaged parts. Because they have grown here for thousands of years, native woody plant species have two main advantages over non-native species. First, native species are well adapted to our site conditions. Second, non-native plants can become weedy (invasive) and crowd out native species. Autumn olive, glossy buckthorn, Scots pine, and other non-native woody plants can be a serious threat to the ecological integrity of forests. Because of the costs and time involved, it is generally wise to consider plantings as a small part of a broader habitat management program that focuses on existing vegetation.
Conservation District Tree Sale: The 2020 Spring Tree Sale will move forward as planned. Expect to see a postcard in the mail with instructions on the pickup process and a reminder of the dates and times. Dates for pickups will continue to be Friday, May 1 from 9am until 5pm at the Alpena Warehouse located on Airport Rd. and Saturday, May 2 from 9am until 2pm at the Montmorency County Fairgrounds located on M-33. We will still have extras available on the day of pickups. For any questions, contact us at 989.785.4083 x5 or 989.356.3596 x5; or email firstname.lastname@example.org. Greg Corace is the forester for the Alpena-Montmorency Conservation District. For more information, including sources used in this article, Greg can be contacted via email (email@example.com) or phone (989.356.3596 x102)
The new strain of coronavirus that has killed hundreds of people in China and caused a travel lockdown of some 56 million people has been classified as a "zoonosis" because of the way it spreads from animals to humans.
Science writer David Quammen says the virus, which the World Health Organization last week declared a global health emergency, is just the latest example of how pathogens that start in animals are migrating to humans with increasing frequency — and with deadly consequences.
"When there's an animal host, then it becomes much, much more difficult to eradicate or even control an infectious virus," Quammen says. "This novel coronavirus — whether or not it turns out to be a huge catastrophe, or something we can control — one thing we know is that it won't be the last."
Quammen's 2012 book, Spillover: Animal Infections and the Next Human Pandemic, traces the rise of different zoonoses around the world, including AIDS, Ebola and severe acute respiratory syndrome (SARS). He says that one of the first questions that arise with any zoonosis pertains to the animal host: How is it being transmitted?
In the case of the new coronavirus, researchers believe that the virus may have originated with horseshoe bats in China and then could have possibly spread to other animals — which people then ate.
Quammen notes that humans are the common link in all zoonoses: "We humans are so abundant and so disruptive on this planet. ... We're cutting the tropical forests. We're building work camps in those forests and villages. We're eating the wildlife," he says. "You go into a forest and you shake the trees — literally and figuratively — and viruses fall out."
Quammen says that the new coronavirus should be taken seriously. But he also warns against panic: "Being educated and understanding it and being ready to respond and support government response is very useful. Panicking and putting on your surgical mask every time you go on a subway ride, an airplane, is not nearly as useful."
Interview highlightsOn wild animal "wet" markets where viruses can mix
When I was in southern China researching [Spillover], only briefly, I got to see some of these markets where all forms of wild animals were on sale. ... By the time I got there, [these sorts of markets] had gone underground ... suppressed after the SARS outbreak. But then [the markets] gradually came back ... allowed to continue again and proliferate when this new virus began.
If you go into a live market, you see cages containing bats stacked upon cages containing porcupines, stacked upon cages containing palm civets, stacked upon cages containing chickens. And hygiene is not great, and the animals are defecating on one another. It's just a natural mixing-bowl situation for viruses. It's a very, very dangerous situation. And one of the things that it allows is ... the occurrence of "amplifying hosts" [a species that rapidly replicates copies of the virus and spreads them].
On the theory that palm civets were "amplifier hosts" for the 2003 SARS outbreak
The civet is a type of mammal that belongs to the family of mongooses. But it's a medium-sized animal, and it is both captured from the wild for food and captive-bred and raised for food, and it was the first big suspect in the SARS outbreak. It was found that some of the people who got sick very early on had eaten butchered civet. And they tested some civets, and they found evidence of the virus. They found antibodies or fragments of DNA or RNA in these civets, suggesting that they had been infected with the virus. And that didn't prove they were the reservoir host, but it made them the No. 1 suspect, until a couple of Chinese scientists did further work and they established that, in fact, the virus was not living permanently in the civet population in the wild or in captivity. It [had] a different reservoir host. It was living in bats and had passed, presumably, at a market somewhere. It had passed from a bat into one or more civets, and they became the amplifier host. ...
Thousands of civets in captivity were butchered and electrocuted and smothered and drowned in this first, panicked blind reaction in China to the SARS outbreak.
On why bats are often hosts for viruses
Bats are implicated in what seems to be more than their share [of zoonoses]. There are a lot of different species of bats. One-quarter of all mammal species are bats. But there are other things [special] about them — including aspects of their immune system. There have been some discoveries lately that bat immune systems are "downregulated" in a certain way that allows for the metabolic stresses of being a mammal that flies. And the downregulating of the immune system to avoid overreaction to those stresses seems, perhaps, also to create an environment in which viruses are more tolerated in bats than in other mammals.
On how coronaviruses have evolved through different species
One of the reasons SARS could adapt from bat to civet to human is the fact that it is a coronavirus, which is a group of viruses that are very readily adaptable. Experts call that intrinsic evolvability. Their rate of mutation is very high when they copy themselves. Their genome contains a lot of mistakes, and that represents mutations that are sort of the random raw material for Darwinian evolution. So viruses that have high mutation rates are able to evolve quickly and adapt quickly. And coronaviruses ... have that characteristic.
On more public investment and research on new viruses
This is absolutely a matter of need for more public investment, more public education, adequately funding, richly funding our CDC, the disease programs through the U.S. Agency for International Development, the World Health Organization, the equivalent organizations in Great Britain, France, China ... and the other institutions and countries around the world. Yes, we need to be training scientists who will become virus hunters, who will go into those caves in those forests doing the hard, dangerous work and will go into the laboratories doing the molecular work to help us identify these viruses. And we need our public health officials to be ready with resources and information to deal with these outbreaks — by containment, contact tracing, quarantine [and], when it's necessary, isolation. We need more resources, and we need more skills.
Lauren Krenzel and Joel Wolfram produced and edited this interview for broadcast. Bridget Bentz and Molly Seavy-Nesper adapted it for the Web.
I think all the "rules" allow most of us to go out by ourselves or in a small group......if so, it's a great time to observe some unique forest wildlife behavior in northern Michigan.....
Perhaps it's a good time to get out at dusk to hear/see American Woodcock males peent in an opening next to some young aspen?
Or go into some mature mixed conifer/deciduous woods to hear/see male Ruffed Grouse drum on a large, rotting log in the early morning?
Or see male and female Sandhill Crane unison call and dance in pine openings or in hayfields?
Or go to the eastern UP (when allowed) and see male Sharp-tailed Grouse dance in the morning in pine openings or hayfields?
Forest types are largely defined by the dominant tree species within the canopy of a stand. However, the under-story regeneration often varies, sometimes suggesting long-term forest type changes.
Bill Cook, Michigan State University Extension - March 16, 2020
Over decades, forests undergo somewhat predictable changes. Foresters call this “forest succession”. One of the best indicators of where a forest stand might be headed is from examining the regeneration. Without major disturbance, there’s a pretty good chance the seedlings of today will become the dominant forest type of the future.
Different forest types have various track records in their ability to reproduce themselves over time. Northern hardwoods can sustain themselves for centuries. Signature species, such as sugar maple, beech, and basswood, can grow in the shade and will take advantage of small canopy gaps as old trees gradually die.
On the other end of the spectrum, paper birch and red pine stands have very low percentages of their own seedlings in the under-story. These are sun-loving tree species. Without disturbance, other forest types will replace these forest types.
Paper birch stands are likely to become balsam fir or northern hardwoods. Red pine stands will trend more towards red maple, black cherry, and different species of oak. Similarly, aspen stands tend to be replaced by red maple or balsam fir. Aspen is particularly popular with most game species and a growing number of birds with declining populations.
Enter disturbance. Over the decades, the likelihood of a major disturbance increases. Such events as wind, wildfire, and pest outbreaks will open the forest floor to lots of sunlight and soils will warm somewhat. These conditions will favor the light-loving species, which tend to grow faster than the more shade tolerant tree species.
Forester and forest owners can mimic these events through management and timber harvesting. Practices such as clear cutting and shelter woods can help maintain forest types such as aspen, red pine, jack pine, and paper birch. Regeneration strategies of these tree species depend upon major disturbance.
In the bar chart, the green bars (lighter gray on the left) indicate a forest type’s ability to regenerate under its own canopy. There is a high percentage of signature species already in the under-story The red bars (darker gray on the right) suggest a need for a major disturbance in order to regenerate, as little regeneration of the signature species exists. Left alone, these “other” species will eventually replace the existing trees.
Most of the Lake States forests are adapted to natural disturbances. Since the glaciers melted about ten thousand years ago, the forest area has ebbed and flowed. Our forests have needed to be flexible. The region historically tends to have large sweeping storms, fires, and major insect outbreaks Native American intervention increased the role of wildfire.
As certain forest types matured, the trees served as host to widespread insect epidemics. Thousands of acres of fir-spruce would be killed by the spruce budworm. Large expanses of old jack pine fell prey to the jack pine budworm. Periodic outbreaks of forest tent caterpillar would defoliate and kill great swaths of aspen.
Wildfire would often result from the huge fire loads created by so many dead trees.
After these catastrophes, the fir, spruce, jack pine, and aspen forests would grow back Such is the way of natural cycles.
With human infrastructure spread nearly everywhere, these calamities came with unacceptable risk to people. Forest management has been developed to reduce the negative effects of natural disasters while maintaining those benefits that different forest types depend upon.
Red pine and paper birch still need major disturbances in order to maintain themselves. However, forestry has provided the solutions to help those forest types and humans coexist. So, the next time you see a clearcut jack pine stand, be grateful the jack pine is being regenerated without a forest fire.
This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).
What a simple word: science. Two short syllables, easily pronounced. Yet, to many, science is mystifying. As we cope with COVID-19, perhaps it is a good time to discuss how science works? According to the National Academies of Sciences, our most prestigious scientific organization, science is, "the use of evidence to construct testable explanation and prediction of natural phenomena, as well as the knowledge generated through this process." To practitioners, science is a process, a product, and a culture. As a human construct, science---by its very nature--is imperfect. But the scientific process acknowledges and addresses imperfections by specific actions aimed at improving data quality, reducing conflict of interest, and increasing repeatability. Science begins when curious individuals ask novel questions. These novel questions are then answered (imperfectly) through the structured collection of data, data analysis, and the preparation of a manuscript describing background, methods, results, and implications of findings. The manuscript is then subjected to peer-review. Peer-review is defined as, “the process of evaluating scientific work by a group of experts in the related field. It is also known as refereeing because the work or project must be critiqued before it is published, funded, or implemented.” Explicitly, peer-review takes into account conflicts of interest. Reviewers are expected to have no relationship with the authors of the submitted manuscripts, making peer-reviewed manuscripts quite different than a report coming from an individual organization or office. Reports often suffer by not being refereed by outside entities devoid of bias. Science is communicated among professionals in a written format. A good scientific moto is: beware what you hear, be skeptical of what you read. The product of peer-reviewed science is called a “paper”. Papers are published in “journals”. Journals, such as Forest Ecology and Management, The Journal of Wildlife Management, or the countless other journals in an array of disciplines compete for prestige either regionally, nationally, or internationally. Journals have a Board, an Editor, and a suite of Associate Editors. These scientists set the direction for the journal and oversee the selection of reviewers that evaluate the quality of submitted manuscripts. For some journals, acceptance rates (the proportion of submitted manuscripts done well enough to be accepted and represent the standards of the journal) can be as low as 20%. The more prestigious the journal, the higher its standards and lower its acceptance rate. For forest and wildlife ecologists, the entire process--from posing a question to seeing a paper through the peer-review process and published in a journal--may take years. Besides describing many aspects of the scientific process, papers also acknowledge the contributions of individuals and organizations. So, what are textbooks? One can think of textbooks as a compilation and summary of relevant papers on a topic. Because science changes, textbooks are updated fairly often. Each new version of a textbook summarizes and references recent papers and those whose findings have lasted the test of time. Science is a human enterprise aimed at serving society by advancing knowledge. Science does not make decisions, but allows decisions to be evidence-based. Not surprisingly, natural resources management guidelines change over time because the scientific foundation they are based on changes and the contexts in which the science is applied change. Natural resource management in 2020 is very different than management in 1950. If we think our knowledge of the natural world is complete, or if we think “one-size-fits-all” approaches apply, we may be fooling ourselves in many instances. Unfortunately, some decisions occur without the transparency of the science that is meant to guide the art that is management. This may occur because too few scientists are employed within our institutions or too few of our leaders are scientists. Scientists are needed to instill a culture of science. A culture of science encourages curiosity and rigorous debate based on data and methodology. At its core, a culture of science openly challenges dogma and rhetoric. Social vagaries, social sensitivities, group thinking, or politics can squash a culture of science. As a critical component of evidence-based decision making, the public should support a culture of science throughout all phases of society. While healthy skepticism is important, the public should also strive to be informed on the current state of science as it relates to issues that impact our lives. Always ask if findings being presented have been published and, if so, where. If interested, Google Scholar can be used to see what science is being done, where, and by which scientists (keywords can include topics of interest, locations, names of authors, or a combination). In science, process, product, and culture matter. Greg Corace is the forester for the Alpena-Montmorency Conservation District. For more information, including sources used in this article, Greg can be contacted via email (firstname.lastname@example.org) or phone (989.356.3596 x102).
Dr. Greg Corace
Want to hear about what is new in the science world? Maybe get more information on the birds around us? Or maybe you want to keep up to date on what is happening in our current environment and with the natural resources we love. Check out some interesting articles shared by our Forester, Dr. Greg Corace.