The management and conservation of our natural resources is ever evolving and based on numerous considerations, including the public’s needs and desires and changes in the natural environment.
The Michigan Department of Natural Resources, the agency with primary responsibility for conserving our state’s wildlife, employs a wide range of scientifically proven conservation methods.
Wildlife Management Practices
Surveying wildlife populations, continually tracking of birth and death rates of various species, reviewing a variety of factors and understanding the condition of their habitat are pillars of conservation management. Consider Michigan’s keystone species, the white-tailed deer. Data such as the number of car-deer crashes, the amount of commercial crops consumed by the animals and the estimated number of deer dying due to disease are important to maintaining a healthy, sustainable herd.
Hunting plays a vital role in maintaining balanced ecosystems – and as an important bonus, the activity also provides funding for the majority of wildlife management activities through license and equipment purchases. In addition, hunting clubs and organizations raise funds for conservation, buy and conserve private lands for wildlife habitat, and partner with state and federal agencies on large-scale conservation efforts.
Without legal, regulated hunting, wildlife populations can outgrow their food sources, potentially leading to die-offs of both animals and plants until equilibrium is restored. Wildlife managers can use a variety of hunting-related techniques to keep species in healthy balance with their habitats.
For example, adjusting bag limits – restrictions on the number of animals within a specific species that hunters may harvest – will affect the overall numbers of a species. Shortening or extending hunting seasons – such as by creating a special, additional season for youth hunters – is another method for controlling populations. When it comes to white-tailed deer, regulations regarding the taking of females can impact the species’ population. For example, removing does from the population interrupts the species’ reproductive cycle, lowering the number of fawns born and, eventually, the overall numbers of deer.
Some species are still present in Michigan or have been reintroduced in limited numbers, but their populations are so low that they are afforded special protections. In fact, almost 400 species are listed as threatened or endangered in Michigan. One of them is the Kirtland’s warbler, a songbird that nests in just a few counties in Michigan’s Lower and Upper peninsulas and a few sites in Wisconsin and Ontario. The DNR works with the Kirtland’s Warbler Recovery Team to manage the bird’s preferred jack pine habitat by logging, burning, seeding and replanting on a rotational basis to provide approximately 38,000 acres of productive nesting habitat at all times. Habitat management for Kirtland’s warblers also benefits other wildlife species, such as rabbits, hare, white-tailed deer and ruffed grouse.
The general public also is enlisted in species preservation efforts. Today, habitat loss due to lawns, pavement, climate change and invasive species represents the greatest threat to endangered species in Michigan. Residents can plant a native plant garden to make food and shelter for wildlife like butterflies or birds.
Water Management Practices
To create and enhance fishing opportunities and to help restore diminished populations, the DNR regularly stocks a variety of fish – including salmon, trout, walleye and musky – in the Great Lakes and inland bodies of water. Stocking decisions are based on science, social and economic considerations, and are designed to meet ecological needs and the wants of fishing enthusiasts. Input comes from a variety of sources, including conservation and sportsmen organizations, and charter boat operators.
The 1966 introduction of Pacific salmon into the Great Lakes is a shining example of how fish stocking enhanced our waters and boosted recreation opportunities. Ecologically, the salmon returned balance to the lakes by introducing a predator to control the growth of invasive alewife populations. At the same time, salmon stocking created what has become a world-class fishery with immense economic importance. Another common fish-stocking example: In many inland lakes, the growth of bluegills is stunted due to a lack of food and habitat degradation. To restore balance (and, ultimately, create bigger, healthier bluegill) the state has planted predators such as walleye into lakes to thin bluegill populations and lessen competition.
Spearheading Michigan’s fish production efforts are six DNR-operated hatcheries, three permanent egg-take stations and numerous rearing ponds, many of which are operated in partnership with sportsmen’s groups.
Managing aquatic species requires monitoring the environment they live in. Agencies at various levels of government track water levels and the presence of nutrients and chemicals in the Great Lakes, inland lakes and rivers and streams. The information helps ensure swimming safety and healthy aquatic environments. For example, high nutrient levels are bad for fish because they reduce oxygen in water. Identifying the source of the extra nutrients – such as leaky septic tanks or agricultural runoff – leads to action plans that encourage best environmental practices. Such plans might call for encouraging a farm to install a strip of vegetation to prevent fertilizer or livestock waste from entering an adjoining stream.
Forest Management Practices
Trees are a renewable resource. This means that they can be grown, harvested, replanted and harvested again and again in a never-ending cycle to provide clean air and water, habitat for wildlife, beautiful views and thousands of products – both today and in the future. The process of growing trees on an area that previously has been harvested or cleared is called reforestation. The two basic methods of reforestation are natural regeneration and artificial regeneration.
Natural regeneration relies on nature to return an area to forestland after trees are harvested. Through natural regeneration, new trees grow from seeds that are carried by the wind, transported or buried by animals, or simply dropped on-site by mature trees. In addition to producing seedlings from seeds, hardwood trees regenerate naturally by sprouting new growth from the stumps of cut trees.
Artificial regeneration involves human intervention in sowing seeds or planting seedlings. This method of forest renewal has several advantages over natural regeneration. It provides better control over tree spacing, more control over the species present in the new forest, the opportunity to plant disease-resistant seedlings, and a higher rate of tree survival. Although artificial regeneration is more expensive than natural regeneration, the result is usually a more productive stand in a shorter period.
Many ecosystems are vitally linked to fire. Fire’s exclusion in recent decades has had a dramatic effect on our landscape. Healthy prairie, wetland and woodland ecosystems are rich with a diversity of plant and animal life. However, in the absence of fire, many fire-intolerant plant species outcompete the native, fire-adapted plants. As a result, our natural areas have a tendency to become thickets of shrubs or invasive plants with very little diversity. Fire clears the way for native plants by helping to control these invasive plants and enrich the soil. Prescribed burning encourages forest regeneration, improves wildlife habitat, helps with brush management and removes fuels to help encourage wildfire safety. Fire specialists conduct these carefully monitored burns to enhance tree growth, prepare sites for tree planting, create fire breaks and reduce fire fuels.
In forest management, trees are harvested for a variety of reasons, including:
- Improving the health of the forest
- Controlling the types of trees that grow on the site
- Attracting certain wildlife species
- Producing paper, lumber and numerous other forest products
- Improving access to the area for hikers, hunters and other recreational users
Just as there are many reasons for harvesting trees, there are many different harvesting methods. Each method has its benefits, drawbacks and conditions under which it is the most suitable way to harvest trees. No one harvesting method is ideal for all situations.
When trees are crowded, they are in greater competition for sunlight, nutrients and water. As a result, they tend to be less healthy and to grow less vigorously. To improve the health and productivity of the forest, forest managers may remove a portion of the trees in the early stages (10 to 15 years) of a growing stand so there is less competition for sunlight, water and nutrients. The forest is “thinned” by taking out a certain percentage of the trees. The remaining trees will grow faster and become stronger and larger. The thinning also improves the growth of the forest’s understory, such as wildflowers and native plants, by increasing the amount of sunlight that reaches the forest floor. This growth provides more food and cover for animals such as quail and rabbits.
Clearcutting removes all the trees in a given area, much like a wildfire or other natural disturbance would do. It is used most frequently in pine, oak and aspen forests, which require full sunlight to grow. While a clear-cut removes all canopy cover and is unattractive for a short time, it is effective for creating habitat for a variety of wildlife species. Animals such as ruffed grouse, hare, rabbits and deer are attracted to the food sources provided by clear-cut areas. Many creatures also find shelter from weather and predators in the low-growing grasses, bushes and briar thickets that follow this type of harvest. In addition, clear-cutting is an important forest management tool because it can be used to create edges – areas where two habitat types or two ages of the same habitat meet. Because edges provide easy access to more than one habitat, they usually have more diverse wildlife communities than large blocks of a single habitat.
In a shelterwood cut, mature trees are removed in two or three harvests over 10 to 15 years. This method allows regeneration of medium- to low-shade-tolerant species because a “shelter” is left to protect them. Many hardwoods, such as oak, hickory and cherry, can produce and maintain seedlings or sprouts in light shade under a partially cut stand. However, the young trees will not grow and develop fully until the remaining overstory trees are removed. One benefit to shelterwood harvests is that they provide cover and early successional food sources for wildlife. However, this method of harvest is not recommended for trees with shallow root systems because the remaining trees are more susceptible to wind damage after neighboring trees are removed.
Seed Tree Harvest
In a seed tree harvest, five or more scattered trees per acre are left in the harvested area to provide seeds for a new forest stand. These trees are selected based on their growth rate, form, seeding ability, wind resistance and future marketability. Wildlife benefit from seed tree harvests in much the same way as they do from a clear-cut harvest, except that they also reap the benefits of the seed trees themselves. If left on-site indefinitely, seed trees eventually may become snags or downed logs, which are important habitat components for woodpeckers and many other species. Seed trees are also excellent food sources and nesting sites for a variety of birds. One disadvantage to seed tree harvests is that the remaining trees are at increased risk of damage from wind, lightning and insect attack. This type of harvest may also require the landowner to make future investments in thinning and competition control because of uncontrolled reseeding.
Group Selection Harvest
Group selection is essentially a small-scale clear-cut where groups of trees in a given area are harvested over many years so that the entire stand has been cut within 40 to 50 years. The size of the group cut determines the tree species that are likely to return after the harvest. Openings that are less than a quarter of an acre favor shade-tolerant species, and larger openings favor sun-loving species. Group selection provides ideal pockets of young vegetation for grouse, deer and songbirds. But because it requires intensive management and frequent access to all areas of the property, it can be an expensive forest regeneration method.
Single-Tree Selection Harvest
Single-tree selection removes individual trees that are ready for harvest, of low value or in competition with other trees. With single-tree selection, the forest continuously produces timber and constantly has new seedlings emerging to take the place of harvested trees. Single-tree selection maintains a late-succession forest that benefits many wildlife species, such as squirrels and turkey. Single-tree selection harvesting is best for the more shade-tolerant tree species such as sugar maple. Sun-loving trees, which are an important source of food for wildlife, do not regenerate well with single-tree selection. The forest stands may be harvested every 10–20 years so there is more frequent activity.