Counting trees

Michigan forests are growing older with larger trees covering more acres according to inventory statistics that reveal a dynamic and ever-changing resource.

The forestry community continually monitors and inventories the forests of Michigan, the federal inventory units collect data across the entire state, the DNR constantly updates the state forestland inventory and public and forest owners use their own status tools for private forest holdings. Many methods and resources are necessary to count trees.

Sometimes we think that forests are static resources that are the same from year to year. In the short-term, this may be true in some ways, however, by reading the forest, almost everyone will see constant change because trees grow, die, reproduce and are harvested and converted to other land uses in some areas. Non-forest areas can even grow trees once again in certain places.

Michigan has about 20 million acres of forest, which is more now than at any other time over the past few decades. The many characteristics vary widely across Michigan especially when comparing the sets of changes in the western Upper Peninsula and the changes that most people see in the southern Lower Peninsula.

The amount of forest data and definitions is overwhelming and can be challenging to sort through. However, there are definite, discernible trends that can be winnowed-out.  However, for every trend there are exceptions, especially when drawn from the statewide pool of data. These trends and rankings change over time as the forests change. With that in mind, here are a few highlights, mostly from the 2017 U.S. Forest Service publication “Michigan Forests 2014” (NRS-110), which focuses primarily on the changes from 2009 to 2014.

  • Michigan has the 12th largest forest among U.S. States, 20.3 million acres, covering about 54 percent of the state.
  • The southern Lower Peninsula has the least amount of forest, but is experiencing the most amount of change. 
  • Michigan is growing about 14 billion trees that are over one inch in diameter. 
  • Most tree species volumes are increasing, however notable exceptions are paper birch, jack pine, quaking aspen, balsam poplar and balsam fir. 
  • Considering growth, natural mortality, timber harvest and other forest removals, Michigan’s forest inventory is increasing every year. Using the average volume per acre, the equivalent volume of over 330,000 acres were added each year. 
  • Almost two-thirds of Michigan forest is privately owned with 45 percent of the total forest area owned by families and individuals. About 190,000 family parcels are at least ten acres in size. 
  • Most family or individual ownerships have not participated in forestry programs between 2006 and 2010 and less than 10 percent have management plans. 
  • Over half of the primary owners of family or individual ownerships are at least 65 years old.
  • Forests are growing older, with larger diameter of trees and are composed predominantly of hardwood, broad-leaved trees. 
  • Northern hardwood, known as sugar maple forests and aspen forest types cover about a third of the forest. Northern hardwoods are increasing while aspen is declining. 
  • The most common tree by volume is sugar maple and the most common tree by count is balsam fir, which are at least one inch in diameter.
  • The least fragmented forests are in the Upper Peninsula, especially the western Upper Peninsula. 
  • Two-thirds of the forest carbon resides in the organic components of soils and wood in standing trees accounts for about a quarter of forest carbon.
  • Forest industries directly employ nearly 35,000 people with a direct product value of $10.2 billion per year. Indirectly and directly, the numbers are nearly 100,000 people and $20 billion dollars.   

Wood, water, habitat and recreation are key values of Michigan forests. Forest ecology is highly variable and increasingly complicated. Managing forests will provide more of all the characteristics we value and offers the best alternatives for forest health and protection.

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