Sunday, April 25, 2010

Apple #452: Forests

I'm sorry the Daily Apple has been getting short shrift lately.  I've been spending a lot of my free time in the woods.  Literally.

There are several large parks that surround the city where I live, and many of them include large tracts of forest.  For the most part, these are lands that were converted to farmland in the early to late 1800s but for one reason or another have become overgrown again and are now natural preserve areas. Walking or hiking trails wind among the trees which are just now beginning to pop out their new leaves all over the place and little wildflowers are beginning to bloom, and the streams are starting to make delightful trickling noises, and those woods are such wonderful places to be, I keep going back.

I've also taken lots of pictures. If you're curious, this is the type of camera I have.

Forest of hardwoods near where I live, on a typical sunny day.
(Photo by the Apple Lady)

There are many depressing facts about forests.  If you want to read about how forests are disappearing and how we're using too much wood and all that, you can read about those things here or here.  But I want to talk about the good things about forests.

There so many different types of plants and animals and bugs and birds that live in forests, and I could talk about all of them.  But for the sake of keeping this entry focused, I'm going to talk mainly about the trees.

Here's one of the biggest old trees in the woods. You come around a curve in the path and come upon this thing and you feel like you've wandered in front of a giant, mossy wizard.
(Photo by the Apple Lady)

  • The UN's Food and Agricultural Organization defines a forest as 
    • a piece of land bigger than 5,000 sq meters, which is slightly larger than one acre
    • with trees higher than 5 meters, or 16.4 ft tall
    • with a tree canopy cover of more than 10%
  • There are different types of forests.  A primary forest is one that has essentially never been disturbed by human activities.  The majority of primary forests left on Earth are in Brazil and, surprisingly, the Russian Federation.
  • Other types of forests are ones that have been cleared at some point and regenerated, either naturally or by having trees replanted by humans.  
  • There are also forest plantations, where people have planted a ton of trees, usually of the same species.  Sometimes they're planted to produce wood but other times they're planted with a protective or ecological purpose in mind such as combating desertification.
  •  About 30% of the total land on Earth is covered by forests of one kind or another.
  • The data for the US is similar.  About 33% of the total land in the country is forest land.

Typical hillside, with lots of tall trees and new growth as well. This was taken in June.
(Photo by the Apple Lady)

    •  The number of species of trees in a forest varies quite a lot depending on the climate.  Generally, the forests containing the greatest diversity of species are in the tropical regions.  Forests with fewer numbers of species are in cold climates where mainly coniferous trees grow.

    Map of the number of tree species in forests, by country
    (Graphic by the FAO's Global Forest Resources Assessment 2005, sourced from Green Facts)

    • Pines, oaks, and spruces are the three most common genera of trees worldwide.  They account for nearly 24% of the total types of trees around the globe. 
    • Fir, birch, beech, and poplar are the next most common, in descending order of prevalence.
    • In the US, the data about tree species diversity gets more fragmented.  Forests are categorized in terms of two or three genera names linked together.  Those names indicate that those types of trees are the most prevalent, but they are by no means the only types of trees that grow there.
    • For example, in the Eastern US, the most common type of forest is the oak-hickory.  In the West, the most common category is "other softwoods," which refers to a variety of coniferous trees.  It's easiest to show you the charts.

    (Source: USDA, US Forest Resource Facts and Historical Trends 2002)

    (Source: USDA, US Forest Resource Facts and Historical Trends 2002)

    • Lest you think that "oak-hickory" means that only oaks and hickories grow there, another study about trees growing in forests in Michigan says they found that 63 different species of trees grow in "oak-hickory" forests.  
    • In Michigan, by the way, the type of forest with the greatest diversity of species is the northern hardwood forest, which are home primarily to maple, basswood, beech, and yellow birch trees.  These forests contain 71 total different species. 

      This is how one of the forests looked only a month ago.  No leaves yet, but pretty nonetheless with the sun and the clouds peeking through.
      (Photo by the Apple Lady)

        • In the US, as of the year 2000, 28% of the country's forests were in counties with large urban centers, or more than 20,000 people.

        (Source: USDA, US Forest Resource Facts and Historical Trends 2002)

          • Forests do all sorts of good things for us. Not only do they help reduce the amount of greenhouse gases in the air, they also 
            • absorb heat energy and provide a cooling effect
            • trap and intercept wind-borne pollution
            • protect soil from wind erosion
            • protect coastal areas from shoreline erosion
            • reduce the impact of avalanches
            • moderate the impact of floods
            • protect water resources by filtering pollutants and mitigating salinity
          • Every type of forest, whether it's primary or otherwise, does at least some if not all of these things.

          If this doesn't shout, "I support life!" I don't know what does.
          (Photo by the Apple Lady)

            • Even trees that have been felled and lie in landfills or those that have been converted to lumber, and yes, even the paper resting in your laser printer right now -- all of those once-upon-a-time trees still retain much of the carbon that they absorbed when they were living trees.
            • About 51% of the country's fresh water supply originates in forested land.

            At the far edge of the woods are bluffs that drop down to a river. Lining the far side of the riverbank are sycamores. Took this at sunset a few days ago.
            (Photo by the Apple Lady)

            • An average tree exhales about 120 pounds of oxygen per year.  One person needs one pound of oxygen to breathe per day, so it takes about three trees to provide enough oxygen for one person to breathe each day.
            • According to the USDA, "In the last half of the nineteenth century, an average of 13 square miles of forest was cleared every day for 50 years." 
            • Today, 55% of the country's timber is younger than 50 years old.  6% of the country's trees is older than 175 years. 

              (Source: USDA, US Forest Resource Facts and Historical Trends 2002)

              One of the huge white oaks that grow in these forests. They're so massive in diameter as well as height that I can't capture the entirety of one of these trees in a single frame.  There are several that are even larger, but I chose this photo because I'm hoping the fencepost in the foreground gives you an idea of the size.  Park officials estimate that these white oaks were planted somewhere around the time of the Civil War.
              (Photo by the Apple Lady)

              • Though there are fewer forests than there used to be, the rate of net loss of forested areas worldwide is declining thanks to increased forest planting and the natural expansion of forests on land that once once developed but has since been abandoned.
              • In the US, the most forested land is still in the West.  Each region of the country has seen a decline in the amount of forested land since 1850.  But in recent years, all areas have increased the amount of forested land.

              (Source: USDA, US Forest Resource Facts and Historical Trends 2002)

              • The amount of forested area in the South will continue to increase, since that area has seen the largest amount of tree planting, with extensive planting programs carried out in the 1950s and again in the 1980s.

              Hopefully the future will hold more trees, more paths, more woods to explore.
              (Photo by the Apple Lady)

              Green Facts Scientific Board, Forest and Scientific Facts on Forests
              FAO, Global Forest Resources Assessment 2005, Chapter 3: Biological diversity
              USDA, US Forest Facts and Historical Trends 2000
              Michigan State University Extension, Tree Diversity Within Michigan Forest Types
              Weyerhauser, Forest Facts


              1. Michigan has more tree species than any other state. That's a fact, a Michigan fact.

              2. The green color is so intense...just beautiful! I live in the Southwest where we have forests of saguaro cacti; a different look altogether.


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