I'm not a lichenologist, so I do not know their names, but I counted what looked like to me nearly 10 different species on this rock. They all had their own beautiful shapes and colors.
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Friday, April 16, 2010
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That you took the time to stop and count says a lot about you ; ) ... good things, of course ...
ReplyDeleteQ: My 10 year old wants to know ... What is the difference between an 'old growth' forest and a regular plain old everyday forest?
Another very good question that, unfortunately doesn't have a very straight-forward or short answer, as it depends on which forest we talk about. Forests go through a series of growth "stages". An idealistic description for western Washington goes like this: some big disturbance (fire, wind, disease, etc.) kills an entire forest stand. After a few years, a new generation of trees (usually shade-intolerant trees like Douglas-fir) establishes on this site. After about 50 years, this new forest is typically dense, often lacks plants in the understory (underneath the tree), and has monotonous "structure" or canopy layers (in other words, many of the trees germinated at the same time so they all are pretty equal in height and girth). As the forests get older, some of these trees die (due to many different cause like bugs, disease, fire, competition with other trees, etc.). As this happens, gaps open up in the forest which allow more light to penetrate and provide more space for shrubs and other plants to grow in the understory. As the trees get taller and space opens up underneath, shade-tolerant trees like western hemlock germinate on the forest floor or on top of fallen trees. Over many hundreds of years, this process continues and the trees that were present when the forest 'germinated' and have survived are now really BIG. So, in western WA the big differences are the size of trees, the kinds of tree and other plants that grow in the forest, the vertical structure of the forest, and the kinds of animals that live in them.
ReplyDeleteForests in eastern Washington have different stages. Dry forests like ponderosa pine historically experienced very frequent (but not intense) fires. These fires killed most of the tree seedlings but because fire spread haphazardly, some trees escape enough fire events to get large enough to survive future fires (their bark is specifically adapted to protected them from fire). This process continues over many years until we get an old growth ponderosa pine forest....which has sporadic, big trees with grasses in between--has a very park-like feel to it. Without periodic fire, these forest get "overgrown" and become very dense with hardly anything growing underneath, which isn't very good habitat for animals either.
Those are the extreme examples...there are lots of variations of these!
If you can open Adobe PDF files, take a look at the drawing on page 5 of this document to see old growth development for a typical western WA forest.
http://www.dnr.wa.gov/Publications/lm_ess_westside_oldgrowth_rpt.pdf
this is a bit technical but lots of good information on old growth in western WA
http://www.dnr.wa.gov/Publications/lm_ess_eastside_oldgrowth_guide.pdf
Page 32 and 33 in this guide has a drawing of old growth ponderosa pine
http://www.dnr.wa.gov/Publications/lm_ess_eastside_oldgrowth_guide.pdf
sorry for the, winded answer. probably way more that you wanted and much more than a 10 year would want!
Thanks Joe! That is a great explanation. Does sound like a complicated process with lots of variables, but your answer helped to satisfy my daughter's curiousity. Thanks ever so much for taking the time to write. Will have to check your additional links as well. Keep the awesome photos coming! : )
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