Leaves are green because of chlorophylls that function by capturing the sun’s energy and to manufacture food for the plant or photosynthesis. All of this takes place in the plastids (specialized cells). During the growing season, the green color of these chlorophylls masks out all the other colors that may be present. So all you see is green.
As the growing season slows in autumn, chlorophyll production slows and the green-color dominance lowers to reveal the other colors of the leaf. Many influences such as amount of water, sunlight, temperature, and microclimate can manipulate the timing of the color changes. A couple of weeks of bright sunny days mixed with clear, cool nights seem to bring out the best fall colors.
The most common cause of thatch is compacted soils. Grass roots will seek air at the soil surface and then die. Other causes:
- Overuse of fast-acting nitrogen fertilizers causes rapid growth at the expense of a good root system. These also tend to acidify the soil, repelling beneficial thatch-eating earthworms.
- Overwatering drowns microorganisms in the soil that decompose thatch
- Mowing too closely or taking off more than one-third of the blade causes more thatch
The Frederick Meijer Sculpture Park in Grand Rapids, Michigan features momentous works of art within a variety of natural settings that are connected by waterways, winding paths, meadows and quiet walkways. Masters such as Auguste Rodin, Henry Moore, Barbara Hepworth, Mark di Suvero, Richard Serra, Roxy Paine and many others have sculptures across the Meijer Gardens. This was one of my favorites by Jaume Plensa.
There are other parts of the museum. See some photos: