دانلود رایگان پاورپوینت گلسنگ (انگلیسی)

Lichens
Definition
Categories
Uses/ Economic Importance
Structure

Uses/ Economic Importance
Because they readily incorporate cations (positively charged ions) into their stuctures, lichens can be quite sensitive to pollutants in the air, so they can be used to determine level of air pollution
Example: In 1985, a study was done that revealed that 81% of the 172 lichen species that were present in Ohio Valley in 1917 were gone because of pollution, especially sulfur dioxide