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Why Do Certain Lichens Grow Only on Acidic Rock Surfaces?
为什么某些地衣只生长在酸性岩石表面？
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Lichens are symbiotic organisms made of fungi and algae or cyanobacteria.
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They survive in extreme environments where few other plants can grow.
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Some lichen species produce acids that slowly dissolve rock minerals to extract nutrients.
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Acidic rocks like granite contain minerals such as quartz and feldspar that resist weathering.
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These lichens thrive there because their acid secretion matches the rock’s low pH buffer capacity.
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On alkaline limestone, the same acids react too strongly and inhibit growth.
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Scientists measure lichen distribution to monitor long-term air quality and rock weathering rates.
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Their slow growth—often less than one millimeter per year—makes them excellent environmental recorders.
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Because they absorb everything from the air, they accumulate pollutants like heavy metals over decades.
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This makes them natural bioindicators for ecological change across centuries.