An acidophobe is an organism that is intolerant of acidic environments.[1] The terms acidophobia, acidophoby and acidophobic are also used.[2] The term acidophobe is variously applied to plants, bacteria, protozoa, animals, chemical compounds, etc. The antonymous term is acidophile.[3]
Plants are known to be well-defined with respect to their pH tolerance, and only a small number of species thrive well under a broad range of acidity.[4][5] Therefore the categorization acidophile/acidophobe is well-defined. Sometimes a complementary classification is used (calcicole/calcifuge, with calcicoles being "lime-loving" plants). In gardening, soil pH is a measure of acidity or alkalinity of soil, with pH = 7 indicating the neutral soil. Therefore acydophobes would prefer pH above 7. Acid intolerance of plants may be mitigated by lime addition and by calcium and nitrogen fertilizers.[6][7]
Acidophobic species are used as a natural instrument of monitoring the degree of acidifying contamination of soil and watercourses. For example, when monitoring vegetation, a decrease of acidophobic species would be indicative of acid rain increase in the area. A similar approach is used with aquatic species.