Abstract: Environmental acidification is one of the major problems caused by global climate change. Due to the long-term effects of acid rain, the pH of terrestrial and lake ecosystems presents a declining trend, and in the meanwhile, acidification of marine ecosystem also occurs because of the dramatic increase of atmospheric CO2 concentration. Calcium homeostasis in organisms or/and ecosystems can be disturbed by environmental acidification. In marine ecosystem, calcium-rich species will have difficulties in maintaining their external calcium carbonate skeletons, resulting in the declining of coral calcification and the corroding of pteropod shell. With the decrease of ocean pH and carbonate ion concentration, the reproduction of marine organisms may be declined. In terrestrial ecosystem, organisms cannot absorb enough essential calcium because large quantity of bio-available calcium has been depleted from the ecosystem by the long-term acid rain. Therefore, anthropogenic acidification has caused the decline in calcium-rich species populations such as snail and Daphnia in soil and fresh waters, and birds also have low reproductive success as a result of calcium deficiency under long-term acid rain stress. In plants, acid rain disturbs calcium signal transduction cascades, and further, negatively affects physiological processes such as photosynthesis, stress-resistance, and reproduction, with the ecological consequences such as primary productivity and biodiversity decrease and forest decline. It may be a universal ecological pattern that calcium-rich species will be much more difficult in survival under the scenario of calcium homeostasis in ecosystems being disturbed by environmental acidification.

Key words: Soil nematode, Bioindicator, Maturity Index, Trophic group