Calcium concentration in leaf litter alters the community composition of soil invertebrates in warm-temperate forests

Many studies have shown the effects of aboveground plant species on soil organisms due to differences in litter quality. However, the calcium concentration in soil has received less attention as a controlling factor of soil invertebrate communities, even though it is an essential element for many animals, especially crustaceans. Litter of Japanese cedar (Cryptomeria japonica) plantations, which account for 19% of the forested area in Japan, has a higher calcium concentration compared to other taxa such as broad-leaved trees. We predicted that C. japonica plantations affect soil invertebrates by altering calcium availability. We compared soil properties including exchangeable calcium concentration and soil invertebrate communities between C. japonica plantations and natural broad-leaved forests. Exchangeable calcium was significantly higher in soil from cedar plantations than in that from broad-leaved forests. The invertebrate community composition differed between the two forest types and was best explained by the exchangeable calcium concentration. In particular, two major taxa of soil crustaceans (Talitridae and Ligidium japonicum) were found only in cedar plantations. Our results suggest that calcium concentrations in soil are altered in C. japonica plantations and that this affects soil invertebrate communities.