CO(2) enrichment and N addition increase nutrient loss from decomposing leaf litter in subtropical model forest ecosystems

As atmospheric CO(2) concentration increases, many experiments have been carried out to study effects of CO(2) enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of CO(2) enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated CO(2) and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated CO(2) and N addition increased nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated CO(2) and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated CO(2) was associated with the increased soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the increased soil microbial biomass and the greater soil acidity. Our results imply that elevated CO(2) and N addition will increase nutrient cycling in subtropical China under the future global change.