Transient Flooding and Soil Covering Interfere with Decomposition Dynamics of Populus euphratica Leaf Litter: Changes of Mass Loss and Stoichiometry of C, N, P, and K

Abstract

Litter decomposition plays a critical role in carbon and nutrient cycling in terrestrial and aquatic ecosystems. However, the effects transient flooding and soil covering have on leaf litter decomposition remain unclear. The changes of litter mass loss and stoichiometric ratio of C:N (the ratio of carbon to nitrogen), C:K (the ratio of carbon to potassium), C:P (the ratio of carbon to phosphorus), N:P (the ratio of nitrogen to phosphorus), and N:K (the ratio of nitrogen to potassium) of fresh Populus euphratica (P. euphratica) leaves in surface, transient flooding, and soil covering treatments were studied using litterbags in a desert riparian forest in a field decomposition experiment for a period of 640 d. The results showed that there was a significant influence of disturbance type and incubation time on litter mass loss rate and stoichiometric ratios of C:N, C:K, C:P, N:P, and N:K of fresh P. euphratica leaves, but no significant influence of the interaction between disturbance type and incubation time on leaf litter mass loss. In three treatments, five sequential phases of leaf litter mass loss rate and different temporal change patterns of stoichiometric ratio were identified within 640 d. Transient flooding was shown to affect P. euphratica leaf litter mass loss phases compared to that in no-disturbance conditions, and especially promote leaf litter mass loss within 0–173 d of incubation time. It was also demonstrated that transient flooding and soil covering can influence leaf litter decomposition, which led to the leaf litter mass loss rate and the stoichiometric ratios of C:N, C:K, C:P, N:P, and N:K exhibiting varied patterns and phases in different treatments during decay.