Biogenic structures of two ant species Formica sanguinea and Lasius flavus altered soil C, N and P distribution in a meadow wetland of the Sanjiang Plain, China

Biogenic structures produced by soil ecosystem engineers influence the soil architecture and mediate soil functions and ecosystem services. Ant mounds in meadow wetlands are important biogenic structures with the potential of altering carbon storage and nutrient cycling in these ecosystems. In this study, we examined the soil nutrient concentrations of ant mounds and their effects on the wetland nutrient storage functions in meadow wetlands of the Sanjiang Plain, in northeastern China. The aims of this study were to investigate C, N and P variation in active ant mounds produced by Formica sanguinea Latreille and Lasius flavus Fabricius to estimate the C, N and P pools of ant mounds in comparison with control soil. The average total N (TN), total P (TP) and available P (AP) concentrations in the ant mounds of both species were higher than in the control soil. Organic carbon (C-org), DOC, NH4+ and NO3- in F. sanguinea mounds were higher than in the control soil, but not for L. flavus mounds. Average concentrations of all the five types of nutrient were higher in F. sanguinea mounds than in L. flavus mounds. The variations in C-org, DOC, TN and TP concentrations in ant mounds were not significant at depths from 0 to 25 cm. NH4+ and NO3- concentrations differed by soil layers for F. sanguinea mounds but not for L. flavus mounds. The C/N ratios were generally lower in the mounds than in the control soil (at 5-25 cm), but no significant differences were found for C/P ratios (except at 10-15 cm). Carbon and DOC pools were smaller, TN and AP pools were larger in ant mounds compared with the control soil, but there was no significant difference for TP pools. NFL4+ and NO3- pools were substantially larger in F. sanguinea mounds, but smaller in L flavus mounds, than those in the control soil. All of the five types of nutrient pools were larger in F. sanguinea than in L flavus mounds. Ant mounds increased the spatial variability of soil nutrient pools in the wetland. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.