Wednesday, November 15, 2006
283-8

Indirect and Direct Effects of Restoration Treatments on Soil Food Web Structure in a Landfill Remediation.

Lori Biederman and Steven Whisenant. Texas A&M University, Tamu 2126, College Station, TX 77843

Severely degraded sites require intervention to reestablish or enhance ecosystem processes. Although the soil food web influences nutrient availability and soil structure, restoration often fails to consider these organisms in project design and management. This can have important consequences for the rate and trajectory of plant community succession and, ultimately, restoration success. We examine the prospect for soil food web management in remediation of a municipal landfill by using two amendment treatments that are known to alter soil food web structure in agricultural systems. The 3x2 factorial design includes three volumes of wood-chip mulch applied to either the soil surface or incorporated to 6 cm. A species-rich prairie seed mix was planted in March 2003. We began soil biological sampling in September 2003 and continued sampling in March, June, and September of 2004 and 2005. Soil microbial biomass increased with time and application rate and carbon mineralization potential responded positively to amendment rate during the first two years of the experiment. In 2005, these relationships were not significant, most likely because drought conditions limited decomposition. The seasonal densities of nematodes increased throughout the experiment, with the exception of June 2005. Mean nematode densities were highest for June in 2004, (6386.5 ±935 individuals 100 g-1 soil) and March and September in 2005 (1407.7 ± 134.7 and 1223.0 ± 76.4 individuals 100 g-1 soil, respectively). Nematode population response cannot be directly attributed to the applied amendment location or amount. Instead, nematode trophic guilds responded positively to food source abundance; specifically, aboveground plant biomass and soil microbial biomass. The strength of these responses varied with season and was strongest in September.