No depth-dependence of fine root litter decomposition in temperate beech forest soils

• DOI: 10.1007/s11104-015-2492-7
• Publication Date: 2015-05-03T04:08:35Z
• Authors: Emily F. Solly; Ingo Schöning; Nadine Herold; Susan E. Trumbore; Marion Schrumpf
• Keywords: Subsoil; Topsoil; Litter; Temperate forest; Plant litter; Soil horizon; Soil carbon

Aims Subsoil organic carbon (OC) tends to be older and is presumed to be more stable than topsoil OC, but the reasons for this are not yet resolved. One hypothesis is that decomposition rates decrease with increasing soil depth. We tested whether decomposition rates of beech finerootlittervariedwithdepthforarangeofsoilsusing a litterbag experiment in German beech forest plots. Methods In three study regions (Schorfheide-Chorin, Hainich-Dun and Schwabische-Alb), we buried 432 litterbags containing 0.5 g of standardized beech root material (fine roots with a similar chemical composition collected from 2 year old Fagus sylvatica L. saplings, rootdiameter<2mm)atthreedifferentsoildepths(5,20 and 35 cm). The decomposition rates as well as the changes in the carbon (C) and nitrogen (N) concentrations of the decomposing fine root litter were determined at a 6 months interval during a 2 years field experiment. Results Theamount ofrootlitterremaining after 2 years of field incubation differed between the study regions (76±2 % in Schorfheide-Chorin, 85±2 % in Schwabische-Alb, and 88±2 % in Hainich-Dun) but did not vary with soil depth. Conclusions Our results indicatethatthe initial fineroot decomposition rates are more influenced by regional scale differences in environmental conditions including climate and soil parent material, than by changes in microbial activities with soil depth. Moreover, they suggest that a similar potential to decompose new resources in the form of root litter exists in both surface and deep soils.