Decomposition and nitrogen transformation rates in a temperate grassland vary among co-occurring plant species

Abstract

Background and aims Decomposition of organic matter varies depending upon interactions between the composition of the organic matter and the source of the microbial community, with differences in these interactions among vegetation types leading to the Home Field Advantage (HFA) hypothesis whereby decomposition of litters is faster in soils previously conditioned by them. It is possible that HFA operates on smaller scales within plant communities with ecosystem processes responding to subtle changes of plant community dominance. Methods and results Using field measurements and laboratory incubations, we found a strong plant species effect on nitrogen availability and transformations and the relative importance of autotrophic and heterotrophic processes to nitrification. We found that the origin of the soil microbial community had little influence on litter decomposition when litter quality was high but was important with low-quality litter, most of which was root material. Conclusions Our results demonstrate that plant species identity has a substantial impact on both litter decomposition and N cycling even within a single vegetation type and on an extremely local scale via both litter chemistry and specificity of the associated soil microbial community. Therefore, changes in botanical composition could alter decomposition and nutrient release altering ecosystem productivity and carbon sequestration potential.

Decomposition of Eucalyptus grandis and Acacia mangium leaves and fine roots in tropical conditions did not meet the Home Field Advantage hypothesis

“…So far as we are aware, only three studies have tested the HFA hypothesis for fine roots and the results do not show a clear pattern (Gholz et al, 2000;Freschet et al, 2012b;Osanai et al, 2012). Although litter decomposition can be controlled by specific mechanisms in tropical regions (Hättenschwiler and Bracht Jørgensen, 2010;Hättenschwiler et al, 2011), only a few studies have tested the HFA hypothesis in tropical forests (Wang et al, 2013;Veen et al, 2015).…”

Plant species richness leaves a legacy of enhanced root litter-induced decomposition in soil

“…Most studies on HFA focus on forest ecosystems and find variable effect sizes ranging from À8% to 28% (with mean value of 8%). But only a few studies have investigated HFA in grassland systems and none could detect any HFA (Hunt et al, 1988;Strickland et al, 2009;Osanai et al, 2012). Possibly the differences in litter quality of grass species are not large enough to lead to specialization of soil microbial communities, thus inducing smaller or no HFA in grasslands than forest systems (Vivanco and Austin, 2008;Ayres et al, 2009a).…”

Soil N cycling processes in a pasture after the cessation of grazing and CO 2 enrichment

“…Heterotrophic nitrification is not often studied in N 2 O flux research. However, it has been observed to be important under eCO 2 in a native grassland in Tasmania (Osanai et al, 2012) and has been inferred to be important from tracer studies and modeling in a long-term grassland site under ambient CO 2 in Germany (Müller et al, 2009) and under eCO 2 at the NZ-FACE (Rütting et al, 2010).…”