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Abstract: The soil community is an often ignored part of research which links plant biodiversity and ecosystem functioning despite their influence on numerous functions such as decomposition and nutrient cycling. Few consistent patterns have been detected that link plant and soil community composition. We used a removal experiment in a northern Canadian grassland to examine the effects of plant functional group identity on soil microbial community structure and function. Plant functional groups (graminoids, legumes and forbs) were removed independently from plots for five growing seasons (2003–2007) and in the fifth year effects on the soil microbial community were examined using substrate-induced respiration (SIR – a measure of metabolic diversity) and phospholipid fatty acid analysis (PLFA – a measure of microbial community composition). Removal treatments were also crossed with both a fertilizer treatment and a fungicide treatment to determine if effects of functional group identity on the soil community were context dependent. Plant functional group identity had almost no effect on the soil microbial community as measured by either SIR or PLFA. Likewise, soil properties including total carbon, pH, moisture and nutrients showed a limited response to plant removals in the fifth year after removals. We found a direct effect of fertilizer on the soil community, with fertilized plots having decreased metabolic diversity, with a decreased ability to metabolize amino acids and a phenolic acid, but there was no direct soil microbial response to fungicide. We show that in this northern Canadian grassland the soil microbial community is relatively insensitive to changes in plant functional group composition, and suggest that in northern ecosystems, where plant material is only slowly incorporated into the soil, five growing seasons may be insufficient to detect the impact of a changing plant community on the soil microbes. [ABSTRACT FROM AUTHOR]

No-till green manure (Gmr) termination creates a unique situation compared to conventional no-till crop management due to the surface mulch generated. However, the impact this practice has on soil biota has been little researched, despite the important role soil biota play in soil ecosystem functions such as decomposition and pest control. This study examines how termination management of Gmr can affect soil biota and their population dynamics. Over two trials, Gmr tillage regimes of fall tilled, spring tilled, or no-till were applied to a spring planted Gmr of hairy vetch/oat (HVO) along with a typical regional practice of tilled red clover Gmr within a four-year grain rotation. Soil microbial biomass (SMB), earthworm density, and beetle and spider activity density were assessed up to three years following Gmr termination. SMB was greatest in the spring for no-till and fall tilled HVO Gmr treatments, but the effect was transient, disappearing after two months. Earthworm densities were negatively affected by tillage (88% and 86% less than no-till in Trial 1 and 2, respectively) but densities recovered three years after tillage to that of the no-till treatment. Beetle activity density was largely unaffected by Gmr termination. Spider captures were more numerous in no-till plots compared to spring tilled in one trial. Impacts of Gmr termination on soil organisms vary by taxa and earthworms were the most sensitive, taking two years to recover from tillage. No-till Gmr termination does not show clear benefits to soil biota. [ABSTRACT FROM AUTHOR]