Stephanie Schelfhout

Linkages between aboveground and belowground community compositions in grasslands along a historical land-use intensity gradient

Background and aimsImproving our understanding of ecosystem responses to land-use intensification requires explicit consideration of linkages between aboveground and belowground communities. Here, we explore linkages between plant, soil microbial and nematode community compositions along a historical land-use intensity (hLUI) gradient.MethodsWe used co-inertia analysis to investigate linkages between each paired community composition in 33 grasslands with similar hydrology and soil texture but contrasting hLUI and associated soil chemical properties (e.g. pH, phosphorus). We estimated the percentage cover of plant species, identified nematodes to genus level, and analysed the microbial community using phospholipid fatty acid (PLFA) profiling.ResultsPlant and nematode communities were more strongly linked as compared to either community’s links with microbes, although all pairwise comparisons were significant. Linkage strength did not depend on the degree of hLUI. We found significant variations in plant and nematode, but not in microbial, community compositions along the hLUI gradient.ConclusionsLarge changes in soil fertility associated with hLUI have led to shifts in vegetation community composition matched by changes in the composition of different soil communities, or vice versa. The nematode community seems to be more responsive to vegetation composition than other trophic groups. Additional research in an experimental setting will elucidate the mechanisms underpinning the observed relationships.

Phosphorus mining efficiency declines with decreasing soil P concentration and varies across crop species

ABSTRACT High soil P concentrations hinder ecological restoration of biological communities typical for nutrient-poor soils. Phosphorus mining, i.e., growing crops with fertilization other than P, might reduce soil P concentrations. However, crop species have different P-uptake rates and can affect subsequent P removal in crop rotation, both of which may also vary with soil P concentration. In a pot experiment with three soil-P-levels (High-P: 125–155 mg POlsen/kg; Mid-P: 51–70 mg POlsen/kg; Low-P: 6–21 mg POlsen/kg), we measured how much P was removed by five crop species (buckwheat, maize, sunflower, flax, and triticale). Total P removal decreased with soil-P-level and depended upon crop identity. Buckwheat and maize removed most P from High-P and Mid-P soils and triticale removed less P than buckwheat, maize, and sunflower at every soil-P-level. The difference in P removal between crops was, however, almost absent in Low-P soils. Absolute and relative P removal with seeds depended upon crop species and, for maize and triticale, also upon soil-P-level. None of the previously grown crop species significantly affected P removal by the follow-up crop (perennial ryegrass). We can conclude that for maximizing P removal, buckwheat or maize could be grown.