Contrasting responses of soil respiration and temperature sensitivity to land use types: Cropland vs. apple orchard on the Chinese Loess Plateau

摘要

Highlights•Contrasting responses of soil respiration andQ10to land use types in fragmented Loess Plateau•Compared to the cropland, the lowerQ10in the apple orchard resulted from varied bacterial community structure and β-glucosidase and cellobiohydrolase activity.•Lower C: N ratios in the apple orchard possibly contributed to its lowerQ10.Graphical abstractDisplay OmittedAbstractLand use plays an essential role in regional carbon cycling, potentially influencing the exchange rates of CO2flux between soil and the atmosphere in terrestrial ecosystems. Temperature sensitivity of soil respiration (Q10), as an efficient parameter to reflect the possible feedback between the global carbon cycle and climate change, has been extensively studied. However, very few reports have assessed the difference in temperature sensitivity of soil respiration under different land use types. In this study, a three-year field experiment was conducted in cropland (winter wheat,Triticum aestivumL.) and apple orchard (Malus domesticaBorkh) on the semi-arid Loess Plateau from 2011 to 2013. Soil respiration (measured using Li-Cor 8100), bacterial community structure (represented by 16S rRNA), soil enzyme activities, and soil physicochemical properties of surface soil were monitored. The average annual soil respiration rate in the apple orchard was 12% greater than that in the cropland (2.01vs.1.80μmolm−2s−1), despite that the averageQ10values in the apple orchard was 15% lower than that in the cropland (ranging from 1.63 to 1.41). As to the differences among predominant phyla, Proteobacteria was 26% higher in the apple orchard than that in the cropland, whereas Actinobacteria and Acidobacteria were 18% and 36% lower in the apple orchard. The β-glucosidase and cellobiohydrolase activity were 15% (44.92vs.39.09nmolh−1g−1) and 22% greater (21.39vs.17.50nmolh−1g−1) in the apple orchard than that in the cropland. Compared to the cropland, the lowerQ10values in the apple orchard resulted from the variations of bacterial community structure and β-glucosidase and cellobiohydrolase activity. In addition, the lower C: N ratios in the apple orchard (6.50vs.8.40) possibly also contributed to its lowerQ10values. Our findings call for further studies to include the varying effects of land use types into consideration when applyingQ10values to predict the potential CO2efflux feedbacks between terrestrial ecosystems and future climate scenarios.