Ecological Engineering 60 (2013) 67–75 Contents lists available at ScienceDirect Ecological Engineering journa l h om epage: www.elsevier.com/locate/ecoleng Microbial responses to simulated water erosion in relation to organic carbon dynamics on a hilly cropland in subtropical China Jinquan Huang a,b , Zhongwu Li a,b,∗ , Guangming Zeng a,b , Jiachao Zhang d , Jianbing Li c , Xiaodong Nie a,b , Wenming Ma a,b , Xue Zhang a,b a College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China b Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China c Environmental Engineering Program, University of Northern British Columbia, Prince George, British Columbia V2N 4Z9, Canada d College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China a r t i c l e i n f o Article history: Received 17 March 2013 Received in revised form 27 June 2013 Accepted 6 July 2013 Available online 14 August 2013 Keywords: Microbial abundance Microbial community structure Water erosion Soil properties Soil organic carbon Rainfall simulation a b s t r a c t Water erosion significantly affects soil properties, and microbial communities are likely to respond to this disturbance, thereby considerably influencing soil organic carbon (SOC) dynamics. This study inves- tigated the impact of water erosion on the soil microbial communities in a hilly, sloped cropland in subtropical China. To this end, 1 h rainfall was simulated, and the soil samples collected from three plots (I, II, and III) during and for 132 h after rainfall simulation were analyzed. The two-stage variations in soil microbial abundance and community structure were identified by quantitative polymerase chain reaction and denaturing gradient gel electrophoresis, respectively. During rain, severe water erosion significantly reduced the bacterial abundance (BA) and fungal abundance (FA) in plot II. Most of the soil properties of the entire land significantly changed because of erosion. The overall redundancy analysis results illustrate that during the subsequent 132 h, soil pH strongly controlled the Shannon index of bacterial diversity and soil moisture had a significant negative correlation with FA and the Shannon index of fungal diversity. By contrast, a positive correlation was found between BA, FA and SOC. These results suggest that the dynam- ics of microbial communities are closely related to erosion-induced changes in soil properties. Bacteria and fungi differentially respond to these changes. Thus, merely analyzing the variations in SOC pool con- tent is therefore insufficient. Elucidating soil microbial dynamics and gaining insight into the dynamics of erosion-sensitive functional groups or species are necessary for evaluating eroded carbon dynamics. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Soil erosion, one of the main driving forces of soil carbon dynamics, has elicited tremendous concern because it directly and indirectly contributes to the global carbon cycle (Lal and Pimentel, 2008; Lü et al., 2012). The contribution of soil erosion in the pedo- sphere to atmospheric CO 2 has been investigated to explore either the effects of soil organic carbon (SOC) mineralization during trans- port as a CO 2 source (Lal et al., 2004) or effects of the deep burial of SOC in landscape as a CO 2 sink (Van Oost et al., 2007). Despite such efforts, however, considerable uncertainties as to how SOC pools Abbreviations: BA, bacterial abundance; FA, fungal abundance; BH, Shannon index of bacterial diversity; FH, Shannon index of fungal diversity. ∗ Corresponding author at: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China. Tel.: +86 731 88640078; fax: +86 731 88640078. E-mail address: lizw@hnu.edu.cn (Z. Li). and dynamics are affected by water erosion remain (Lal, 2006; Van Oost et al., 2007). A key uncertainty is the implication of lat- eral movement and the mineralization of eroded SOC through the terrestrial system for the global carbon cycle (Berhe et al., 2007; Schwanghart and Jarmer, 2011). A combined eco-geomorphologic and geomorphologic approach has been recognized as delivering a comprehensive explanation of the role of soil erosion in the global carbon cycle (Kuhn et al., 2009). This approach concerns interactions among the biosphere, landforms, and geomorphic processes at or near land surfaces (Otero et al., 2011; Viles, 1988). As a main component of the terrestrial biosphere, soil microorganisms play an important role in the decomposition of soil organic matter, which regulates soil CO 2 efflux (Abbasi and Khizar, 2012; Lopez-Sangil et al., 2011). Soil microorganisms undergo heterotrophic respiration, thereby releasing a large amount of SOC to the atmosphere (Schwanghart and Jarmer, 2011). Abiotic and biotic stresses, in turn, significantly affect the community structure of soil microorganisms. Microbial habitats experience a series of disturbances that are caused by 0925-8574/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ecoleng.2013.07.040