TY - JOUR
T1 - Soil organic carbon and mineral interactions on climatically different hillslopes
AU - Wang, Xiang
AU - Yoo, Kyungsoo
AU - Wackett, Adrian A.
AU - Gutknecht, Jessica L
AU - Amundson, Ronald
AU - Heimsath, Arjun
N1 - Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/7/15
Y1 - 2018/7/15
N2 - Climate and topography have been widely recognized but studied separately as important factors controlling soil organic carbon (SOC) dynamics. Subsequently, the significance of their interplay in determining SOC storages and their pools is not well understood. Here we examined SOC storages and SOC-mineral interactions along two hillslope transects in differing climate zones (MAP = 549 mm in semi-arid eucalyptus savannah vs. 816 mm in temperate eucalyptus forest) in southeastern Australia. On eroding slopes, SOC inventories were twice as large at the wetter site (4.5 ± 0.6 vs. 2.3 ± 0.9 kg m−2), whereas depositional soils had similar SOC inventories at both locations (7.5 ± 2.0 vs.7.0 ± 2.2 kg m−2). On eroding slopes, carbon concentrations of the mineral-associated SOC fraction (<250 μm and >2.0 g cm−3) increased by ~50% with increasing rainfall, which was also positively correlated to abundances of clay minerals and pedogenic iron oxides. Within individual hillslopes, carbon concentrations of the mineral-associated SOC fraction doubled from eroding to depositional soils at the drier site, but no topographic trend was observed at the wetter site. The effects of topography on SOC inventories and mineral-associated SOC were more strongly expressed under the drier climate, where vegetation was sparser and soil erosion involved mineral grain size sorting. Our results demonstrate that SOC pools and their interactions with minerals are dependent on topographic locations, emphasizing the need to include geomorphic data when assessing climatic controls of SOC.
AB - Climate and topography have been widely recognized but studied separately as important factors controlling soil organic carbon (SOC) dynamics. Subsequently, the significance of their interplay in determining SOC storages and their pools is not well understood. Here we examined SOC storages and SOC-mineral interactions along two hillslope transects in differing climate zones (MAP = 549 mm in semi-arid eucalyptus savannah vs. 816 mm in temperate eucalyptus forest) in southeastern Australia. On eroding slopes, SOC inventories were twice as large at the wetter site (4.5 ± 0.6 vs. 2.3 ± 0.9 kg m−2), whereas depositional soils had similar SOC inventories at both locations (7.5 ± 2.0 vs.7.0 ± 2.2 kg m−2). On eroding slopes, carbon concentrations of the mineral-associated SOC fraction (<250 μm and >2.0 g cm−3) increased by ~50% with increasing rainfall, which was also positively correlated to abundances of clay minerals and pedogenic iron oxides. Within individual hillslopes, carbon concentrations of the mineral-associated SOC fraction doubled from eroding to depositional soils at the drier site, but no topographic trend was observed at the wetter site. The effects of topography on SOC inventories and mineral-associated SOC were more strongly expressed under the drier climate, where vegetation was sparser and soil erosion involved mineral grain size sorting. Our results demonstrate that SOC pools and their interactions with minerals are dependent on topographic locations, emphasizing the need to include geomorphic data when assessing climatic controls of SOC.
KW - Bioturbation
KW - Climate
KW - Erosion
KW - Microclimate
KW - Mineral associated organic carbon
KW - Soil carbon
KW - Topography
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U2 - 10.1016/j.geoderma.2018.02.021
DO - 10.1016/j.geoderma.2018.02.021
M3 - Article
AN - SCOPUS:85042316915
SN - 0016-7061
VL - 322
SP - 71
EP - 80
JO - Geoderma
JF - Geoderma
ER -