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Soil Biogeochemical Processes across a Lateral Toposequence in an Old‐Growth Floodplain Forest
Author(s) -
Ricker Matthew C.,
Lockaby B. Graeme
Publication year - 2014
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2014.05.0205
Subject(s) - biogeochemical cycle , floodplain , biogeochemistry , environmental science , hydric soil , mineralization (soil science) , ecosystem , hydrology (agriculture) , soil water , biomass (ecology) , nutrient , watershed , ecology , soil science , geology , biology , geotechnical engineering , machine learning , computer science
Floodplain forests are important landscapes that retain and transform nutrients derived from watershed sources. Although research has been conducted regarding biogeochemical processes in floodplains, few studies have been in old‐growth bottomland forests. Therefore, the goal of this study was to quantify how landscape variability and environmental factors influence floodplain biogeochemistry in old‐growth ecosystems of Congaree National Park (CONG), SC. During a 2‐yr period, we measured biogeochemical indices along an alluvial soil toposequence that included seasonal variation in microbial biomass and net N mineralization. Soil microbial biomass was relatively consistent throughout the study and displayed few relationships to environmental variables. Net N mineralization showed distinct seasonal variations ranging from 37 ± 9 to 412 ± 73 g N ha −1 d −1 during cool winter and warm summer months, respectively. Nitrate‐N was the major product of net N mineralization in all seasons, and only hydric soils in low‐lying topographic positions had appreciable net NH 4 –N production (>15% total N mineralized), which typically occurred after spring flooding. These results suggest that the intrinsic biogeochemical processes within the old‐growth bottomland forests of CONG differ from those of aggrading floodplain forests of the southeastern United States, especially with regard to production of excess NO 3 –N.