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Effects of Riparian Buffer Vegetation and Width: A 12‐Year Longitudinal Study
Author(s) -
King S. E.,
Osmond D. L.,
Smith J.,
Burchell M. R.,
Dukes M.,
Evans R. O.,
Knies S.,
Kunickis S.
Publication year - 2016
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2015.06.0321
Subject(s) - riparian buffer , riparian zone , groundwater , buffer strip , environmental science , hydrology (agriculture) , nitrate , dissolved organic carbon , buffer zone , soil science , chemistry , water quality , environmental chemistry , ecology , geology , geotechnical engineering , organic chemistry , habitat , biology
Agricultural contributions of nitrogen are a serious concern for many water resources and have spurred the implementation of riparian buffer zones to reduce groundwater nitrate (NO 3 ). The optimum design for buffers is subject to debate, and there are few long‐term studies. The objective of this project was to determine the effectiveness over time (12 yr) of buffer types (trees, switchgrass, fescue, native, and a control) and buffer widths (8 and 15 m) by measuring groundwater NO 3 –N and dissolved organic carbon (DOC) trends. At the intermediate groundwater depth (1.5–2.1 m), NO 3 –N reduction effectiveness was 2.5 times greater (46 vs. 16%) for the wider buffer, and, regardless of width, buffer effectiveness increased 0.62% yr −1 . Buffer vegetative type was never statistically significant. In the deep‐groundwater depth (2.1–3.5 m), there was no change in NO 3 –N removal over time, although the statistical interaction of width and vegetative type indicated a wide range of removal rates (19–82%). The DOC concentrations were analyzed at the field/buffer and buffer/stream sampling locations. Depending on location position and groundwater sampling depth, DOC concentrations ranged from 1.6 to 2.8 mg L −1 at Year 0 and increased at a rate of 0.13 to 0.18 mg L −1 yr −1 but always remained low (≤5.0 mg L −1 ). Greater DOC concentrations in the intermediate‐depth groundwater did not increase NO 3 –N removal; redox measurements indicated intermittent reduced soil conditions may have been limiting. This study suggests that riparian buffer width, not vegetation, is more important for NO 3 –N removal in the middle coastal plain of North Carolina for a newly established buffer. Core Ideas Unique, long‐term replicated riparian buffer study in the southeastern United States. Long‐term riparian buffer study from establishment through Year 12. Effects of five different riparian‐buffer vegetation types of nitrate reduction.