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URBANIZATION AND NUTRIENT RETENTION IN FRESHWATER RIPARIAN WETLANDS
Author(s) -
Hogan Dianna M.,
Walbridge Mark R.
Publication year - 2007
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/06-0185
Subject(s) - riparian zone , impervious surface , wetland , environmental science , nutrient , hydrology (agriculture) , watershed , soil water , ecosystem , environmental chemistry , ecology , soil science , chemistry , geology , biology , geotechnical engineering , machine learning , habitat , computer science
Urbanization can degrade water quality and alter watershed hydrology, with profound effects on the structure and function of both riparian wetlands (RWs) and aquatic ecosystems downstream. We used freshwater RWs in Fairfax County, Virginia, USA, as a model system to examine: (1) the effects of increasing urbanization (indexed by the percentage of impervious surface cover [%ISC] in the surrounding watershed) on nitrogen (N) and phosphorus (P) concentrations in surface soils and plant tissues, soil P saturation, and soil iron (Fe) chemistry; and (2) relationships between RW soil and plant nutrient chemistries vs. the physical and biotic integrity of adjacent streams. Soil total P and NaOH‐extractable P (representing P bound to aluminum [Al] and Fe hydrous oxides) varied significantly but nonlinearly with %ISC ( r 2 = 0.69 and 0.57, respectively); a similar pattern was found for soil P saturation but not for soil total N. Relationships were best described by second‐order polynomial equations. Riparian wetlands appear to receive greater P loads in moderately (8.6–13.3% ISC) than in highly (25.1–29.1% ISC) urbanized watersheds. These observations are consistent with alterations in watershed hydrology that occur with increasing urbanization, directing water and nutrient flows away from natural RWs. Significant increases in total and crystalline soil Fe ( r 2 = 0.57 and 0.53, respectively) and decreases in relative soil Fe crystallinity with increasing %ISC suggest the mobilization and deposition of terrestrial sediments in RWs, likely due to construction activities in the surrounding watershed. Increases in RW plant tissue nutrient concentrations and %ISC in the surrounding watershed were negatively correlated with standard indices of the physical and biotic integrity of adjacent streams. In combination, these data suggest that nutrient and sediment inputs associated with urbanization and storm‐water management are important variables that affect wetland ecosystem services, such as water quality improvement, in urbanizing landscapes.