| Urban remnant forests are receiving high levels of nitrogen (N) deposition, especially in the form of nitrate. Environmental interactions at the forest edge may affect N dynamics and plant nutrient use differently than in the forest center. We selected four forest patches on the State University of New York- Binghamton campus. Two are relatively large (CW and NW) and two small (WG and FA). In addition we sampled the Nature Preserve (NP), composed of center only, and SW, edge only. Soil cores were taken underneath the focal tree, Quercus rubra, on four sampling dates in 2004.; Percentage soil organic matter (SOM) at the edge location was significantly lower than the center in the surface soil (0-5 cm). FA and WG had significantly lower SOM than NP, while CW and NW are not significantly different from NP. Soil moisture followed a similar pattern to SOM with the two highly correlated (r2=0.604). Both N mineralization and nitrification were higher in the center than in the edge (P<0.001). WG and FA had significantly higher nitrification than the other sites, at which it was almost negligible (P<0.001). Only WG and FA had significant NO3-N levels (P<0.001). Compared to the center the edge areas had higher root biomass (P<0.001) but lower tissue N and P concentrations (P=0.002, P<0.001). Root biomass was lowest in WG, a site with highest N mineralization and nitrification rates, but tissue N and P concentrations were highest in WG (P<0.001). These findings suggest that the smaller patches are more affected by urban conditions than larger ones and display more of the symptoms related to N saturation. Furthermore, the forest edge responded differently to the urban environment compared to the center of the remnant forests. |
