Long-Term Biogeochemical Study Plots (presentation)

LOREFICE, ALAN and Peter M. Groffman

Over the last two years, the Baltimore Ecosystem Study (BES) has established a network of long-term permenant biogeochemical study plots. These plots will provide long-term data on vegetation, soil and hydrologic processes in the key ecosystem types within the urban ecosystem. Plots are currently instrumented with lysimeters (drainage and tension) to sample soil solution chemistry, time domain reflectometry probes to measure soil moisture and trace gas flux chambers to measure the flux of carbon dixoide, nitrous oxide and methane from soil to the atmosphere. Measurements of in situ nitrogen mineralization, nitrification and denitrification are made at approximately monthly intervals. Detailed vegetation characterization (all layers) was done in summer 1998.

The current network of study plots includes eight forest plots, chosen to represent the range of forest conditions in the area, and 2 grass plots. The network is being expanded to include more grass plots, urban yards and wetlands.

Here we present preliminary data on nitrogen cycling from the forest plots. These data show the nature and extent of variability within the most natural ecosystem type in the BES area. They will be very useful for comparison with the more heavily human-dominated ecosystems that we are also studying.