ALBERT

Description: [1]  Everglades freshwater marshes were once carbon sinks, but human-driven hydrologic changes have led to uncertainty about the current state of their carbon dynamics. To investigate the effect of hydrology on CO 2 exchange, we used eddy covariance measurements for 2 years (2008–2009) in marl (short-hydroperiod) and peat (long-hydroperiod) wetlands in Everglades National Park. The importance of site, season, and environmental drivers was evaluated using linear and nonlinear modeling, and a novel method was used to test for temporally lagged patterns in the data. Unexpectedly, the long-hydroperiod peat marsh was a small CO 2 source (19.9 g C m −2 from July to December 2008 and 80.0 g C m −2 in 2009), and at no time over the study period was it a strong sink. Contrary to previous research suggesting high productivity rates from a short-hydroperiod marsh, we estimated that the marl site was a small CO 2 sink in 2008 (net ecosystem exchange [NEE] = −78.8 g C m −2 ) and was near neutral for carbon balance in 2009. In addition, both sites had relatively low gross ecosystem exchange (GEE) over the 2 years of this study. The two sites showed similar responses for NEE versus air temperature, ecosystem respiration (R eco ) versus air temperature, and R eco versus water depth, although the magnitude of the responses differed. We saw small lags (30 min in most cases) between carbon fluxes and environmental drivers. This study is foundational for understanding the carbon balance of these ecosystems prior to implementation of the planned Everglades restoration of historical water flow that will likely alter the future trajectory of the carbon dynamics of the Everglades as a whole.

Description: Everglades freshwater marshes were once carbon sinks, but human-driven hydrologic changes have led to uncertainty about the current state of their carbon dynamics. To investigate the effect of hydrology on CO2 exchange, we used eddy covariance measurements for 2 years (2008–2009) in marl (short-hydroperiod) and peat (long-hydroperiod) wetlands in Everglades National Park. The importance of site, season, and environmental drivers was evaluated using linear and nonlinear modeling, and a novel method was used to test for temporally lagged patterns in the data. Unexpectedly, the long-hydroperiod peat marsh was a small CO2 source (19.9 g C m−2 from July to December 2008 and 80.0 g C m−2 in 2009), and at no time over the study period was it a strong sink. Contrary to previous research suggesting high productivity rates from a short-hydroperiod marsh, we estimated that the marl site was a small CO2 sink in 2008 (net ecosystem exchange [NEE] = −78.8 g C m−2) and was near neutral for carbon balance in 2009. In addition, both sites had relatively low gross ecosystem exchange (GEE) over the 2 years of this study. The two sites showed similar responses for NEE versus air temperature, ecosystem respiration (Reco) versus air temperature, and Reco versus water depth, although the magnitude of the responses differed. We saw small lags (30 min in most cases) between carbon fluxes and environmental drivers. This study is foundational for understanding the carbon balance of these ecosystems prior to implementation of the planned Everglades restoration of historical water flow that will likely alter the future trajectory of the carbon dynamics of the Everglades as a whole.

Description: Characteristics, availability, and present uses of computer programs for solid state circuit analysis and design

Description: Basic algorithms for matrix manipulations by computer for network analysis

Description: Approximation technique for flow graph that eliminates nonessential equivalent circuit elements, providing for derivation of most concise model with preassigned accuracy

Description: Critical excitation function used to estimate transient response of thin film devices at time intervals exceeding greatest time constant