air temperature
; brackish water
; carbon cycle
; carbon dioxide
; eddy covariance
; light use efficiency
; marsh
; net ecosystem exchange
; photosynthesis
; respiration
; tide
; vapor pressure
; water table
; wetland
; California
; United States
; White tip die-back phytoplasma
英文摘要:
We investigated the direct and indirect influence of tides on net ecosystem exchange (NEE) of carbon dioxide (CO2) in a temperate brackish tidal marsh. NEE displayed a tidally driven pattern with obvious characteristics at the multiday scale, with greater net CO2 uptake during spring tides than neap tides. Based on the relative mutual information between NEE and biophysical variables, this was driven by a combination of higher water table depth (WTD), cooler air temperature, and lower vapor pressure deficit (VPD) during spring tides relative to neap tides, as the fortnightly tidal cycle not only influenced water levels but also strongly modulated water and air temperature and VPD. Tides also influenced NEE at shorter timescales, with a reduction in nighttime fluxes during growing season spring tides when the higher of the two semidiurnal tides caused inundation at the site. WTD significantly influenced ecosystem respiration (Reco), with lower Reco during spring tides than neap tides. While WTD did not appear to affect ecosystem photosynthesis (gross ecosystem production, GPP) directly, the impact of tides on temperature and VPD influenced GPP, with higher daily light-use efficiency and photosynthetic activity during spring tides than neap tides when temperature and VPD were lower. The strong direct and indirect influence of tides on NEE across the diel and multiday timescales has important implications for modeling NEE in tidal wetlands and can help inform the timing and frequency of chamber measurements as annual or seasonal net CO2 uptake may be underestimated if measurements are only taken during nonflooded periods. Published 2018. This article is a US Government work and is in the public domain in the United States of America.
National Research Program, U.S. Geological Survey, Menlo Park, CA, United States; Department of Earth System Science, Stanford University, Stanford, CA, United States; California Water Science Center, U.S. Geological Survey, Sacramento, CA, United States; National Ecological Observatory Network, Battelle, Boulder, CO, United States
Recommended Citation:
Knox S.H.,Windham-Myers L.,Anderson F.,et al. Direct and Indirect Effects of Tides on Ecosystem-Scale CO2 Exchange in a Brackish Tidal Marsh in Northern California[J]. Journal of Geophysical Research: Biogeosciences,2018-01-01,123(3)