While growth history of vegetation within upland systems is well studied, plant phenology within coastal tidal systems is less understood. Landscape-scale, satellite-derived indicators of plant ...greenness may not adequately represent seasonality of vegetation biomass and productivity within tidal wetlands due to limitations of cloud cover, satellite temporal frequency, and attenuation of plant signals by tidal flooding. However, understanding plant phenology is necessary to gain insight into aboveground biomass, photosynthetic activity, and carbon sequestration. In this study, we use a modeling approach to estimate plant greenness throughout a year in tidal wetlands located within the San Francisco Bay Area, USA. We used variables such as EVI history, temperature, and elevation to predict plant greenness on a 14-day timestep. We found this approach accurately estimated plant greenness, with larger error observed within more dynamic restored wetlands, particularly at early post-restoration stages. We also found modeled EVI can be used as an input variable into greenhouse gas models, allowing for an estimate of carbon sequestration and gross primary production. Our strategy can be further developed in future research by assessing restoration and management effects on wetland phenological dynamics and through incorporating the entire Sentinel-2 time series once it becomes available within Google Earth Engine.
Support for coastal wetland restoration projects that consider carbon (C) storage as a climate mitigation benefit is growing as coastal wetlands are sites of substantial C sequestration. However, the ...climate footprint of wetland restoration remains controversial as wetlands can also be large sources of methane (CH4). We quantify the vertical fluxes of C in restored fresh and oligohaline nontidal wetlands with managed hydrology and a tidal euhaline marsh in California's San Francisco Bay‐Delta. We combine the use of eddy covariance atmospheric flux measurements with 210Pb‐derived soil C accumulation rates to quantify the C sequestration efficiency of restored wetlands and their associated climate mitigation service. Nontidal managed wetlands were the most efficient in burying C on‐site, with soil C accumulation rates as high as their net atmospheric C uptake (−280 ± 90 and −350 ± 150 g C m−2 yr−1). In contrast, the restored tidal wetland exhibited lower C burial rates over decadal timescales (70 ± 19 g C m−2 yr−1) that accounted for ∼13%–23% of its annual C uptake, suggesting that the remaining fraction is exported via lateral hydrologic flux. From an ecosystem radiative balance perspective, the restored tidal wetland showed a > 10 times higher CO2‐sequestration to CH4‐emission ratio than the nontidal managed wetlands. Thus overall, tidal wetland restoration resulted in a negative radiative forcing (cooling) through increased soil C accumulation, while nontidal wetland restoration led to an early positive forcing (warming) through increased CH4 emissions potentially lasting between 2.1 ± 2.0 to 8 ± 4 decades.
Plain Language Summary
Coastal wetlands have great potential to remove carbon dioxide from the atmosphere and mitigate climate change. This study aims to understand how effectively restored wetlands bury carbon in soils and sequester it, and the extent to which they produce methane, a potent greenhouse gas. We measured how much carbon dioxide and methane flow into and out of three restored wetlands differing in their restoration design, salinity, and tidal influence. We found that most of the carbon dioxide removed from the atmosphere by nontidal wetlands was stored in their soils, while restored tidal wetland soils stored a smaller fraction (13%–23%) of the removed carbon. Despite the lower carbon sequestration efficiency, the restored tidal wetland was a greater greenhouse gas sink and climate intervention because it emitted very little methane. Methane emissions in nontidal freshwater and brackish marshes fully offset the carbon dioxide removed via carbon burial for roughly the first 2–8 decades, while the tidal wetland contributed to greenhouse gas removal immediately after restoration. The merits of nontidal managed wetland restoration lie in increased soil and C accretion, but it should not be assumed that soil carbon storage results in an immediate climate mitigation benefit.
Key Points
Net atmospheric C uptake and soil C accumulation rates were equivalent measures of C sequestration in nontidal managed wetlands
Managed wetlands showed the largest C accumulation but had lower CO2‐sequestration to CH4‐emission ratios than the restored tidal wetland
Nontidal wetland restoration resulted in an early warming effect, while tidal restoration resulted in immediate climatic cooling
To understand patterns in CO
2
partial pressure (P
CO2
) over time in wetlands’ surface water and porewater, we examined the relationship between P
CO2
and land–atmosphere flux of CO
2
at the ...ecosystem scale at 22 Northern Hemisphere wetland sites synthesized through an open call. Sites spanned 6 major wetland types (tidal, alpine, fen, bog, marsh, and prairie pothole/karst), 7 Köppen climates, and 16 different years. Ecosystem respiration (R
eco
) and gross primary production (GPP), components of vertical CO
2
flux, were compared to P
CO2
, a component of lateral CO
2
flux, to determine if photosynthetic rates and soil respiration consistently influence wetland surface and porewater CO
2
concentrations across wetlands. Similar to drivers of primary productivity at the ecosystem scale, P
CO2
was strongly positively correlated with air temperature (T
air
) at most sites. Monthly average P
CO2
tended to peak towards the middle of the year and was more strongly related to R
eco
than GPP. Our results suggest R
eco
may be related to biologically driven P
CO2
in wetlands, but the relationship is site-specific and could be an artifact of differently timed seasonal cycles or other factors. Higher levels of discharge do not consistently alter the relationship between R
eco
and temperature normalized P
CO2
. This work synthesizes relevant data and identifies key knowledge gaps in drivers of wetland respiration.
Tidal wetlands play an important role in global carbon cycling by storing carbon in sediment at millennial time scales, transporting dissolved carbon into coastal waters, and contributing ...significantly to global CH4 budgets. However, these ecosystems' greenhouse gas monitoring and predictions are challenging due to spatial heterogeneity and tidal flooding. We utilized eddy covariance and chamber measurements to quantify fluxes of CO2 and CH4 at a restored tidal saltmarsh across spatial and temporal scales. Eddy covariance data revealed that the site was a strong net sink for CO2 (−387 g C‐CO2 m−2 yr−1, SD = 46) and a small net source of CH4 (0.7 g C‐CH4 m−2 yr−1, SD = 0.4). After partitioning net ecosystem exchange of CO2 into gross primary production and ecosystem respiration, we found that high net uptake of CO2 was due to low respiration emissions rather than high photosynthetic rates. We also found that respiration rates varied between land covers with increased respiration in mudflats compared to vegetated areas. Daytime soil chamber measurements revealed that the greatest CO2 emission was from higher elevation mudflat soils (0.5 μmol m−2s−1, SE = 1.3) and CH4 emission was greatest from lower elevation Spartina foliosa soils (1.6 nmol m−2s−1, SD = 8.2). Overall, these results highlight the importance of the relationships between wetland plant community and elevation, and inundation for CO2 and CH4 fluxes. Future research should include the use of high‐resolution imagery, automated chambers, and a focus on quantifying carbon exported in tidal waters.
Plain Language Summary
At the ecosystem level, a restored tidal salt marsh in the South San Francisco Bay California took in more carbon dioxide (CO2) from the atmosphere through photosynthetic activity than it emitted through respiration, and it emitted very small amounts of methane (CH4). This site appears to be a stronger sink for CO2 compared to other tidal marsh sites due to the very low rate of CO2 being lost through respiration to the atmosphere, rather than strong photosynthetic rates. We also found that ecosystem level CO2 emissions and the responses to temperature and light varied based on land cover type. By measuring soil surface emissions from each of the main land cover types of pickleweed, cordgrass, and mudflats we found that on average soils with lower elevation where cordgrass grows were stronger sources of CH4 while mudflat soils with greater elevation were stronger sources of CO2.
Key Points
Soil chamber measurements were able to detect significant differences in CO2 and CH4 fluxes between land cover types
Vegetation and microtopography are drivers of the spatially heterogeneous CO2 and CH4 emissions within the wetland
At the ecosystem level, high net uptake of CO2 was the result of low respiration emissions, suggesting lateral transport of dissolved CO2
Abstract
Tidal wetlands play an important role in global carbon cycling by storing carbon in sediment at millennial time scales, transporting dissolved carbon into coastal waters, and contributing ...significantly to global CH
4
budgets. However, these ecosystems' greenhouse gas monitoring and predictions are challenging due to spatial heterogeneity and tidal flooding. We utilized eddy covariance and chamber measurements to quantify fluxes of CO
2
and CH
4
at a restored tidal saltmarsh across spatial and temporal scales. Eddy covariance data revealed that the site was a strong net sink for CO
2
(−387 g C‐CO
2
m
−2
yr
−1
, SD = 46) and a small net source of CH
4
(0.7 g C‐CH
4
m
−2
yr
−1
, SD = 0.4). After partitioning net ecosystem exchange of CO
2
into gross primary production and ecosystem respiration, we found that high net uptake of CO
2
was due to low respiration emissions rather than high photosynthetic rates. We also found that respiration rates varied between land covers with increased respiration in mudflats compared to vegetated areas. Daytime soil chamber measurements revealed that the greatest CO
2
emission was from higher elevation mudflat soils (0.5 μmol m
−2
s
−1
, SE = 1.3) and CH
4
emission was greatest from lower elevation
Spartina foliosa
soils (1.6 nmol m
−2
s
−1
, SD = 8.2). Overall, these results highlight the importance of the relationships between wetland plant community and elevation, and inundation for CO
2
and CH
4
fluxes. Future research should include the use of high‐resolution imagery, automated chambers, and a focus on quantifying carbon exported in tidal waters.
Plain Language Summary
At the ecosystem level, a restored tidal salt marsh in the South San Francisco Bay California took in more carbon dioxide (CO
2
) from the atmosphere through photosynthetic activity than it emitted through respiration, and it emitted very small amounts of methane (CH
4
). This site appears to be a stronger sink for CO
2
compared to other tidal marsh sites due to the very low rate of CO
2
being lost through respiration to the atmosphere, rather than strong photosynthetic rates. We also found that ecosystem level CO
2
emissions and the responses to temperature and light varied based on land cover type. By measuring soil surface emissions from each of the main land cover types of pickleweed, cordgrass, and mudflats we found that on average soils with lower elevation where cordgrass grows were stronger sources of CH
4
while mudflat soils with greater elevation were stronger sources of CO
2
.
Key Points
Soil chamber measurements were able to detect significant differences in CO
2
and CH
4
fluxes between land cover types
Vegetation and microtopography are drivers of the spatially heterogeneous CO
2
and CH
4
emissions within the wetland
At the ecosystem level, high net uptake of CO
2
was the result of low respiration emissions, suggesting lateral transport of dissolved CO
2
Avian influenza virus (AIV) infections occur naturally in wild bird populations and can cross the wildlife-domestic animal interface, often with devastating impacts on commercial poultry. Migratory ...waterfowl and shorebirds are natural AIV reservoirs and can carry the virus along migratory pathways, often without exhibiting clinical signs. However, these species rarely inhabit poultry farms, so transmission into domestic birds likely occurs through other means. In many cases, human activities are thought to spread the virus into domestic populations. Consequently, biosecurity measures have been implemented to limit human-facilitated outbreaks. The 2015 avian influenza outbreak in the United States, which occurred among poultry operations with strict biosecurity controls, suggests that alternative routes of virus infiltration may exist, including bridge hosts: wild animals that transfer virus from areas of high waterfowl and shorebird densities.
Here, we examined small, wild birds (songbirds, woodpeckers, etc.) and mammals in Iowa, one of the regions hit hardest by the 2015 avian influenza epizootic, to determine whether these animals carry AIV. To assess whether influenza A virus was present in other species in Iowa during our sampling period, we also present results from surveillance of waterfowl by the Iowa Department of Natural Resources and Unites Stated Department of Agriculture.
Capturing animals at wetlands and near poultry facilities, we swabbed 449 individuals, internally and externally, for the presence of influenza A virus and no samples tested positive by qPCR. Similarly, serology from 402 animals showed no antibodies against influenza A. Although several species were captured at both wetland and poultry sites, the overall community structure of wild species differed significantly between these types of sites. In contrast, 83 out of 527 sampled waterfowl tested positive for influenza A via qPCR.
These results suggest that even though influenza A viruses were present on the Iowa landscape at the time of our sampling, small, wild birds and rodents were unlikely to be frequent bridge hosts.
In this innovative guidebook Julie Baretz takes readers to twenty-one off-the-beaten-path locations in Israel where Bible stories are said to have happened. At each site she sets the scene by ...relating the historical context of the event, then follows with the biblical text itself and her own lively commentary. Captivating and complex Bible characters bring the locations to life as they face social, ethical, and spiritual dilemmas not unlike our own today. Baretz's narratives draw on history, archaeology, academic scholarship, and rabbinic literature for interpretations that enhance the meaning of the biblical events. Each story is told in the voice of Baretz as the tour guide-knowledgeable yet informal and friendly.
The Bible on Locationtraces the chronology and narrative arc of the historical books of Joshua, Judges, Ruth, 1 and 2 Samuel, 1 and 2 Kings, Ezra, and Nehemiah. The book begins with the Israelites' arrival in the land of Israel (following the exodus from Egypt and the forty years of wandering) and continues over more than six hundred years, until the return of the Jewish exiles from Babylon to their homeland.
Baretz's descriptions are accompanied by colorful maps and photographs that put actual and armchair visitors in the middle of the action. Each location reveals a new episode in the biblical narrative and provides inspiration and commentary that will enhance visits to the various sites.
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