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Methane dynamics within salt marshes are complex because vegetation types, temperature, oscillating water levels, and changes in salinity and redox conditions influence CH4 production, consumption, oxidation, and emissions. These non‐linear and complex interactions among variables affect the traditionally expected functional relationships and present challenges for interpreting and developing process‐based models. We employed empirical dynamic modeling (EDM) and convergent cross mapping (CCM) as a novel approach for characterizing seasonal/multiday and diurnal CH4 dynamics by inferring causal variables, lags, and interconnections among multiple biophysical variables within a temperate salt marsh using 5 years of eddy covariance data. EDM/CCM is a nonparametric approach capable of quantifying the coupling between variables while determining time scales where variable interactions are the most relevant. We found that gross primary productivity, tidal creek dissolved oxygen, and temperature were important for seasonal/multiday dynamics (rho = 0.73–0.80), while water level was most important for diurnal dynamics during both the growing and dormancy phenoperiods (rho = 0.72 and 0.56, respectively). Lags for the top‐ranked variables (i.e., gross primary productivity, dissolved oxygen, temperature, water level) occurred between 1 and 5 weeks at the seasonal scale and 1–24 hr at the diurnal scale. The EDM had high prediction capabilities for intra‐/inter‐seasonal patterns and annual CH4 sums but had limitations in representing large, infrequent fluxes. Results highlight the importance of non‐linearity, drivers, lag times, and interconnections among multiple biophysical variables that regulate CH4 fluxes in tidal wetlands. This research introduces a novel approach to examining CH4 fluxes, which will aid in evaluating current paradigms in wetlands and other ecosystems. Plain Language Summary: The movement of methane gas in salt marshes is complex and influenced by various factors such as plant types, temperature, water level, and changes in water salinity and oxygen levels. These factors interact in complex ways, making predicting the outcome of methane production and movement difficult. We applied a new method of studying methane dynamics using Empirical Dynamic Modeling and Convergent Cross Mapping. After analyzing 5 years of ecosystem‐scale measurements of methane fluxes, we show that the amount of oxygen in the water, the temperature, and the amount of light received by plants are crucial for understanding regulating methane fluxes within days and across seasons. The interconnections among these variables are complex, and methane fluxes may have delayed responses (i.e., lag times), highlighting the importance of these interactions. This research improves our comprehension of how environmental factors interact to affect methane fluxes in wetlands. Key Points: Methane dynamics in salt marshes are complex and influenced by multiple variablesEmpirical dynamic modeling and convergent cross mapping are novel approaches to characterizing CH4 dynamicsResults highlight drivers, non‐linearities, lag times, and interconnections among multiple biophysical variables for CH4 dynamics [ABSTRACT FROM AUTHOR]

Soil respiration (Rs), the soil‐to‐atmosphere flux of CO2, is a dominant but uncertain part of the carbon cycle, even after decades of study. This review focuses on progress in understanding Rs from laboratory incubations to global estimates. We survey key developments of in situ ecosystem‐scale Rs observations and manipulations, synthesize Rs meta‐analyses and global flux estimates, and discuss the most compelling challenges and opportunities for the future. Increasingly sophisticated lab experiments have yielded insights into the interaction among heterotrophic respiration, substrate supply, and enzymatic kinetics, and extended incubation‐based analyses across space and time. Observational and manipulative field‐based experiments have used improved measurement approaches to deepen our understanding of the integrated effects of environmental change and disturbance on Rs. Freely‐available observational databases have enabled meta‐analyses and studies probing the magnitude of, and constraints on, the global Rs flux. Key challenges for the field include expanding Rs measurements, experiments, and opportunities to under‐represented communities and ecosystems; reconciling independent estimates of global respiration fluxes and trends; testing and leveraging the power of machine learning and process‐based models, both independently and in conjunction with each other; and continuing the field's tradition of using novel experiments to explore diverse mechanisms and ecosystems. Plain Language Summary: "Soil respiration" refers to the flow of carbon dioxide, mostly generated by plant roots and microbes, from the soil to the atmosphere. This flux is large and highly uncertain, and understanding it has significant implications for our ability to predict the effects of land use and climate change. This review summarizes advances, insights, and challenges in soil respiration science. It examines laboratory approaches and findings; documents changes in how researchers measure and understand soil respiration in the natural world; and describes efforts to estimate the global dynamics of soil respiration from openly‐available databases of observations. We conclude by discussing the most compelling challenges and opportunities for the future. Key Points: Recent decades have seen large advances in measurement methods, experimental approaches, and data availability in soil respiration scienceLab and field‐based experiments have improved our understanding of the integrated effect of environmental change on soil respirationKey challenges include broadening access and continuing to explore diverse mechanisms and ecosystems using novel model‐experiment approaches [ABSTRACT FROM AUTHOR]

Application of the best available science to improve quantification of greenhouse gas (GHG) emissions at regional and national scales is key to climate action. Here, we present a two‐decade (2000–2019) GHG (CO2, CH4, and N2O) budget for Mexico derived from multiple products. Data from the National GHG Inventory, global observations, and the scientific literature were compared to identify knowledge gaps on GHG flux dynamics and discrepancies among estimates. Total mean annual GHG emissions were estimated at 695–910 TgCO2‐eq year−1 over these two decades, with 70% of the emissions attributable to CO2, 23% to CH4, and 5% to N2O (2% to other gases). When divided by sectors, we found agreement across emission estimates from various sources for fossil fuels, cattle, agriculture, and waste for all GHGs. However, considerable discrepancies were identified in the fluxes from terrestrial ecosystems. The disagreement was particularly large for the land CO2 sink, where net biome production estimations from the national inventory were double those from any other observational product. Extensive knowledge gaps exist, mainly related to aquatic systems (e.g., outgassing in rivers) and the lateral fluxes (e.g., wood trade). In addition, limited information is available on CH4 emissions from wetlands and soil CH4 consumption. We expect these results to guide future research to reduce estimation uncertainties and fill the information gaps across Mexico. Plain Language Summary: Mexico represents the 13th global emitter of greenhouse gases (GHGs) and the second among Latin American countries, releasing roughly 485 million tons of CO2, six million tons of CH4 (equivalent to 160 million tons of CO2), and 0.1 million tons of N2O (equivalent to 35 million tons of CO2). However, large uncertainties prevail in the estimation of several components of each flux; thus, the application of the best available science to account for and improve these estimations is essential for sound mitigation policies. Here, we used multiple available products (national inventories, satellites, flux towers, dynamic global vegetation models, inversion models, and other data sources) to advance our understanding of the GHG budget of Mexico over the last 20 years. We found that fluxes from fossil fuel combustion (including energy production, transportation, industry, etc.), agriculture, livestock, and waste management agree remarkably well across products. In contrast, we documented large differences among products for land‐based fluxes (e.g., CO2 capture) and scant available information on aquatic ecosystems (e.g., CH4 emission from wetlands) and on lateral fluxes (e.g., emissions from trade). We expect these results to help in guiding future measuring efforts and policies to mitigate GHG emissions from Mexico. Key Points: A greenhouse gas (GHG) budget for Mexico was calculated based on multiple products. We estimated fluxes for CO2, CH4, and N2O over the 2000–2019 periodTotal GHG emissions were 695 TgCO2‐eq year−1 in the national inventory and as much as a mean 910 TgCO2‐eq year−1 across productsGHG fluxes agreed well across products for emissions, but large discrepancies exist for the land CO2 and CH4 sinks [ABSTRACT FROM AUTHOR]

We made a commitment to better include underrepresented members of our community in the publication pipeline of JGR: Biogeosciences. This commitment consists of regular updates on our policies and practices, and concrete actions we intend to implement over the next year. So far, our progress to tackle biases and ensure equitable research in the biogeosciences has focused on improving diversity of our associate editor and reviewer pools, increasing awareness of unconscious bias in peer‐review, and promoting inclusion in global collaborations. In this update, we explore manuscript submissions and manuscript decisions by gender, and we present a pilot that aims to promote ethical and equitable global collaborations in resource‐poor settings. We end our editorial by presenting our next set of actions that we plan on completing over the next year, which include a more thorough analysis of reviewer demographics. Key Points: Here we report on our progress for equitable and inclusive peer‐review and publishing for JGR: BiogeosciencesIn the past year we prioritized a pilot program to ensure equitable global collaborationsOur next set of key priorities to expand and diversify our reviewer pool and publishing community are highlighted [ABSTRACT FROM AUTHOR]

Tidal channels are biogeochemical hotspots that horizontally exchange carbon (C) with marsh platforms, but the physiochemical drivers controlling these dynamics are poorly understood. We hypothesized that C‐bearing iron (Fe) oxides precipitate and immobilize dissolved organic carbon (DOC) during ebb tide as the soils oxygenate, and dissolve into the porewater during flood tide, promoting transport to the channel. The hydraulic gradient physically controls how these solutes are horizontally exchanged across the marsh platform‐tidal channel interface; we hypothesized that this gradient alters the concentration and source of C being exchanged. We further hypothesized that trace soil gases (i.e., CO2, CH4, dimethyl sulfide) are pushed out of the channel bank as the groundwater rises. To test these hypotheses, we measured porewater, surface water, and soil trace gases over two 24‐hr monitoring campaigns (i.e., summer and spring) in a mesohaline tidal marsh. We found that Fe2+ and DOC were positively related during flood tide but not during ebb tide in spring when soils were more oxidized. This finding shows evidence for the formation and dissolution of C‐bearing Fe oxides across a tidal cycle. In addition, the tidal channel contained significantly (p < 0.05) more terrestrial‐like DOC when the hydraulic gradient was driving flow toward the channel. In comparison, the channel water was saltier and contained significantly (p < 0.05) more marine‐like DOC when the hydraulic gradient reversed direction. Trace gas fluxes increased with rising groundwater levels, particularly dimethyl sulfide. These findings suggest multiple physiochemical mechanisms controlling the horizontal exchange of C at the marsh platform‐tidal channel interface. Plain Language Summary: Tidal salt marshes store large amounts of carbon belowground in soils, but there is also a significant amount of carbon flowing into and out of these ecosystems via tidal channels. We investigated the carbon flowing between the channel bank and surface water in a salt marsh in Delaware. We found that soil minerals (i.e., iron oxides) control the mobility of carbon as iron oxides retain carbon during ebb tides and release carbon during flood tides as the minerals dissolve. The gradient between the groundwater and surface water elevation (i.e., hydraulic gradient) controls the flow direction for dissolved carbon, altering the concentration and source of carbon found in the tidal channel across tidal cycles. In addition, gases trapped in channel banks are pushed out of the soils as the tide rises. These findings will improve our understanding of carbon cycles in these critical carbon sinks. Key Points: Physiochemical mechanisms control horizontal exchange of carbon across marsh‐tidal channel interfaces, affecting lateral carbon fluxDissolution and reprecipitation of carbon‐bearing Fe oxides during flood and ebb tides control the horizontal mobility of carbonHydraulic gradients control the carbon character in the tidal channel, and rising tides push greenhouse gases out of the channel bank [ABSTRACT FROM AUTHOR]

Salt marsh ecosystems are underrepresented in process‐based models due to their unique location across the terrestrial–aquatic interface. Particularly, the role of leaf nutrients on canopy photosynthesis (FA) remains unclear, despite their relevance for regulating vegetation growth. We combined multiyear information of canopy‐level nutrients and eddy covariance measurements with canopy surface hyperspectral remote sensing (CSHRS) to quantify the spatial and temporal variability of FA in a temperate salt marsh. We found that FA showed a positive relationship with canopy‐level N at the ecosystem scale and for areas dominated by Spartina cynosuroides, but not for areas dominated by short S. alterniflora. FA showed a positive relationship with canopy‐level P, K, and Na, but a negative relationship with Fe, for areas associated with S. cynosuroides, S. alterniflora, and at the ecosystem scale. We used partial least squares regression (PLSR) with CSHRS and found statistically significant data–model agreements to predict canopy‐level nutrients and FA. The red‐edge electromagnetic region and ∼770 nm showed the highest contribution of variance in PLSR models for canopy‐level nutrients and FA, but we propose that underlying sediment biogeochemistry can complicate interpretation of reflectance measurements. Our findings highlight the relevance of spatial variability in salt marshes vegetation and the promising application of CSHRS for linking information of canopy‐level nutrients with FA. We call for further development of canopy surface hyperspectral methods and analyses across salt marshes to improve our understanding of how these ecosystems will respond to global environmental change. Plain Language Summary: Canopy photosynthesis in salt marshes contributes to the carbon stored in these ecosystems; however, its relationship with canopy‐level nutrients has been underrepresented in models. Reflectance from near surface remote sensing could be a cost‐effective nondestructive tool to monitor canopy photosynthesis and associated nutrients in salt marshes. We combined canopy‐level nutrient information with hyperspectral canopy reflectance to represent the spatial and temporal variability of canopy photosynthesis in a salt marsh in the Mid‐Atlantic cost of the U.S. We found that local variability such as different salt marsh species have an influence on the relationship between canopy photosynthesis and associated nutrients, in consequence the most limiting nutrients for photosynthesis were phosphorus, potassium, and sodium. We propose that underlying sediment biogeochemistry can potentially obscure the expected relationships between plant nutrients and photosynthesis in remote sensing of coastal wetlands. These results open the possibility to use similar reflectance information from airborne or spaceborne platforms to explore these relationships at broader scales. Key Points: Local environmental variability influences the relationship of canopy nutrients with canopy photosynthesis in a salt marsh ecosystemSediment biogeochemistry can obscure expected relationships between plant nutrients and photosynthesis in remote sensing of coastal wetlandsCanopy surface hyperspectral remote sensing is a promising technique for studying vegetation dynamics of salt marshes [ABSTRACT FROM AUTHOR]

Continental North America has been found to be a carbon (C) sink over recent decades by multiple studies employing a variety of estimation approaches. However, several key questions and uncertainties remain with these assessments. Here we used results from an ensemble of 19 state‐of‐the‐art dynamic global vegetation models from the TRENDYv9 project to improve these estimates and study the drivers of its interannual variability. Our results show that North America has been a C sink with a magnitude of 0.37 ± 0.38 (mean and one standard deviation) PgC year−1 for the period 2000–2019 (0.31 and 0.44 PgC year−1 in each decade); split into 0.18 ± 0.12 PgC year−1 in Canada (0.15 and 0.20), 0.16 ± 0.17 in the United States (0.14 and 0.17), 0.02 ± 0.05 PgC year−1 in Mexico (0.02 and 0.02) and 0.01 ± 0.02 in Central America and the Caribbean (0.01 and 0.01). About 57% of the new C assimilated by terrestrial ecosystems is allocated into vegetation, 30% into soils, and 13% into litter. Losses of C due to fire account for 41% of the interannual variability of the mean net biome productivity for all North America in the model ensemble. Finally, we show that drought years (e.g., 2002) have the potential to shift the region to a small net C source in the simulations (−0.02 ± 0.46 PgC year−1). Our results highlight the importance of identifying the major drivers of the interannual variability of the continental‐scale land C cycle along with the spatial distribution of local sink‐source dynamics. Plain Language Summary: In recent decades terrestrial ecosystems in North America have absorbed more carbon (C) from the atmosphere than they have released, thus acting as a net land C sink. Nonetheless, several gaps remain in our understanding of how the newly assimilated C is partitioned among the various components of the land ecosystem, and about the impact of recent fires and extreme climatic events on the C stored in vegetation and the soil. In this study, we employed 19 state‐of‐the‐art global dynamic vegetation models to advance our understanding of the land C dynamics over North America over the period 2000–2019. Our results suggest that 57% of the newly assimilated C over this period went into the vegetation, 30% to the soils, and the rest as litter. These new land C gains were found mostly over the temperate and boreal forest regions, which together accounted for 81% of the entire North American sink. Finally, we show that fire and drought are closely related to the year‐to‐year variability of the sink magnitude, and during extreme conditions (e.g., during 2002) they have the potential to reverse the land into a C source to the atmosphere. Key Points: Land C sink dynamics for North America were evaluated using 19 state‐of‐the‐art Dynamic Global Vegetation Models during 2000–2019North America has been a net C sink with a magnitude of 0.37 ± 0.38 PgC year−1 and an increasing trend over timeWe identify different spatial and temporal drivers of the variability in land C fluxes across the region, including fire and drought [ABSTRACT FROM AUTHOR]

Tidal wetlands are comprised of complex interdependent pathways where measurements of carbon exchange are often scale dependent. Common data collection methods (i.e., chambers and eddy covariance) are inherently constrained to different spatial and temporal scales which could generate biased information for applications of carbon accounting, identifying functional relationships and predicting future responses to climate change. Consequently, it is needed to systematically evaluate measurements derived from multiple approaches to identify differences and how techniques complement each other to reconcile interpretations. To accomplish this, we tested ecosystem‐scale eddy covariance with plot‐scale chamber measurements within a temperate salt marsh. We found good agreement (R2 = 0.71–0.95) when comparing measurements of CH4 emissions and CO2 exchange but this agreement was dependent upon canopy phenology with discrepancies mainly arising during senescence and dormancy phenophases. The environmental drivers for CH4 and CO2 fluxes were mostly preserved across different measurement techniques, but the number of drivers increases while their individual strength decreases at the ecosystem scale. Empirical upscaling models parameterized with chamber measurements overestimated annual net ecosystem exchange (NEE; 108%) and gross primary production (GPP; 12%) while underestimating ecosystem respiration (Reco; 14%) and CH4 emissions (69%) compared to eddy covariance measurements. Our results suggest that the environmental complexity of CH4 and CO2 fluxes in salt marshes may be underestimated by chamber‐based measurements, and highlights how different techniques are complementary while considering limitations at each level of measurement. Plain Language Summary: Tidal wetlands are important landscape features which play a significant role in regional carbon cycling between land, ocean and the atmosphere. These ecosystems are very productive, with high rates of photosynthesis during the growing season, but they also emit methane and carbon dioxide which can offset carbon gains. Therefore, it is important to accurately measure and understand what factors regulate carbon cycling processes to better characterize how these systems function, calculate carbon budgets and help predict possible reposes to climate change. We compare several common measurement techniques including chamber and eddy covariance which incorporate information across different scales to evaluate the level of agreement and how these techniques can be combined to increase our understanding of ecosystem functionality. We found that techniques agree well when comparing time‐matched measurement windows but different plant development stages across the ecosystem likely impacted agreement during autumn and early winter. We found that primary factors regulating fluxes were similar across techniques but when considering data collected over more hours of the day with eddy covariance, additional factors were identified indicating measurements from chambers which are limited in both coverage across space and time may present an oversimplified view within tidal wetlands. Key Points: Plot‐level and eddy covariance measurements had good overall agreement, but the strength of agreement was dependent upon plant phenologyThe relevance and influence of environmental drivers varied for all fluxes across different techniquesModels parameterized with plot‐level data overestimated ecosystem‐scale net ecosystem exchange but underestimated CO2 and CH4 emissions [ABSTRACT FROM AUTHOR]

Measurements of atmospheric ammonia (NH3) concentrations and fluxes are limited in coastal regions in the eastern U.S. In this study, continuous and high temporal resolution measurements (5s) of atmospheric NH3 concentrations were recorded using a cavity ring‐down spectrometer in a temperate tidal salt marsh at the St Jones Reserve (Dover, DE). Micrometeorological variables were measured using an eddy covariance system which is part of the AmeriFlux network (US‐StJ). Soil, plant, and water chemistry were also analyzed to characterize the sources and sinks of atmospheric NH3. A new analytical methodology was used to estimate the average ecosystem‐scale diurnal cycle of NH3 fluxes by replicating the characteristics of a chamber experiment. This virtual chamber approach estimates positive surface fluxes in continuing strongly stable conditions when mixing with the air above is minimal. Our findings show that tidal water level may have a significant impact on NH3 emissions from the marsh. The largest fluxes were observed at low tide when more soil was exposed. While it is expected that NH3 fluxes will peak when the air temperature maximizes, high tide occurred concurrently with midday peaks in solar irradiance led to a decrease in NH3 fluxes. Furthermore, soil, plant, and water chemistry measurements underpinning the NH3 concentrations and fluxes lead us to conclude that this coastal wetland ecosystem can act as either a sink or a source of NH3. Such measurements provide novel data on which we can base reliable parameterizations to simulate NH3 emissions from coastal salt marsh ecosystems using surface‐atmosphere transfer models. Plain Language Summary: Coastal wetlands such as salt marshes, mangroves, and seagrasses provide a natural environment for the sequestration and long‐term storage of carbon dioxide (CO2) from the atmosphere. As a fertilizer, nitrogen (N) increases the vegetative growth and thus more CO2 may be fixed in plants as biomass representing the short‐term storage pool of carbon, therefore reducing its atmospheric level. Salt marshes, in particular, have been identified as being highly effective at carbon sequestration as well as adsorbing and transforming N. However, there are limited atmospheric measurements of ammonia (NH3) concentrations and exchanges in coastal areas of the Eastern and Mid‐Atlantic U.S. This pilot study represents one of the few atmospheric measurements of NH3 over temperate tidal salt marshes in the Mid‐Atlantic U.S. The high temporal resolution measurements of NH3 concentrations indicated that local sources, such as agriculture and industry, may have a considerable impact on the local atmospheric NH3 concentrations. The results also show that tidal water levels in salt marshes may have a significant effect on NH3 emissions. Key Points: Continuous and high temporal resolution of ammonia (NH3) concentrations were measured using cavity ring‐down spectroscopy over a salt marshAverage diurnal cycles of NH3 fluxes were estimated in a coastal ecosystem using a new analytical methodologyTidal water level was identified as a key parameter influencing NH3 emissions in wetlands [ABSTRACT FROM AUTHOR]

Environmental observatory networks (EONs) provide information to understand and forecast the spatial and temporal dynamics of Earth's biophysical processes. Consequently, representativeness analyses are important to provide insights for improving EONs' management, design, and interpretation of their value‐added products. We assessed the representativeness of registered FLUXNET sites (n = 41, revised on September 2018) across Latin America (LA), a region of great importance for the global carbon and water cycles, which represents 13% of the world's land surface. Nearly 46% of registered FLUXNET sites are located in evergreen broad‐leaf forests followed by sites in woody savannas (∼20%). Representativeness analyses were performed using a 0.05° spatial grid for multiple environmental variables, gross primary productivity (GPP), and evapotranspiration (ET). Our results showed a potential representativeness of 34% of the surface area for climate properties, 36% for terrain parameters, 34% for soil resources, and 45% when all aforementioned environmental variables were summarized into a principal component analysis. Furthermore, there was a 48% potential representativeness for GPP and 34% for ET. Unfortunately, data from these 41 sites are not all readily available for the scientific community, limiting synthesis studies and model benchmarking/parametrization. The implication is that global/regional data‐driven products are forced to use information from FLUXNET sites outside LA to predict patterns in LA. Representativeness could increase to 86% (for GPP) and 80% (for ET) if 200 sites are optimally distributed. We discussed ongoing challenges, the need to enhance interoperability and data sharing, and promote monitoring efforts across LA to increase the accuracy of regional‐to‐global data‐driven products. Plain Language Summary: Environmental observatory networks (EONs) provide information to better understand, model, and forecast the spatial and temporal dynamics of Earth's biophysical processes. Consequently, representativeness analyses of EON's are important to provide insights for improving EONs' management, design, and interpretation of their value‐added products (e.g., datasets, model predictions). We assessed the representativeness of registered FLUXNET sites (n = 41, revised on September 2018) across Latin America (LA), a region of great importance for the global carbon and water cycles, which represents nearly 13% of the world's land surface area. Representativeness analyses were performed using multiple environmental variables, gross primary productivity (GPP), and evapotranspiration (ET) across LA. Our results showed potential spatial representativeness of 34% of the surface area for climate properties, 36% for terrain parameters, 34% for soil resources, and 45% when all aforementioned environmental variables were summarized. Furthermore, there was a 48% potential representativeness for GPP and 34% for ET. Our results represent a best‐case scenario because data from these 41 sites is not all readily available for the scientific community. We discussed the need to enhance collaboration, promote the participation of active/inactive sites to share information with local, regional and international networks, and promote monitoring efforts across this region of the world. Key Points: There is a need to promote data sharing and improve the representativeness of environmental networks across Latin AmericaCurrently, 48% of gross primary productivity and 34% of evapotranspiration patterns are represented by FLUXNET sitesData‐driven products are forced to use information outside Latin America to predict patterns within this region [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geophysical Research. Biogeosciences is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Here we are presenting a statement of Diversity, Equity and Inclusion (DEI) for JGR: Biogeosciences. This statement includes current policies and practices, and details concrete actions that we intend to implement over the next year to better include underrepresented groups in the publication process. Key Points: The impact of our journal is enhanced when a representative pool of contributors participates in the process of scientific publicationIncreasing reviewer and editor diversity is the best opportunity we have to remove bias from the peer review processKey priorities to expand and diversify our editorial, reviewing, and publishing community are highlighted [ABSTRACT FROM AUTHOR]

Coastal salt marshes store large amounts of carbon but the magnitude and patterns of greenhouse gas (GHG; i.e., carbon dioxide (CO2) and methane (CH4)) fluxes are unclear. Information about GHG fluxes from these ecosystems comes from studies of sediments or at the ecosystem‐scale (eddy covariance) but fluxes from tidal creeks are unknown. We measured GHG concentrations in water, water quality, meteorological parameters, sediment CO2 efflux, ecosystem‐scale GHG fluxes, and plant phenology; all at half‐hour intervals over 1 year. Manual creek GHG flux measurements were used to calculate gas transfer velocity (k) and parameterize a model of water‐to‐atmosphere GHG fluxes. The creek was a source of GHGs to the atmosphere where tidal patterns controlled diel variability. Dissolved oxygen and wind speed were negatively correlated with creek CH4 efflux. Despite lacking a seasonal pattern, creek CO2 efflux was correlated with drivers such as turbidity across phenological phases. Overall, nighttime creek CO2 efflux (3.6 ± 0.63 μmol/m2/s) was at least 2 times higher than nighttime marsh sediment CO2 efflux (1.5 ± 1.23 μmol/m2/s). Creek CH4 efflux (17.5 ± 6.9 nmol/m2/s) was 4 times lower than ecosystem‐scale CH4 fluxes (68.1 ± 52.3 nmol/m2/s) across the year. These results suggest that tidal creeks are potential hotspots for CO2 emissions and could contribute to lateral transport of CH4 to the coastal ocean due to supersaturation of CH4 (>6,000 μmol/mol) in water. This study provides insights for modeling GHG efflux from tidal creeks and suggests that changes in tide stage overshadow water temperature in determining magnitudes of fluxes. Key Points: A tidal creek was a hotspot for CO2 efflux compared to the surrounding wetlandChanges in tide stage, not water temperature variability, regulated diel creek CO2 and CH4 effluxThe relative influence of nontidal drivers of creek CO2 and CH4 efflux varied by plant phenological phases [ABSTRACT FROM AUTHOR]

Tropical dry forests (TDF) are one of the most widely distributed tropical land‐cover types in Mexico, but their regional‐to‐global contribution to the carbon and water cycles is still highly uncertain. We measured CO2 and water vapor fluxes between the ecosystem and atmosphere using the eddy covariance technique from 2016 to 2018 in an old‐growth TDF in northwestern Mexico. First, we investigated the magnitude and seasonality of evapotranspiration (ET), net ecosystem production (NEP) and its contributing fluxes, gross ecosystem production (GEP), and ecosystem respiration (Reco). Second, we explored the main environmental factors controlling carbon and water fluxes as well as tested if this ecosystem acted as a net carbon source or sink. During the study period, all precipitation entering the ecosystem went back to the atmosphere through ET (738.9 ±58.26 mm y−1). Ecosystem respiration (2203.16 ±244.2 g C m−2 y−1) was consistently larger than GEP (1975.32 ±295.52 g C m−2 y−1), determining an annual NEP (−227.6 ±59.4 g C m−2 y−1) that resulted in net annual carbon losses. This forest maintained its water use efficiency (WUE; GEP/ET) across years (2.53–3.24), but water availability constrained light use and maximum carbon assimilation rates. Our results render relevance to the feedback between soil water content and net radiation as the main environmental variables controlling ecosystem fluxes in this old‐growth TDF. Resumen: El bosque tropical seco (BTS) es una de las coberturas terrestres más ampliamente distribuidas en México, pero su contribución regional y global a los ciclos del carbono y del agua es aún muy incierta. Medimos los flujos de CO2 y vapor de agua entre el ecosistema y la atmósfera utilizando la técnica de covarianza de vórtices entre 2016 y 2018 en un BTS maduro en el noroeste de México. Primero, investigamos la magnitud y la estacionalidad de la evapotranspiración (ET), la producción neta del ecosistema (NEP) y sus flujos contribuyentes, la producción bruta del ecosistema (GEP) y la respiración del ecosistema (Reco). En segundo lugar, exploramos los principales factores ambientales que controlan los flujos de carbono y de agua, y probamos si este ecosistema actuó como fuente o sumidero neto de carbono. Durante el período de estudio, la precipitación que recibió el ecosistema regresó a la atmósfera a través de ET (738.9 ± 58.26 mm y−1). La respiración del ecosistema (2203.16 ± 244.2 g C m−2 y−1) fue consistentemente mayor que la GEP (1,975.32 ± 295.52 g C m−2 y‐1), determinando una NEP anual (−227.6 ± 59.4 g C m−2 y−1) que resultó en pérdidas netas anuales de carbono. Este bosque mantuvo su eficiencia en el uso del agua (WUE; GEP / ET) a lo largo de los años (2.53–3.24), pero la disponibilidad de agua restringió el uso de la luz y las tasas máximas de asimilación de carbono. Nuestros resultados dan relevancia a la retroalimentación entre el contenido de agua del suelo y la radiación neta como las principales variables ambientales que controlan los flujos del ecosistema en este bosque tropical seco maduro. Plain Language Summary: The contribution of tropical forests to the carbon and water cycles is still uncertain. This is especially true for tropical dry forests with high rainfall seasonality and light availability that may affect their carbon sequestration potential. In this study, we report the results of continuous measurements over a 3 year period of carbon and water fluxes between the atmosphere and a tropical dry forest ecosystem in northwestern Mexico using the eddy covariance technique. We found that the studied old‐growth forest was a net carbon source to the atmosphere across years. This result can be explained by ecosystem respiration (the sum of plant and microbial respiration) since it was constantly larger than the gross ecosystem production (or whole‐ecosystem photosynthesis). The main drivers of carbon and water fluxes were soil water content and net solar radiation, but the relative effect of net solar radiation was strongly dependent on soil moisture. In addition to demonstrating the importance of water and light for controlling whole‐ecosystem processes in seasonally dry tropical forests, our results suggest old‐growth tropical forests with little disturbance can act as carbon sources to the atmosphere. Therefore, further studies should investigate ecosystem fluxes in forests under different disturbance or successional stages. Key Points: An old‐growth tropical dry forest was a net carbon source regardless of precipitation variabilityCarbon and water fluxes were highly seasonal and varied interannuallyMain drivers of carbon and water fluxes were soil water content and net solar radiation [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geophysical Research. Biogeosciences is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Large storm events possess significant erosive energy capable of mobilizing large amounts of sediment and particulate organic matter (POM) into fluvial systems. This study investigated how stream POM composition varied as a function of the watershed POM source, particle size, storm event magnitude, and seasonal timing. POM composition was characterized for multiple watershed sources and for stream POM following storms in a second‐order forested stream. Carbon (C) and nitrogen (N) amount, C:N ratio and isotopic content (13C and 15N) were determined for solid phase POM, whereas dissolved organic C, total N concentrations, and fluorescence characteristics were determined for solution/extracted POM. Key findings from this study were the following: (1) Composition of POM varied greatly with watershed sources with forest floor litter being C and N rich and labile, while stream banks and bed were C and N poor and recalcitrant. (2) Summer storms mobilized more carbon and nitrogen‐rich labile sources, while winter events mobilized more carbon‐ and nitrogen‐poor refractory material from near‐stream sources. (3) POM composition varied by size class, with the coarse POM showing more C and N rich and labile properties, while the fine POM displayed more degraded and refractory properties. If climate variability increases the magnitude and intensity of large storm events, our observations suggest that this will not only increase the inputs of POM to aquatic systems but also result in the delivery of coarser, C and N rich, and more bioavailable POM to the stream drainage network. [ABSTRACT FROM AUTHOR]