Gap-filling eddy covariance methane fluxes : Comparison of machine learning model predictions and uncertainties at FLUXNET-CH4 wetlands

Time series of wetland methane fluxes measured by eddy covariance require gap-filling to estimate daily, seasonal, and annual emissions. Gap-filling methane fluxes is challenging because of high variability and complex responses to multiple drivers. To date, there is no widely established gap-filling standard for wetland methane fluxes, with regards both to the best model algorithms and predictors. This study synthesizes results of different gap-filling methods systematically applied at 17 wetland sites spanning boreal to tropical regions and including all major wetland classes and two rice paddies. Procedures are proposed for: 1) creating realistic artificial gap scenarios, 2) training and evaluating gap-filling models without overstating performance, and 3) predicting halfhourly methane fluxes and annual emissions with realistic uncertainty estimates. Performance is compared between a conventional method (marginal distribution sampling) and four machine learning algorithms. The conventional method achieved similar median performance as the machine learning models but was worse than the best machine learning models and relatively insensitive to predictor choices. Of the machine learning models, decision tree algorithms performed the best in cross-validation experiments, even with a baseline predictor set, and artificial neural networks showed comparable performance when using all predictors. Soil temperature was frequently the most important predictor whilst water table depth was important at sites with substantial water table fluctuations, highlighting the value of data on wetland soil conditions. Raw gap-filling uncertainties from the machine learning models were underestimated and we propose a method to calibrate uncertainties to observations. The python code for model development, evaluation, and uncertainty estimation is publicly available. This study outlines a modular and robust machine learning workflow and makes recommendations for, and evaluates an improved baseline of, methane gap-filling models that can be implemented in multi-site syntheses or standardized products from regional and global flux networks (e.g., FLUXNET).Peer reviewe

Minimum Information about a Biosynthetic Gene cluster

A wide variety of enzymatic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Minimum Information about a Biosynthetic Gene cluster (MIBiG) data standard.Chemistry and Chemical Biolog

The Potential of Satellite Remote Sensing Time Series to Uncover Wetland Phenology under Unique Challenges of Tidal Setting

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.Arts, Faculty ofNon UBCGeography, Department ofReviewedFacult

Remotely sensed phenological heterogeneity of restored wetlands: linking vegetation structure and function

Seasonal phenological dynamics of vegetation hold important clues on ecosystem performance towards management goals, such as carbon uptake, and thus should be considered in projections of their targeted services. However, in wetlands spatio-temporal heterogeneity due to mixing of open water, soil, green and dead vegetation makes it difficult to generalize ecosystem functioning across different regions. Remote sensing observations can provide spatially-explicit, cost-effective phenology indicators; however, little is known about their capacity to indicate the links between wetland ecosystem structure and function. Here we assessed this potential by comparing one-year Enhanced Vegetation Index (EVI) from satellite products at high (5m; RapidEye) and low (30m; Landsat) spatial resolutions with eddy covariance time series of net carbon exchange, field digital camera (phenocam) greenness and water temperature among three floristically similar restored wetlands in California, USA. Phenological timing differed by wetland site: depending on satellite, the range in site-median start of greening was up to 28 days, end of greening – up to 73 days, start of senescence – up to 79 days, and end of senescence – up to 10 days. Key transition dates from satellite inputs agreed with seasonal changes in net carbon exchange, phenocam greenness and water temperatures, suggesting that phenological contrasts could result in part from site differences in vegetation configuration and litter affecting the exposure of canopy, soil and water to sunlight and thus sub-canopy microclimate and ecosystem functioning. Yet, the agreement between satellite inputs was non-systematic, with the greatest disparities at the more heterogeneous, less vegetated site. Phenological model fitting uncertainty increased with greater spatial resolution, highlighting the tradeoff between the accuracy of representing vegetation and the complexity of local seasonal variation. These findings highlight the sensitivity of satellite-derived phenology to structural and functional heterogeneity of ecosystems and call for more rigorous spatially-explicit analyses to inform assessments of restoration and management outcomes

Análisis de la morfometría y de la dimensión fractal en la lesión del tejido muscular esquelético expuesto en la combinación de los tratamientos de crioterapia y ultrasonido

The aim of this study was to analyze the effects of an association of cryotherapy and therapeutic ultrasound on the treatment of muscle injured by impact. Fifty-five Wistar rats were divided into five groups (n = 11), Acute Injury (AI), Injury (I), Cryotherapy (CR), Therapeutic Ultrasound (TU) and Association of Cryotherapy and Therapeutic Ultrasound (CRTU). The CR and CRTU groups received applications of Cryotherapy three times (immediately, 24 and 48 h after injury) of 20 minutes duration. The TU and CRTU groups received applications of Therapeutic Ultrasound for seven days, for five minutes, in pulsed mode, 0.5 w/cm intensity, frequency 1 MHz. Body mass and gastrocnemius mass were analyzed. In addition to histological slides stained with hematoxylin and eosin used for morphometric analysis, picrosirius dye was used for quantification of collagen by Fractal Dimension (FD). The results of the intra-group analysis showed lower body mass and gastrocnemius in the CRTU group in relation to the AI (p = 0.001), I (p = 0.001), CR (p = 0.001) and TU groups (p = 0.001), and lower values of FD to quantify collagen in the CRTU group in relation to the AI (p = 0.007) and CR groups (p = 0.014). In summary, the present study showed that the association of Cryotherapy with Therapeutic Ultrasound promoted better results in the aspects analyzed compared to application of the therapies in isolation34310761082El objetivo del estudio fue evaluar los efectos de la asociación de las técnicas de crioterapia y ultrasonido terapéutico en el tratamiento de la lesión muscular por impacto. Fueron utilizadas 55 ratas Wistar, expuestas a lesión y separadas en grupos (n = 11): Lesión aguda (LA), Lesión (L), Crioterapia (CR), Ultrasonido Terapéutico (UT) y Crioterapia + Ultrasonido Terapéutico (CRUT). Los grupos CR y CRUT recibieron la aplicación, durante 20 minutos, en tres momentos (inmediatamente, 24 y 48 horas, después de la lesión). Los grupos UT y CRUT, recibieron UT por siete días, con una duración de cinco minutos, en modo pulsado, con una intensidad de 0,5 W/cm2 y frecuencia de 1 MHz. Fueran medidos el peso corporal y el peso de los músculos gastrocnemios y se realizaron cortes histológicos del músculo gastrocnemio, los cuales fueron teñidos con hematoxilina-eosina (HE) para el análisis morfométrico y con picrosirius para el análisis del colágeno por dimensión fractal (DF). Los resultados de los análisis intragrupo demostraron una menor disminución de la masa coporal y muscular en el grupo CRUT. Además, fue observado un valor inferior en la morfometría en el grupo CRUT en comparación a los grupos LA (p = 0,001), L (p = 0,001), CR (p = 0,001) y UT (p = 0,001), y un menor valor de la DF con respecto al colágeno en el grupo CRUT en comparación a los grupos LA (p = 0,007) y CR (p = 0,014). En síntesis, el presente estudio demostró que el protocolo de asociación de las técnicas de CR y UT causaron mayores respuestas benéficas en los aspectos analizados en comparación a los protocolos con los tratamientos aplicados de forma aisladasem informaçã

Soil properties and sediment accretion modulate methane fluxes from restored wetlands.

Wetlands are the largest source of methane (CH4 ) globally, yet our understanding of how process-level controls scale to ecosystem fluxes remains limited. It is particularly uncertain how variable soil properties influence ecosystem CH4 emissions on annual time scales. We measured ecosystem carbon dioxide (CO2 ) and CH4 fluxes by eddy covariance from two wetlands recently restored on peat and alluvium soils within the Sacramento-San Joaquin Delta of California. Annual CH4 fluxes from the alluvium wetland were significantly lower than the peat site for multiple years following restoration, but these differences were not explained by variation in dominant climate drivers or productivity across wetlands. Soil iron (Fe) concentrations were significantly higher in alluvium soils, and alluvium CH4 fluxes were decoupled from plant processes compared with the peat site, as expected when Fe reduction inhibits CH4 production in the rhizosphere. Soil carbon content and CO2 uptake rates did not vary across wetlands and, thus, could also be ruled out as drivers of initial CH4 flux differences. Differences in wetland CH4 fluxes across soil types were transient; alluvium wetland fluxes were similar to peat wetland fluxes 3 years after restoration. Changing alluvium CH4 emissions with time could not be explained by an empirical model based on dominant CH4 flux biophysical drivers, suggesting that other factors, not measured by our eddy covariance towers, were responsible for these changes. Recently accreted alluvium soils were less acidic and contained more reduced Fe compared with the pre-restoration parent soils, suggesting that CH4 emissions increased as conditions became more favorable to methanogenesis within wetland sediments. This study suggests that alluvium soil properties, likely Fe content, are capable of inhibiting ecosystem-scale wetland CH4 flux, but these effects appear to be transient without continued input of alluvium to wetland sediments

Soil properties and sediment accretion modulate methane fluxes from restored wetlands.

Wetlands are the largest source of methane (CH4 ) globally, yet our understanding of how process-level controls scale to ecosystem fluxes remains limited. It is particularly uncertain how variable soil properties influence ecosystem CH4 emissions on annual time scales. We measured ecosystem carbon dioxide (CO2 ) and CH4 fluxes by eddy covariance from two wetlands recently restored on peat and alluvium soils within the Sacramento-San Joaquin Delta of California. Annual CH4 fluxes from the alluvium wetland were significantly lower than the peat site for multiple years following restoration, but these differences were not explained by variation in dominant climate drivers or productivity across wetlands. Soil iron (Fe) concentrations were significantly higher in alluvium soils, and alluvium CH4 fluxes were decoupled from plant processes compared with the peat site, as expected when Fe reduction inhibits CH4 production in the rhizosphere. Soil carbon content and CO2 uptake rates did not vary across wetlands and, thus, could also be ruled out as drivers of initial CH4 flux differences. Differences in wetland CH4 fluxes across soil types were transient; alluvium wetland fluxes were similar to peat wetland fluxes 3 years after restoration. Changing alluvium CH4 emissions with time could not be explained by an empirical model based on dominant CH4 flux biophysical drivers, suggesting that other factors, not measured by our eddy covariance towers, were responsible for these changes. Recently accreted alluvium soils were less acidic and contained more reduced Fe compared with the pre-restoration parent soils, suggesting that CH4 emissions increased as conditions became more favorable to methanogenesis within wetland sediments. This study suggests that alluvium soil properties, likely Fe content, are capable of inhibiting ecosystem-scale wetland CH4 flux, but these effects appear to be transient without continued input of alluvium to wetland sediments

Leaf and root pectin methylesterase activity and 13C/12C stable isotopic ratio measurements of methanol emissions give insight into methanol production in Lycopersicon esculentum

Plant production of methanol (MeOH) is a poorly understood aspect of metabolism, and understanding MeOH production in plants is crucial for modeling MeOH emissions. Here, we have examined the source of MeOH emissions from mature and immature leaves and whether pectin methylesterase (PME) activity is a good predictor of MeOH emission. We also investigated the significance of below-ground MeOH production for mature leaf emissions. We present measurements of MeOH emission, PME activity, and MeOH concentration in mature and immature tissues of tomato (Lycopersicon esculentum). We also present stable carbon isotopic signatures of MeOH emission and the pectin methoxyl pool. Our results suggest that below-ground MeOH production was not the dominant contributor to daytime MeOH emissions from mature and immature leaves. Stable carbon isotopic signatures of mature and immature leaf MeOH were similar, suggesting that they were derived from the same pathway. Foliar PME activity was related to MeOH flux, but unexplained variance suggested PME activity could not predict emissions. The data show that MeOH production and emission are complex and cannot be predicted using PME activity alone. We hypothesize that substrate limitation of MeOH synthesis and MeOH catabolism may be important regulators of MeOH emission

Reconstruction of source water using the δ18O of tree ring phenylglucosazone: A potential tool in paleoclimate studies

The oxygen isotope ratios of tree ring cellulose have a great potential as proxy for the oxygen isotope ratios of source water, which is related to climate. However, source water isotopic signatures can be masked by plant physiological and biochemical processes during cellulose synthesis. To minimize biochemical effects in the recording of source water, we modified the cellulose molecule to phenylglucosazone, which only has oxygen attached to carbon 3–6 (OC3–6) of the cellulose glucose moieties, thus eliminating the oxygen attached to carbon 2 of the cellulose glucose moieties (OC-2). Here we developed a method to use small amounts of inter and intra-annual tree ring cellulose for phenylglucosazone synthesis. Using this new method we tested if the oxygen isotope ratios of source water reconstructed from tree ring phenylglucosazone (δ18OswPG) and the observed source water (δ18Oswobs) would have a better agreement than those reconstructed from the tree ring cellulose molecule. Annual tree ring samples were obtained from Pinus sylvestris (1997–2003) (Finland) and Picea abies (1971–1992) (Switzerland) and intra-annual tree ring samples were obtained from Pinus radiata (October 2004–March 2006) (New Zealand), each near a meteorological station where precipitation and relative humidity (RH) were measured periodically. The δ18O of tree ring cellulose and tree ring phenylglucosazone for each of the three species were then used to back calculate the δ18O of source water according to a previous published empirical equation. As expected, the δ18O of tree ring phenylglucosazone was superior than cellulose in the reconstruction of source water available to the plant. Deviation between δ18OswPG and δ18Oswobs was in part correlated with variation in atmospheric relative humidity (RH) which was not observed for the cellulose molecule. We conclude that this new method can be applicable to inter and intra-annual tree ring studies and that the use of the tree ring phenylglucosazone will significantly improve the quality of paleoclimate studies