Spontaneous behaviour is structured by reinforcement without explicit reward.

Spontaneous animal behaviour is built from action modules that are concatenated by the brain into sequences1,2. However, the neural mechanisms that guide the composition of naturalistic, self-motivated behaviour remain unknown. Here we show that dopamine systematically fluctuates in the dorsolateral striatum (DLS) as mice spontaneously express sub-second behavioural modules, despite the absence of task structure, sensory cues or exogenous reward. Photometric recordings and calibrated closed-loop optogenetic manipulations during open field behaviour demonstrate that DLS dopamine fluctuations increase sequence variation over seconds, reinforce the use of associated behavioural modules over minutes, and modulate the vigour with which modules are expressed, without directly influencing movement initiation or moment-to-moment kinematics. Although the reinforcing effects of optogenetic DLS dopamine manipulations vary across behavioural modules and individual mice, these differences are well predicted by observed variation in the relationships between endogenous dopamine and module use. Consistent with the possibility that DLS dopamine fluctuations act as a teaching signal, mice build sequences during exploration as if to maximize dopamine. Together, these findings suggest a model in which the same circuits and computations that govern action choices in structured tasks have a key role in sculpting the content of unconstrained, high-dimensional, spontaneous behaviour.

Home-based video assessment of children's autism-related behaviours: Psychometric analysis and linkages with parental responsiveness and context.

OBJECTIVES: Assessment of autism-related behaviours (ARBs) in children has generally been limited to direct observations in clinical settings or informant-based reports. The widespread availability of video-streaming devices has made home observations of children's ARBs feasible. This approach could enable assessment of the generalization and durability of interventions and may be able to overcome methodological limitations of predominant current assessment approaches (response biases, limited sensitivity to treatment). DESIGN AND METHODS: Forty-four autistic children and their families participated in a repeated-measures study with a correlational design. Approximately 10 hr of unprompted behaviour at home were videorecorded over the course of a week (2 hr per day) for each participant. Gold standard measures of ARBs were also administered (ADOS-2 and ADI-R). Two home-based observational measures of ARBs utilizing streaming video were developed and evaluated: the ARCHER and the CHEERS. Trained independent evaluators made ratings on the ARCHER, CHEERS and an observational measure of parental responsiveness. RESULTS: Correlations with the ADOS-2 and ADI-R were .47 and .34 for ARCHER scores and .51 and .48 for CHEERS scores, respectively. In linear mixed models, more responsive parenting was associated with fewer ARBs on a daily basis. Children spent their afternoons engaged in many typical activities including electronics, homework and games with family members, and ARBs were more prominent in some of these contexts (e.g., electronics) than others (e.g., family games). CONCLUSIONS: Home-based observational assessment of ARBs may be useful for clinical and descriptive research.

Meta-analysis of Psychotherapy for Autistic Youth.

In order to provide more individualized support, it is imperative to further understand the effectiveness of different types of psychotherapy on the clinical areas of need common in autistic youth (Wood et al. in Behav Ther 46:83-95, 2015). Randomized controlled trials of psychotherapy for autistic youth were included if published in English, included random assignment to treatment or control group, required a previous diagnosis of autism, had a mean age of 6-17 years, and provided outcome measure data from both intervention and control groups. A total of 133 measures were coded across 29 studies and included 1464 participants with a mean age of 10.39 years (1.89). A small mean effect size (0.38,95% CI [0.26, 0.47]) was found overall, with the largest effects for cognitive behavioral therapies on autism-related clinical needs (0.81) and overall mental health (0.78). The results show the significant impact of psychotherapy interventions for autistic youth. Additional research should further assess the details of the most effective psychotherapies for each area of clinical need.

The ecosystem wilting point defines drought response and recovery of a Quercus-Carya forest.

Soil and atmospheric droughts increasingly threaten plant survival and productivity around the world. Yet, conceptual gaps constrain our ability to predict ecosystem-scale drought impacts under climate change. Here, we introduce the ecosystem wilting point (ΨEWP ), a property that integrates the drought response of an ecosystem's plant community across the soil-plant-atmosphere continuum. Specifically, ΨEWP defines a threshold below which the capacity of the root system to extract soil water and the ability of the leaves to maintain stomatal function are strongly diminished. We combined ecosystem flux and leaf water potential measurements to derive the ΨEWP of a Quercus-Carya forest from an "ecosystem pressure-volume (PV) curve," which is analogous to the tissue-level technique. When community predawn leaf water potential (Ψpd ) was above ΨEWP (=-2.0 MPa), the forest was highly responsive to environmental dynamics. When Ψpd fell below ΨEWP , the forest became insensitive to environmental variation and was a net source of carbon dioxide for nearly 2 months. Thus, ΨEWP is a threshold defining marked shifts in ecosystem functional state. Though there was rainfall-induced recovery of ecosystem gas exchange following soaking rains, a legacy of structural and physiological damage inhibited canopy photosynthetic capacity. Although over 16 growing seasons, only 10% of Ψpd observations fell below ΨEWP , the forest is commonly only 2-4 weeks of intense drought away from reaching ΨEWP , and thus highly reliant on frequent rainfall to replenish the soil water supply. We propose, based on a bottom-up analysis of root density profiles and soil moisture characteristic curves, that soil water acquisition capacity is the major determinant of ΨEWP , and species in an ecosystem require compatible leaf-level traits such as turgor loss point so that leaf wilting is coordinated with the inability to extract further water from the soil.

Suicidal Risk Behaviors in Adolescents With Rare Neurodevelopmental Disorders: The Role of Sex, Autistic Traits, and Mental Health Difficulties.

OBJECTIVE: Autistic traits are associated with mental health difficulties and risk of suicidal risk behaviors among adolescents. Little is known about how autistic traits affect the mental health of adolescents with rare neurodevelopmental disorders (RNDs). The aim of this study was to investigate the relationship between autistic traits, mental health difficulties, and suicidal risk behaviors in adolescents with RNDs. METHODS: Parents (N = 93) completed the Child Behavior Checklist, Social Communication Questionnaire, and Social Responsiveness Scale about their adolescent (Mage = 13.1, SD = 2.3, 62.4% females) with an RND (e.g., sex chromosome aneuploidies, Fragile X syndrome, 22q11.2 deletion syndrome). The data were analyzed with hierarchical logistic regression analysis. RESULTS: The prevalence of suicidal risk behaviors (16.1%) was similar to that reported among autistic youth and was higher among boys than girls. More autistic traits were associated with suicidal risk behaviors in bivariate analysis. In multivariate analysis, more anxiety/depressive symptoms were associated with more suicidal risk behaviors and externalizing problems associated with suicidal risk behaviors beyond autistic traits and anxiety/depressive symptoms. CONCLUSION: Adolescents with RNDs are at risk of suicidal risk behaviors, especially those with higher levels of autistic traits, anxiety/depressive symptoms, and externalizing problems. Assessment of autistic traits, mental health difficulties, and suicide risk may be indicated for adolescents with RNDs to determine if corresponding intervention is needed.

Empirically-identified subgroups of children with autism spectrum disorder and their response to two types of cognitive behavioral therapy.

Autism spectrum disorder (ASD) is heterogeneous and likely entails distinct phenotypes with varying etiologies. Identifying these subgroups may contribute to hypotheses about differential treatment responses. The present study aimed to discern subgroups among children with ASD and anxiety in context of the five-factor model of personality (FFM) and evaluate treatment response differences to two cognitive-behavioral therapy treatments. The present study is a secondary data analysis of children with ASD and anxiety (N=202; ages 7-13; 20.8% female) in a cognitive behavioral therapy (CBT) randomized controlled trial (Wood et al., 2020). Subgroups were identified via latent profile analysis of parent-reported FFM data. Treatment groups included standard-of-practice CBT (CC), designed for children with anxiety, and adapted CBT (BIACA), designed for children with ASD and comorbid anxiety. Five subgroups with distinct profiles were extracted. Analysis of covariance revealed CBT response was contingent on subgroup membership. Two subgroups responded better to BIACA on the primary outcome measure and a third responded better to BIACA on a peer-social adaptation measure, while a fourth subgroup responded better to CC on a school-related adaptation measure. These findings suggest that the FFM may be useful in empirically identifying subgroups of children with ASD, which could inform intervention selection decisions for children with ASD and anxiety.

Reward Sensitivity Predicts the Response to Cognitive Behavioral Therapy for Children with Autism and Anxiety.

OBJECTIVE: Cognitive-behavioral therapy (CBT) is an effective treatment for anxiety in youth with autism spectrum disorder (ASD). However, research has yet to examine what cognitive characteristics may influence treatment response. The current study investigated decision-making ability and social cognition as potential (a) predictors of differential treatment response to two versions of CBT and (b) moderators of the effect of treatment condition. METHOD: The study included 148 children (mean age = 9.8 years) with interfering anxiety and a diagnosis of ASD who were enrolled in a randomized clinical trial comparing two versions of CBT for anxiety (standard and adapted for ASD). Participants completed pretreatment measures of decision-making ability (adapted Iowa Gambling Task) and social cognition (Strange Stories) and analyses tested whether task performance predicted treatment response across and between (moderation) treatment conditions. RESULTS: Our findings indicate that decision-making ability moderated treatment outcomes in youth with ASD and anxiety, with a better decision-making performance being associated with higher post-treatment anxiety scores for those who received standard, not adapted, CBT. CONCLUSIONS: Children with ASD and anxiety who are more sensitive to reward contingencies and reinforcement may benefit more from adapted CBT approaches that work more explicitly with reward.

The xylem of anisohydric Quercus alba L. is more vulnerable to embolism than isohydric codominants.

The coordination of plant leaf water potential (ΨL ) regulation and xylem vulnerability to embolism is fundamental for understanding the tradeoffs between carbon uptake and risk of hydraulic damage. There is a general consensus that trees with vulnerable xylem more conservatively regulate ΨL than plants with resistant xylem. We evaluated if this paradigm applied to three important eastern US temperate tree species, Quercus alba L., Acer saccharum Marsh. and Liriodendron tulipifera L., by synthesizing 1600 ΨL observations, 122 xylem embolism curves and xylem anatomical measurements across 10 forests spanning pronounced hydroclimatological gradients and ages. We found that, unexpectedly, the species with the most vulnerable xylem (Q. alba) regulated ΨL less strictly than the other species. This relationship was found across all sites, such that coordination among traits was largely unaffected by climate and stand age. Quercus species are perceived to be among the most drought tolerant temperate US forest species; however, our results suggest their relatively loose ΨL regulation in response to hydrologic stress occurs with a substantial hydraulic cost that may expose them to novel risks in a more drought-prone future.

Treatment Fidelity and Outcome in CBT for Youth with Autism: The MEYA Fidelity Scale.

OBJECTIVE: Assessing treatment fidelity in effectiveness research is critical to interpreting study findings. This paper details the development and initial psychometric evaluation of the Modular Evidence-Based Practices for Youth with Autism Fidelity Scale (MEYA-FS) designed to support the assessment of cognitive-behavioral treatments for youth with autism in effectiveness research. METHOD: Recorded treatment sessions (N = 338) were randomly selected from 77 youth (M age = 9.65 years, SD = 1.87; 50.67% White; 85.33% male) who received the Schema, Emotion, and Behavior-Focused Therapy for Children (SEBASTIEN) (n = 51) or Coping Cat (n = 24) program. RESULTS: The MEYA-FS Adherence items displayed acceptable interrater reliability, but more than half of the MEYA-FS Competence items did not. The magnitude and pattern of correlations supported the score validity of the MEYA-FS Adherence and Competence items and subscales. However, some corresponding Adherence and Competence items displayed significant overlap. Scores on each Adherence subscale distinguished between the SEBASTIEN and Coping Cat programs, providing support for discriminant validity. Finally, higher Adherence and Competence subscales predicted significant improvements in youth clinical outcomes (adjustment problems in the school setting, social-communication difficulties, restrictive/repetitive behaviors, and externalizing problems), providing initial evidence for predictive validity. CONCLUSIONS: The psychometric properties of the MEYA-FS make it appropriate for supporting efforts to evaluate cognitive-behavioral interventions for youth with autism in effectiveness and implementation research.

Accommodation of Anxiety in Youth with Autism Spectrum Disorder: Results from the TAASD Study.

Objective: Accommodation, or the ways in which families modify their routines and expectations in response to a child's anxiety, is common and interferes with anxiety treatment outcomes. However, little research has examined family accommodation among youth with autism spectrum disorder and anxiety. The current study aimed to (a) identify pre-treatment correlates of accommodation, (b) examine changes in accommodation after treatment, and (c) assess relationships between accommodation and post-treatment anxiety severity.Method: The sample consisted of 167 youth (mean age = 9.90 years; 79.6% male; 18% Latinx) with clinically significant anxiety and a diagnosis of autism spectrum disorder who were enrolled in a randomized clinical trial comparing two cognitive behavioral therapy interventions for anxiety and treatment-as-usual. Participants were evaluated for symptom severity and family accommodation at pre- and post-treatment.Results: Results indicated that clinician-rated anxiety severity and parent-rated externalizing behaviors and autism spectrum disorder severity significantly predicted pre-treatment accommodation. Accommodation significantly decreased from pre- to post-treatment and non-responders showed significantly higher accommodation at post-treatment compared to responders. Finally, youth with higher pre-treatment accommodation had higher post-treatment anxiety.Conclusions: Findings indicate that accommodation for anxiety is common among youth with autism spectrum disorder and anxiety. Furthermore, accommodation is implicated in treatment outcomes and should be targeted in treatment for youth with autism spectrum disorder and anxiety.

Advancing the assessment of mindful eating: Exploring the psychometric properties and validating the mindful eating behaviour scale in English.

Background: Mindful eating has been described as significant in motivating research and clinical outcomes in weight regulation and healthy eating. The use of psychometric tools to measure mindful eating is problematic, with results often leading to interpretations that are not reflective of mindful eating theory and fundamentals of mindfulness. Aim: In this research, we explored the Mindful Eating Behaviour Scale (MEBS) within a British sample to validate the factorial structure, and widen the use of a scale that appears appropriate for measuring mindful eating. Methods: A community sample (n = 742) was recruited via social media, and the findings supported the factorial structure proposed through the original Dutch sample. Predictive validity was also assessed, with the scale and subscales predicting fat and sugar consumption. Results: Cronbach's α values were acceptable and similar to the original findings, also supporting the internal consistency of the scale. Conclusion: While factorial structure, predictive validity and internal consistency propose a scale that can be adopted with English speaking populations, we propose the potential of furthering scientific inquiry on mindful eating research by highlighting the behavioural aspects of the scale.

Predictors of Suicidal Thoughts in Children with Autism Spectrum Disorder and Anxiety or Obsessive-Compulsive Disorder: The Unique Contribution of Externalizing Behaviors.

Children with autism spectrum disorder (ASD) are at elevated risk of suicidal ideation, particularly those with comorbid anxiety disorders and/or obsessive-compulsive disorder (OCD). We investigated the risk factors associated with suicidal ideation in 166 children with ASD and comorbid anxiety disorders/OCD, and the unique contribution of externalizing behaviors. Suicidal ideation was reported in the child sample by 13% of parents. Controlling for child age, sex, and IQ, perceived loneliness positively predicted the likelihood of suicidal ideation. In addition, externalizing behaviors positively predicted suicidal ideation, controlling for all other factors. Reliance on parental report to detect suicidal ideation in youth with ASD is a limitation of this study. Nonetheless, these findings highlight the importance of assessing and addressing suicidal ideation in children with ASD and comorbid anxiety disorders/OCD, and more importantly in those with elevated externalizing behaviors and perceptions of loneliness.

Anger Outbursts in Youth with ASD and Anxiety: Phenomenology and Relationship with Family Accommodation.

Anger outbursts (AO) are associated with severe symptoms, impairment and poorer treatment outcomes for anxious children, though limited research has examined AO in youth with co-occurring autism and anxiety disorders. This study examined AO in children with autism and anxiety by evaluating clinical characteristics, family accommodation, and changes in AO following anxiety-focused treatment. The sample comprised 167 youth with autism and anxiety enrolled in a multi-site randomized clinical trial comparing standard care CBT for anxiety, CBT adapted for youth with autism, and usual care. Most participants (60%) had AO, which contributed to impairment above and beyond anxiety and autism. AO impacted functional impairment indirectly through a pathway of parental accommodation. AO reduced with anxiety-focused treatment. Findings highlight that AO are common in this population and uniquely contribute to functional impairment, indicating a need for direct targeting in treatment.

Detecting forest response to droughts with global observations of vegetation water content.

Droughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil-plant-atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more. Unlike water potential, which requires demanding in situ measurements, VWC can be retrieved from remote sensing measurements, particularly at microwave frequencies using radar and radiometry. Here, we highlight key frontiers through which VWC has the potential to significantly increase our understanding of forest responses to water stress. To validate remote sensing observations of VWC at landscape scale and to better relate them to data assimilation model parameters, we introduce an ecosystem-scale analog of the pressure-volume curve, the non-linear relationship between average leaf or branch water potential and water content commonly used in plant hydraulics. The sources of variability in these ecosystem-scale pressure-volume curves and their relationship to forest response to water stress are discussed. We further show to what extent diel, seasonal, and decadal dynamics of VWC reflect variations in different processes relating the tree response to water stress. VWC can also be used for inferring belowground conditions-which are difficult to impossible to observe directly. Lastly, we discuss how a dedicated geostationary spaceborne observational system for VWC, when combined with existing datasets, can capture diel and seasonal water dynamics to advance the science and applications of global forest vulnerability to future droughts.

The Pediatric Autism Spectrum Therapy Observation System: Development, Psychometric Properties, and Sensitivity to Treatment.

An observational coding system was developed to track clinical change in children with autism spectrum disorder (ASD) during psychotherapy. The Pediatric Autism Spectrum Therapy Observation System (PASTOS) consists of 23 items divided into 5 subscales and is used to rate child behaviors in individual psychotherapy sessions. Manual-based cognitive behavioral therapy session transcripts of 22 children diagnosed with ASD (IQ > 70) and a concurrent anxiety disorder (M = 9.41 years, SD = 1.56 years) enrolled in a randomized, controlled trial were coded. Results suggested that the PASTOS exhibited promising interrater reliability, internal consistency, convergent validity at post-treatment, and treatment sensitivity. The PASTOS may be a useful tool for studying process and outcome in psychotherapy research on children with ASD.

Use of Helicopter Emergency Medical Services in the Transport of Patients With Known or Suspected Coronavirus Disease 2019.

OBJECTIVE: Limited information exists regarding the response of helicopter emergency medical services (HEMS) programs to patients with known or suspected coronavirus disease 2019 (COVID-19). The purpose of this study was to determine changes in flight operations during the early stages of the pandemic. METHODS: A survey of the American College of Emergency Physicians Air Medical Section was conducted between May 13, 2020, and August 1, 2020. COVID-19 prevalence was defined as high versus low based on cases > 2,500 or ≤ 2,500. RESULTS: Of the 48 respondents, the majority (89.6%) reported that their patient guidelines had changed because of COVID-19; 89.6% of programs reported transporting COVID-19-positive patients, whereas 91.5% reported transporting persons under investigation. The majority of respondents reported additional training in COVID-19 airway management (79.2%) and personal protective equipment use (93.6%). Permitted aerosol-generating procedures included bilevel positive airway pressure (40.4%) and high-flow nasal oxygen (66.0%). No difference in guideline changes, positive COVID-19/persons under investigation transport restrictions, or permitted aerosol-generating procedures were noted between high- and low-prevalence settings. CONCLUSION: COVID-19 has resulted in changes to HEMS guidelines regardless of local disease prevalence. The pandemic has persisted sufficiently long that data regarding the effectiveness of guideline changes should be analyzed. In the absence of definitive data, national best practices should be developed to guide COVID-19 HEMS transport.

Nitrous oxide emissions are enhanced in a warmer and wetter world.

Nitrous oxide (N2O) has a global warming potential that is 300 times that of carbon dioxide on a 100-y timescale, and is of major importance for stratospheric ozone depletion. The climate sensitivity of N2O emissions is poorly known, which makes it difficult to project how changing fertilizer use and climate will impact radiative forcing and the ozone layer. Analysis of 6 y of hourly N2O mixing ratios from a very tall tower within the US Corn Belt-one of the most intensive agricultural regions of the world-combined with inverse modeling, shows large interannual variability in N2O emissions (316 Gg N2O-N⋅y-1 to 585 Gg N2O-N⋅y-1). This implies that the regional emission factor is highly sensitive to climate. In the warmest year and spring (2012) of the observational period, the emission factor was 7.5%, nearly double that of previous reports. Indirect emissions associated with runoff and leaching dominated the interannual variability of total emissions. Under current trends in climate and anthropogenic N use, we project a strong positive feedback to warmer and wetter conditions and unabated growth of regional N2O emissions that will exceed 600 Gg N2O-N⋅y-1, on average, by 2050. This increasing emission trend in the US Corn Belt may represent a harbinger of intensifying N2O emissions from other agricultural regions. Such feedbacks will pose a major challenge to the Paris Agreement, which requires large N2O emission mitigation efforts to achieve its goals.

The Impact of Comorbidity on Cognitive-Behavioral Therapy Response in Youth with Anxiety and Autism Spectrum Disorder.

The impact of externalizing comorbidity on treatment outcome was examined in 104 youth ages 7-16 (M = 11.09 years) with autism spectrum disorder and primary anxiety/obsessive compulsive disorder who completed modular cognitive behavioral therapy (CBT) for anxiety/OCD. Three comorbidity profiles were utilized for group comparisons: participants with oppositional defiant or conduct disorder with attention-deficit hyperactivity disorder (ODD; CD; ADHD; group EXT, n = 25); those without ODD/CD and only ADHD (group ADHD, n = 46); and those without externalizing comorbidity (NO-EXT, n = 33). Post-treatment outcomes were measured continuously (Pediatric Anxiety Rating Scale, Clinical Global Impression-Severity) and categorically (treatment response, remission). The ADHD group was four times more likely of being a treatment responder compared to NO-EXT (OR 4.05). Comorbidity group did not impact remission. After controlling for pre-treatment scores, there was a significantly greater reduction of the CGI-S for ADHD versus NO-EXT and EXT versus NO-EXT, but results did not significantly differ for the PARS. Results suggest that a modular CBT approach yields positive impact for treatment outcomes in youth with comorbid externalizing problems, particularly among those with comorbid ADHD.

Sun-induced Chl fluorescence and its importance for biophysical modeling of photosynthesis based on light reactions.

Recent progress in observing sun-induced Chl fluorescence (SIF) provides an unprecedented opportunity to advance photosynthesis research in natural environments. However, we still lack an analytical framework to guide SIF studies and integration with the well-developed active fluorescence approaches. Here, we derive a set of coupled fundamental equations to describe the dynamics of SIF and its relationship with C3 and C4 photosynthesis. These equations show that, although SIF is dynamically as complex as photosynthesis, the measured SIF simplifies photosynthetic modeling from the perspective of light reactions by integrating over the dynamic complexities of photosynthesis. Specifically, the measured SIF contains direct information about the actual electron transport from photosystem II to photosystem I, giving a quantifiable link between light and dark reactions. With much-reduced requirements on inputs and parameters, the light-reactions-centric, SIF-based biophysical model complements the traditional, dark-reactions-centric biochemical model of photosynthesis. The SIF-photosynthesis relationship, however, is nonlinear. This is because photosynthesis saturates at high light whereas SIF has a stronger tendency to keep increasing, as fluorescence quantum yield has a relatively muted sensitivity to light levels. Successful applications of the SIF-based model of photosynthesis will depend on a predictive understanding of several previously underexplored physiological and biophysical processes. Advances can be facilitated by coordinated efforts in plant physiology, remote sensing, and eddy covariance flux observations.

Error characterization of methane fluxes and budgets derived from a long-term comparison of open- and closed-path eddy covariance systems.

Wetlands represent the dominant natural source of methane (CH4) to the atmosphere. Thus, substantial effort has been spent examining the CH4 budgets of global wetlands via continuous ecosystem-scale measurements using the eddy covariance (EC) technique. Robust error characterization for such measurements, however, remains a major challenge. Here, we quantify systematic, random and gap-filling errors and the resulting uncertainty in CH4 fluxes using a 3.5 year time series of simultaneous open- and closed path CH4 flux measurements over a sub-boreal wetland. After correcting for high- and low frequency flux attenuation, the magnitude of systematic frequency response errors were negligible relative to other uncertainties. Based on three different random flux error estimations, we found that errors of the CH4 flux measurement systems were smaller in magnitude than errors associated with the turbulent transport and flux footprint heterogeneity. Errors on individual half-hourly CH4 fluxes were typically 6%-41%, but not normally distributed (leptokurtic), and thus need to be appropriately characterized when fluxes are compared to chamber-derived or modeled CH4 fluxes. Integrated annual fluxes were only moderately sensitive to gap-filling, based on an evaluation of 4 different methods. Calculated budgets agreed on average to within 7% (≤ 1.5 g - CH4 m-2 yr-1). Marginal distribution sampling using open source code was among the best-performing of all the evaluated gap-filling approaches and it is therefore recommended given its transparency and reproducibility. Overall, estimates of annual CH4 emissions for both EC systems were in excellent agreement (within 0.6 g - CH4 m-2 yr-1) and averaged 18 g - CH4 m-2 yr-1. Total uncertainties on the annual fluxes were larger than the uncertainty of the flux measurement systems and estimated between 7-17%. Identifying trends and differences among sites or site years requires that the observed variability exceeds these uncertainties.