Do we (need to) care about canopy radiation schemes in DGVMs? Caveats and potential impacts

Dynamic global vegetation models (DGVMs) are an essential part of current state-of-the-art Earth system models. In recent years, the complexity of DGVMs has increased by incorporating new important processes like, e.g., nutrient cycling and land cover dynamics, while biogeophysical processes like surface radiation have not been developed much further. Canopy radiation models are however very important for the estimation of absorption and reflected fluxes and are essential for a proper estimation of surface carbon, energy and water fluxes. The present study provides an overview of current implementations of canopy radiation schemes in a couple of state-of-the-art DGVMs and assesses their accuracy in simulating canopy absorption and reflection for a variety of different surface conditions. Systematic deviations in surface albedo and fractions of absorbed photosynthetic active radiation (faPAR) are identified and potential impacts are assessed. The results show clear deviations for both, absorbed and reflected, surface solar radiation fluxes. FaPAR is typically underestimated, which results in an underestimation of gross primary productivity (GPP) for the investigated cases. The deviation can be as large as 25% in extreme cases. Deviations in surface albedo range between −0.15 ≤ Δα ≤ 0.36, with a slight positive bias on the order of Δα ≈ 0.04. Potential radiative forcing caused by albedo deviations is estimated at −1.25 ≤ RF ≤ −0.8 (W m−2), caused by neglect of the diurnal cycle of surface albedo. The present study is the first one that provides an assessment of canopy RT schemes in different currently used DGVMs together with an assessment of the potential impact of the identified deviations. The paper illustrates that there is a general need to improve the canopy radiation schemes in DGVMs and provides different perspectives for their improvement

Vitality club:a proof-of-principle of peer coaching for daily physical activity by older adults

Many age-related diseases can be prevented or delayed by daily physical activity. Unfortunately, many older adults do not perform physical activity at the recommended level. Professional interventions do not reach large numbers of older adults for a long period of time. We studied a peer-coach intervention, in which older adults coach each other, that increased daily physical activity of community dwelling older adults for over 6 years. We studied the format and effects of this peer coach intervention for possible future implementation elsewhere. Through interviews and participatory observation we studied the format of the intervention. We also used a questionnaire (n = 55) and collected 6-min walk test data (n = 261) from 2014 to 2016 to determine the motivations of participants and effects of the intervention on health, well-being and physical capacity. Vitality Club is a self-sustainable group of older adults that gather every weekday to exercise coached by an older adult. Members attend on average 2.5 days per week and retention rate is 77.5% after 6 years. The members perceived improvements in several health measures. In line with this, the 6-min walk test results of members of this Vitality Club improved with 21.7 meters per year, compared with the decline of 2-7 meters per year in the general population. This Vitality Club is successful in durably engaging its members in physical activity. The members perceive improvements in health that are in line with improvements in a physical function test. Because of the self-sustainable character of the intervention, peer coaching has the potential to be scaled up at low cost and increase physical activity in the increasing number of older adults

Tailoring information about climate change and its impacts

Resultaten van onderzoek naar klimaatverandering en de mogelijke effecten zijn vaak niet beschikbaar in een vorm waarin ze direct door anderen gebruikt kunnen worden. Gebruikers van klimaat- en impactinformatie hebben vaak ook geen goed overzicht over de beschikbare gegevens van alle sectoren en resultaten zijn soms inconsistent

N deposition and elevated CO2 on methane emissions: Differential responses of indirect effects compared to direct effects through litter chemistry feedbacks

Increases in atmospheric CO2 concentration and N deposition are expected to affect methane (CH4) production in soils and emission to the atmosphere, directly through increased plant litter production and indirectly through changes in substrate quality. We examined how CH4 emission responded to changes in litter quality under increased N and CO2, beyond differences in CH4 resulting from changes in litter production. We used senesced leaves from 13C-labeled plants of Molinia caerulea grown at elevated and ambient CO2 and affected by N fertilization to carry out two experiments: a laboratory litter incubation and a pot experiment. N fertilization increased N and decreased C concentrations in litter whereas elevated CO2 decreased litter quality as reflected in litter C and N concentrations and in the composition of lignin and saturated fatty acids within the litter. In contrast to our expectations, CH4 production in the laboratory incubation decreased when using litter from N-fertilized plants as substrate, whereas litter from elevated CO2 had no effect, compared to controls without N and at ambient CO2. Owing to high within-treatment variability in CH4 emissions, none of the treatment effects were reflected in the pot experiment. C mineralization rates were not affected by any of the treatments. The decrease in CH4 emissions due to indirect effects of N availability through litter quality changes (described here for the first time) contrast direct effects of N fertilization on CH4 production. The complex interaction of direct effects with indirect effects of increased N on litter quality may potentially result in a net decrease in CH4 emissions from wetlands in the long term.Fil: Pancotto, Veronica Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Bodegom, P. M. van. University Of Amsterdam; Países BajosFil: Hal, J. van. University Of Amsterdam; Países BajosFil: Logtestijn, R. S. P. van. University Of Amsterdam; Países BajosFil: Blokker, P.. University Of Amsterdam; Países BajosFil: Toet, S.. University Of Amsterdam; Países Bajos. University Of York; Reino UnidoFil: Aerts, R.. University Of Amsterdam; Países Bajo

Methane emissions from floodplains in the Amazon Basin: challenges in developing a process-based model for global applications

Tropical wetlands are estimated to represent about 50% of the natural wetland methane (CH₄) emissions and explain a large fraction of the observed CH₄ variability on timescales ranging from glacial–interglacial cycles to the currently observed year-to-year variability. Despite their importance, however, tropical wetlands are poorly represented in global models aiming to predict global CH₄ emissions. This publication documents a first step in the development of a process-based model of CH₄ emissions from tropical floodplains for global applications. For this purpose, the LPX-Bern Dynamic Global Vegetation Model (LPX hereafter) was slightly modified to represent floodplain hydrology, vegetation and associated CH₄ emissions. The extent of tropical floodplains was prescribed using output from the spatially explicit hydrology model PCR-GLOBWB. We introduced new plant functional types (PFTs) that explicitly represent floodplain vegetation. The PFT parameterizations were evaluated against available remote-sensing data sets (GLC2000 land cover and MODIS Net Primary Productivity). Simulated CH₄ flux densities were evaluated against field observations and regional flux inventories. Simulated CH₄ emissions at Amazon Basin scale were compared to model simulations performed in the WETCHIMP intercomparison project. We found that LPX reproduces the average magnitude of observed net CH₄ flux densities for the Amazon Basin. However, the model does not reproduce the variability between sites or between years within a site. Unfortunately, site information is too limited to attest or disprove some model features. At the Amazon Basin scale, our results underline the large uncertainty in the magnitude of wetland CH₄ emissions. Sensitivity analyses gave insights into the main drivers of floodplain CH₄ emission and their associated uncertainties. In particular, uncertainties in floodplain extent (i.e., difference between GLC2000 and PCR-GLOBWB output) modulate the simulated emissions by a factor of about 2. Our best estimates, using PCR-GLOBWB in combination with GLC2000, lead to simulated Amazon-integrated emissions of 44.4 ± 4.8 Tg yr⁻¹. Additionally, the LPX emissions are highly sensitive to vegetation distribution. Two simulations with the same mean PFT cover, but different spatial distributions of grasslands within the basin, modulated emissions by about 20%. Correcting the LPX-simulated NPP using MODIS reduces the Amazon emissions by 11.3%. Finally, due to an intrinsic limitation of LPX to account for seasonality in floodplain extent, the model failed to reproduce the full dynamics in CH₄ emissions but we proposed solutions to this issue. The interannual variability (IAV) of the emissions increases by 90% if the IAV in floodplain extent is accounted for, but still remains lower than in most of the WETCHIMP models. While our model includes more mechanisms specific to tropical floodplains, we were unable to reduce the uncertainty in the magnitude of wetland CH₄ emissions of the Amazon Basin. Our results helped identify and prioritize directions towards more accurate estimates of tropical CH₄ emissions, and they stress the need for more research to constrain floodplain CH₄ emissions and their temporal variability, even before including other fundamental mechanisms such as floating macrophytes or lateral water fluxes

Self-organizing peer coach groups to increase daily physical activity in community dwelling older adults

Many older adults do not reach the recommended level of physical activity, despite many professional-delivered physical activity interventions. Here we study the implementation of a novel physical activity intervention for older adults that is self-sustainable (no financial support) and self-organizing (participants act as organizers) due to peer coaching. We implemented three groups and evaluated process and effect using participatory observations, questionnaires, six-minute walk tests and body composition measures from October 2016 to September 2018. The intervention was implemented by staff without experience in physical activity interventions. Facilitators were a motivated initiator and a non-professional atmosphere for participants to take ownership. Barriers were the absence of motivated participants to take ownership and insufficient participants to ensure the presence of participants at every exercise session. The groups exercised outside five days a week and were self-organizing after 114, 216 and 263 days. The initial investments were 170_ for sport equipment and 81-187 h. The groups reached 118 members and a retention of 86.4% in two years. The groups continue to exist at the time of writing and are self-sustainable. Quality of life increased 0.4 on a ten-point scale (95%CI 0.1-0.7; p = 0.02) and six-minute walk test results improved with 33 m (95%CI 18-48; p < 0.01) annually. Self-organizing peer coach groups for physical activity are feasible, have positive effects on health and require only a small investment at the start. It is a sustainable and potentially scalable intervention that could be a promising method to help many older adults age healthier

Linking a peer coach physical activity intervention for older adults to a primary care referral scheme

Background Physical inactivity has contributed to the current prevalence of many age-related diseases, including type 2 diabetes and cardiovascular disease. Peer coach physical activity intervention are effective in increasing long term physical activity in community dwelling older adults. Linking peer coach physical activity interventions to formal care could therefore be a promising novel method to improve health in inactive older adults to a successful long-term physical activity intervention. Methods We evaluated the effects of linking a peer coach physical activity intervention in Leiden, The Netherlands to primary care through an exercise referral scheme from July 2018 to April 2020. Primary care practices in the neighborhoods of three existing peer coach physical activity groups were invited to refer patients to the exercise groups. Referrals were registered at the primary care practice and participation in the peer coach groups was registered by the peer coaches of the exercise groups. Results During the study, a total of 106 patients were referred to the peer coach groups. 5.7% of patients participated at the peer coach groups and 66.7% remained participating during the 1 year follow up. The number needed to refer for 1 long term participant was 26.5. The mean frequency of participation of the referred participants was 1.2 times a week. Conclusion Linking a peer coach physical activity intervention for older adults to a primary care referral scheme reached only a small fraction of the estimated target population. However, of the people that came to the peer coach intervention a large portion continued to participate during the entire study period. The number needed to refer to engage one older person in long term physical activity was similar to other referral schemes for lifestyle interventions. The potential benefits could be regarded proportional to the small effort needed to refer