COSORE: A community database for continuous soil respiration and other soil‐atmosphere greenhouse gas flux data

Globally, soils store two to three times as much carbon as currently resides in the atmosphere, and it is critical to understand how soil greenhouse gas (GHG) emissions and uptake will respond to ongoing climate change. In particular, the soil‐to‐atmosphere CO2 flux, commonly though imprecisely termed soil respiration (RS), is one of the largest carbon fluxes in the Earth system. An increasing number of high‐frequency RS measurements (typically, from an automated system with hourly sampling) have been made over the last two decades; an increasing number of methane measurements are being made with such systems as well. Such high frequency data are an invaluable resource for understanding GHG fluxes, but lack a central database or repository. Here we describe the lightweight, open‐source COSORE (COntinuous SOil REspiration) database and software, that focuses on automated, continuous and long‐term GHG flux datasets, and is intended to serve as a community resource for earth sciences, climate change syntheses and model evaluation. Contributed datasets are mapped to a single, consistent standard, with metadata on contributors, geographic location, measurement conditions and ancillary data. The design emphasizes the importance of reproducibility, scientific transparency and open access to data. While being oriented towards continuously measured RS, the database design accommodates other soil‐atmosphere measurements (e.g. ecosystem respiration, chamber‐measured net ecosystem exchange, methane fluxes) as well as experimental treatments (heterotrophic only, etc.). We give brief examples of the types of analyses possible using this new community resource and describe its accompanying R software package

Fine root dynamics and partitioning of root respiration into growth and maintenance components in cool temperate deciduous and evergreen forests

Aims: We aim to show the seasonality of fine root dynamics and examine the relationship between root respiration (Rr) and fine root dynamics. In addition, we try partitioning Rr into growth (Rg) and maintenance (Rm) components. Methods: Soil respiration (Rs), fine root biomass (B), and fine root production (P) were measured simultaneously over a growing season in adjoining deciduous (DF) and evergreen (EF) forests. The Rr was separated from Rs by the trenching method, and Rr was partitioned into Rg and Rm using an empirical model. Results: The seasonality of P was almost the same in both forests, though that of B was different. The Rr showed a positive correlation with P in both sites. Annual Rr was estimated to be 610 (DF) and 393 (EF) g C m⁻² year-¹. Annual Rg and Rm were 121 and 166 (DF), and 86 and 182 (EF) g C m⁻² year-¹, respectively. Conclusions We found a clear seasonal pattern in P and a positive linearity between Rr and P. Despite considerable uncertainty due to the small sample size, presence of larger roots, and measurement uncertainty, the results suggest that our approach is capable of partitioning Rr

Partitioning of root respiration into growth, maintenance, and ion uptake components in a young larch-dominated forest

Purpose Fine roots play an essential role in global carbon cycles, but phenological variations in root function and metabolism are poorly understood. To illustrate the dynamics of fine root function and metabolism in the field, we partitioned root respiration (R-r) into growth (R-g), maintenance (R-m), and ion uptake (R-ion) components using a modified traditional model. Methods A year-round experiment was conducted in a young larch-dominated forest regrowing on bare soil. Soil respiration was measured with a chamber method and partitioned into R-r and heterotrophic respiration by trenching. Fine root biomass and production were measured simultaneously. Using the field data, the model was parameterized, and R-r was further partitioned. Results Annually, R-r (210-253 g C m(-2) yr(-1)) accounts for 45-47% of the total soil respiration. The contribution of fine root R-g, fine root R-m, coarse root R-m, and fine root R-ion were 26-40, 46-51, 10-16, and 12%, respectively. The R-g contribution showed a clear seasonal variation, with a peak in mid-spring and a minimum in early fall, mainly because of different seasonality between fine root production and soil temperature. Conclusion The model parameters were consistent with those from our previous study conducted by the same method in the same site. Thus, we believe that our approach was robust under a relatively simple condition. However, our growth respiration parameter resulting from only field data was much higher than those from laboratory experiments. To further improve our understanding of root respiration, more field data should be accumulated

Variations in biomass, production and respiration of fine roots in a young larch forest

Root respiration (R-r) plays a crucial role in the global carbon balance, because R-r accounts for about a half of soil respiration in typical forest ecosystems. Plant roots are different in metabolism and functions according to size. Fine roots, which are typically defined as roots < 2 mm in diameter, perform important ecosystem functions and consequently govern belowground carbon cycles mainly because of their high turnover rates. However, the phenological variation of fine root functions is not well understood yet. To quantitatively examine the fine mot functions, we adopted an approach to partition R-r into growth respiration (R-g) and maintenance respiration (R-m) using a modified traditional model, in which R-s was proportional to root production, and R-m was proportional to root biomass and exponentially related to soil temperature. We conducted a field experiment on soil respiration and fine root biomass and production over a year in a larch-dominated young forest developing on the bare ground after removing surface organic soil to parameterize the model. The model was significantly parameterized using the field data measured in such simplified field conditions, because we could control spatial variation in heterotrophic respiration and contamination from roots other than fine roots. The annual R-r of all roots was 94 g C m(-2) yr(-1) and accounted for 25% of total soil respiration on average. The annual R-r was partitioned into fine root R-g , fine root R-m and coarse root R-m by 30,44 and 26%, respectively; coarse root R-g was presumed to be negligible. Fine root R-g and R-m varied according to the seasonal variations of fine root production and soil temperature, respectively; the contribution of fine root biomass was minor because of its small seasonality. The contribution of R-g to total fine root respiration was lower in the cold season with low production

Soil carbon flux research in the Asian region : review and future perspectives

Soil respiration (Rs ) is the largest flux of carbon dioxide (CO2) next to photosynthesis in terrestrial ecosystems. With the absorption of atmospheric methane (CH4), upland soils become a large CO2 source and CH4 sink. These soil carbon (C) fluxes are key factors in the mitigation and adaption of future climate change. The Asian region spans an extensive area from the northern boreal to tropical regions in Southeast Asia. As this region is characterised by highly diverse ecosystems, it is expected to experience the strong impact of ecosystem responses to global climate change. For the past two decades, researchers in the AsiaFlux community have meaningfully contributed to improve the current understanding of soil C dynamics, response of soil C fluxes to disturbances and climate change, and regional and global estimation based on model analysis. This review focuses on five important aspects: 1) the historical methodology for soil C flux measurement; 2) responses of soil C flux components to environmental factors; 3) soil C fluxes in typical ecosystems in Asia; 4) the influence of disturbance and climate change on soil C fluxes; and 5) model analysis and the estimation of soil C fluxes in research largely focused in Asia

Sustained large stimulation of soil heterotrophic respiration rate and its temperature sensitivity by soil warming in a cool-temperate forested peatland

We conducted a soil warming experiment in a cool-temperate forested peatland in northern Japan during the snow-free seasons of 2007-2011, to determine whether the soil warming would change the heterotrophic respiration rate and its temperature sensitivity. We elevated the soil temperature by 3 degrees C at 5-cm depth by using overhead infrared heaters and continuously measured hourly soil CO2 fluxes with a 15-channel automated chamber system. The 15 chambers were divided into three groups each with five replications for the control, unwarmed-trenched and warmed-trenched treatments. Soil warming enhanced heterotrophic respiration by 82% (mean of four seasons (2008-2011) observation +/- SD, 6.84 +/- 2.22 mu mol C m(-2) s(-1)) as compared to the unwarmed-trenched treatment (3.76 +/- 0.98 mu mol C m(-2) s(-1)). The sustained enhancement of heterotrophic respiration with soil warming suggests that global warming will accelerate the loss of carbon substantially more from forested peatlands than from other upland forest soils. Soil warming likewise enhanced temperature sensitivity slightly (Q(10), 3.1 +/- 0.08 and 3.3 +/- 0.06 in the four-season average in unwarmed- and warmed-trenched treatments, respectively), and significant effect was observed in 2009 (p<0.001) and 2010 (p<0.01). However, there was no significant difference in the basal respiration rate at 10 degrees C (R-10, 2.2 +/- 0.52 and 2.8 +/- 1.2 mmol C m(-2) s(-1)) between treatments, although the values tended to be high by warming throughout the study period. These results suggest that global warming will enhance not only the heterotrophic respiration rate itself but also its Q(10) in forests with high substrate availability and without severe water stress, and predictions for such ecosystems obtained by using models assuming no change in Q(10) are likely to underestimate the carbon release from the soil to the atmosphere in a future warmer environment