Periodic Reporting for period 2 - FluxWIN (The role of non-growing season processes in the methane and nitrous oxide budgets in pristine northern ecosystems)
Okres sprawozdawczy: 2021-10-01 do 2023-03-31
The response of the terrestrial biosphere to climate change is still largely unknown and represents a key uncertainty in climate change predictions. High latitude regions, including Arctic and boreal ecosystems, constitute a key component of the earth system due to significant soil carbon stocks. High latitude regions are net sources of the greenhouse gases methane (CH4) and nitrous oxide (N2O), but there is significant disagreement among flux estimates using different approaches (process-based modeling, ground based measurements, atmospheric measurements) plus an additional further uncertainty due to a rapidly changing environment. Climate change effects are particularly strong during the non-growing season, altering the timing of spring snowmelt, fall freeze-up, and increasing winter temperatures. The changes have significant implications for biogeochemical cycles and ecosystem function across high latitude regions, but there is a lack of baseline measurements for the winter period.
The FluxWIN project addresses the measurement gap for winter, spring and fall CO2, CH4, and N2O measurements that was earlier noted for pristine Arctic and boreal ecosystems. Non-growing season CH4 emissions can account for 10-100% of annual CH4 flux, while next to nothing is known about emissions of N2O during this period. Process-based models miss non-growing season emissions of CH4, underestimating them by 67% and annual emissions by 25%. To develop new baseline measurements of the annual exchange for the three major greenhouse gases, the FluxWIN project installed a new automated flux chamber measurement system at a pristine bog and upland forest site in boreal Finland (see picture; https://www.awi.de/en/science/geosciences/permafrost-research/research-focus/permafrost-region-greenhouse-gases.html ) consisting of 12 chambers, 9 transparent and 3 opaque. We are measuring greenhouse gas fluxes and other key environmental data year-round since 2021. This comprehensively equipped field site offers great opportunities for testing new sensors and methods in a controlled and well-studied system with a reliable environmental reference baseline.
To understand what key biogeochemical processes differ between the growing season and the rest of the year, we are using complementary field measurements, laboratory experiments, data synthesis and process-based modelling. The field measurement results from our site in boreal Finland have shown that freeze-thaw dynamics in the spring and fall can affect the measured fluxes. The laboratory results and data synthesis have quantified rates of methane and CO2 production at low temperatures for not only the FluxWIN sites but also for permafrost sites in Siberia. This illustrates whether process rates in the permafrost ecosystems are similar to other ecosystems. This comparison to permafrost-affected ecosystems is of particular interest since permafrost regions are very remote and it is therefore difficult to maintain an automated chamber system for accurate annual GHG budgets. The process-based modelling approach allows us to extrapolate our measurements both over longer time periods (2011-2021) and over broader spatial scales. The overall impact is to shift the paradigm from “nothing happens outside of the growing season” to “capturing non-growing season processes is key to understanding ecosystem dynamics.” Ultimately, results will provide novel insights into greenhouse gas budgets and transform our understanding of fundamental earth system dynamics.
The FluxWIN project addresses the measurement gap for winter, spring and fall CO2, CH4, and N2O measurements that was earlier noted for pristine Arctic and boreal ecosystems. Non-growing season CH4 emissions can account for 10-100% of annual CH4 flux, while next to nothing is known about emissions of N2O during this period. Process-based models miss non-growing season emissions of CH4, underestimating them by 67% and annual emissions by 25%. To develop new baseline measurements of the annual exchange for the three major greenhouse gases, the FluxWIN project installed a new automated flux chamber measurement system at a pristine bog and upland forest site in boreal Finland (see picture; https://www.awi.de/en/science/geosciences/permafrost-research/research-focus/permafrost-region-greenhouse-gases.html ) consisting of 12 chambers, 9 transparent and 3 opaque. We are measuring greenhouse gas fluxes and other key environmental data year-round since 2021. This comprehensively equipped field site offers great opportunities for testing new sensors and methods in a controlled and well-studied system with a reliable environmental reference baseline.
To understand what key biogeochemical processes differ between the growing season and the rest of the year, we are using complementary field measurements, laboratory experiments, data synthesis and process-based modelling. The field measurement results from our site in boreal Finland have shown that freeze-thaw dynamics in the spring and fall can affect the measured fluxes. The laboratory results and data synthesis have quantified rates of methane and CO2 production at low temperatures for not only the FluxWIN sites but also for permafrost sites in Siberia. This illustrates whether process rates in the permafrost ecosystems are similar to other ecosystems. This comparison to permafrost-affected ecosystems is of particular interest since permafrost regions are very remote and it is therefore difficult to maintain an automated chamber system for accurate annual GHG budgets. The process-based modelling approach allows us to extrapolate our measurements both over longer time periods (2011-2021) and over broader spatial scales. The overall impact is to shift the paradigm from “nothing happens outside of the growing season” to “capturing non-growing season processes is key to understanding ecosystem dynamics.” Ultimately, results will provide novel insights into greenhouse gas budgets and transform our understanding of fundamental earth system dynamics.
In the FluxWIN project, we have made significant progress in establishing methods and systems for the measurement of greenhouse gases in the field and laboratory. We have invested a significant amount of time in the set-up of the field measurement site, the setup of the research group, and the setup of the necessary laboratory facilities at AWI. We have successfully established the field measurement site with the installation of the automated chamber measurement system in June 2021 consisting of 12 chambers. In order to do this, we established line power connection, installed the chambers, measurement control system, and ancillary measurement system, as well as establishing the data transfer protocol that enables remote data access and monitoring of the system. We have been measuring fluxes throughout the year since 2021. One major result from these findings showed the release of methane during the spring thaw period at the wetland site, demonstrating that the system is functioning well and with a high degree of sensitivity to detect this transient effect. This sensitivity also enables the testing of other measurement sensors for CO2 and CH4.
The FluxWIN project team has completed eight expeditions to Finland for site setup, measurement, and sample collection. All together, we have more than one full year of additional experimental-based measurements that will let us test for seasonal differences in the rates of CH4 production, oxidation, and transport. We conducted four laboratory experiments to test key process rates at low temperatures with samples from our main field sites as well as other permafrost sites across the pan-Arctic. These two project parts have provided significant training opportunities for students in both field and laboratory methods, resulting in 3 completed Masters Theses with several more in progress. We have also made progress on the modelling work package in order to test hypotheses of the processes controlling growing and non-growing season CH4 fluxes. We have the preliminary modelling results for the period 2011-2022 and are working on model calibration and evaluation using independent datasets from project collaborators. In addition, the FluxWIN project team work has resulted in 14 related peer-reviewed publications and 4 conference presentations related to polar regions biogeochemistry. Overall, progress is better than expected due to severe corona-related delays restricting project setup and travel to the field site that we encountered since the beginning of the project in 2020.
The FluxWIN project team has completed eight expeditions to Finland for site setup, measurement, and sample collection. All together, we have more than one full year of additional experimental-based measurements that will let us test for seasonal differences in the rates of CH4 production, oxidation, and transport. We conducted four laboratory experiments to test key process rates at low temperatures with samples from our main field sites as well as other permafrost sites across the pan-Arctic. These two project parts have provided significant training opportunities for students in both field and laboratory methods, resulting in 3 completed Masters Theses with several more in progress. We have also made progress on the modelling work package in order to test hypotheses of the processes controlling growing and non-growing season CH4 fluxes. We have the preliminary modelling results for the period 2011-2022 and are working on model calibration and evaluation using independent datasets from project collaborators. In addition, the FluxWIN project team work has resulted in 14 related peer-reviewed publications and 4 conference presentations related to polar regions biogeochemistry. Overall, progress is better than expected due to severe corona-related delays restricting project setup and travel to the field site that we encountered since the beginning of the project in 2020.
In the FluxWIN project, we expect to identify flux magnitude of greenhouses gases and understand the underlying processes using complementary observations (WP1), modelling (WP2), and experiments (WP3) to quantify the annual magnitude of CH4 and N2O flux, identify controls on non-growing season flux, and assess why existing models of CH4 flux fail outside of the growing season. Currently, our progress is aimed at attaining state-of-the-art chamber measurement systems (manual and automated) in WP1. We are on track to achieve this goal within the next six months. In WP1, we expect to measure fluxes of greenhouse gases (CO2, CH4, and N2O) throughout the year; preliminary observational results indicate that these measurements are successful even during colder conditions found in the fall period. Results from WP3 will show magnitudes and controls on processes that produce greenhouse gases. Results from WP2 will identify whether models can reproduce observations; results from model experiments in WP2 will assess whether processes tested in WP1 and WP2 can be reproduced. This is how we plan to progress beyond the state-of-the-art knowledge about greenhouse gas fluxes and underlying processes.