Diagnosing the temperature sensitivity of ecosystem respiration in northern high‐latitude regions

2021 ◽  
Author(s):  
Dongxing Wu ◽  
Shaomin Liu ◽  
Xiuchen Wu ◽  
Xiaofan Yang ◽  
Tongren Xu ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
High Latitude ◽  
Ecosystem Respiration ◽  
Northern High Latitude

Diagnosing temperature sensitivity of respiration at multiple spatial scale in the northern high-latitude regions

2020 ◽  
Author(s):  
Dongxing Wu ◽  
Shaomin Liu ◽  
Ziwei Xu ◽  
Xiaofan Yang ◽  
Xiuchen Wu ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Temperature Sensitivity ◽  
High Latitude ◽  
High Frequency ◽  
Climate Models ◽  
Weighted Average ◽  
Terrestrial Ecosystem ◽  
Accurate Estimation ◽  
Mean Temperature ◽  
Northern High Latitude

<p>Accurate estimation of the temperature sensitivity of respiration (Q<sub>10</sub>) is important for understanding terrestrial ecosystem carbon cycle and its response to climate change, especially in the northern high-latitude regions (NHL). The conventional calculation of temperature sensitivity contain seasonal confounding effects on annual temporal scale. The scale-dependent parameter estimation (SCAPE) method which is based on singular spectral analysis could circumvent confounding effects. However, the process of screening a series of high frequency subsignals to identify the best intrinsic Q<sub>10</sub> produce large error. In this study, we proposed the SCAPE-M method to improve the approach of screening high frequency subsignals. Three datasets were used to validate the SCAPE-M method in the NHL, namely FLUXNET2015 datasets, MsTMIP multi-model weighted average outputs, and ERA_interim reanalysis data. The main results were as follows: (1) On the site scale, the confounding effects in the forest ecosystems were less than grassland and cropland ecosystems in the NHL. The apparent Q<sub>10 </sub>derived from conventional approach differed among biomes in the NHL and increased with annual mean temperature. The mean apparent Q<sub>10</sub> across 36 FLUXNET sites in the NHL was 2.71 ± 0.77. Contrary to the results of apparent Q<sub>10</sub>, the intrinsic Q<sub>10</sub> across 36 FLUXNET sites in the NHL were independent of annual mean temperature, and were confined to values around 1.54 ± 0.38. (2) On the grid scale, the apparent Q<sub>10</sub> increased with annual mean temperature, with high values in the Western Europe and low values in the Mongolian Plateau. There were no significant changes of intrinsic Q<sub>10</sub> in the spatial distribution. While the convergence value 1.01 ± 0.15 on the grid scale was smaller than the site scale. The results in this study indicated that the response of carbon cycle to climate warming in the NHL was less pronounced than suggested by most carbon cycle climate models.</p>

Climatic thresholds shape northern high-latitude fire regimes and imply vulnerability to future climate change

Ecography ◽  
2016 ◽  
Vol 40 (5) ◽  
pp. 606-617 ◽  
Author(s):  
Adam M. Young ◽  
Philip E. Higuera ◽  
Paul A. Duffy ◽  
Feng Sheng Hu
Keyword(s):  
Climate Change ◽  
High Latitude ◽  
Fire Regimes ◽  
Future Climate ◽  
Future Climate Change ◽  
Northern High Latitude

Sub-decadally-resolved Asian monsoon dynamics during Chinese interstadial 21 in response to northern high-latitude climate

2019 ◽  
Vol 172 ◽  
pp. 243-248 ◽  
Author(s):  
Xiuyang Jiang ◽  
Yaoqi He ◽  
Xiaoyan Wang ◽  
Jinguo Dong ◽  
Zhizhong Li ◽  
...  
Keyword(s):  
High Latitude ◽  
Asian Monsoon ◽  
Northern High Latitude ◽  
Monsoon Dynamics

scholarly journals Temperature Sensitivity in Individual Components of Ecosystem Respiration Increases along the Vertical Gradient of Leaf–Stem–Soil in Three Subtropical Forests

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 140
Author(s):  
Yonggang Chi ◽  
Qingpeng Yang ◽  
Lei Zhou ◽  
Ruichang Shen ◽  
Shuxia Zheng ◽  
...  
Keyword(s):  
Loblolly Pine ◽  
Temperature Sensitivity ◽  
Ecosystem Respiration ◽  
Terrestrial Ecosystems ◽  
Vertical Gradient ◽  
Central China ◽  
Masson Pine ◽  
Stem Respiration ◽  
Crucial Parameter ◽  
Process Based Models

Temperature sensitivity (Q10) of ecosystem respiration (ER) is a crucial parameter for predicting the fate of CO2 in terrestrial e cosystems under global warming. Most studies focus their attention in the variation of Q10 in one or two components of ER, but not in the integration or comparison among Q10 in major components of ER. Vertical and seasonal variations in individual components, including leaf respiration, stem respiration and soil respiration, of ER were observed synchronously along the gradient of leaf–stem–soil over a 2 year period in three forest stands dominated by masson pine, loblolly pine and oak, respectively, in a subtropical forest ecosystem of central China. We found that Q10 in individual components of ER increased along the vertical gradient of leaf–stem–soil. The vertical pattern of Q10 in individual components of ER was ascribed to variations of diurnal temperature range (DTR) and activation energy (ΔHa). These results suggest that a vertical pattern of Q10 in individual components of ER along the gradient of leaf–stem–soil should be taken into consideration in process-based models that simulate respiratory carbon flux in terrestrial ecosystems.

scholarly journals Mosaicking Landsat and Sentinel-2 Data to Enhance LandTrendr Time Series Analysis in Northern High Latitude Permafrost Regions

2020 ◽  
Vol 12 (15) ◽  
pp. 2471
Author(s):  
Alexandra Runge ◽  
Guido Grosse
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
High Latitude ◽  
High Latitudes ◽  
Series Analysis ◽  
Data Gaps ◽  
Northern High Latitude ◽  
Study Sites ◽  
Sentinel 2 ◽  
Permafrost Regions

Permafrost is warming in the northern high latitudes, inducing highly dynamic thaw-related permafrost disturbances across the terrestrial Arctic. Monitoring and tracking of permafrost disturbances is important as they impact surrounding landscapes, ecosystems and infrastructure. Remote sensing provides the means to detect, map, and quantify these changes homogeneously across large regions and time scales. Existing Landsat-based algorithms assess different types of disturbances with similar spatiotemporal requirements. However, Landsat-based analyses are restricted in northern high latitudes due to the long repeat interval and frequent clouds, in particular at Arctic coastal sites. We therefore propose to combine Landsat and Sentinel-2 data for enhanced data coverage and present a combined annual mosaic workflow, expanding currently available algorithms, such as LandTrendr, to achieve more reliable time series analysis. We exemplary test the workflow for twelve sites across the northern high latitudes in Siberia. We assessed the number of images and cloud-free pixels, the spatial mosaic coverage and the mosaic quality with spectral comparisons. The number of available images increased steadily from 1999 to 2019 but especially from 2016 onward with the addition of Sentinel-2 images. Consequently, we have an increased number of cloud-free pixels even under challenging environmental conditions, which then serve as the input to the mosaicking process. In a comparison of annual mosaics, the Landsat+Sentinel-2 mosaics always fully covered the study areas (99.9–100 %), while Landsat-only mosaics contained data-gaps in the same years, only reaching coverage percentages of 27.2 %, 58.1 %, and 69.7 % for Sobo Sise, East Taymyr, and Kurungnakh in 2017, respectively. The spectral comparison of Landsat image, Sentinel-2 image, and Landsat+Sentinel-2 mosaic showed high correlation between the input images and mosaic bands (e.g., for Kurungnakh 0.91–0.97 between Landsat and Landsat+Sentinel-2 mosaic and 0.92–0.98 between Sentinel-2 and Landsat+Sentinel-2 mosaic) across all twelve study sites, testifying good quality mosaic results. Our results show that especially the results for northern, coastal areas was substantially improved with the Landsat+Sentinel-2 mosaics. By combining Landsat and Sentinel-2 data we accomplished to create reliably high spatial resolution input mosaics for time series analyses. Our approach allows to apply a high temporal continuous time series analysis to northern high latitude permafrost regions for the first time, overcoming substantial data gaps, and assess permafrost disturbance dynamics on an annual scale across large regions with algorithms such as LandTrendr by deriving the location, timing and progression of permafrost thaw disturbances.

scholarly journals Reviews and syntheses: Changing ecosystem influences on soil thermal regimes in northern high-latitude permafrost regions

2018 ◽  
Vol 15 (17) ◽  
pp. 5287-5313 ◽  
Author(s):  
Michael M. Loranty ◽  
Benjamin W. Abbott ◽  
Daan Blok ◽  
Thomas A. Douglas ◽  
Howard E. Epstein ◽  
...  
Keyword(s):  
Climate Change ◽  
Surface Energy ◽  
High Latitude ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Energy Partitioning ◽  
Climate Feedback ◽  
Permafrost Soil ◽  
Thermal Dynamics ◽  
Northern High Latitude

Abstract. Soils in Arctic and boreal ecosystems store twice as much carbon as the atmosphere, a portion of which may be released as high-latitude soils warm. Some of the uncertainty in the timing and magnitude of the permafrost–climate feedback stems from complex interactions between ecosystem properties and soil thermal dynamics. Terrestrial ecosystems fundamentally regulate the response of permafrost to climate change by influencing surface energy partitioning and the thermal properties of soil itself. Here we review how Arctic and boreal ecosystem processes influence thermal dynamics in permafrost soil and how these linkages may evolve in response to climate change. While many of the ecosystem characteristics and processes affecting soil thermal dynamics have been examined individually (e.g., vegetation, soil moisture, and soil structure), interactions among these processes are less understood. Changes in ecosystem type and vegetation characteristics will alter spatial patterns of interactions between climate and permafrost. In addition to shrub expansion, other vegetation responses to changes in climate and rapidly changing disturbance regimes will affect ecosystem surface energy partitioning in ways that are important for permafrost. Lastly, changes in vegetation and ecosystem distribution will lead to regional and global biophysical and biogeochemical climate feedbacks that may compound or offset local impacts on permafrost soils. Consequently, accurate prediction of the permafrost carbon climate feedback will require detailed understanding of changes in terrestrial ecosystem distribution and function, which depend on the net effects of multiple feedback processes operating across scales in space and time.

scholarly journals Assessment of the theoretical limit in instrumental detectability of northern high-latitude methane sources using <i>δ</i><sup>13</sup>C<sub>CH4</sub> atmospheric signals

2019 ◽  
Vol 19 (19) ◽  
pp. 12141-12161 ◽  
Author(s):  
Thibaud Thonat ◽  
Marielle Saunois ◽  
Isabelle Pison ◽  
Antoine Berchet ◽  
Thomas Hocking ◽  
...  
Keyword(s):  
High Latitude ◽  
Oil And Gas ◽  
Transport Model ◽  
Isotopic Signatures ◽  
Sources And Sinks ◽  
Regional Sources ◽  
Northern High Latitude ◽  
Source Signal ◽  
Methane Source ◽  
Remote Sites

Abstract. Recent efforts have brought together bottom-up quantification approaches (inventories and process-based models) and top-down approaches using regional observations of methane atmospheric concentrations through inverse modelling to better estimate the northern high-latitude methane sources. Nevertheless, for both approaches, the relatively small number of available observations in northern high-latitude regions leaves gaps in our understanding of the drivers and distributions of the different types of regional methane sources. Observations of methane isotope ratios, performed with instruments that are becoming increasingly affordable and accurate, could bring new insights on the contributions of methane sources and sinks. Here, we present the source signal that could be observed from methane isotopic 13CH4 measurements if high-resolution observations were available and thus what requirements should be fulfilled in future instrument deployments in terms of accuracy in order to constrain different emission categories. This theoretical study uses the regional chemistry-transport model CHIMERE driven by different scenarios of isotopic signatures for each regional methane source mix. It is found that if the current network of methane monitoring sites were equipped with instruments measuring the isotopic signal continuously, only sites that are significantly influenced by emission sources could differentiate regional emissions with a reasonable level of confidence. For example, wetland emissions require daily accuracies lower than 0.2 ‰ for most of the sites. Detecting East Siberian Arctic Shelf (ESAS) emissions requires accuracies lower than 0.05 ‰ at coastal Russian sites (even lower for other sites). Freshwater emissions would be detectable with an uncertainty lower than 0.1 ‰ for most continental sites. Except Yakutsk, Siberian sites require stringent uncertainty (lower than 0.05 ‰) to detect anthropogenic emissions from oil and gas or coal production. Remote sites such as Zeppelin, Summit, or Alert require a daily uncertainty below 0.05 ‰ to detect any regional sources. These limits vary with the hypothesis on isotopic signatures assigned to the different sources.

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