scholarly journals Multi-Year Monitoring of Ecosystem Metabolism in Two Branches of a Cold-Water Stream

Environments ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 19
Author(s):  
Daniel J. Hornbach
Keyword(s):  
Climate Change ◽  
Cold Water ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Ecosystem Metabolism ◽  
Freshwater Biodiversity ◽  
Water Stream ◽  
Stream Discharge ◽  
Biodiversity And Ecosystem Function

Climate change is likely to have large impacts on freshwater biodiversity and ecosystem function, especially in cold-water streams. Ecosystem metabolism is affected by water temperature and discharge, both of which are expected to be affected by climate change and, thus, require long-term monitoring to assess alterations in stream function. This study examined ecosystem metabolism in two branches of a trout stream in Minnesota, USA over 3 years. One branch was warmer, allowing the examination of elevated temperature on metabolism. Dissolved oxygen levels were assessed every 10 min from spring through fall in 2017–2019. Gross primary production (GPP) was higher in the colder branch in all years. GPP in both branches was highest before leaf-out in the spring. Ecosystem respiration (ER) was greater in the warmer stream in two of three years. Both streams were heterotrophic in all years (net ecosystem production—NEP < 0). There were significant effects of temperature and light on GPP, ER, and NEP. Stream discharge had a significant impact on all GPP, ER, and NEP in the colder stream, but only on ER and NEP in the warmer stream. This study indicated that the impacts of temperature, light, and discharge differ among years, and, at least at the local scale, may not follow expected patterns.

Mismatch between the optimal ages for ecosystem productivity and net CO2 sequestration in Norway spruce forests

2021 ◽  
Author(s):  
Junbin Zhao ◽  
Holger Lange ◽  
Helge Meissner
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Norway Spruce ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Economic Benefits ◽  
Sink Strength ◽  
Climate Change Scenarios ◽  
Ecosystem Productivity ◽  
Spruce Forests

&lt;p&gt;Forests have climate change mitigation potential since they sequester carbon. However, their carbon sink strength might depend on management. As a result of the balance between CO&lt;sub&gt;2&lt;/sub&gt; uptake and emission, forest net ecosystem exchange (NEE) reaches optimal values (maximum sink strength) at young stand ages, followed by a gradual NEE decline over many years. Traditionally, this peak of NEE is believed to be concurrent with the peak of primary production (e.g., gross primary production, GPP); however, in theory, this concurrence may potentially vary depending on tree species, site conditions and the patterns of ecosystem respiration (R&lt;sub&gt;eco&lt;/sub&gt;). In this study, we used eddy-covariance (EC)-based CO&lt;sub&gt;2&lt;/sub&gt; flux measurements from 8 forest sites that are dominated by Norway spruce (Picea abies L.) and built machine learning models to find the optimal age of ecosystem productivity and that of CO&lt;sub&gt;2&lt;/sub&gt; sequestration. We found that the net CO&lt;sub&gt;2&lt;/sub&gt; uptake of Norway spruce forests peaked at ages of 30-40 yrs. Surprisingly, this NEE peak did not overlap with the peak of GPP, which appeared later at ages of 60-90 yrs. The mismatch between NEE and GPP was a result of the R&lt;sub&gt;eco&lt;/sub&gt; increase that lagged behind the GPP increase associated with the tree growth at early age. Moreover, we also found that newly planted Norway spruce stands had a high probability (up to 90%) of being a C source in the first year, while, at an age as young as 5 yrs, they were likely to be a sink already. Further, using common climate change scenarios, our model results suggest that net CO&lt;sub&gt;2&lt;/sub&gt; uptake of Norway spruce forests will increase under the future climate with young stands in the high latitude areas being more beneficial. Overall, the results suggest that forest management practices should consider NEE and forest productivity separately and harvests should be performed only after the optimal ages of both the CO&lt;sub&gt;2&lt;/sub&gt; sequestration and productivity to gain full ecological and economic benefits.&lt;/p&gt;

Data-based machine learning unveils ecosystem metabolic regimes at the scale of entire stream networks

2020 ◽  
Author(s):  
Pier Luigi Segatto ◽  
Tom J. Battin ◽  
Enrico Bertuzzo
Keyword(s):  
Machine Learning ◽  
Carbon Cycle ◽  
Ecosystem Respiration ◽  
Spatial Scales ◽  
Gross Primary Production ◽  
Data Availability ◽  
Ecosystem Metabolism ◽  
Sensor Technology ◽  
Stream Network ◽  
Metabolic Fluxes

&lt;p&gt;Inland waters are major contributors to the global carbon cycle. Nowadays, new sensor technology has changed the way we study ecosystem metabolism in streams. We are able to produce long-term time series of gross primary production (GPP) and ecosystem respiration (ER) to infer drivers of the stream ecosystem metabolic regime and its seasonal timing. Despite big data availability, most studies are limited to individual stream reaches and do not allow the appreciation of metabolic regimes at the scale of entire networks, which, however, would be fundamental to properly assess the relevance of metabolic fluxes within streams and rivers for carbon cycling at the regional and global scale. Machine learning (ML) has great potential in this direction. Firstly, ML could be used to extrapolate both in time and space heterogeneous forcings (e.g., streamwater temperature (T) and photosynthetic active radiation (PAR)) required to run a process-based model for reach-scale metabolism to the scale of an entire stream network. Secondly, the same procedure could be applied to reach-scale estimates of ecosystem metabolism to check whether available data contain enough information to explain the network scale variability. In this study, we used Random Forest to predict patterns of environmental forcings (T and PAR) and stream metabolism (GPP and ER) at the scale of an entire stream network. We used available high-frequency measurements of T and PAR, estimates of ecosystem metabolism and major proximal controls (e.g., incident light, discharge, stream-bed slope, drainage area, water level, &amp;#160;air temperature) from twelve reaches within the Ybbs River network (Austria) and explicitly trained our Random Forests by integrating distal factors, namely: &amp;#160;vegetation type, canopy cover, hydro-geomorphic properties, light, &amp;#160;precipitation, and other climatic variables. We designed two different training setups to assess spatial and temporal predicting model capabilities, respectively. This approach allowed us to reliably infer the target variables (T, PAR, GPP, and ER) on annual basis across a stream network, to filter the most important predictors, to assess the relative contribution of the metabolic fluxes from small to large streams, to estimate annual metabolic budgets at different spatial scales and to provide empirical evidence for long-standing theory predicting shifts of ecosystem metabolism along the stream continuum. Finally, we estimated autochthonous and allochthonous respiration for the entire stream network, which is crucial to integrate the role of ecosystem processes for the carbon cycle.&lt;/p&gt;

scholarly journals Hydromorphological restoration stimulates river ecosystem metabolism

2016 ◽  
Author(s):  
Benjamin Kupilas ◽  
Daniel Hering ◽  
Armin W. Lorenz ◽  
Christoph Knuth ◽  
Björn Gücker
Keyword(s):  
Open Channel ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Ecosystem Metabolism ◽  
Ecosystem Structure ◽  
Third Order ◽  
Goods And Services ◽  
Ecosystem Structure And Functioning ◽  
The One ◽  
Substantial Effort

Abstract. Both, ecosystem structure and functioning determine ecosystem status and are important for the provision of goods and services to society. However, there is a paucity of research that couples functional measures with assessments of ecosystem structure. In mid-sized and large rivers, effects of restoration on key ecosystem processes, such as ecosystem metabolism, have rarely been addressed and remain poorly understood. We compared three reaches of the third-order, gravel-bed river Ruhr in Germany: two reaches restored with moderate (R1) and substantial effort (R2) and one upstream degraded reach (D). Hydromorphology, habitat composition and hydrodynamics were assessed. We estimated gross primary production (GPP) and ecosystem respiration (ER) using the one-station open-channel diel dissolved oxygen change method over a 50-day period at the end of each reach. Values for hydromorphological variables increased with restoration intensity (D 

scholarly journals Long-term drainage reduces CO<sub>2</sub> uptake and increases CO<sub>2</sub> emission on a Siberian floodplain due to shifts in vegetation community and soil thermal characteristics

2016 ◽  
Vol 13 (14) ◽  
pp. 4219-4235 ◽  
Author(s):  
Min Jung Kwon ◽  
Martin Heimann ◽  
Olaf Kolle ◽  
Kristina A. Luus ◽  
Edward A. G. Schuur ◽  
...  
Keyword(s):  
Primary Production ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Thermal Characteristics ◽  
Growing Season ◽  
Co2 Uptake ◽  
Vegetation Community ◽  
Uptake Rates ◽  
Soil Temperatures

Abstract. With increasing air temperatures and changing precipitation patterns forecast for the Arctic over the coming decades, the thawing of ice-rich permafrost is expected to increasingly alter hydrological conditions by creating mosaics of wetter and drier areas. The objective of this study is to investigate how 10 years of lowered water table depths of wet floodplain ecosystems would affect CO2 fluxes measured using a closed chamber system, focusing on the role of long-term changes in soil thermal characteristics and vegetation community structure. Drainage diminishes the heat capacity and thermal conductivity of organic soil, leading to warmer soil temperatures in shallow layers during the daytime and colder soil temperatures in deeper layers, resulting in a reduction in thaw depths. These soil temperature changes can intensify growing-season heterotrophic respiration by up to 95 %. With decreased autotrophic respiration due to reduced gross primary production under these dry conditions, the differences in ecosystem respiration rates in the present study were 25 %. We also found that a decade-long drainage installation significantly increased shrub abundance, while decreasing Eriophorum angustifolium abundance resulted in Carex sp. dominance. These two changes had opposing influences on gross primary production during the growing season: while the increased abundance of shrubs slightly increased gross primary production, the replacement of E. angustifolium by Carex sp.  significantly decreased it. With the effects of ecosystem respiration and gross primary production combined, net CO2 uptake rates varied between the two years, which can be attributed to Carex-dominated plots' sensitivity to climate. However, underlying processes showed consistent patterns: 10 years of drainage increased soil temperatures in shallow layers and replaced E. angustifolium by Carex sp., which increased CO2 emission and reduced CO2 uptake rates. During the non-growing season, drainage resulted in 4 times more CO2 emissions, with high sporadic fluxes; these fluxes were induced by soil temperatures, E. angustifolium abundance, and air pressure.

Net ecosystem exchange of CO2 and ecosystem respiration in two bogs in Estonia along disturbance gradient

2021 ◽  
Author(s):  
Martin Maddison ◽  
Gert Veber ◽  
Ain Kull
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Water Table ◽  
Air Temperature ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Growing Period ◽  
Disturbance Gradient ◽  
Study Sites

&lt;p&gt;Northern peatlands are important terrestrial carbon (C) stores, but their ability to sequestrate C is at delicate balance affected by management and also by climate change. The climate change causes less snow pack and warmer winters with faster water table drop in spring and drier summers in most boreal areas. Due to those changes natural peatlands may become C source instead of sink.&lt;/p&gt;&lt;p&gt;This study presents ecosystem respiration (ER) over five-year period and the annual estimates of net ecosystem exchange (NEE) of CO&lt;sub&gt;2&lt;/sub&gt; in Umbusi and Laukasoo in Estonia along disturbance gradient from drained to natural ombrotrophic bog. Both study sites locate next to the active cutaway peatlands. There were four CO&lt;sub&gt;2&lt;/sub&gt; flux measurements plots with three measurements points at different distance from the drainage ditch (10, 50, 100 and 200 m in Umbusi; 3, 40, 50, 125 m in Laukasoo) to form a water table depth and soil moisture gradient on both study sites. ER was measured using opaque static chamber throughout of the year in period 2012-2016. A vented and thermostated transparent plastic chamber with removable opaque cover was used for CO&lt;sub&gt;2&lt;/sub&gt; exchange measurements. NEE measurements occurred biweekly from April to December in 2015, totally were done 648 measurements. NEE was derived from modelling of ER and gross primary production with temperature, photosynthetically active radiation, water level and days of year (as phenological phase) as driving variables.&lt;/p&gt;&lt;p&gt;Annual mean NEE at four different distance from the ditch toward undisturbed area in Umbusi and Laukasoo were 0.37, 0.28, 0.15, 0.08 and 0.44, 0.34, 0.04, 0.21 kg C m&lt;sup&gt;-2&lt;/sup&gt; y&lt;sup&gt;-1&lt;/sup&gt;, respectively. Although mean NEE was positive for all plots on both sites, there were also negative annual NEE values in some points in undisturbed plots (100 and 200 m from the ditch in Umbusi and 50 and 125 m in Laukasoo).&lt;/p&gt;&lt;p&gt;Average water level at four different distance from the ditch toward undisturbed area in Umbusi and Laukasoo during growing period (from the beginning of May to the end of October) in 2015 were -94, -45, -22, -22 and -124, -33, -21, -22 cm, respectively. Monthly mean air temperature and sum of precipitation were not different from the long-term measurements in studied growing period in 2015 while winter was significantly warmer.&lt;/p&gt;&lt;p&gt;Modelled ER remained high for cold period because of higher air temperature in 2015. Due to higher respiration rate from non-frozen peat layer in cold season, more CO&lt;sub&gt;2&lt;/sub&gt; was released back to atmosphere and annually less C was accumulated. Monthly mean air temperature for cold period was 3.5 &amp;#186;C warmer than the long-term average.&lt;/p&gt;

Long-term impact of nitrogen addition on the carbon balance of a boreal pine forest in Northern Sweden

2020 ◽  
Author(s):  
Peng Zhao ◽  
Jinshu Chi ◽  
Mats Nilsson ◽  
Mikaell Ottosson.Lofvenius ◽  
Sune Linder ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Weather Conditions ◽  
C Sequestration ◽  
Nitrogen Addition ◽  
N Addition ◽  
Climate Conditions ◽  
Sequestration Potential

&lt;p&gt;Nitrogen (N) added through atmospheric deposition or as fertilizer in boreal forests may alter their carbon (C) sequestration potential and sensitivity to climatic changes. While previous studies have primarily explored the responses of individual ecosystem components such as stem biomass production and soil carbon changes following N addition, the long-term impacts of N addition on the ecosystem-scale C balance of boreal forests still remain unclear. Here, we use data from eddy-covariance measurements in a fertilized Scots pine (Pinus sylvestris L.) forest (i.e. 16 ha receiving 100 and 50 kg N ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; since 2006 and 2012, respectively) and an adjacent unfertilized control stand in boreal Sweden to investigate how one decade of N addition affected the net ecosystem productivity (NEP), gross primary production (GPP) and ecosystem respiration (ER) over five fertilization years (2015-2019). Results showed that N fertilization increased GPP in all five years with by 18% at average to 1183&amp;#177;41 g C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; in the N-fertilized stand compared to 1003&amp;#177;56 g C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; in the control stand. ER was also increased from 744&amp;#177;29 g C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; in the control stand to 875&amp;#177;37 g C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; in the fertilized stand. As a result, fertilization increased NEP from 259&amp;#177;28 g C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; in the control stand to 308&amp;#177;20 g C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; in the N-fertilized stand. Our results further suggested that the annual NEP was similar between stands during years with normal weather conditions (2015-2016) while NEP diverged due to a larger reduction in the control stand in years with environmental constraints (i.e. a cool summer in 2017 and droughts in 2018 and 2019). These findings indicate that enhanced N input to boreal forests increases and stabilizes their C sequestration potential under future climate conditions.&lt;/p&gt;

scholarly journals Hydromorphological restoration stimulates river ecosystem metabolism

2017 ◽  
Vol 14 (7) ◽  
pp. 1989-2002 ◽  
Author(s):  
Benjamin Kupilas ◽  
Daniel Hering ◽  
Armin W. Lorenz ◽  
Christoph Knuth ◽  
Björn Gücker
Keyword(s):  
Ecosystem Functioning ◽  
Open Channel ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Ecosystem Metabolism ◽  
Transient Storage ◽  
Ecosystem Structure ◽  
Goods And Services ◽  
Wetted Area ◽  
Particulate Nutrients

Abstract. Both ecosystem structure and functioning determine ecosystem status and are important for the provision of goods and services to society. However, there is a paucity of research that couples functional measures with assessments of ecosystem structure. In mid-sized and large rivers, effects of restoration on key ecosystem processes, such as ecosystem metabolism, have rarely been addressed and remain poorly understood. We compared three reaches of the third-order, gravel-bed river Ruhr in Germany: two reaches restored with moderate (R1) and substantial effort (R2) and one upstream degraded reach (D). Hydromorphology, habitat composition, and hydrodynamics were assessed. We estimated gross primary production (GPP) and ecosystem respiration (ER) using the one-station open-channel diel dissolved oxygen change method over a 50-day period at the end of each reach. Moreover, we estimated metabolic rates of the combined restored reaches (R1 + R2) using the two-station open-channel method. Values for hydromorphological variables increased with restoration intensity (D  <  R1  <  R2). Restored reaches had lower current velocity, higher longitudinal dispersion and larger transient storage zones. However, fractions of median travel time due to transient storage were highest in R1 and lowest in R2, with intermediate values in D. The share of macrophyte cover of total wetted area was highest in R2 and lowest in R1, with intermediate values in D. Station R2 had higher average GPP and ER than R1 and D. The combined restored reaches R1 + R2 also exhibited higher GPP and ER than the degraded upstream river (station D). Restoration increased river autotrophy, as indicated by elevated GPP : ER, and net ecosystem production (NEP) of restored reaches. Temporal patterns of ER closely mirrored those of GPP, pointing to the importance of autochthonous production for ecosystem functioning. In conclusion, high reach-scale restoration effort had considerable effects on river hydrodynamics and ecosystem functioning, which were mainly related to massive stands of macrophytes. High rates of metabolism and the occurrence of dense macrophyte stands may increase the assimilation of dissolved nutrients and the sedimentation of particulate nutrients, thereby positively affecting water quality.

scholarly journals Drivers of Ecosystem Metabolism in Two Managed Shallow Lakes with Different Salinity and Trophic Conditions: The Sauce Grande and La Salada Lakes (Argentina)

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1136 ◽  
Author(s):  
María Alfonso ◽  
Andrea Brendel ◽  
Alejandro Vitale ◽  
Carina Seitz ◽  
María Piccolo ◽  
...  
Keyword(s):  
Water Management ◽  
Shallow Lakes ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Eutrophic Lake ◽  
Ecosystem Metabolism ◽  
Management Policy ◽  
Effective Management ◽  
Trophic Conditions ◽  
Lake Volume

Understanding the drivers and how they affect ecosystem metabolism is essential for developing effective management policy and plans. In this study, net ecosystem production (NEP), ecosystem respiration (R), and gross primary production (GPP) rates were estimated in relation to physicochemical, hydrological, and meteorological variables in La Salada (LS) and Sauce Grande (SG), two shallow lakes located in an important agricultural region with water management. LS is a mesosaline, mesotrophic-eutrophic lake, whereas SG is a hyposaline and eutrophic lake. GPP and R showed daily and seasonal variations, with R exceeding GPP during most of the study period in both lakes. Net heterotrophic conditions prevailed during the study period (NEP LS: −1.1 mmol O2 m−2 day−1 and NEP SG: −1.25 mmol O2 m−2 day−1). From data analysis, the temperature, wind speed, and lake volume are the main drivers of ecosystem metabolism for both lakes. Despite the significant differences between the two lakes, the NEP values were similar. The different hydrological characteristics (endorheic vs. flushing lake) were crucial in explaining why the two different systems presented similar ecosystem metabolic rates, emphasizing the importance of water management.

scholarly journals Simulation of Carbon Exchange from a Permafrost Peatland in the Great Hing’an Mountains Based on CoupModel

Atmosphere ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 44
Author(s):  
Yue Li ◽  
Zhongmei Wan ◽  
Li Sun
Keyword(s):  
Climate Change ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Net Ecosystem Exchange ◽  
Carbon Accumulation ◽  
Future Climate ◽  
Future Climate Change ◽  
Growing Seasons ◽  
Source Sink

Climate change is accelerating its impact on northern ecosystems. Northern peatlands store a considerable amount of C, but their response to climate change remains highly uncertain. In order to explore the feedback of a peatland in the Great Hing’an Mountains to future climate change, we simulated the response of the overall net ecosystem exchange (NEE), ecosystem respiration (ER), and gross primary production (GPP) during 2020–2100 under three representative concentration pathways (RCP2.6, RCP6.0, and RCP8.5). Under the RCP2.6 and RCP6.0 scenarios, the carbon sink will increase slightly until 2100. Under the RCP8.5 scenario, the carbon sink will follow a trend of gradual decrease after 2053. These results show that when meteorological factors, especially temperature, reach a certain degree, the carbon source/sink of the peatland ecosystem will be converted. In general, although the peatland will remain a carbon sink until the end of the 21st century, carbon sinks will decrease under the influence of climate change. Our results indicate that in the case of future climate warming, with the growing seasons experiencing overall dryer and warmer environments and changes in vegetation communities, peatland NEE, ER, and GPP will increase and lead to the increase in ecosystem carbon accumulation.

scholarly journals Uncertainty sources in simulated ecosystem indicators of the 21st century climate change

2019 ◽  
Author(s):  
Jarmo Mäkelä ◽  
Francesco Minunno ◽  
Tuula Aalto ◽  
Annikki Mäkelä ◽  
Tiina Markkanen ◽  
...  
Keyword(s):  
Climate Change ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Ecosystem Model ◽  
Forest Growth ◽  
Model Parameters ◽  
Management Actions ◽  
Uncertainty Sources ◽  
Ecosystem Indicators ◽  
Rcp Scenario

Abstract. The forest ecosystems are already responding to increased CO2 concentrations and changing environmental conditions. These ongoing developments affect how societies can utilise and benefit from the woodland areas in the future, be it e.g. climate change mitigation as carbon sinks, lumber for wood industry or preserved for nature tourism and recreational activities. We assess the effect and the relative magnitude of different uncertainty sources in ecosystem model simulations from the year 1980 to 2100 for two Finnish boreal forest sites. The models used in this study are the land ecosystem model JSBACH and the forest growth model PREBAS. The considered uncertainty sources for both models are model parameters, four prescribed climates and two RCP (Representative Concentration Pathway) scenarios. PREBAS simulations also include an additional RCP scenario and two forest management actions. We assess the effect of these sources at four different stages of the simulations on several ecosystem indicators of climate change, e.g. gross primary production (GPP), ecosystem respiration, soil moisture, recurrence of drought, length of the vegetation active period (VAP), length of the snow melting period and the stand volume. The climate model uncertainty remains roughly the same throughout the simulations and is overtaken by the RCP scenario impact halfway through the experiment. The management actions are the most dominant uncertainty factors for Hyytiälä and as important as RCP scenarios at the end of the simulations, but contribute only half as much for Sodankylä. The parameter uncertainty is the most elusive to estimate due to non-linear and adverse effects on the simulated ecosystem indicators.

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