scholarly journals Massive C loss from subalpine grassland soil with seasonal warming larger than 1.5 °C in an altitudinal transplantation experiment

2021 ◽  
Author(s):  
Matthias Volk ◽  
Matthias Suter ◽  
Anne-Lena Wahl ◽  
Seraina Bassin
Keyword(s):  
Climate Change ◽  
Primary Productivity ◽  
Plant Material ◽  
Ecosystem Respiration ◽  
Irrigation Treatment ◽  
Climate Scenario ◽  
N Deposition ◽  
Transplantation Experiment ◽  
C Stock ◽  
Leachate Water

Abstract. Climate change is associated with a change in soil organic carbon (SOC) stocks, implying a feedback mechanism on global warming. Grassland soils represent 28 % of the global soil C sink and are therefore important for the atmospheric greenhouse gas concentration. In a field experiment in the Swiss Alps we recorded changes in the ecosystem organic carbon stock under climate change conditions, while quantifying the ecosystem C fluxes at the same time (ecosystem respiration, gross primary productivity, C export in plant material and leachate water). We exposed 216 grassland monoliths to six different climate scenarios (CS) in an altitudinal transplantation experiment. In addition, we applied an irrigation treatment (+12–21 % annual precipitation) and an N deposition treatment (+3 and +15 kg N ha−1 a−1) in a factorial design, simulating summer-drought mitigation and atmospheric N pollution. In five years the ecosystem C stock, consisting of plant C and SOC, dropped dramatically by about −14 % (−1034 ± 610 g C m−2) with the CS treatment representing a +3.0 °C seasonal (Apr.–Oct.) warming. N deposition and the irrigation treatment caused no significant effects. Measurements of C fluxes revealed that ecosystem respiration increased by 10 % at the +1.5 °C warmer CS site and by 38 % at the +3 °C warmer CS site (P ≤ 0.001 each), compared to the CS reference site with no warming. However, gross primary productivity was unaffected by warming, as were the amounts of exported C in harvested plant material and leachate water (dissolved organic C). As a result, the five year C flux balance resulted in a climate scenario effect of −936 ± 138 g C m−2 at the +3.0 °C CS, similar to the C stock climate scenario effect. It is likely that this dramatic C loss of the grassland is a transient effect before a new, climate adjusted steady state is reached.

Effects of climate change and nitrogen deposition on the carbon sequestration of a forest ecosystem in the boreal zone

1999 ◽  
Vol 29 (10) ◽  
pp. 1490-1501 ◽  
Author(s):  
Raisa Mäkipää ◽  
Timo Karjalainen ◽  
Ari Pussinen ◽  
Seppo Kellomäki
Keyword(s):  
Climate Change ◽  
Carbon Sequestration ◽  
Nitrogen Deposition ◽  
Forest Ecosystem ◽  
Rotation Period ◽  
N Deposition ◽  
Climatic Conditions ◽  
Deposition Rates ◽  
Soil C ◽  
C Stock

Global warming and nitrogen deposition are expected to modify the carbon sequestration of boreal forests, causing feedback to atmospheric CO2 and climate. The objective of this study was to assess the effects of climate change and various N deposition rates on C sequestration of a forest ecosystem. The study uses a gap-type forest model for a managed Scots pine (Pinus sylvestris L.) stand in conditions representing southern Finland. Model computations indicated that, for both current and changed (+4°C and +10% in precipitation) climatic conditions, increased levels of N deposition from 6 to 12 kg·ha-1 per year increased C uptake by 4-6.5%. Total C stock (vegetation, litter, and soil organic matter) was 11% higher for current level of N deposition than without deposition. Changed climate resulted in a 10% higher C stock of the vegetation but 30% lower C stock in the forest soil. Consequently, the total C stock in forests was decreased because of the greater decline in soil C stock. The combined effects of climate change and N deposition decreased the average C stock of forest (over a 100-year rotation period) with annual deposition rates under 12 kg N·ha-1 but slightly increased C stock with deposition of 24 kg N·ha-1.

scholarly journals The rising productivity of alpine grassland under warming, drought and N-deposition treatments

2020 ◽  
Author(s):  
Matthias Volk ◽  
Matthias Suter ◽  
Anne-Lena Wahl ◽  
Seraina Bassin
Keyword(s):  
Temperature Change ◽  
Irrigation Treatment ◽  
Climate Scenario ◽  
Growing Season ◽  
Experimental Period ◽  
N Deposition ◽  
Climate Conditions ◽  
Common Location ◽  
The Mean ◽  
C 50

Abstract. We conducted a four-year warming × moisture × N-deposition field-experiment (AlpGrass) with 216 turf monoliths from six different subalpine pastures (sites of origin). At a common location, the monoliths were replanted at six climate scenario sites (CS) along an altitudinal gradient from 2360 to 1680 m a.s.l., representing an April–October temperature change of −1.4 °C to +3.0 °C, compared to CSreference with no temperature change and with climate conditions comparable to the sites of origin. We further applied an irrigation treatment (+12–21 % of ambient precipitation) and an N-deposition treatment (+3 kg and +15 kg N ha−1 a−1), the latter simulating a fertilizing air pollution effect. Moderate warming led to increased productivity. Across the four-year experimental period, the mean annual yield peaked at intermediate CSs (+43 % at +0.7 °C and +44 % at +1.8 °C), coinciding with c. 50 % of days with dry soil during the growing season (growing-season-days with soil moisture

scholarly journals Effects of climatic factors on the net primary productivity in the source region of Yangtze River, China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhe Yuan ◽  
Yongqiang Wang ◽  
Jijun Xu ◽  
Zhiguang Wu
Keyword(s):  
Climate Change ◽  
Primary Productivity ◽  
Yangtze River ◽  
Net Primary Productivity ◽  
Climatic Factors ◽  
Source Region ◽  
Primary Reason ◽  
Vegetation Types ◽  
Temperature And Precipitation ◽  
Increasing Trend

AbstractThe ecosystem of the Source Region of Yangtze River (SRYR) is highly susceptible to climate change. In this study, the spatial–temporal variation of NPP from 2000 to 2014 was analyzed, using outputs of Carnegie–Ames–Stanford Approach model. Then the correlation characteristics of NPP and climatic factors were evaluated. The results indicate that: (1) The average NPP in the SRYR is 100.0 gC/m2 from 2000 to 2014, and it shows an increasing trend from northwest to southeast. The responses of NPP to altitude varied among the regions with the altitude below 3500 m, between 3500 to 4500 m and above 4500 m, which could be attributed to the altitude associated variations of climatic factors and vegetation types; (2) The total NPP of SRYR increased by 0.18 TgC per year in the context of the warmer and wetter climate during 2000–2014. The NPP was significantly and positively correlated with annual temperature and precipitation at interannual time scales. Temperature in February, March, May and September make greater contribution to NPP than that in other months. And precipitation in July played a more crucial role in influencing NPP than that in other months; (3) Climatic factors caused the NPP to increase in most of the SRYR. Impacts of human activities were concentrated mainly in downstream region and is the primary reason for declines in NPP.

Analyzing competing land use policy objectives under climate change – a regional case study from Austria

2021 ◽  
Author(s):  
Katrin Karner ◽  
Hermine Mitter ◽  
Erwin Schmid
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Organic Carbon ◽  
Nitrate Leaching ◽  
Climate Scenario ◽  
Groundwater Extraction ◽  
Climate Scenarios ◽  
Abandoned Land ◽  
Policy Objectives ◽  
Net Benefits

<p>In the semi-arid Seewinkel region in Austria, competing demands exist for land and water such as from agriculture, nature protection, tourism and settlements. In addition, water quality problems are prevalent due to nitrate leaching in groundwater in the region. Climate change likely will amplify existing resource demands and environmental impacts, imposing considerable challenges for adapting and regulating agriculture in the Seewinkel. Hence, compromises between competing policy objectives are needed. <br>The aim of this presentation is to assess efficient land and water management strategies considering several economic and agro-ecological policy objectives in the Seewinkel region in context of climate scenarios. A multi-objective optimization experiment was performed with an integrated modelling framework to compute agro-economic-ecological Pareto frontiers. The frontiers combine levels of (i) net benefits from agricultural production, (ii) groundwater extraction for agricultural irrigation, (iii) nitrate leaching from agricultural production, and (iv) topsoil organic carbon stocks. 30 stochastic realizations of three climate scenarios are considered for a future period of 31 years: WET, SIMILAR and DRY, which mainly differ regarding annual precipitation volumes. <br>Model results show that a 1% (20%) reduction of agricultural net benefits can lower groundwater extraction by 11-83% (61-100%) and nitrate leaching by 18-19% (49-53%) as well as increase topsoil organic carbon sequestration by 1% (5%) depending on the climate scenario. However, substantial changes in land use and management would be required. For instance, less groundwater extraction by 11-83% requires a 6-21% reduction of irrigated cropland, a 21-33% reduction of highly fertilized cropland, a 10-24% increase of grassland, and a 23-52% increase of abandoned land depending on the climate scenario. Less nitrate leaching by 18-19% (or higher topsoil organic carbon stocks by 1%) require that highly fertilized cropland decreases by 9-13% (4-7%), abandoned land increases by 5-9% (19-49%) and grassland either declines by 3% (14%) or increases by up to 5% (32%) depending on the climate scenario. In general, the share of grassland increases in the wetter climate scenario.<br>Overall, the analysis reveals that especially groundwater extraction and nitrate leaching can be reduced substantially for fairly small reduction in agricultural net benefits in all climate scenarios. 50% of maximum modelled improvements of agro-ecological objectives can be already achieved at 1-15% reductions of agricultural net benefit depending on climate scenarios. Thus, respective land use policies would allow considerable improvements of the agro-ecological performance at relatively low costs. However, improving the agro-ecological performance beyond a particular level can quickly lead to high reductions of agricultural net benefits, as depicted by the non-linear form of the Pareto frontiers. This is mainly related to large declines of cropland and increases in grassland or abandoned land. Furthermore, the results indicate that water management policies are less costly than climate change mitigation policies, at least in the Seewinkel region.</p>

scholarly journals Assessment of model estimates of land-atmosphere CO<sub>2</sub> exchange across Northern Eurasia

2015 ◽  
Vol 12 (14) ◽  
pp. 4385-4405 ◽  
Author(s):  
M. A. Rawlins ◽  
A. D. McGuire ◽  
J. S. Kimball ◽  
P. Dass ◽  
D. Lawrence ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Soil Carbon ◽  
Residence Time ◽  
Primary Productivity ◽  
Ecosystem Respiration ◽  
Regional Scale ◽  
Northern Eurasia ◽  
Sink Strength ◽  
Vegetation Productivity ◽  
Co2 Sink

Abstract. A warming climate is altering land-atmosphere exchanges of carbon, with a potential for increased vegetation productivity as well as the mobilization of permafrost soil carbon stores. Here we investigate land-atmosphere carbon dioxide (CO2) cycling through analysis of net ecosystem productivity (NEP) and its component fluxes of gross primary productivity (GPP) and ecosystem respiration (ER) and soil carbon residence time, simulated by a set of land surface models (LSMs) over a region spanning the drainage basin of Northern Eurasia. The retrospective simulations cover the period 1960–2009 at 0.5° resolution, which is a scale common among many global carbon and climate model simulations. Model performance benchmarks were drawn from comparisons against both observed CO2 fluxes derived from site-based eddy covariance measurements as well as regional-scale GPP estimates based on satellite remote-sensing data. The site-based comparisons depict a tendency for overestimates in GPP and ER for several of the models, particularly at the two sites to the south. For several models the spatial pattern in GPP explains less than half the variance in the MODIS MOD17 GPP product. Across the models NEP increases by as little as 0.01 to as much as 0.79 g C m−2 yr−2, equivalent to 3 to 340 % of the respective model means, over the analysis period. For the multimodel average the increase is 135 % of the mean from the first to last 10 years of record (1960–1969 vs. 2000–2009), with a weakening CO2 sink over the latter decades. Vegetation net primary productivity increased by 8 to 30 % from the first to last 10 years, contributing to soil carbon storage gains. The range in regional mean NEP among the group is twice the multimodel mean, indicative of the uncertainty in CO2 sink strength. The models simulate that inputs to the soil carbon pool exceeded losses, resulting in a net soil carbon gain amid a decrease in residence time. Our analysis points to improvements in model elements controlling vegetation productivity and soil respiration as being needed for reducing uncertainty in land-atmosphere CO2 exchange. These advances will require collection of new field data on vegetation and soil dynamics, the development of benchmarking data sets from measurements and remote-sensing observations, and investments in future model development and intercomparison studies.

scholarly journals Effects of experimental nitrogen deposition on peatland carbon pools and fluxes: a modelling analysis

2015 ◽  
Vol 12 (1) ◽  
pp. 79-101 ◽  
Author(s):  
Y. Wu ◽  
C. Blodau ◽  
T. R. Moore ◽  
J. Bubier ◽  
S. Juutinen ◽  
...  
Keyword(s):  
Ecosystem Respiration ◽  
Model Performance ◽  
Net Ecosystem Exchange ◽  
N Fertilization ◽  
N Deposition ◽  
Competitive Advantages ◽  
Long Term Effects ◽  
N Content ◽  
Modelling Analysis

Abstract. Nitrogen (N) pollution of peatlands alters their carbon (C) balances, yet long-term effects and controls are poorly understood. We applied the model PEATBOG to explore impacts of long-term nitrogen (N) fertilization on C cycling in an ombrotrophic bog. Simulations of summer gross ecosystem production (GEP), ecosystem respiration (ER) and net ecosystem exchange (NEE) were evaluated against 8 years of observations and extrapolated for 80 years to identify potential effects of N fertilization and factors influencing model behaviour. The model successfully simulated moss decline and raised GEP, ER and NEE on fertilized plots. GEP was systematically overestimated in the model compared to the field data due to factors that can be related to differences in vegetation distribution (e.g. shrubs vs. graminoid vegetation) and to high tolerance of vascular plants to N deposition in the model. Model performance regarding the 8-year response of GEP and NEE to N input was improved by introducing an N content threshold shifting the response of photosynthetic capacity (GEPmax) to N content in shrubs and graminoids from positive to negative at high N contents. Such changes also eliminated the competitive advantages of vascular species and led to resilience of mosses in the long-term. Regardless of the large changes of C fluxes over the short-term, the simulated GEP, ER and NEE after 80 years depended on whether a graminoid- or shrub-dominated system evolved. When the peatland remained shrub–Sphagnum-dominated, it shifted to a C source after only 10 years of fertilization at 6.4 g N m−2 yr−1, whereas this was not the case when it became graminoid-dominated. The modelling results thus highlight the importance of ecosystem adaptation and reaction of plant functional types to N deposition, when predicting the future C balance of N-polluted cool temperate bogs.

scholarly journals Technical note: Dynamic INtegrated Gap-filling and partitioning for OzFlux (DINGO)

2017 ◽  
Vol 14 (6) ◽  
pp. 1457-1460 ◽  
Author(s):  
Jason Beringer ◽  
Ian McHugh ◽  
Lindsay B. Hutley ◽  
Peter Isaac ◽  
Natascha Kljun
Keyword(s):  
Primary Productivity ◽  
Active Sites ◽  
Ecosystem Respiration ◽  
Technical Note ◽  
Gross Primary Productivity ◽  
Quality Data ◽  
Gap Filling ◽  
Continental Scale ◽  
Flux Data ◽  
Processing Pathways

Abstract. Standardised, quality-controlled and robust data from flux networks underpin the understanding of ecosystem processes and tools necessary to support the management of natural resources, including water, carbon and nutrients for environmental and production benefits. The Australian regional flux network (OzFlux) currently has 23 active sites and aims to provide a continental-scale national research facility to monitor and assess Australia's terrestrial biosphere and climate for improved predictions. Given the need for standardised and effective data processing of flux data, we have developed a software suite, called the Dynamic INtegrated Gap-filling and partitioning for OzFlux (DINGO), that enables gap-filling and partitioning of the primary fluxes into ecosystem respiration (Fre) and gross primary productivity (GPP) and subsequently provides diagnostics and results. We outline the processing pathways and methodologies that are applied in DINGO (v13) to OzFlux data, including (1) gap-filling of meteorological and other drivers; (2) gap-filling of fluxes using artificial neural networks; (3) the u* threshold determination; (4) partitioning into ecosystem respiration and gross primary productivity; (5) random, model and u* uncertainties; and (6) diagnostic, footprint calculation, summary and results outputs. DINGO was developed for Australian data, but the framework is applicable to any flux data or regional network. Quality data from robust systems like DINGO ensure the utility and uptake of the flux data and facilitates synergies between flux, remote sensing and modelling.

scholarly journals Carbon dioxide fluxes over an ancient broadleaved deciduous woodland in southern England

2011 ◽  
Vol 8 (6) ◽  
pp. 1595-1613 ◽  
Author(s):  
M. V. Thomas ◽  
Y. Malhi ◽  
K. M. Fenn ◽  
J. B. Fisher ◽  
M. D. Morecroft ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Primary Productivity ◽  
Management Practices ◽  
Net Primary Productivity ◽  
Deciduous Forest ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Flux Chamber ◽  
Southern England ◽  
Temperate Deciduous

Abstract. We present results from a study of canopy-atmosphere fluxes of carbon dioxide from 2007 to 2009 above a site in Wytham Woods, an ancient temperate broadleaved deciduous forest in southern England. Gap-filled net ecosystem exchange (NEE) data were partitioned into gross primary productivity (GPP) and ecosystem respiration (Re) and analysed on daily, monthly and annual timescales. Over the continuous 24 month study period annual GPP was estimated to be 21.1 Mg C ha−1 yr−1 and Re to be 19.8 Mg C ha−1 yr−1; net ecosystem productivity (NEP) was 1.2 Mg C ha−1 yr−1. These estimates were compared with independent bottom-up estimates derived from net primary productivity (NPP) and flux chamber measurements recorded at a plot within the flux footprint in 2008 (GPP = 26.5 ± 6.8 Mg C ha−1 yr−1, Re = 24.8 ± 6.8 Mg C ha−1 yr−1, biomass increment = ~1.7 Mg C ha−1 yr−1). Over the two years the difference in seasonal NEP was predominantly caused by changes in ecosystem respiration, whereas GPP remained similar for equivalent months in different years. Although solar radiation was the largest influence on daily values of CO2 fluxes (R2 = 0.53 for the summer months for a linear regression), variation in Re appeared to be driven by temperature. Our findings suggest that this ancient woodland site is currently a substantial sink for carbon, resulting from continued growth that is probably a legacy of past management practices abandoned over 40 years ago. Our GPP and Re values are generally higher than other broadleaved temperate deciduous woodlands and may represent the influence of the UK's maritime climate, or the particular species composition of this site. The carbon sink value of Wytham Woods supports the protection and management of temperate deciduous woodlands (including those managed for conservation rather than silvicultural objectives) as a strategy to mitigate atmospheric carbon dioxide increases.

Interactive effects of elevated CO2, N deposition and climate change on plant litter quality in a California annual grassland

Oecologia ◽  
2004 ◽  
Vol 142 (3) ◽  
pp. 465-473 ◽  
Author(s):  
Hugh A. L. Henry ◽  
Elsa E. Cleland ◽  
Christopher B. Field ◽  
Peter M. Vitousek
Keyword(s):  
Climate Change ◽  
Elevated Co2 ◽  
Litter Quality ◽  
N Deposition ◽  
Plant Litter ◽  
Interactive Effects ◽  
Annual Grassland ◽  
California Annual Grassland

scholarly journals Modelling pesticide leaching under climate change: parameter vs. climate input uncertainty

2013 ◽  
Vol 10 (8) ◽  
pp. 10461-10494 ◽  
Author(s):  
K. Steffens ◽  
M. Larsbo ◽  
J. Moeys ◽  
E. Kjellström ◽  
N. Jarvis ◽  
...  
Keyword(s):  
Climate Change ◽  
Parameter Uncertainty ◽  
Climate Model ◽  
Climate Scenario ◽  
Climate Scenarios ◽  
Data Set ◽  
South West ◽  
Climate Uncertainty ◽  
Pesticide Losses ◽  
Pesticide Leaching

Abstract. The assessment of climate change impacts on the risk for pesticide leaching needs careful consideration of different sources of uncertainty. We investigated the uncertainty related to climate scenario input and its importance relative to parameter uncertainty of the pesticide leaching model. The pesticide fate model MACRO was calibrated against a comprehensive one-year field data set for a well-structured clay soil in south-west Sweden. We obtained an ensemble of 56 acceptable parameter sets that represented the parameter uncertainty. Nine different climate model projections of the regional climate model RCA3 were available as driven by different combinations of global climate models (GCM), greenhouse gas emission scenarios and initial states of the GCM. The future time series of weather data used to drive the MACRO-model were generated by scaling a reference climate data set (1970–1999) for an important agricultural production area in south-west Sweden based on monthly change factors for 2070–2099. 30 yr simulations were performed for different combinations of pesticide properties and application seasons. Our analysis showed that both the magnitude and the direction of predicted change in pesticide leaching from present to future depended strongly on the particular climate scenario. The effect of parameter uncertainty was of major importance for simulating absolute pesticide losses, whereas the climate uncertainty was relatively more important for predictions of changes of pesticide losses from present to future. The climate uncertainty should be accounted for by applying an ensemble of different climate scenarios. The aggregated ensemble prediction based on both acceptable parameterizations and different climate scenarios could provide robust probabilistic estimates of future pesticide losses and assessments of changes in pesticide leaching risks.

Sign in / Sign up

Export Citation Format

Share Document