Ecological responses of Stipa steppe in Inner Mongolia to experimentally increased temperature and precipitation. 4. Carbon exchange

2018 ◽  
Vol 40 (2) ◽  
pp. 159 ◽  
Author(s):  
Luomeng Chao ◽  
Zhiqiang Wan ◽  
Yulong Yan ◽  
Rui Gu ◽  
Yali Chen ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Air Temperature ◽  
Inner Mongolia ◽  
Ecosystem Respiration ◽  
Block Design ◽  
Net Ecosystem Exchange ◽  
Carbon Exchange ◽  
Ecosystem Productivity ◽  
Temperature And Precipitation ◽  
Gross Ecosystem Productivity

Aspects of carbon exchange were investigated in typical steppe east of Xilinhot city in Inner Mongolia. Four treatments with four replicates were imposed in a randomised block design: Control (C), warming (T), increased precipitation (P) and combined warming and increased precipitation (TP). Increased precipitation significantly increased both ecosystem respiration (ER) and soil respiration (SR) rates. Warming significantly reduced the ER rate but not the SR rate. The combination of increased precipitation and warming produced an intermediate response. The sensitivity of ER and SR to soil temperature and air temperature was assessed by calculating Q10 values: the increase in respiration for a 10°C increase in temperature. Q10 was lowest under T and TP, and highest under P. Both ER and SR all had significantly positive correlation with soil moisture. Increased precipitation increased net ecosystem exchange and gross ecosystem productivity, whereas warming reduced them. The combination of warming and increased precipitation had an intermediate effect. Both net ecosystem exchange and gross ecosystem productivity were positively related to soil moisture and negatively related to soil and air temperature. These findings suggest that predicted climate change in this region, involving both increased precipitation and warmer temperatures, will increase the net ecosystem exchange in the Stipa steppe meaning that the ecosystem will fix more carbon.

Ecological responses of Stipa steppe in Inner Mongolia to experimentally increased temperature and precipitation 5: Synthesis and implications

2018 ◽  
Vol 40 (2) ◽  
pp. 167 ◽  
Author(s):  
Guozheng Hu ◽  
Zhiqiang Wan ◽  
Yali Chen ◽  
Luomeng Chao ◽  
Qingzhu Gao ◽  
...  
Keyword(s):  
Climate Change ◽  
Soil Respiration ◽  
Inner Mongolia ◽  
Temporal Dynamics ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Community Diversity ◽  
Future Climate Change ◽  
Ecosystem Productivity ◽  
Gross Ecosystem Productivity

A randomised block experiment was conducted to study the response of plant community characteristics (biomass, density and diversity) and ecosystem carbon exchange processes to warming, increased precipitation and their combination on Stipa steppe in Inner Mongolia. Increased precipitation enhanced the effect that warming had in promoting community diversity and biomass. Increased precipitation directly increased net ecosystem exchange and gross ecosystem productivity, although ecosystem respiration and soil respiration also increased. However, warming did not have a significant effect on net ecosystem exchange and gross ecosystem productivity, whereas ecosystem respiration and soil respiration were significantly decreased by warming. All carbon flux processes had a significantly positive correlation with soil moisture. However, the carbon sequestration processes, gross ecosystem productivity and net ecosystem exchange, were significantly negatively correlated with temperature, contrary to carbon emission processes, soil respiration and ecosystem respiration. Results suggest that Stipa steppe may be benefited by future climate change, as the predicted precipitation is increasing with warming in Inner Mongolia. However, it is hard to predict the feedback of Stipa steppe to climate, because of the uncertainty in magnitude and temporal dynamics of climate change. To reveal the mechanism of the observed responses, further studies are suggested in this region on the effects of altered climate variables on plant species interactions, soil organic carbon composition, soil extracellular enzyme activity, microbial biomass and microbial respiration.

scholarly journals Moist moss tundra on Kapp Linne, Svalbard is a net source of CO<sub>2</sub> and CH<sub>4</sub> to the atmosphere

2021 ◽  
Author(s):  
Anders Lindroth ◽  
Norbert Pirk ◽  
Ingibjörg S. Jónsdóttir ◽  
Christian Stiegler ◽  
Leif Klemedtsson ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Air Temperature ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Growing Season ◽  
Mean Value ◽  
The Arctic ◽  
Spatial And Temporal Variability ◽  
Annual Nee ◽  
Greenness Index

Abstract. We measured CO2 and CH4 fluxes using chambers and eddy covariance (only CO2) from a moist moss tundra in Svalbard. The average net ecosystem exchange (NEE) during the summer (June–August) was −0.40 g C m−2 day−1 or −37 g C m−2 for the whole summer. Including spring and autumn periods the NEE was reduced to −6.8 g C m−2 and the annual NEE became positive, 24.7 gC m−2 due to the losses during the winter. The CH4 flux during the summer period showed a large spatial and temporal variability. The mean value of all 214 samples was 0.000511 ± 0.000315 µmol m−2s−1 which corresponds to a growing season estimate of 0.04 to 0.16 g CH4 m−2. We find that this moss tundra emits about 94–100 g CO2-equivalents m−2 yr−1 of which CH4 is responsible for 3.5–9.3 % using GWP100 of 27.9 respectively GWP20. Air temperature, soil moisture and greenness index contributed significantly to explain the variation in ecosystem respiration (Reco) while active layer depth, soil moisture and greenness index were the variables that best explained CH4 emissions. Estimate of temperature sensitivity of Reco and gross primary productivity showed that a modest increase in air temperature of 1 degree did not significantly change the NEE during the growing season but that the annual NEE would be even more positive adding another 8.5 g C m−2 to the atmosphere. We tentatively suggest that the warming of the Arctic that has already taken place is partly responsible for the fact that the moist moss tundra now is a source of CO2 to the atmosphere.

Ecological responses of Stipa steppe in Inner Mongolia to experimentally increased temperature and precipitation. 3. Soil respiration

2018 ◽  
Vol 40 (2) ◽  
pp. 153 ◽  
Author(s):  
Xuexia Wang ◽  
Yali Chen ◽  
Yulong Yan ◽  
Zhiqiang Wan ◽  
Ran Chao ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Respiration ◽  
Soil Temperature ◽  
Respiration Rate ◽  
Inner Mongolia ◽  
Growing Season ◽  
Climatic Warming ◽  
Soil Respiration Rate ◽  
Natural Rainfall ◽  
Temperature And Precipitation

The response of soil respiration to simulated climatic warming and increased precipitation was evaluated on the arid–semi-arid Stipa steppe of Inner Mongolia. Soil respiration rate had a single peak during the growing season, reaching a maximum in July under all treatments. Soil temperature, soil moisture and their interaction influenced the soil respiration rate. Relative to the control, warming alone reduced the soil respiration rate by 15.6 ± 7.0%, whereas increased precipitation alone increased the soil respiration rate by 52.6 ± 42.1%. The combination of warming and increased precipitation increased the soil respiration rate by 22.4 ± 11.2%. When temperature was increased, soil respiration rate was more sensitive to soil moisture than to soil temperature, although the reverse applied when precipitation was increased. Under the experimental precipitation (20% above natural rainfall) applied in the experiment, soil moisture was the primary factor limiting soil respiration, but soil temperature may become limiting under higher soil moisture levels.

scholarly journals Influência de Mudanças Climáticas no Balanço Hídrico da Amazônia Ocidental (Influence of Climate Change on Water Budget of Western Amazonia)

2011 ◽  
Vol 3 (3) ◽  
pp. 170 ◽  
Author(s):  
Ailton Marcolino Liberato ◽  
José Ivaldo B. De Brito
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Air Temperature ◽  
Water Budget ◽  
Fire Risk ◽  
Climate Index ◽  
Climate Trends ◽  
Climatological Data ◽  
Temperature And Precipitation

A presente pesquisa teve por objetivo investigar possíveis alterações em componentes do balanço hídrico climático, associadas a diferentes cenários (A2 e B2) das mudanças climáticas do IPCC, para a Amazônia Ocidental (Acre, Amazonas, Rondônia e Roraima). Os dados climatológicos de temperatura do ar e totais de precipitação pluvial usados como referência neste estudo, são oriundos do INMET (1961-2005), da CEPLAC (1983-1999) e da reanálise do NCEP/NCAR (1983-1995). O método utilizado na elaboração do balanço hídrico é o de Thornthwaite e Mather (1957) modificado por Krishan (1980). Os resultados das projeções mostram tendência de clima mais seco, diminuição na umidade do solo, redução na vazão dos rios, aumento no risco de incêndio e diminuição no escoamento superficial e sub-superficial para a Amazônia Ocidental até 2100.Palavras-chave: cenários, índices climáticos, Amazônia. Influence of Climate Change on Water Budget of Western Amazonia ABSTRACTThe main objective of this study was investigate possible alterations in the climatic water budget components associated with different scenarios (A2 and B2) of the IPCC to Amazonian Western (Acre, Amazonas, Rondônia and Roraima). The climatological data of air temperature and precipitation from the INMET (1961-2005), CEPLAC (1983-1999) and NCEP/NCAR reanalysis (1983-1995) were used in the present study. The Thornthwaite and Mather (1955) method was used in the elaboration of the climatic water budget modified by Krishan (1980). The results of the projections show drier climate trends and decrease of the soil moisture, reduction in the rivers discharge, increase in the fire risk and decrease in the runoff for the Amazonian Western up to 2100. Keywords: scenarios, climate index, Amazonian.

scholarly journals Effects of Air Temperature and Precipitation on Soil Moisture on the Qinghai-Tibet Plateau during the 2015 Growing Season

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Qingyan Xie ◽  
Jianping Li ◽  
Yufei Zhao
Keyword(s):  
Soil Moisture ◽  
Air Temperature ◽  
Hydrological Cycle ◽  
Critical Role ◽  
Growing Season ◽  
Tibet Plateau ◽  
Ecosystem Stability ◽  
Near Surface ◽  
Temperature And Precipitation ◽  
Qinghai Tibet Plateau

The Qinghai-Tibet Plateau (QTP) holds massive freshwater resources and is one of the most active regions in the world with respect to the hydrological cycle. Soil moisture (SM) plays a critical role in hydrological processes and is important for plant growth and ecosystem stability. To investigate the relationship between climatic factors (air temperature and precipitation) and SM during the growing season in various climate zones on the QTP, data from three observational stations were analyzed. The results showed that the daily average (Tave) and minimum air temperatures (Tmin) significantly influenced SM levels at all depths analyzed (i.e., 10, 20, 30, 40, and 50 cm deep) at the three stations, and Tmin had a stronger effect on SM than did Tave. However, the daily maximum air temperature (Tmax) generally had little effect on SM, although it had showed some effects on SM in the middle and deeper layers at the Jiali station. Precipitation was an important factor that significantly influenced the SM at all depths at the three stations, but the influence on SM in the middle and deep layers lagged the direct effect on near-surface SM by 5–7 days. These results suggest that environment characterized by lower temperatures and higher precipitation may promote SM conservation during the growing season and in turn support ecosystem stability on the QTP.

Responses to air temperature and soil moisture of growth of four dominant species on sand dunes of central Inner Mongolia

2008 ◽  
Vol 121 (5) ◽  
pp. 473-482 ◽  
Author(s):  
Yuanrun Zheng ◽  
Glyn M. Rimmington ◽  
Zhixiao Xie ◽  
Lei Zhang ◽  
Ping An ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Air Temperature ◽  
Inner Mongolia ◽  
Dominant Species ◽  
Sand Dunes

scholarly journals Effects of Grazing Pattern on Ecosystem Respiration and Methane Flux in a Sown Pasture in Inner Mongolia, China

Atmosphere ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Baoling Mei ◽  
Hongyu Yue ◽  
Xunhua Zheng ◽  
William McDowell ◽  
Qingshan Zhao ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Soil Temperature ◽  
Inner Mongolia ◽  
Nitrate Nitrogen ◽  
Ecosystem Respiration ◽  
Ammonium Nitrogen ◽  
Agricultural Practice ◽  
Ch4 Flux

The establishment of sown pasture is an important agricultural practice in many landscapes. Although both native grassland and sown pasture play a key role in the global carbon cycle, due to lack of data and field experiments, our understanding of grassland CH4 fluxes and CO2 emissions remains limited, especially when it comes to sown pasture. We measured ecosystem respiration and CH4 fluxes in response to a variety of potential drivers (soil temperature, soil moisture, ammonium nitrogen, nitrate nitrogen and dissolved organic carbon) in CG (continuous grazing), RG (rotational grazing) and UG (ungrazed) plots in sown grassland for one year in Inner Mongolia. Fluxes of CH4 and ecosystem respiration were measured using static opaque chambers and gas chromatography. Grazing significantly reduced ecosystem respiration (p < 0.01), and grazing pattern significantly influenced respiration in CG and RG plots (p < 0.01). We find that the sown grassland is a net sink for atmospheric CH4. No influence of grazing pattern was observed on CH4 flux in CG, RG and UG (p > 0.05). Soil temperature is the most important factor influencing ecosystem respiration and CH4 flux in the sown grassland, with soil moisture playing a secondary role to soil temperature. Variation in levels of ammonium nitrogen, nitrate nitrogen and dissolved organic carbon had little influence on ecosystem respiration or CH4 flux (except in UG plots). The values obtained for ecosystem respiration of grasslands have a large uncertainty range, which may be due to spatial variability as well as differences in research methods. Mean CH4 fluxes measured only during the growing season were much higher than the annual mean CH4 fluxes.

scholarly journals Observed and modelled ecosystem respiration and gross primary production of a grassland in southwestern France

2010 ◽  
Vol 7 (1) ◽  
pp. 429-462 ◽  
Author(s):  
C. Albergel ◽  
J.-C. Calvet ◽  
A.-L. Gibelin ◽  
S. Lafont ◽  
J.-L. Roujean ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Primary Production ◽  
Root Zone ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Net Ecosystem Exchange ◽  
Co2 Flux ◽  
Single Equation ◽  
Complex Model ◽  
Area Index

Abstract. In this work, a simple representation of the soil moisture effect on the ecosystem respiration is implemented into the A-gs version of the Interactions between Soil, Biosphere, and Atmosphere (ISBA) model. It results in an improvement of the modelled CO2 flux over a grassland, in southwestern France. The former temperature-only dependent respiration formulation used in ISBA-A-gs is not able to model the limitation of the respiration under dry conditions. In addition to soil moisture and soil temperature, the only parameter required in this formulation is the ecosystem respiration parameter Re25. It can be estimated by the mean of eddy covariance measurements of turbulent nighttime CO2 flux (i.e. ecosystem respiration). The resulting correlation between observed and modelled net ecosystem exchange is r2=0.63 with a bias of −2.18 μmol m−2 s−1. It is shown that when CO2 observations are not available, it is possible to use a more complex model, able to represent the heterotrophic respiration and all the components of the autotrophic respiration, to estimate Re25 with similar results. The modelled ecosystem respiration estimates are provided by the Carbon Cycle (CC) version of ISBA (ISBA-CC). ISBA-CC is a version of ISBA able to simulate all the respiration components whereas ISBA-A-gs uses a single equation for ecosystem respiration. ISBA-A-gs is easier to handle and more convenient than ISBA-CC for practical use in atmospheric or hydrological models. Surface water and energy flux observations as well as gross primary production (GPP) estimates are compared with model outputs. The dependence of GPP to air temperature is investigated. The observed GPP is less sensitive to temperature than the modelled GPP. Finally, the simulations of the ISBA-A-gs model are analysed over a seven year period (2001–2007). Modelled soil moisture and leaf area index (LAI) are confronted with the observed root-zone soil moisture content (m3 m−3), and with LAI estimates derived from surface reflectance measurements.

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;

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