scholarly journals Modeling of the Interannual Variation in Ecosystem Respiration of a Semiarid Grassland

10.5772/30454 ◽  
2011 ◽  
Author(s):  
Tomoko Nakano ◽  
Masato Shino
Keyword(s):  
Interannual Variation ◽  
Ecosystem Respiration ◽  
Semiarid Grassland

scholarly journals Temporal variations in atmospheric CO<sub>2</sub> on Rishiri Island in 2006–2013: responses of the interannual variation in amplitude to climate and the terrestrial sink in East Asia

2014 ◽  
Vol 5 (1) ◽  
pp. 809-848
Author(s):  
C. Zhu ◽  
H. Yoshikawa-Inoue
Keyword(s):  
East Asia ◽  
Interannual Variation ◽  
Climatic Factors ◽  
Ecosystem Respiration ◽  
Anthropogenic Activities ◽  
Time Lag ◽  
Co2 Concentration ◽  
Temporal Variations ◽  
Atmospheric Co2 ◽  
Growing Season Length

Abstract. Surface observation of the atmospheric CO2 mixing ratio implies the combined influences of both natural fluctuations and anthropogenic activities on the carbon cycle. Atmospheric CO2 has been measured on Rishiri Island in the outflow region of Eurasia since May 2006. We report the first 7 year temporal atmospheric CO2 variations from diurnal to interannual scales. In the diurnal scale, an obvious cycle appeared as a minimum in the afternoon and maximum at midnight in the summer months. Seasonally, the maximum CO2 concentration appeared around the beginning of April, while the minimum appeared around the middle of August. A mean growing season length of ~126 days was estimated. In the period from 2007 to 2012, the peak-to-peak amplitude increased until 2009 and decreased thereafter, with a mean value of 19.7 ppm. In the long term, atmospheric CO2 is increasing by a mean growth rate of 2.1 ppm year−1. Investigations on the driving climatic factors on the interannual variation in amplitude indicated that temperature in East Asia (40–60° N, 90–150° E) affected the CO2 amplitude by affecting the seasonal maximum, with a time lag of 1–2 years. On the contrary, precipitation did not likely affect CO2 amplitudes. The amplitude also responded to a natural carbon source/sink variation in East Asia. We suggest that temperature in the first year would affect carbon sinks in the second year in the fetch regions, which further affect CO2 amplitude mainly through ecosystem respiration. Circulation changes also likely contributed to the decreasing amplitude since 2009, as indicated by the simultaneous decrease in the 222Rn concentration in spring and summer.

Contribution of plant traits to the explanation of temporal variations in carbon and water fluxes in semiarid grassland patches

2020 ◽  
Vol 13 (6) ◽  
pp. 773-784
Author(s):  
Mengyu Wang ◽  
Nan Lu ◽  
Qinglin Li ◽  
Weiwei Fang ◽  
Bojie Fu
Keyword(s):  
Plant Traits ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Temporal Variations ◽  
Water Fluxes ◽  
Spatiotemporal Variations ◽  
Closed Chamber ◽  
Semiarid Grassland ◽  
Plant Trait ◽  
Gas Fluxes

Abstract Aims Accurate prediction of spatiotemporal variations in carbon and water fluxes of heterogeneous landscape is critical to comprehensively address the effects of climate change and vegetation dynamics on landscape and regional carbon and water cycling. Methods A field study was conducted to characterize the seasonal variations in gas fluxes and explore their relationships with abiotic and biotic factors in a small grassland landscape. Daytime carbon and water fluxes including net ecosystem exchange, gross ecosystem productivity, ecosystem respiration and evapotranspiration (ET) were measured for three types of grassland patches over a growing season using the closed chamber method. The key plant trait variables were measured, based on which community weighted mean (CWM) and functional variance (FDvar) were calculated. Important Findings The results showed that the temporal variations in the carbon and water fluxes were regulated by meteorological, soil and community functional variables. Inclusion of the CWM and FDvar of plant trait measures greatly improved the degree of explanation of the predict models. Specific leaf area and leaf δ13C content (Lδ13C) were the most important trait variables in affecting the variations of the gas fluxes. CWMs indices had greater importance than FDvar indices in predicting the variation of the C fluxes but FDvar indices were more important for ET than C fluxes. Our findings demonstrated that mass ratio hypothesis and the complementary effects hypothesis are not mutually exclusive but have different relative importance for different ecosystem processes. Community functional traits played important roles in predicting the spatiotemporal variations of carbon and water fluxes in semiarid grassland.

scholarly journals Biophysical effects on the interannual variation in carbon dioxide exchange of an alpine meadow on the Tibetan Plateau

2017 ◽  
Vol 17 (8) ◽  
pp. 5119-5129 ◽  
Author(s):  
Lei Wang ◽  
Huizhi Liu ◽  
Jihua Sun ◽  
Yaping Shao
Keyword(s):  
Carbon Dioxide ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Interannual Variation ◽  
Alpine Meadow ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Seasonal Pattern ◽  
Carbon Dioxide Exchange ◽  
The Tibetan Plateau

Abstract. Eddy covariance measurements from 2012 to 2015 were used to investigate the interannual variation in carbon dioxide exchange and its control over an alpine meadow on the south-east margin of the Tibetan Plateau. The annual net ecosystem exchange (NEE) in the 4 years from 2012 to 2015 was −114.2, −158.5, −159.9 and −212.6 g C m−2 yr−1, and generally decreased with the mean annual air temperature (MAT). An exception occurred in 2014, which had the highest MAT. This was attributed to higher ecosystem respiration (RE) and similar gross primary production (GPP) in 2014 because the GPP increased with the MAT, but became saturated due to the limit in photosynthetic capacity. In the spring (March to May) of 2012, low air temperature (Ta) and drought events delayed grass germination and reduced GPP. In the late wet season (September to October) of 2012 and 2013, the low Ta in September and its negative effects on vegetation growth caused earlier grass senescence and significantly lower GPP. This indicates that the seasonal pattern of Ta has a substantial effect on the annual total GPP, which is consistent with results obtained using the homogeneity-of-slopes (HOS) model. The model results showed that the climatic seasonal variation explained 48.6 % of the GPP variability, while the percentages explained by climatic interannual variation and the ecosystem functional change were 9.7 and 10.6 %, respectively.

scholarly journals Seasonal and Interannual Variation in Energy Balance in the Semiarid Grassland Area of China

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Qun’ou Jiang ◽  
Enjun Ma ◽  
Jinyan Zhan ◽  
Nana Shi
Keyword(s):  
Climate Change ◽  
Energy Balance ◽  
Land Cover ◽  
Interannual Variation ◽  
Short Wave ◽  
Wave Radiation ◽  
Short Wave Radiation ◽  
Semiarid Grassland ◽  
Long Wave ◽  
Long Wave Radiation

Near surface energy budget changes have been proved to be induced by the land cover conversion through changing the surface physical properties, which can further impact the regional climate change. This study applies the DLS model to simulate the land cover under the business as usual (BAU) scenario and then analyses the seasonal and interannual variation of energy balance in the semiarid grassland area of China based on the simulated land cover with the Weather Research and Forecasting (WRF) model. The results indicate that the grassland will show a growing trend under the BAU scenario. Downward long wave radiation and downward short wave radiation will all have small-scale increase with time going by, while the surface net radiation will decrease from 2030 to 2050. However, there is obvious seasonal variation. Summer has the highest downward long wave radiation and downward short wave radiation, followed by spring and autumn. The lowest are in winter. As for the net surface radiation, there is obvious decrease in southeast of study area due to returning cropland to grassland. Those research conclusions can offer valuable information for the land use planning and relieving the effects of land cover change on climate change at the semiarid grassland area.

scholarly journals Biophysical effects on the interannual variation in carbon dioxide exchange of an alpine meadow on the Tibetan Plateau

2016 ◽  
Author(s):  
Lei Wang ◽  
Huizhi Liu ◽  
Jihua Sun ◽  
Yaping Shao
Keyword(s):  
Carbon Dioxide ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
Interannual Variation ◽  
Alpine Meadow ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Seasonal Pattern ◽  
Carbon Dioxide Exchange ◽  
The Tibetan Plateau

Abstract. Eddy covariance measurements from 2012 to 2015 were used to investigate the interannual variation in carbon dioxide exchange and its control over an alpine meadow on the southeast margin of the Tibetan Plateau. The annual net ecosystem exchange (NEE) from 2012 to 2015 was −114.2, −158.5, −159.9 and −212.6 g C m−2 yr−1 and generally decreased with the mean annual air temperature (MAT). An exception occurred in 2014, which had the highest MAT. This was attributed to higher ecosystem respiration (RE) and similar gross primary production (GPP) in 2014 because the GPP increased with MAT but became saturated due to the photosynthesis capacity limit. In the spring (March to May) of 2012, lower air temperature (Ta) and drought events delayed grass germination and reduced GPP. In the late wet season (September to October) of 2012 and 2013, the lower Ta in September and its negative effects on vegetation growth caused earlier grass senescence and significantly lower GPP. This indicates that the seasonal pattern of Ta greatly affected the annual total GPP, which is consistent with the result of the homogeneity-of-slopes model. The model shows that the climatic seasonal variation explained 48.6 % of the GPP variability, and the percentage of climatic interannual variation and the ecosystem functional change were 9.7 % and 10.6 %, respectively.

scholarly journals Interannual variation in ecosystem respiration in an Inner Mongolian meadow steppe in response to livestock grazing

2021 ◽  
Vol 131 ◽  
pp. 108121
Author(s):  
Ruirui Yan ◽  
Yu Zhang ◽  
Miao Wang ◽  
Ruiqiang Li ◽  
Dongyan Jin ◽  
...  
Keyword(s):  
Interannual Variation ◽  
Ecosystem Respiration ◽  
Livestock Grazing ◽  
Meadow Steppe

scholarly journals Stability of Ecosystem CO2 Flux in Response to Changes in Precipitation in a Semiarid Grassland

2019 ◽  
Vol 11 (9) ◽  
pp. 2597 ◽  
Author(s):  
Kaiqiang Bao ◽  
Haifeng Tian ◽  
Min Su ◽  
Liping Qiu ◽  
Xiaorong Wei ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Ecosystem Respiration ◽  
Co2 Flux ◽  
Co2 Exchange ◽  
Semiarid Grassland ◽  
Considerable Uncertainty ◽  
C Cycling ◽  
Precipitation Regimes ◽  
Carbon Dioxide Co2

Carbon dioxide (CO2) flux provides feedback between C cycling and the climatic system. There is considerable uncertainty regarding the direction and magnitude of the responses of this process to precipitation changes, hindering accurate prediction of C cycling in a changing world. We examined the responses of ecosystem CO2 flux to ambient precipitation and experimentally decreased (−35%) and increased precipitation (+20%) in a semiarid grassland in China between July 2013 and September 2015. The measured CO2 flux components included the gross ecosystem productivity (GEP), net ecosystem CO2 exchange (NEE), ecosystem respiration (Re), and soil respiration (Rs). The results showed that the seasonal and diurnal patterns of most components of ecosystem CO2 flux were minimally affected by precipitation treatments, with less than 4% changes averaged across the three growing seasons. GEP and NEE had a quadratic relationship, while Re and Rs increased exponentially with soil temperature. GEP, RE, and Rs, however, decreased with soil moisture. Decreased precipitation reduced the dependence of CO2 flux on soil temperature but partly increased the dependence on soil moisture; in contrast, increased precipitation had the opposite influence. Our results suggested a relatively stable CO2 flux in this semiarid grassland across the tested precipitation regimes.

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