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Interannual variation in carbon sequestration depends mainly on the carbon uptake period in two croplands on the North China Plain.

Bao X, Wen X, Sun X, Zhao F, Wang Y - PLoS ONE (2014)

Bottom Line: A significant and positive relationship was found between the annual carbon uptake period (CUP) and the NEP as well as the NBP.The annual air temperature, through its negative effect on the start date of the CUP, determined the length of the CUP.Thus, global warming can be expected to extend the length of the CUP and thus increase carbon sequestration in croplands.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.

ABSTRACT
Interannual variation in plant phenology can lead to major modifications in the interannual variation of net ecosystem production (NEP) and net biome production (NBP) as a result of recent climate change in croplands. Continuous measurements of carbon flux using the eddy covariance technique were conducted in two winter wheat and summer maize double-cropped croplands during 2003-2012 in Yucheng and during 2007-2012 in Luancheng on the North China Plain. Our results showed that the difference between the NEP and the NBP, i.e., the crop economic yield, was conservative even though the NEP and the NBP for both sites exhibited marked fluctuations during the years of observation. A significant and positive relationship was found between the annual carbon uptake period (CUP) and the NEP as well as the NBP. The NEP and the NBP would increase by 14.8±5.2 and 14.7±6.6 g C m(-2) yr(-1), respectively, if one CUP-day was extended. A positive relationship also existed between the CUP and the NEP as well as the NBP for winter wheat and summer maize, respectively. The annual air temperature, through its negative effect on the start date of the CUP, determined the length of the CUP. The spring temperature was the main indirect factor controlling the annual carbon sequestration when a one-season crop (winter wheat) was considered. Thus, global warming can be expected to extend the length of the CUP and thus increase carbon sequestration in croplands.

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The relationships between the CUP and the start date of the CUP (CUPstart-date).The relationships between the CUP of (a) winter wheat, (b) summer maize, (c) the whole year and the start date of the CUP (CUPstart-date) on the North China Plain. CUP is the abbreviation of C uptake period. The start date of the CUP represents the beginning of the CUP. The solid line is the regression line.
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pone-0110021-g005: The relationships between the CUP and the start date of the CUP (CUPstart-date).The relationships between the CUP of (a) winter wheat, (b) summer maize, (c) the whole year and the start date of the CUP (CUPstart-date) on the North China Plain. CUP is the abbreviation of C uptake period. The start date of the CUP represents the beginning of the CUP. The solid line is the regression line.

Mentions: Fig. 4 shows the dependence of the annual NEP and NBP on the mean annual air temperature (MAT) and the annual carbon uptake period (CUP). Table 1 also lists the annual values of the growing season length (GSL), the CUP and the LAI. The interannual variations in the NEP and NBP were significantly correlated with both the MAT (R2 = 0.78 for the NEP and 0.72 for the NBP, p<0.001) (Fig. 4a) and the annual total CUP (R2 = 0.74 for the NEP and 0.64 for the NBP, p<0.001) (Fig. 4b) when the two sites were combined. The starting date of CUP (CUPstart-date) had a strongly effect on annual CUP (R2 = 0.78, p<0.0001 for two sites combined; R2 = 0.78, p<0.01 in Yucheng; R2 = 0.67, p<0.0001 in Lucheng) (Fig. 5), and the CUPstart-date was significantly affected by the MAT (R2 = 0.49, p = 0.04 for sites combined; R2 = 0.49, p = 0.025 in Yucheng; R2 = 0.047, p = 0.21 in Lucheng) (Fig. 6). No relationship was observed between the annual NEP or the NBP and the GSL or between the NEP or the NBP and the mean annual LAI. The annual total GSL was very close to the length of an entire year because of the short duration (only several days) of the fallow stage (this refers to the interval stage between the two crops). Compared with the GSL, the crop CUP experienced a large fluctuation between years. The CUP of the winter wheat ranged from 78 to 108 days (88.9±10.6 days) in Yucheng and from 64 to 97 days (82.0±11.8 days) in Luancheng. The CUP of the summer maize was shorter than that of the winter wheat, which was 74.0±6.0 days and 60.0±11.6 days in Yucheng and Luancheng, respectively. As a result, the annual total CUP, which was the sum of the CUP of the winter wheat and the CUP of the summer maize, increased from 147 to 186 days with a long-term mean of 162.3±12.5 days in Yucheng and from 116 to 161 days with a mean of 142.2±17.9 days in Luancheng. The linear regression models suggested that the NEP would increase by 144.1±47.2 g C m−2 yr−1 per additional degree Celsius and by 14.8±5.2 g C m−2 yr−1 per additional CUP day. The NBP also increased by a similar amount when one additional unit temperature was added and the CUP was extended (Fig. 4). Despite both the NEP and NBP being affected by the CUP, the difference between them, i.e., the crop yield was not obviously influenced by the CUP and was conservative over a long time scale (Fig. 4c).


Interannual variation in carbon sequestration depends mainly on the carbon uptake period in two croplands on the North China Plain.

Bao X, Wen X, Sun X, Zhao F, Wang Y - PLoS ONE (2014)

The relationships between the CUP and the start date of the CUP (CUPstart-date).The relationships between the CUP of (a) winter wheat, (b) summer maize, (c) the whole year and the start date of the CUP (CUPstart-date) on the North China Plain. CUP is the abbreviation of C uptake period. The start date of the CUP represents the beginning of the CUP. The solid line is the regression line.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4197033&req=5

pone-0110021-g005: The relationships between the CUP and the start date of the CUP (CUPstart-date).The relationships between the CUP of (a) winter wheat, (b) summer maize, (c) the whole year and the start date of the CUP (CUPstart-date) on the North China Plain. CUP is the abbreviation of C uptake period. The start date of the CUP represents the beginning of the CUP. The solid line is the regression line.
Mentions: Fig. 4 shows the dependence of the annual NEP and NBP on the mean annual air temperature (MAT) and the annual carbon uptake period (CUP). Table 1 also lists the annual values of the growing season length (GSL), the CUP and the LAI. The interannual variations in the NEP and NBP were significantly correlated with both the MAT (R2 = 0.78 for the NEP and 0.72 for the NBP, p<0.001) (Fig. 4a) and the annual total CUP (R2 = 0.74 for the NEP and 0.64 for the NBP, p<0.001) (Fig. 4b) when the two sites were combined. The starting date of CUP (CUPstart-date) had a strongly effect on annual CUP (R2 = 0.78, p<0.0001 for two sites combined; R2 = 0.78, p<0.01 in Yucheng; R2 = 0.67, p<0.0001 in Lucheng) (Fig. 5), and the CUPstart-date was significantly affected by the MAT (R2 = 0.49, p = 0.04 for sites combined; R2 = 0.49, p = 0.025 in Yucheng; R2 = 0.047, p = 0.21 in Lucheng) (Fig. 6). No relationship was observed between the annual NEP or the NBP and the GSL or between the NEP or the NBP and the mean annual LAI. The annual total GSL was very close to the length of an entire year because of the short duration (only several days) of the fallow stage (this refers to the interval stage between the two crops). Compared with the GSL, the crop CUP experienced a large fluctuation between years. The CUP of the winter wheat ranged from 78 to 108 days (88.9±10.6 days) in Yucheng and from 64 to 97 days (82.0±11.8 days) in Luancheng. The CUP of the summer maize was shorter than that of the winter wheat, which was 74.0±6.0 days and 60.0±11.6 days in Yucheng and Luancheng, respectively. As a result, the annual total CUP, which was the sum of the CUP of the winter wheat and the CUP of the summer maize, increased from 147 to 186 days with a long-term mean of 162.3±12.5 days in Yucheng and from 116 to 161 days with a mean of 142.2±17.9 days in Luancheng. The linear regression models suggested that the NEP would increase by 144.1±47.2 g C m−2 yr−1 per additional degree Celsius and by 14.8±5.2 g C m−2 yr−1 per additional CUP day. The NBP also increased by a similar amount when one additional unit temperature was added and the CUP was extended (Fig. 4). Despite both the NEP and NBP being affected by the CUP, the difference between them, i.e., the crop yield was not obviously influenced by the CUP and was conservative over a long time scale (Fig. 4c).

Bottom Line: A significant and positive relationship was found between the annual carbon uptake period (CUP) and the NEP as well as the NBP.The annual air temperature, through its negative effect on the start date of the CUP, determined the length of the CUP.Thus, global warming can be expected to extend the length of the CUP and thus increase carbon sequestration in croplands.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.

ABSTRACT
Interannual variation in plant phenology can lead to major modifications in the interannual variation of net ecosystem production (NEP) and net biome production (NBP) as a result of recent climate change in croplands. Continuous measurements of carbon flux using the eddy covariance technique were conducted in two winter wheat and summer maize double-cropped croplands during 2003-2012 in Yucheng and during 2007-2012 in Luancheng on the North China Plain. Our results showed that the difference between the NEP and the NBP, i.e., the crop economic yield, was conservative even though the NEP and the NBP for both sites exhibited marked fluctuations during the years of observation. A significant and positive relationship was found between the annual carbon uptake period (CUP) and the NEP as well as the NBP. The NEP and the NBP would increase by 14.8±5.2 and 14.7±6.6 g C m(-2) yr(-1), respectively, if one CUP-day was extended. A positive relationship also existed between the CUP and the NEP as well as the NBP for winter wheat and summer maize, respectively. The annual air temperature, through its negative effect on the start date of the CUP, determined the length of the CUP. The spring temperature was the main indirect factor controlling the annual carbon sequestration when a one-season crop (winter wheat) was considered. Thus, global warming can be expected to extend the length of the CUP and thus increase carbon sequestration in croplands.

Show MeSH
Related in: MedlinePlus