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Impacts of diffuse radiation on light use efficiency across terrestrial ecosystems based on Eddy covariance observation in China.

Huang K, Wang S, Zhou L, Wang H, Zhang J, Yan J, Zhao L, Wang Y, Shi P - PLoS ONE (2014)

Bottom Line: Our results showed that the ecosystem LUE at the six sites was significantly correlated with the cloudiness variation (0.24 ≤ R(2) ≤ 0.85), especially at the Changbaishan temperate forest ecosystem (R(2) = 0.85).Meanwhile, the CI values appeared more frequently between 0.8 and 1.0 in two subtropical forest ecosystems (Qianyanzhou and Dinghushan) and were much larger than those in temperate ecosystems.Besides, cloudiness thresholds which were favorable for enhancing ecosystem carbon sequestration existed at the three forest sites, respectively.

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 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.

ABSTRACT
Ecosystem light use efficiency (LUE) is a key factor of production models for gross primary production (GPP) predictions. Previous studies revealed that ecosystem LUE could be significantly enhanced by an increase on diffuse radiation. Under large spatial heterogeneity and increasing annual diffuse radiation in China, eddy covariance flux data at 6 sites across different ecosystems from 2003 to 2007 were used to investigate the impacts of diffuse radiation indicated by the cloudiness index (CI) on ecosystem LUE in grassland and forest ecosystems. Our results showed that the ecosystem LUE at the six sites was significantly correlated with the cloudiness variation (0.24 ≤ R(2) ≤ 0.85), especially at the Changbaishan temperate forest ecosystem (R(2) = 0.85). Meanwhile, the CI values appeared more frequently between 0.8 and 1.0 in two subtropical forest ecosystems (Qianyanzhou and Dinghushan) and were much larger than those in temperate ecosystems. Besides, cloudiness thresholds which were favorable for enhancing ecosystem carbon sequestration existed at the three forest sites, respectively. Our research confirmed that the ecosystem LUE at the six sites in China was positively responsive to the diffuse radiation, and the cloudiness index could be used as an environmental regulator for LUE modeling in regional GPP prediction.

No MeSH data available.


The seasonal variations of monthly mean cloudiness index (CI), monthly mean light use efficiency (LUE) from 2003 to 2007 at the five sites.
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pone-0110988-g002: The seasonal variations of monthly mean cloudiness index (CI), monthly mean light use efficiency (LUE) from 2003 to 2007 at the five sites.

Mentions: Figure 2 showed the seasonal variations of the cloudiness index and light use efficiency of the six sites from 2003 to 2006. Mostly, cloudiness index (CI) was greater at QYZ and DHS than the other temperate ecosystems (CBS, NMG, HB and DX). The CI values of subtropical ecosystems (QYZ and DHS) reached the maximum in March, and were higher during the mid-growing season than the two ends of the year (Figure 2b, c). At the temperate ecosystems, the CI values peaked during the mid-growing season (Figure 2a, d, e and f), while the CI values of the subtropical ecosystems failed to show substantial variations with the seasonal changes. This indicated that sky conditions of two subtropical ecosystem sites were cloudier than those of four temperate ecosystem sites, and cloudy days were more during the mid-growing seasons at the temperate sites. It was also noted that negative CI values were found at NMG site, which was in consistency with meteorological observation that the NMG site received stronger solar radiation during the non-growing season. Meanwhile, the forest ecosystems LUE were significantly higher than grassland ecosystem LUE (Figure 2g, h, i, j, k and l). The LUE at subtropical forest sites (QYZ and DHS) failed to show significantly seasonality, while LUE of the temperate ecosystems (CBS, NMG, HB and DX) peaked during mid-growing season. Furthermore, the ecosystem LUE at QYZ site reached its turning point in July during mid-growing season, presented by a sharp fall resulting from the epidemic summer drought [38]. Among grassland sites, the LUE at HB site exhibited apparently higher values than the other two grassland sites and reached its maximal value in August, whereas the ecosystem LUE at NMG and DX site peaked in July and August, respectively (Figure 2j, k and l).


Impacts of diffuse radiation on light use efficiency across terrestrial ecosystems based on Eddy covariance observation in China.

Huang K, Wang S, Zhou L, Wang H, Zhang J, Yan J, Zhao L, Wang Y, Shi P - PLoS ONE (2014)

The seasonal variations of monthly mean cloudiness index (CI), monthly mean light use efficiency (LUE) from 2003 to 2007 at the five sites.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230921&req=5

pone-0110988-g002: The seasonal variations of monthly mean cloudiness index (CI), monthly mean light use efficiency (LUE) from 2003 to 2007 at the five sites.
Mentions: Figure 2 showed the seasonal variations of the cloudiness index and light use efficiency of the six sites from 2003 to 2006. Mostly, cloudiness index (CI) was greater at QYZ and DHS than the other temperate ecosystems (CBS, NMG, HB and DX). The CI values of subtropical ecosystems (QYZ and DHS) reached the maximum in March, and were higher during the mid-growing season than the two ends of the year (Figure 2b, c). At the temperate ecosystems, the CI values peaked during the mid-growing season (Figure 2a, d, e and f), while the CI values of the subtropical ecosystems failed to show substantial variations with the seasonal changes. This indicated that sky conditions of two subtropical ecosystem sites were cloudier than those of four temperate ecosystem sites, and cloudy days were more during the mid-growing seasons at the temperate sites. It was also noted that negative CI values were found at NMG site, which was in consistency with meteorological observation that the NMG site received stronger solar radiation during the non-growing season. Meanwhile, the forest ecosystems LUE were significantly higher than grassland ecosystem LUE (Figure 2g, h, i, j, k and l). The LUE at subtropical forest sites (QYZ and DHS) failed to show significantly seasonality, while LUE of the temperate ecosystems (CBS, NMG, HB and DX) peaked during mid-growing season. Furthermore, the ecosystem LUE at QYZ site reached its turning point in July during mid-growing season, presented by a sharp fall resulting from the epidemic summer drought [38]. Among grassland sites, the LUE at HB site exhibited apparently higher values than the other two grassland sites and reached its maximal value in August, whereas the ecosystem LUE at NMG and DX site peaked in July and August, respectively (Figure 2j, k and l).

Bottom Line: Our results showed that the ecosystem LUE at the six sites was significantly correlated with the cloudiness variation (0.24 ≤ R(2) ≤ 0.85), especially at the Changbaishan temperate forest ecosystem (R(2) = 0.85).Meanwhile, the CI values appeared more frequently between 0.8 and 1.0 in two subtropical forest ecosystems (Qianyanzhou and Dinghushan) and were much larger than those in temperate ecosystems.Besides, cloudiness thresholds which were favorable for enhancing ecosystem carbon sequestration existed at the three forest sites, respectively.

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 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.

ABSTRACT
Ecosystem light use efficiency (LUE) is a key factor of production models for gross primary production (GPP) predictions. Previous studies revealed that ecosystem LUE could be significantly enhanced by an increase on diffuse radiation. Under large spatial heterogeneity and increasing annual diffuse radiation in China, eddy covariance flux data at 6 sites across different ecosystems from 2003 to 2007 were used to investigate the impacts of diffuse radiation indicated by the cloudiness index (CI) on ecosystem LUE in grassland and forest ecosystems. Our results showed that the ecosystem LUE at the six sites was significantly correlated with the cloudiness variation (0.24 ≤ R(2) ≤ 0.85), especially at the Changbaishan temperate forest ecosystem (R(2) = 0.85). Meanwhile, the CI values appeared more frequently between 0.8 and 1.0 in two subtropical forest ecosystems (Qianyanzhou and Dinghushan) and were much larger than those in temperate ecosystems. Besides, cloudiness thresholds which were favorable for enhancing ecosystem carbon sequestration existed at the three forest sites, respectively. Our research confirmed that the ecosystem LUE at the six sites in China was positively responsive to the diffuse radiation, and the cloudiness index could be used as an environmental regulator for LUE modeling in regional GPP prediction.

No MeSH data available.