Cloudy Sky Conditions Promote Net Ecosystem CO2 Exchange in a Subtropical Coniferous Plantation across Seasons

doi:10.5814/j.issn.1674-764X.2019.02.004

Abstract

Abstract:

Dynamic changes in solar radiation have an important influence on ecosystem carbon sequestration, but the effects of changes caused by sky conditions on net ecosystem CO₂ exchange (NEE) are unclear. This study analyzed the effects of sunny, cloudy, and overcast sky conditions on NEE using carbon flux and meteorological data for a subtropical coniferous plantation in 2012. Based on one-year data, we found no seasonal variation in the light response curve under various sky conditions. Compared with sunny sky conditions, the apparent quantum yield (α) and potential photosynthetic rate at a light intensity of 150 and 750 W m^-2 (P₁₅₀ and P₇₅₀) under cloudy sky conditions increased by an average of 82.3%, 217.7%, and 22.5%; α and P₁₅₀ under overcast sky conditions increased by 118.5% and 301% on average. Moderate radiation conditions were more favorable for maximum NEE, while low radiation conditions inhibited NEE. In most cases, when the sunny NEE was used as a baseline for comparison, the relative change in NEE (%NEE) was positive under cloudy sky conditions and negative under overcast sky conditions. The average maximal %NEE under cloudy sky conditions was 42.4% in spring, 34.1% in summer, 1.6% in autumn and -87.3% in winter. This study indicates that cloudy sky conditions promote photosynthetic rates and NEE in subtropical coniferous plantations.

Key words: eddy covariance, sky conditions, diffuse radiation, clearness index, NEE

HAN Jiayin,YE Shu,GUO Chuying,ZHANG Leiming,LI Shenggong,WANG Huimin. Cloudy Sky Conditions Promote Net Ecosystem CO₂ Exchange in a Subtropical Coniferous Plantation across Seasons[J]. Journal of Resources and Ecology, 2019, 10(2): 137-146.

Figures/Tables 10

Fig. 1 Scatterplots and regressions between global radiation (Ig), clearness index (kt) and the sine of solar elevation angles (sinβ) in 2012.Note: (a) (e) spring, (b) (f) summer, (c) (g) autumn, and (d) (h) winter. Data were fitted by cubic polynomials in the morning (solid line) and afternoon (dashed line), respectively.

Table 1 Light response parameters of the net ecosystem CO2 exchange (NEE) response to global radiation

Season	Weather	α(g C W^-1 s^-1)	P_max(g C m^-2 s^-1)	R_d(g C m^-2 s^-1)	P₁₅₀(g C m^-2 s^-1)	P₇₅₀(g C m^-2 s^-1)	R²
Spring	Sunny	1.1 × 10^-3	1.14	0.07	0.08	0.52	0.88
	Cloudy	2.6 × 10^-3	0.97	0.09	0.23	0.75	0.96
	Overcast	2.7 × 10^-3	1.15	0.06	0.28	-	0.94
Summer	Sunny	1.9 × 10^-3	1.02	0.19	0.06	0.58	0.92
	Cloudy	2.7 × 10^-3	1.03	0.10	0.23	0.79	0.97
	Overcast	4.8 × 10^-3	0.76	0.13	0.34	-	0.96
Autumn	Sunny	1.7 × 10^-3	2.80	0.16	0.08	0.86	0.91
	Cloudy	2.9 × 10^-3	1.09	0.10	0.26	0.84	0.97
	Overcast	3.5 × 10^-3	1.42	0.12	0.32	-	0.63
Winter	Sunny	1.0 × 10^-3	1.34	0.06	0.08	0.51	0.90
	Cloudy	1.8 × 10^-3	0.66	0.00	0.22	0.57	0.98
	Overcast	1.7 × 10^-3	1.10	0.00	0.23	-	0.98

Fig. 2 Light response curves of net ecosystem CO2 exchange (NEE) to global radiation (Ig) in 2012Note: (a) spring, (b) summer, (c) autumn, and (d) winter. All points with standard error bars are averaged by the Ig data per 50 W m-2 under the same sky condition in the same season. All curves are best fitted by Eq. (8) and light response parameters are described in detail in Table 1.

Fig. 3 Relationship between light response parameters ((a) α, (b) P150, and (c) P750) and diffuse fraction (kd) presented in Table 1. Note: Only data under sunny and cloudy sky conditions are presented in (c). α is the apparent quantum yield, P150 is the potential photosynthetic rate under a low light intensity of 150 W m-2, P750 is the potential photosynthetic rate under a high light intensity of 750 W m-2, and R2 is the coefficient of determination.

Fig. 4 Scatterplots and quadratic regressions for net ecosystem CO2 exchange (NEE) and clearness index (kt) for (a-d) the 50o-60o and (e-f) 80o-90o intervals of solar elevation angles (β) in 2012. Note: There are no 80o-90o intervals of β in autumn and winter.

Fig. 5 Changes in (a-d) diffuse radiation (Id), (e-h) air temperatures (Ta), and (i-l) vapor pressure deficit (VPD) with clearness index (kt) for 50o-60o and 80o-90o intervals of solar elevation angles (β) in 2012. Note: There are no 80o-90o intervals of β in autumn and winter.

Table 2 Maximal relative change in net ecosystem CO2 exchange (NEE) under cloudy sky conditions compared with sunny sky conditions (%NEE) for every 10° interval of solar elevation angle (β) in 2012

Season	%NEE (30°<β≤40°)	%NEE (40°<β≤50°)	%NEE (50°<β≤60°)	%NEE (60°<β≤70°)	%NEE (70°<β≤80°)	%NEE (80°<β≤90°)	%NEE (Mean)
Spring	39.8	42	18.3	26.4	39	86.4	42.4
Summer	38.9	27.1	31.2	30.6	41.4	35.4	34.1
Autumn	5.6	-12.8	-0.2	14	-	-	1.6
Winter	39.9	-251.2	-50.7	-	-	-	-87.3

Fig. 6 Scatterplots and cubic regressions between the sunny net ecosystem CO2 exchange (NEE) and the sine of solar elevation angles (sinβ) in 2012 Note: The obtained cubic regression equations are used to calculate NEEs(β) in Eq. (9).

Fig. 7 Relationship between relative change in net ecosystem CO2 exchange (NEE) under (a-d) cloudy and (e-h) overcast sky conditions compared with sunny sky conditions (%NEE) and the clearness index (kt) for 50o-60o and 80o-90o intervals of solar elevation angles (β) in 2012.Note: There are no 80 o-90o intervals of β in autumn and winter.

Fig. 8 Histograms of the clearness index (kt) in 2012

References 40

[1]	Alton P B, North P R, Los S O.2007. The impact of diffuse sunlight on canopy light-use efficiency, gross photosynthetic product and net ecosystem exchange in three forest biomes.Global Change Biology, 13(4): 776-787.
[2]	Alton P B.2008. Reduced carbon sequestration in terrestrial ecosystems under overcast skies compared to clear skies.Agricultural and Forest Meteorology, 148(10): 1641-1653.
[3]	Baldocchi D D.2003. Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosystems: past, present and future.Global Change Biology, 9(4): 479-492.
[4]	Bassman J H, Zwier J C.1991. Gas exchange characteristics of Populus trichocarpa, Populus deltoides and Populus trichocarpa × P. deltoides clones. Tree Physiology, 8(2): 145-159.
[5]	Dengel S, Grace J.2010. Carbon dioxide exchange and canopy conductance of two coniferous forests under various sky conditions.Oecologia, 164(3): 797-808.
[6]	Falge E, Baldocchi D, Olson R, et al.2001. Gap filling strategies for defensible annual sums of net ecosystem exchange.Agricultural and Forest Meteorology, 107(1): 43-69.
[7]	Farquhar G D, Roderick M L.2003. Pinatubo, diffuse light, and the carbon cycle.Science, 299(5615): 1997-1998.
[8]	Freedman J M, Firzjarrald D R, Moore K E, et al.2001. Boundary layer clouds and vegetation-atmosphere feedbacks.Journal of Climate, 14(2): 180-197.
[9]	Gu L H, Baldocchi D D, Wofsy S C, et al.2003. Response of a deciduous forest to the Mount Pinatubo eruption: enhanced photosynthesis.Science, 299(5615): 2035-2038.
[10]	Gu L H, Baldocchi D, Verma S B, et al.2002. Advantages of diffuse radiation for terrestrial ecosystem productivity.Journal of Geophysical Research, D6(4050): 107.
[11]	Gu L H, Fuentes J D, Shugart H H, et al.1999. Responses of net ecosystem exchanges of carbon dioxide to changes in cloudiness: Results from two North American deciduous forests. Journal of Geophysical Research, 104(D24): 31421-31434.
[12]	Han J Y, Li S G, Zhang L M, et al.2015a. Comparative observation of diffuse radiation in Qianyanzhou during the spring of 2012.Chinese Journal of Applied Ecology, 26(3): 697-703. (in Chinese)
[13]	Han J Y, Li S G, Zhang L M, et al.2015b. Simulation and validation of diffuse radiation in Qianyanzhou area, Jiangxi, China.Chinese Journal of Applied Ecology, 26(10): 2991-2999. (in Chinese)
[14]	Han J Y, Li S G, Zhang L M, et al.2019. Effects of sky conditions on net ecosystem productivity of a subtropical coniferous plantation vary from half-hourly to daily timescales.Science of the Total Environment, 651: 3002-3014.
[15]	He X Z, Zhou T, Jia G S, et al.2011. Modeled effects of changes in the amount and diffuse fraction of PAR on forest GPP.Journal of Natural Resources, 26(4): 619-634. (in Chinese)
[16]	Kanniah K D, Beringer J, Hutley L.2013. Exploring the link between clouds, radiation, and canopy productivity of tropical savannas. Agricultural and Forest Meteorology, 182-183: 304-313.
[17]	Knohl A, Baldocchi D D.2008. Effects of diffuse radiation on canopy gas exchange processes in a forest ecosystem.Journal of Geophysical Research, 113(G2): G02023.
[18]	Law B E, Falge E, Gu L H, et al.2002. Environmental controls over carbon dioxide and water vapor exchange of terrestrial vegetation.Agricultural and Forest Meteorology, 113(1-4): 97-120.
[19]	Li D Q, Zhou Y L, Ju W M, et al.2014. Modelling the effects of changes in solar radiation on gross primary production in subtropical evergreen needle-leaf plantations.Chinese Journal of Plant Ecology, 38(3): 219-230. (in Chinese)
[20]	Lloyd J L, Taylor J A.1994. On the temperature dependence of soil respiration.Functional Ecology, 8(3): 315-323.
[21]	Mercado L M, Bellouin N, Sitch S, et al.2009. Impact of changes in diffuse radiation on the global land carbon sink.Nature, 458(7241): 1014-1017.
[22]	Reindl D T, Beckman W A, Duffie J A.1990. Diffuse fraction correlations.Solar Energy, 45(1): 1-7.
[23]	Şen Z.2008. Atmospheric environment and renewable energy. In: Şen Z (ed.). Solar Energy Fundamentals and Modeling Techniques: Atmosphere, Environment, Climate Change and Renewable Energy. Berlin: Springer, 21-45.
[24]	Seo K H, Ok J.2013. Assessing future changes in the East Asian summer monsoon using CMIP3 models: results from the best model ensemble.Journal of Climate, 26(5): 1807-1817.
[25]	Stjern C W, Hansen A W.2010. Global dimming and global brightening - an analysis of surface radiation and cloud cover data in northern Europe.International Journal of Climatology, 29(5): 643-653.
[26]	Szeicz C.1974. Solar radiation for plant growth.Journal of Applied Ecology, 11(2): 617-636.
[27]	Tang Y K, Wen X F, Sun X M, et al.2014. The limiting effect of deep soil water on evapotranspiration of a subtropical coniferous plantation subjected to seasonal drought.Advances in Atmospheric Sciences, 31(2): 385-395.
[28]	Wang K C, Dickinson R E, Liang S L.2008. Observational evidence on the effects of clouds and aerosols on net ecosystem exchange and evapotranspiration.Geophysical Research Letters, 35(10): L10401.
[29]	Wang M M, Zhang M, Wang H M, et al.2015. Effects of changes in solar radiation on net ecosystem exchange of carbon dioxide of planted subtropical coniferous forest in Qianyanzhou.Chinese Journal of Ecology, 34(2): 303-311. (in Chinese)
[30]	Wang Y D, Li Q K, Wang H M, et al.2011. Precipitation frequency controls interannual variation of soil respiration by affecting soil moisture in a subtropical forest plantation.Canadian Journal of Forest Research, 41(9): 1897-1906.
[31]	Wang Y D, Wang Z L, Wang H M, et al.2012. Rainfall pulse primarily drives litterfall respiration and its contribution to soil respiration in a young exotic pine plantation in subtropical China.Canadian Journal of Forest Research, 42(4): 657-666.
[32]	Webb E K, Pearman G I, Leuning R.1980. Correction of flux measurements for density effects due to heat and water vapour transfer.Quarterly Journal of the Royal Meteorological Society, 106(447): 85-100.
[33]	Wen X F, Wang H M, Wang J L, et al.2010. Ecosystem carbon exchanges of a subtropical evergreen coniferous plantation subjected to seasonal drought, 2003-2007.Biogeosciences, 7(1): 357-369.
[34]	Wilczak J M, Oncley S P, Stage S A.2001. Sonic anemometer tilt correction algorithms.Boundary-Layer Meteorology, 99(1): 127-150.
[35]	Wild M.2009. Global dimming and brightening: a review. Journal of Geophysical Research, 114: D00D16. doi:10.1029/2008JD011470.
[36]	Wu D.2012. Hazy weather research in China in the last decade: A review.Acta Scientiae Circumstantiae, 32(2): 257-269. (in Chinese)
[37]	Yu G R, Chen Z, Piao S L, et al.2014. High carbon dioxide uptake by subtropical forest ecosystems in the east Asian monsoon region.Proceedings of the National Academy of Sciences, 111(13): 4910-4915.
[38]	Yu G R, Fu Y L, Sun X M, et al.2006. Recent progress and future directions of ChinaFLUX.Science in China Series D: Earth Sciences, 49(Supp.II): 1-23.
[39]	Zhang M, Yu G R, Zhang L M, et al.2010. Impact of cloudiness on net ecosystem exchange of carbon dioxide in different types of forest ecosystems in China.Biogeosciences, 7(2): 711-722.
[40]	Zhang M, Yu G R, Zhuang J, et al.2011. Effects of cloudiness change on net ecosystem exchange, light use efficiency, and water use efficiency in typical ecosystems of China.Agricultural and Forest Meteorology, 151(7): 803-816.

Cloudy Sky Conditions Promote Net Ecosystem CO₂ Exchange in a Subtropical Coniferous Plantation across Seasons

RichHTML

PDF (PC)

Knowledge

Abstract

Cite this article

share this article

Figures/Tables 10

References 40

Related Articles 3

Recommended Articles

Metrics

Comments

[1]	USOLTSEV Vladimir Andreevich, SHOBAIRI Seyed Omid Reza, TSEPORDEY Ivan Stepanovich, AHRARI Amirhossein, ZHANG Meng, SHOAIB Ahmad Anees, CHASOVSKIKH Viktor Petrovich. Are There Differences in the Response of Natural Stand and Plantation Biomass to Changes in Temperature and Precipitation? A Case for Two-needled Pines in Eurasia [J]. Journal of Resources and Ecology, 2020, 11(4): 331-341.
[2]	NIU Ben, ZHANG Xianzhou, HE Yongtao, SHI Peili, FU Gang, DU Mingyuan, ZHANG Yangjian, ZONG Ning, ZHANG Jing, WU Jianshuang. Satellite-based Estimation of Gross Primary Production in an Alpine Swamp Meadow on the Tibetan Plateau: A Multi-model Comparison [J]. Journal of Resources and Ecology, 2017, 8(1): 57-66.
[3]	ZHOU Yujie, JIANG Jusheng, PENG Zongbo, WANG Qunhui, XIONG Daiqun. Ecosystem Management in the Natural Rubber Industry [J]. Journal of Resources and Ecology, 2012, 3(3): 230-235.