The effect of phenology on the carbon exchange process in grassland and maize cropland ecosystems across a semiarid area of China.

Phenology plays an important role in the carbon exchange process. Seven years of continuous eddy covariance data across two different ecosystems in a semiarid area were used to investigate the variation in phenology indices, its effect on the carbon exchange process, and responses to climate change. The results showed that there was large annual variation for vegetation phenology. The GSL (growing season length) displayed an obvious increasing trend for the grassland ecosystem during the 7 years, and it was most determined by SOS (the start day of growing season). The growing season was divided into three periods, the recovery period (S1), the stable period (S2), and the senescence period (S3). Both ecosystems had a similar ratio of Re (ecosystem respiration) to GPP (gross primary production) during S1 and S2 periods but a much larger Re/GPP ratio during the last growing period. The inter-annual variation of the peak rate was most responsible for the NEP (net ecosystem production) and its components (GPP and Re) in both ecosystems. The inter-annual variation of recovery rate, GSL and SOS was found to be closely correlated to Re for the grassland ecosystem, while that could not be found for the cropland ecosystem. The temperature in June was most closely correlated with the peak rate of GPP and NEP for grassland ecosystem, with a significant correlation coefficient of -0.90 and -0.82, respectively. Meanwhile, the precipitation in July was found to be closely correlated with GPP for both ecosystems, with a similar correlation coefficient of 0.83. The precipitation and temperature roughly exhibited an inverse effect on vegetation phenology in this semiarid area. The variation of temperature in the early month and precipitation in mid growing season showed a more significant effect on main phenology indicators for the cropland ecosystem than those for grassland ecosystem.

[1]  Guirui Yu,et al.  Effects of vegetation control on ecosystem water use efficiency within and among four grassland ecosystems in China , 2008 .

[2]  M. Schaepman,et al.  Intercomparison, interpretation, and assessment of spring phenology in North America estimated from remote sensing for 1982–2006 , 2009 .

[3]  W. Oechel,et al.  Environmental controls over carbon dioxide and water vapor exchange of terrestrial vegetation , 2002 .

[4]  J. Peñuelas,et al.  European phenological response to climate change matches the warming pattern , 2006 .

[5]  Yanhong Tang,et al.  Influences of temperature and precipitation before the growing season on spring phenology in grasslands of the central and eastern Qinghai-Tibetan Plateau , 2011 .

[6]  J. Bonnefond,et al.  Simultaneous measurements of CO 2 and water exchanges over three agroecosystems in South-West France , 2009 .

[7]  Huizhi Liu,et al.  Evaluating of simulated carbon flux phenology over a cropland ecosystem in a semiarid area of China with SiBcrop , 2017, International Journal of Biometeorology.

[8]  T. Vesala,et al.  On the separation of net ecosystem exchange into assimilation and ecosystem respiration: review and improved algorithm , 2005 .

[9]  Hans Peter Schmid,et al.  Evidence of increased net ecosystem productivity associated with a longer vegetated season in a deciduous forest in south‐central Indiana, USA , 2010 .

[10]  W. Ju,et al.  Grassland dynamics in response to climate change and human activities in Inner Mongolia, China between 1985 and 2009 , 2013 .

[11]  Tiina Markkanen,et al.  Air temperature triggers the recovery of evergreen boreal forest photosynthesis in spring , 2003 .

[12]  Jennifer N. Hird,et al.  Noise reduction of NDVI time series: An empirical comparison of selected techniques , 2009 .

[13]  Xuguang Tang,et al.  Characterizing ecosystem water-use efficiency of croplands with eddy covariance measurements and MODIS products , 2015 .

[14]  Bradley C. Reed,et al.  Remote Sensing Phenology , 2009 .

[15]  P. Ciais,et al.  Variations in satellite‐derived phenology in China's temperate vegetation , 2006 .

[16]  D. Baldocchi,et al.  Inter-annual variability in carbon dioxide exchange of an oak/grass savanna and open grassland in California , 2007 .

[17]  Hongyan Liu,et al.  Consistent shifts in spring vegetation green‐up date across temperate biomes in China, 1982–2006 , 2013, Global change biology.

[18]  Xuguang Tang,et al.  Potential and environmental control of carbon sequestration in major ecosystems across arid and semi-arid regions in China. , 2018, The Science of the total environment.

[19]  Liu Huizhi,et al.  Seven years of carbon dioxide exchange over a degraded grassland and a cropland with maize ecosystems in a semiarid area of China , 2013 .

[20]  Christopher M. Gough,et al.  Evidence of autumn phenology control on annual net ecosystem productivity in two temperate deciduous forests , 2013 .

[21]  P. Ciais,et al.  Net carbon dioxide losses of northern ecosystems in response to autumn warming , 2008, Nature.

[22]  Murugesu Sivapalan,et al.  Soil moisture controls on patterns of grass green-up in Inner Mongolia: an index based approach , 2012 .

[23]  Natascha Kljun,et al.  Climatic controls on the carbon and water balances of a boreal aspen forest, 1994–2003 , 2007 .

[24]  Per Jönsson,et al.  TIMESAT - a program for analyzing time-series of satellite sensor data , 2004, Comput. Geosci..

[25]  E. K. Webb,et al.  Correction of flux measurements for density effects due to heat and water vapour transfer , 1980 .

[26]  Guirui Yu,et al.  Seasonal dynamics of water use efficiency of typical forest and grassland ecosystems in China , 2014, Journal of Forest Research.

[27]  Jiquan Chen,et al.  Biophysical regulations of carbon fluxes of a steppe and a cultivated cropland in semiarid Inner Mongolia , 2007 .

[28]  Todd N. Rosenstiel,et al.  Climatic influences on net ecosystem CO2 exchange during the transition from wintertime carbon source to springtime carbon sink in a high-elevation, subalpine forest , 2005, Oecologia.

[29]  D. Hollinger,et al.  Influence of spring phenology on seasonal and annual carbon balance in two contrasting New England forests. , 2009, Tree physiology.

[30]  A. G. Barr,et al.  Response of Net Ecosystem Productivity of Three Boreal Forest Stands to Drought , 2005, Ecosystems.

[31]  D. Baldocchi.  A comparative study of mass and energy exchange rates over a closed C3 (wheat) and an open C4 (corn) crop: II. CO2 exchange and water use efficiency , 1994 .

[32]  Peter Lesica,et al.  Precipitation and temperature are associated with advanced flowering phenology in a semi-arid grassland , 2010 .

[33]  Qiang Liu,et al.  Analysis of the Phenology in the Mongolian Plateau by Inter-Comparison of Global Vegetation Datasets , 2013, Remote. Sens..

[34]  Z. Sha,et al.  Spatio-temporal patterns of satellite-derived grassland vegetation phenology from 1998 to 2012 in Inner Mongolia, China , 2016, Journal of Arid Land.

[35]  M. Friedl,et al.  Land Surface Phenology from MODIS: Characterization of the Collection 5 Global Land Cover Dynamics Product , 2010 .

[36]  Jing M. Chen,et al.  Land surface phenology from optical satellite measurement and CO2 eddy covariance technique , 2012 .

[37]  A. Verhoef,et al.  Seasonal variation of surface energy balance over two Sahelian surfaces , 1999 .

[38]  Yi Y. Liu,et al.  Contribution of semi-arid ecosystems to interannual variability of the global carbon cycle , 2014, Nature.

[39]  Ankur R. Desai,et al.  Climatic and phenological controls on coherent regional interannual variability of carbon dioxide flux in a heterogeneous landscape , 2010 .

[40]  Andrew E. Suyker,et al.  Characterizing the Seasonal Dynamics of Plant Community Photosynthesis Across a Range of Vegetation Types , 2009 .

[41]  Karl Auerswald,et al.  Changes in the abundance of C3/C4 species of Inner Mongolia grassland: evidence from isotopic composition of soil and vegetation , 2009 .

[42]  J. Seaquist,et al.  Phenology and its role in carbon dioxide exchange processes in northern peatlands , 2014 .

[43]  Guillermo E. Ponce-Campos,et al.  Vegetation productivity responds to sub-annual climate conditions across semiarid biomes , 2016 .

[44]  Dennis D. Baldocchi,et al.  Phenology of Vegetation Photosynthesis , 2003 .

[45]  J. Peñuelas,et al.  Changed plant and animal life cycles from 1952 to 2000 in the Mediterranean region , 2002 .

[46]  P. Ciais,et al.  Influence of spring and autumn phenological transitions on forest ecosystem productivity , 2010, Philosophical Transactions of the Royal Society B: Biological Sciences.

[47]  I. Wing,et al.  Net carbon uptake has increased through warming-induced changes in temperate forest phenology , 2014 .

[48]  Shilong Piao,et al.  Temperature, precipitation, and insolation effects on autumn vegetation phenology in temperate China , 2016, Global change biology.

[49]  O. Sonnentag,et al.  Climate change, phenology, and phenological control of vegetation feedbacks to the climate system , 2013 .

[50]  Allison L. Dunn,et al.  A long‐term record of carbon exchange in a boreal black spruce forest: means, responses to interannual variability, and decadal trends , 2007 .

[51]  Y. Xue,et al.  Terrestrial biosphere models need better representation of vegetation phenology: results from the North American Carbon Program Site Synthesis , 2012 .

[52]  Josep Peñuelas,et al.  Phenology Feedbacks on Climate Change , 2009, Science.

[53]  Xiangming Xiao,et al.  Spatial analysis of growing season length control over net ecosystem exchange , 2005 .

[54]  Hong Jiang,et al.  Water use efficiency in response to interannual variations in flux-based photosynthetic onset in temperate deciduous broadleaf forests , 2017 .

[55]  Hans W. Linderholm,et al.  Growing season changes in the last century , 2006 .

[56]  R. Monson,et al.  Model‐data synthesis of diurnal and seasonal CO2 fluxes at Niwot Ridge, Colorado , 2006 .

[57]  J. Tenhunen,et al.  Severe drought effects on ecosystem CO2 and H2O fluxes at three Mediterranean evergreen sites: revision of current hypotheses? , 2002 .

[58]  Andrew E. Suyker,et al.  Gap filling strategies for long term energy flux data sets , 2001 .

[59]  Jörg Schaber,et al.  Physiology-based phenology models for forest tree species in Germany , 2003, International journal of biometeorology.