scholarly journals Response to Comment on “Unexpected reversal of C3 versus C4 grass response to elevated CO2 during a 20-year field experiment”

Science ◽  
2018 ◽  
Vol 361 (6407) ◽  
pp. eaau8982 ◽  
Author(s):  
Peter B. Reich ◽  
Sarah E. Hobbie ◽  
Tali D. Lee ◽  
Melissa A. Pastore
Keyword(s):  
Field Experiment ◽  
Elevated Co2 ◽  
Temporal Dynamics ◽  
Climate Variation ◽  
C4 Grass

Nie and colleagues suggest a key role for interannual climate variation as an explanation for the temporal dynamics of an unexpected 20-year reversal of biomass responses of C3-C4 grasses to elevated CO2. However, we had already identified some climate-dependent differences in C3 and C4 responses to eCO2 and shown that these could not fully explain the temporal dynamics we observed.

Comment on “Unexpected reversal of C3 versus C4 grass response to elevated CO2 during a 20-year field experiment”

Science ◽  
2018 ◽  
Vol 361 (6405) ◽  
pp. eaau3016 ◽  
Author(s):  
Ming Nie ◽  
Junyu Zou ◽  
Xiao Xu ◽  
Chao Liang ◽  
Changming Fang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Field Experiment ◽  
Elevated Co2 ◽  
Elevated Carbon Dioxide ◽  
Climate Variation ◽  
Potential Mechanism ◽  
Term Experiment ◽  
C4 Grass ◽  
Long Term Experiment

Reich et al. (Reports, 20 April 2018, p. 317) reported that elevated carbon dioxide (eCO2) switched its effect from promoting C3 grasses to favoring C4 grasses in a long-term experiment. We argue that the authors did not appropriately elucidate the interannual climate variation as a potential mechanism for the reversal of C4-C3 biomass in response to eCO2.

scholarly journals Response to Comment on “Unexpected reversal of C3 versus C4 grass response to elevated CO2 during a 20-year field experiment”

Science ◽  
2018 ◽  
Vol 361 (6402) ◽  
pp. eaau1300 ◽  
Author(s):  
Peter B. Reich ◽  
Sarah E. Hobbie ◽  
Tali D. Lee ◽  
Melissa A. Pastore
Keyword(s):  
Field Experiment ◽  
Elevated Co2 ◽  
C4 Grass

High vapour pressure deficit and low soil water availability enhance shoot growth responses of a C4 grass (Panicum coloratum cv. Bambatsi) to CO2 enrichment

1998 ◽  
Vol 25 (3) ◽  
pp. 287 ◽  
Author(s):  
Saman P. Seneweera ◽  
Oula Ghannoum ◽  
Jann Conroy
Keyword(s):  
Soil Water ◽  
Elevated Co2 ◽  
Vapour Pressure ◽  
Shoot Growth ◽  
Vapour Pressure Deficit ◽  
C4 Grasses ◽  
Growth Responses ◽  
High Co2 ◽  
C4 Grass ◽  
Shoot Mass

The hypothesis that shoot growth responses of C4 grasses to elevated CO2 are dependent on shoot water relations was tested using a C4 grass, Panicum coloratum (NAD-ME subtype). Plants were grown for 35 days at CO2 concentrations of 350 or 1000 µL CO2 L-1. Shoot water relations were altered by growing plants in soil which was brought daily to 65, 80 or 100% field capacity (FC) and by maintaining the vapour pressure deficit (VPD) at 0.9 or 2.1 kPa. At 350 µL CO2 L-1, high VPD and lower soil water content depressed shoot dry mass, which declined in parallel at each VPD with decreasing soil water content. The growth depression at high VPD was associated with increased shoot transpiration, whereas at low soil water, leaf water potential was reduced. Elevated CO2 ameliorated the impact of both stresses by decreasing transpiration rates and raising leaf water potential. Consequently, high CO2 approximately doubled shoot mass and leaf length at a VPD of 2.1 kPa and soil water contents of 65 and 80% FC but had no effect on unstressed plants. Water use efficiency was enhanced by elevated CO2 under conditions of stress but this was primarily due to increases in shoot mass. High CO2 had a greater effect on leaf growth parameters than on stem mass. Elevated CO2 increased specific leaf area and leaf area ratio, the latter at high VPD only. We conclude that high CO2 increases shoot growth of C4 grasses by ameliorating the effects of stress induced by either high VPD or low soil moisture. Since these factors limit growth of field-grown C4 grasses, it is likely that their biomass will be enhanced by rising atmospheric CO2 concentrations.

scholarly journals Epidemiology of dengue and the effect of seasonal climate variation on its dynamics: a spatio-temporal descriptive analysis in the Chao-Shan area on China’s southeastern coast

BMJ Open ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. e024197 ◽  
Author(s):  
Qin Zhang ◽  
Yuliang Chen ◽  
Yu Fu ◽  
Tao Liu ◽  
Qingying Zhang ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Temporal Dynamics ◽  
Descriptive Analysis ◽  
Additive Model ◽  
Climate Variation ◽  
Generalised Additive Model ◽  
Seasonal Climate ◽  
Southeastern Coast ◽  
Climatic Drivers ◽  
Spatio Temporal

ObjectiveDengue is a mosquito-transmitted virus infection that remains rampant across the tropical and subtropical areas worldwide. However, the spatial and temporal dynamics of dengue transmission are poorly understood in Chao-Shan area, one of the most densely populated regions on China’s southeastern coast, limiting disease control efforts. We aimed to characterise the epidemiology of dengue and assessed the effect of seasonal climate variation on its dynamics in the area.DesignA spatio-temporal descriptive analysis was performed in three cities including Shantou, Chaozhou and Jieyang in Chao-Shan area during the period of 2014–2017.SettingData of dengue cases of three cities including Shantou, Chaozhou and Jieyang in Chao-Shan area during 2014–2017 were extracted. Data for climatic variables including mean temperature, relative humidity and rainfall were also compiled.MethodologyThe epidemiology and dynamics of dengue were initially depicted, and then the temporal dynamics related to climatic drivers was assessed by a wavelet analysis method. Furthermore, a generalised additive model for location, scale and shape model was performed to study the relationship between seasonal dynamics of dengue and climatic drivers.ResultsAmong the cities, the number of notified dengue cases in Chaozhou was greatest, accounting for 78.3%. The median age for the notified cases was 43 years (IQR: 27.0–58.0 years). Two main regions located in Xixin and Chengxi streets of Chaozhou with a high risk of infection were observed, indicating that there was substantial spatial heterogeneity in intensity. We found an annual peak incidence occurred in autumn across the region, most markedly in 2015. This study reveals that periods of elevated temperatures can drive the occurrence of dengue epidemics across the region, and the risk of transmission is highest when the temperature is between 25°C and 28°C.ConclusionOur study contributes to a better understanding of dengue dynamics in Chao-Shan area.

Genetic variation in response to elevated CO2 in three grassland perennials — a field experiment with two competition regimes

1997 ◽  
Vol 18 (3) ◽  
pp. 263-268 ◽  
Author(s):  
Thomas Steinger ◽  
Claire Lavigne ◽  
Andreas Birrer ◽  
Kathleen Groppe ◽  
Bernhard Schmid
Keyword(s):  
Genetic Variation ◽  
Field Experiment ◽  
Elevated Co2
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