Acclimation and adaptation of gross primary production to global warming depend on water
文献类型：学位论文
| 作者 | 王冰雪 |
| 答辩日期 | 2020-04 |
| 文献子类 | 博士后出站报告 |
| 授予单位 | 中国科学院地理科学与资源研究所 |
| 授予地点 | 中国科学院地理科学与资源研究所 |
| 导师 | 牛书丽 |
| 关键词 | gross primary production thermal acclimation and adaptation optimum air temperature of GPP (TGPPopt) the maximum GPP (GPPmax) plant funciional types |
| 学位名称 | 博士后 |
| 英文摘要 | Gross primary production (GPP), which is the photosynthesis at the ecosystem-scale， represents the largest carbon flux on earth. GPP is sensitive to changes in air temperature since photosynthesis is ensentially an enzyme-catalyzed biochemical process. The global air temperature is projected to increase by 0.3-4.8 °C by 2100, which could lead to wide-ranging effects on the global carbon balance and its feedback to climate change through influencing GPP, In addition, stomatal conductance is controlled by vapor pressure deficit that is tie to air temperature and humidity, indicating that water cycle may play an important role in the reponse of GPP to global climate warming. Therefore, a better understanding of photosynthesis-temperature response at the ecosystem-scale and the role water plays in it are essential to an accurate prediction of future carbon cycle. In order to quantify the response of GPP to air temperature, we used the FLUXNET data that includes 326 sites with 1634 site-years data covering large geographical areas (37°S-79°N). For each site-year, GPP-temperature response curve was constructed, which was a one-humped parabola with two critical properties, the maximum GPP (GPPmax) and the optimum air temperature, at which GPP peaked (TGPPopt). Plants are able to maintain carbon uptake under warmer climate by adjusting optimum temperature to surrounding air temperature and meanwhile maintain or increase peak photosynthetic rates. Yet it is not clear if ecosystems also have the capacities, not to mention the magnitude of the thermal adjustment capacity for GPP. To anser these questions，we investigated the adjustment of TGPPopt and GPPmax to air temperature across time and over space，considered as thermal acclimation and thermal adaptation，respectively. Further, we also analyzed the role water and plant functional types plays in GPP thermal acclimation and adaptation. We have found that ecosystems had the full capacity to adapt to the maximum temperature of the year (Tmax) that TGPPopt increased by 1°C per 1°C increase in Tmax when aridity index is larger than 1 or Tmax is less than 24.9°C. This 1ed to an equation with a slope of one (TGPPopt =Tmax -4.7) for two-thirds of the 326 sites from 37°S to79°N. TGPPopt increased by 0.64°C per 1°C increase in Tmax across sites suffered from drought. The slope between TGPPopt and Tmax varied among different plant functional types, attributable to the differences in climatic preferences. The acclimation of TGPPopt to Tmax was assessed using linear mixed model. The temporal slopes of TGPPopt to Tmax was less steep than the spatial slope, indicating that ecosystems has a stronger capcity to adjust TGPPopt to long-term (eg. centuries) thermal conditions than short-term (eg. years) thermal conditions. Water deficiency also lowered the acclimation capacity of T: TGPPopt to Tmax from 0.86 to 0.58. Overall，the increase in the yearly maximum temperature under future climate warming likely increases the temperature optima of GPP. However, warming-associated droughts likely slow down both thermal adaptation and acclimation. The maximum gross primary production (GPPmax) is another critical property of the photosynthetic temperature responses. Thermal adjustments of TGPPopt alone does not guarentean a stable carbon uptake unless GPPraax does not decrease under future climate. We have found GPPmax changed with soil moisture (SM), global solar radiation (GSR), mean annual temperature (MAT), vapor pressure deficit (VPD) and plant functional types (PFTs), which in combination explained 63% of the spatial variation. The direction and magnitude of climate drivers5 effects on GPPmax depended on the balance between water and energy. Across water-limited sites， GPPmax linearly increased with SM and decreased with air dryness. Similar phenomone was also observed for the temporal variation within water-limited sites that GPPmax was significantly lower in drier or warmer years. Across energy-limited sites，high temperature and it induced air dryness increased GPPmax while SM did not affect GPPmax. Yet Energy-limited sites tended to maintain a stable GPPmax across years regardless of changes in air temperature. The discrepancy between spatial and temporal pattern in energy-limited sites indicates that higher temperature are able to boost carbon uptake capacities of water-sufficient ecosystems through evolutionary adaption through centries. Yet such benefit cannot be realized within several years. PFTs that inhabit humid climate tend to have higher normalized GPPmax and are more likely benefit from a warmer climate. The novelty and highlight of this study resides in that the major climate drivers of GPPmax depends on the interplay between water and energy, which is essential to a realistic prediction of terrestrial carbon uptake under future climate conditions. In conclusion, our study indicates that ecosystems are capable of acclimating and adapting to changes in air temperature, which eases the pressure of global climate warming on carbon cycle. Nevertheless, the magnitude of thermal adjustments depends on water supply. Based on our analysis, GPP in water sufficient regions is predicted to increase by 2100, through fully adjusting TGPPopt to the maximum temperature and increasing GPPmax in the long run. Although water-deficient ecosystems are also able to adjusting TGPPopt to air temperature, indicating a higher carbon uptake than model predictions assuming no thermal acclimation and adaptation. Yet the magnitude of adjustment is compromised due to drought. In combined with the fact that GPPmax is also reduced by lower soil moisture, lower carbon uptake is expected in the future. Our work improves understanding of how ecosystems cope with higher temperature and reveals the crucial rule water played in it. Results showed in this work will contribute to more accurate projections of GPP under future climate. |
| 语种 | 英语 |
| 页码 | 82 |
| 源URL | [http://ir.igsnrr.ac.cn/handle/311030/194103]  |
| 专题 | 地理科学与资源研究所_研究生部 |
| 推荐引用方式 GB/T 7714 | Wang BX. Acclimation and adaptation of gross primary production to global warming depend on water[D]. 中国科学院地理科学与资源研究所. 中国科学院地理科学与资源研究所. 2020. |
入库方式： OAI收割
来源：地理科学与资源研究所
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