How will global change affect photosynthesis and carbon transfer of future forests?

由于加拿大拥有世界上33%的北方针叶林，这些森林对全球变化的反应具有至关重要的生态和经济意义。这些生态系统的生长和生产力的变化将直接影响它们的经济价值、固碳能力以及可持续管理实践或生物燃料生产。生物圈的物候，例如碳吸收期，已经被全球变化所改变。有证据表明，由于生长季节长度的增加，森林的生产力有所提高，但也有迹象表明，其他生理过程同时对生产力产生负面影响。在生长季节开始和结束时，全球变化的影响仍然存在很大的不确定性，例如秋春温度升高对北方针叶树光合作用碳吸收的调节以及冷硬化和去硬化的影响。本研究项目研究全球变化对未来森林和树木物候过程、光合作用和碳转移模式的影响。它的具体目的是确定温度升高和CO2升高对北方针叶树秋季冷硬化过程和抗冻性发展的影响，以及了解（ii）春季脱硬化过程的后果。该计划将减少树木对众多（而不是单一）全球变化因素的响应的不确定性，并提供对适应过程背后的调节网络的更好理解。此外，该计划将产生可用于参数化的新数据，以改进大型模型，并将为森林部门提供知识，使管理实践适应未来的气候条件。

Because Canada holds 33% of the world's boreal conifer forests, the response of these forests to global change is of paramount ecological and economic importance. Changes in growth and productivity of these ecosystems will directly affect their economic value, their ability to sequester carbon as well as sustainable management practice or biofuel production. The phenology of the biosphere, indicated by e.g. the carbon uptake period, has already been altered by global change. There is evidence of an increased productivity of forests due to an increase in growing season length, but there are also indications of other physiological processes concurrently having negative effects on productivity. Large uncertainties remain on the impact of global change at the beginning and the end of the growing season, such as the effect of increased autumn and spring temperature on e.g. the regulation of photosynthetic carbon uptake and the cold hardening and dehardening in boreal conifers. This research program investigates the impact of global change on phenological processes, photosynthesis and carbon transfer patterns of future forests and trees. It specifically aims to determine the effect of increased temperature and elevated CO2 on the (i) regulation of the cold hardening process of boreal conifers and the development of freezing resistance in autumn as well as to understand the (ii) consequences for the dehardening process in spring. This program will reduce uncertainties on tree responses to a multitude (not single!) of global change factors and provide better understanding of the regulatory network underlying acclimational processes. In addition, the program will generate novel data that can be used for parameterization to improve large scale models and it will provide knowledge to the forest sector to adapt management practices to future climatic conditions.