Ecophysiology of northern forests: scaling physiological processes and states in space and time

北方森林的生态生理学：在空间和时间上缩放生理过程和状态

• 批准号: 3744-2007
• 负责人: Margolis, Hank
• 金额: $ 3.5万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=364270
• 关键词: Ecophysiology; northern; forests; scaling; physiological

Small-scale ecophysiological processes can have large-scale impacts on terrestrial carbon cycling.  As a complement to my participation and leadership in the Fluxnet-Canada and Canadian Carbon Program Research Networks, I propose research focused on improving our ability to use measurements of physiological processes and states at the leaf and canopy level to evaluate these processes at larger spatial scales. I propose three complementary areas of study that address some key knowledge gaps in carbon cycle science. (1) We will examine how we might link the dynamic spectral characteristics of boreal forest vegetation to its photosynthetic light use efficiency (LUE).  We will add measurements of spectral reflectance and foliar pigments at our Quebec flux sites so as to better understand the contributions of sunlit and shadow canopy fractions to LUE under different levels of stress and stages of phenological development. This could lead to a robust methodology for scaling LUE. (2) We will test different approaches for evaluating forest biomass at large spatial scales using an airborne and a satellite-based lidar and thereby obtain more reliable estimates of aboveground autotrophic respiration for northern ecosystems. We will assess the extent to which different aspects of the sampling (e.g., cover type, slope) drive the variability. We will then use this information to scale the satellite measurements to provincial, national, and circumpolar scales.  (3) We will use our flux tower data to evaluate methods for scaling freeze-thaw events and their physiological implications at local to regional scales.  We will do this by linking physiological processes and environmental conditions at our flux sites to freeze-thaw data products obtained from a satellite-based microwave sensor.  This will allow us to examine how the severity, duration, and distribution of freezing and thawing across a landscape relates to the photosynthetic and respiratory fluxes at our flux sites.  It will also allow us to determine how these freeze-thaw dynamics relate to the several thousand square km footprints sampled by the high-precision carbon dioxide concentration measurements we are making as part of the Canadian Carbon Program.

小规模的生态生理过程可以对陆地碳循环产生大规模的影响。作为我在Fluxnet-Canada和加拿大碳计划研究网络的参与和领导的补充，我建议研究的重点是提高我们在叶片和冠层水平上使用生理过程和状态测量的能力，以在更大的空间尺度上评估这些过程。我提出了三个互补的研究领域，以解决碳循环科学中的一些关键知识空白。(1)我们将研究如何将北方森林植被的动态光谱特征与其光合光能利用效率（LUE）联系起来。我们将在魁北克通量站点增加光谱反射率和叶面色素的测量，以便更好地了解不同胁迫水平和物候发育阶段下阳光和阴影冠层组分对LUE的贡献。这可能导致一种健壮的方法来扩展LUE。(2)利用机载激光雷达和卫星激光雷达，在大空间尺度上测试不同的森林生物量评估方法，从而获得更可靠的北方生态系统地上自养呼吸估算值。我们将评估采样的不同方面（例如，覆盖类型，坡度）驱动变异性的程度。然后，我们将使用这些信息将卫星测量结果按省、国家和极地范围进行缩放。(3)我们将利用通量塔的数据来评估冻融事件的尺度方法及其在局部和区域尺度上的生理意义。为此，我们将把通量站点的生理过程和环境条件与从卫星微波传感器获得的冻融数据产品联系起来。这将使我们能够研究整个景观中冻结和融化的严重程度、持续时间和分布与通量点的光合作用和呼吸通量之间的关系。它还将使我们能够确定这些冻融动力学与我们作为加拿大碳计划的一部分进行的高精度二氧化碳浓度测量所取样的数千平方公里足迹之间的关系。