Projection of Abies balsamea distribution under conditions of climate change: incorporation of species plasticity to environmental change

种源测试最初被严格用于营林目的，现在被认为非常适合于研究树木适应气候变化的种内差异。然而，当在受控条件下进行时，在变化的气候条件下评估树木表现的研究受到空间和时间限制。这些限制使得在北美建立的长期种源图有助于提供数据，这些数据可以提供关于物种在其自然范围之外的表现的可靠信息。*植物生产力的一个重要的生理过程是光合作用，光合作用的速率可以受到种源变异的影响。植物物种对环境变化的光合作用反应可以在小的叶水平和大的生态系统水平上进行评估。位于新不伦瑞克(NB)中南部的阿卡迪亚研究森林中的一座涡流协方差塔将提供在大型生态系统尺度上描述光合作用所需的数据。物种在生态系统尺度上的光合作用响应是通过将基于塔式的净二氧化碳交换(或净生态系统生产力的负值，-NEP)的测量数学分解为与光截留和同化相关的总生态系统生产和呼吸的组成通量，并使用简单的NEP模型和数值优化。然后，由叶级和生态系统级数据收集产生的信息可用于指定相同模型的参数作为叶级信息的函数。这将允许使用这些模型为缺乏塔楼数据的森林提供生态系统级别的物种反应特征，就像目前在北卡罗来纳州西北部北极星种源测试中生长的12个种源的情况一样。种源的种子来自现今范围内的香脂冷杉，这是加拿大一种具有重要商业和生态意义的树种。根据这项工作制定的生态系统级别的物种响应函数将有助于重新定义加拿大大西洋大部分地区的香脂冷杉分布预测。目前的物种分布模型使用“清晰”的阈值，这些阈值是从与气候有关的范围特征评估中得出的。这项工作将在大西洋加拿大的香脂冷杉分布预测中增加一个新的现实主义水平(即物种可塑性)。

Having intially been used strictly for silvicultural purposes, provenance tests are now being viewed as well-suited to study intra-specific variation in adaptation of trees to changes in climate. Studies which assess tree performance under changing climatic conditions, when conducted under controlled conditions are, however, limited by spatial and temporal restrictions. These limitations make long term provenance plots established in North America useful in providing data that may give reliable information on species performance outside their natural range.***An important physiological process in plant productivity is photosynthesis, the rate of which can be influenced by provenance variation. Photosynthetic response of plant species to variations in environment can be assessed at both the small, leaf-level, and large, ecosystem-level, scales. An eddy covariance tower in the Acadian Research Forest, southcentral New Brunswick (NB), will provide the data needed to characterise photosynthesis at the large, ecosystem scale. Species photosynthetic response at the ecosystem scale is determined by mathematically decomposing tower-based measurements of net CO2 exchange (or the negative of net ecosystem productivity, -NEP) into its component fluxes of gross ecosystem production, associated with light interception and assimilation, and respiration with simple NEP models and numerical optimisation. Information generated by the leaf- and ecosystem-level data collection can then be used to specify the parameters of the same models as a function of leaf-level information. This would allow the use of the models to provide an ecosystem-level characterisation of species response for forests lacking tower data, as is the case for 12 provenances currently growing at the North Star Provenance Test in northwest NB. The seeds for the provenances come from source areas within the present-day range of balsam fir, a commercially- and ecologically-important tree species in Canada. Ecosystem-level species-response functions formulated from the work will help re-define balsam fir distribution projections for a significant part of Atlantic Canada. Current species distribution models use "crisp" thresholds that are derived from assessments of range characteristics related to climate. This work will add a new level of realism (i.e., species plasticity) in balsam fir distribution projections for Atlantic Canada.******