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

种源试验最初严格用于造林目的，现在被认为非常适合研究树木适应气候变化的种内变异。然而，在受控条件下进行的评估气候条件变化下树木表现的研究受到空间和时间的限制。这些限制使得在北美建立的长期种源图在提供数据方面很有用，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生理过程是光合作用，其速率受种源变异的影响。植物物种对环境变化的光合响应可以在小尺度（叶片水平）和大尺度（生态系统水平）进行评估。位于新不伦瑞克省中南部阿卡迪亚研究森林（Acadian Research Forest）的涡动相关塔将提供描述大生态系统尺度下光合作用特征所需的数据。生态系统尺度上的物种光合作用响应是通过简单的NEP模型和数值优化，将基于塔的净二氧化碳交换（或净生态系统生产力的负值-NEP）测量值数学分解为其总生态系统生产的组分通量，与光拦截和同化以及呼吸有关。由叶级和生态系统级数据收集产生的信息可以用来指定相同模型的参数，作为叶级信息的函数。这将允许使用模型为缺乏塔数据的森林提供物种响应的生态系统级特征，就像目前在新英格兰西北部的北极星种源试验中生长的12个种源的情况一样。种源的种子来自于香脂冷杉（一种在加拿大具有重要商业和生态价值的树种）现今生长范围内的地区。从这项工作中制定的生态系统级物种响应函数将有助于重新定义加拿大大西洋地区重要部分的香脂冷杉分布预测。目前的物种分布模型使用“清晰”阈值，这些阈值来自与气候有关的范围特征评估。这项工作将在加拿大大西洋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.******