Abstract Site-index models based on dominant height and age are commonly accepted measures of site productivity in forest plantations. Therefore, reliable estimates of dominant height over time are critical, as they provide the foundations for site productivity estimates used in growth and yield models. Forest site productivity depends on the combination of many environmental factors, whereas tree height is only a general proxy indicator of these factors interacting over time, and as such, subject to large errors. Hence, selection of appropriate environmental variables along with field-based data is expected to result in more consistent estimates. Although previous studies have incorporated climatic variables into site-index models, there is still a lack of understanding among the forest research community with respect to the selection of suitable climatic variables. Models including climatic water balance components such as water-deficit and excess-water are scarce. These components are especially important to address the influence of drought on plant growth. The main objective of this study is to evaluate the change in dominant height estimates of forest stands with respect to changes in water balance components. High-resolution actual evapotranspiration (AET) and potential evapotranspiration (PET) were combined to determine water excess/deficit of sites. These were incorporated into a loblolly pine polymorphic site index model using a generalized algebraic difference approach and maximum likelihood calibration methods that accounted for long-term uncertainty in the results. Our model further improves the precision in dominant height estimates for loblolly pine in the southeast US.

中文翻译：

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使用美国西部海湾火炬松的林分和水分平衡变量模拟优势高度

摘要 基于优势高度和年龄的立地指数模型是普遍接受的人工林立地生产力度量。因此，随着时间的推移对显性高度的可靠估计至关重要，因为它们为生长和产量模型中使用的场地生产力估计提供了基础。林地生产力取决于许多环境因素的组合，而树木高度只是这些因素随时间相互作用的一般代理指标，因此容易出现较大误差。因此，选择适当的环境变量以及基于实地的数据预计将导致更一致的估计。虽然之前的研究已经将气候变量纳入了场地指数模型，森林研究界对选择合适的气候变量仍然缺乏了解。包括气候水平衡成分（如缺水和过量水）的模型很少。这些成分对于解决干旱对植物生长的影响尤为重要。本研究的主要目的是评估林分优势高度估计值相对于水平衡成分变化的变化。结合高分辨率实际蒸散量 (AET) 和潜在蒸散量 (PET) 来确定场地的水过量/缺水。使用广义代数差分方法和最大似然校准方法将这些纳入火炬松多态性位点指数模型，这些方法考虑了结果中的长期不确定性。我们的模型进一步提高了美国东南部火炬松优势高度估计的精度。