Abstract Freeze-thaw cycles, where temperatures fluctuate above and below 0 °C, are the cause of elevated stem pressures that drive sap flow from within the sugar maple. This temperature-dependency has historically limited the production of maple syrup to select regions of North America. The plantation method of sap harvesting (which uses densely planted saplings instead of mature trees) now raises the possibility of a New Zealand-based maple syrup industry. In this study, a transient 2D heat transfer model was developed to predict freeze-thaw events in trees, and thereby evaluate potential plantation locations based on their climate. The heat transfer phenomena which have been modelled are bulk thermal diffusion, diffusion across discrete wood layers, convection, infrared radiation and solar radiation. Through experimental validation the model was found capable of predicting temperatures in real-life trees with high accuracy. Sensitive parameters were the bark absorptivity and sapwood diffusivity. Simulation results also indicate that the frequency of freeze-thaw cycles increase dramatically in saplings, as compared to mature trees, making maple syrup production potentially viable in locations that would otherwise fail when using traditional methods.

中文翻译：

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一种预测糖槭树冻融事件的二维传热模型

摘要 温度在 0 °C 以上和以下波动的冻融循环是导致糖槭树液流出的茎压升高的原因。这种温度依赖性历来限制了枫糖浆的生产仅限于北美的某些地区。树液收获的种植方法（使用密集种植的树苗代替成熟的树木）现在提高了新西兰枫糖浆产业的可能性。在这项研究中，开发了一种瞬态二维传热模型来预测树木的冻融事件，从而根据气候评估潜在的种植园位置。已建模的传热现象是整体热扩散、跨离散木层的扩散、对流、红外辐射和太阳辐射。通过实验验证，发现该模型能够以高精度预测现实树木中的温度。敏感参数是树皮吸收率和边材扩散率。模拟结果还表明，与成熟树木相比，树苗的冻融循环频率显着增加，这使得枫糖浆生产在使用传统方法时可能会失败的地方具有潜在可行性。