Ecophysiological interpretation of the mechanisms and dynamics of sap production in sugar maple

糖枫是加拿大经济的关键树种，在林业、旅游、食品和农业中发挥着重要作用。在当前全球变暖的情况下，该物种及其主要产品枫糖浆正经历着环境条件变化的巨大压力。现在的当务之急是预见这些变化，调整南方地区的树液提取生产系统，并利用北方地区新的发展机遇。我建议使用自动传感器进行创新的长期监测，以自动收集生理和天气数据，并以高时间分辨率生产糖枫的汁液。我的建议旨在开发和测试第一个描述树液流动和生产的机械模型。具体地说，我(1)描述了树干液流和变化的昼夜循环；(2)确定了与高产量树液相关的解剖和生理特性；(3)量化了天气对春季树液产生的动态和数量的影响；(4)结合所有的经验观察，建立了描述糖枫树液产生机制的第一个理论模型。从2017年以来已经运行的一块永久地块开始，我想为糖枫范围内的其他永久地块配备树干测量仪和树液流动探头，以每30分钟监测一次春季休眠结束时茎的生理状况。可以使用连接到割胶糖枫的雨量计自动测量树液产量。通过Phenocam，即使用安装在田间的数码相机收集的数字图像，以每天的分辨率检测裂芽和落叶。所有传感器都由收集环境和土壤湿度情况的气象站的数据记录器激活。该模型将被用来预测变化的条件对树干复水和春季生长恢复的影响，以及它们对树液产生的时间和持续时间的影响。这些结果将有助于理解和量化树液流动和春季树液生产的基本过程，并有助于量化气候变化对糖季的影响。该项目将建议在树液收获期间对生产系统进行调整。更广泛地说，它将支持生产者的战略，以维持南部人口的生产力，并增加北部林地糖枫的开采。

Sugar maple is a key species in Canada's economy, playing an important role in forestry, tourism, food and agriculture. Under the current global warming, this species and its main product, maple syrup, are experiencing a significant pressure by the changing environmental conditions. It is now urgent to anticipate these changes, adapt the productive system of sap extraction in the Southern regions, and take advantage of new development opportunities for the Northern regions. I propose innovative long-term monitoring using automatic sensors for the automatic collection of physiological and weather data, and sap production in sugar maple at high temporal resolution. My proposal aims to develop and test the first mechanistic model describing flow and production of sap. In particular, I (1) describe the circadian cycles of sap flow and variation in the stem; (2) determine the anatomical and physiological traits associated with a high productivity of sap; (3) quantify the impact of weather on the dynamics and amount of sap produced in spring; and (4) combine all empirical observations to build a first theoretical model describing the mechanisms of sap production in sugar maple. Starting with one permanent plot already running since 2017, I would like to equip other permanent plots across the sugar maple range with dendrometers and sap flow probes to monitor each 30 min the physiological conditions of stems in spring, at the end of dormancy. Sap production can be measured automatically using rain gauges connected to tapping sugar maples. Bud break and leafing are detected at a daily resolution by phenocam, i.e. using digital images collected by digital cameras installed in the field. All sensors are activated by dataloggers of a weather station collecting environmental and soil moisture conditions. The model will be used to predict the effects of changing conditions on stem rehydration and spring growth reactivation and their consequences on the timings and duration of sap production. The results will help to understand and quantify the processes underlying sap flow and spring sap production, and quantify how the sugar season will be affected by the climate change. This project will suggest the adaptations of the production system during sap harvesting. More generally, it will support the strategies of producers to maintain the productivity of populations in the South, and increase the exploitation of sugar maple at the Northern stands.