Exposure to cold temperature affects the spring phenology of Alaskan deciduous vegetation types
Exposure to cold temperature affects the spring phenology of Alaskan deciduous vegetation types
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DOI：
10.1088/1748-9326/ab6502
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发表时间：
2020-02
影响因子：
6.7
通讯作者：
M. Shi;N. Parazoo;Sujong Jeong;L. Birch;P. Lawrence;E. Euskirchen;C. Miller
中科院分区：
文献类型：
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作者：
M. Shi;N. Parazoo;Sujong Jeong;L. Birch;P. Lawrence;E. Euskirchen;C. Miller
温度是驱动北极和北方生态系统物候的主导因子，包括阿拉斯加春季叶芽和总初级生产（GPP）的发生。以往的研究假设累积生长日数（GDD）和低温暴露（chilling temperature）对叶芽萌发都有重要影响。我们通过将卫星和飞机植被测量数据与社区土地模型版本4.5 （CLM）相结合来验证这一假设，其中植物休眠的结束取决于热条件（即GDD）。本文研究了阿拉斯加不同落叶植被类型对GDD模型（GC模型）的敏感性。与极地植被光合作用和呼吸模式的卫星约束估计相比，默认CLM模拟在阿拉斯加植被地区的GPP开始时间提前了1-12天。将GC模型集成到CLM中会使GPP的相位和幅度发生偏移。2007-2016年，阿拉斯加北部苔原、灌木和森林的平均GPP发病时间分别推迟了5±7、4±8和1±6 d。GC模式在暖春期间影响最大，这对预测未来变暖的物候响应至关重要。总体而言，弹簧GPP高偏置降低了10%。因此，在热强迫模式中加入冷却需求改善了北方高纬度物候，但在生长季节会导致其他影响，这些影响需要进一步研究。
Temperature is a dominant factor driving arctic and boreal ecosystem phenology, including leaf budburst and gross primary production (GPP) onset in Alaskan spring. Previous studies hypothesized that both accumulated growing degree day (GDD) and cold temperature (chilling) exposure are important to leaf budburst. We test this hypothesis by combining both satellite and aircraft vegetation measurements with the Community Land Model Version 4.5 (CLM), in which the end of plant dormancy depends on thermal conditions (i.e. GDD). We study the sensitivity of GPP onset of different Alaskan deciduous vegetation types to a GDD model with chilling requirement (GC model) included. The default CLM simulations have a 1–12 d earlier day of year GPP onset over Alaska vegetated regions compared to satellite constrained estimates from the Polar Vegetation Photosynthesis and Respiration Model. Integrating a GC model into CLM shifts the phase and amplitude of GPP. During 2007–2016, mean GPP onset is postponed by 5 ± 7, 4 ± 8, and 1 ± 6 d over Alaskan northern tundra, shrub, and forest, respectively. The GC model has the greatest impact during warm springs, which is critical for predicting phenology response to future warming. Overall, spring GPP high bias is reduced by 10%. Thus, including chilling requirement in thermal forcing models improves northern high-latitude phenology, but leads to other impacts during the growing season which require further investigation.