Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China.
Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; Research Center for Global Change and Ecological Forecasting, East China Normal University, Shanghai 200000, China.
Sci Total Environ. 2021 Mar 25;762:143177. doi: 10.1016/j.scitotenv.2020.143177. Epub 2020 Oct 22.
Temperature is the primary factor controlling plant phenology. As temperature changes with latitude, leaf phenology in spring always shows a significant latitudinal pattern. However, under asymmetric warming at the low and high latitudes, the variability of the spring leaf phenology with latitude is becoming unclear. Based on the 23,094 observations of the leaf unfolding date (LUD) for woody species located in eastern China within latitudes 23-49°N, we analyzed the variability of LUD and its latitudinal sensitivity (S, days °N, expressed in delayed days per degree in latitude) during 1963-2008. The results showed an earlier LUD at the mid- (-2.2 days decade) and high (-2.5 days decade) latitude regions, while a stable LUD at the low-latitude regions during 1963-2008. However, the temperature sensitivity of LUD (S, days °C, expressed in advanced days per degree in temperature) remained stable across the latitudes although a slight decreasing trend from 1963 to 2008. As a result, the non-uniform optimal preseason warming with latitude (T, °C °N, expressed in the increase of temperature per degree in latitude) decreased S from 2.38 (days °N) in 1963 to 1.55 (days °N) in 2008. Further analyses indicated that the Growing Degree Hours (GDH) played a critical role in these processes, although the Chilling Hours (CH) showed significant variability after 1991. Our results provide evidence that the change in the balance of CH and GDH across latitude induced declining S over the last 40 years in eastern China. Furthermore, it may continue under the future climate warming scenarios and ultimately has important consequences on the structure and function of ecosystems.
温度是控制植物物候的主要因素。由于温度随纬度变化，春季叶片物候总是呈现出显著的纬度模式。然而，在低纬度和高纬度的不对称变暖下，春季叶片物候与纬度的可变性变得不清楚。基于中国东部纬度 23-49°N 内的木质物种叶片展开日期（LUD）的 23094 个观测值，我们分析了 1963-2008 年 LUD 的可变性及其纬度敏感性（S，天数°N，以每度纬度延迟天数表示）。结果表明，在中纬度（-2.2 天十年）和高纬度（-2.5 天十年）地区，LUD 较早，而在 1963-2008 年低纬度地区，LUD 较稳定。然而，LUD 的温度敏感性（S，天数°C，以每度温度提前天数表示）在整个纬度范围内保持稳定，尽管从 1963 年到 2008 年略有下降趋势。因此，非均匀的最优 preseason 变暖随纬度（T，°C °N，以每度纬度温度升高表示）使 S 从 1963 年的 2.38（天°N）下降到 2008 年的 1.55（天°N）。进一步分析表明，生长度日（GDH）在这些过程中起着关键作用，尽管在 1991 年后，冷却度日（CH）表现出显著的可变性。我们的研究结果表明，过去 40 年来，中国东部地区 CH 和 GDH 平衡的变化导致 S 的下降，未来气候变暖情景下，S 可能会继续下降，这最终对生态系统的结构和功能具有重要影响。
