Earth Surface System Research Center, Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanazawa-ku, Yokohama, Japan.
River Basin Research Center, Gifu University, Gifu, Japan.
PLoS One. 2021 Jul 30;16(7):e0255078. doi: 10.1371/journal.pone.0255078. eCollection 2021.
The effects of climate change on plant phenological events such as flowering, leaf flush, and leaf fall may be greater in steep river basins than at the horizontal scale of countries and continents. This possibility is due to the effect of temperature on plant phenology and the difference between vertical and horizontal gradients in temperature sensitivities. We calculated the dates of the start (SGS) and end of the growing season (EGS) in a steep river basin located in a mountainous region of central Japan over a century timescale by using a degree-day phenological model based on long-term, continuous, in situ observations. We assessed the generality and representativeness of the modelled SGS and EGS dates by using phenological events, live camera images taken at multiple points in the basin, and satellite observations made at a fine spatial resolution. The sensitivity of the modelled SGS and EGS dates to elevation changed from 3.29 days (100 m)-1 (-5.48 days °C-1) and -2.89 days (100 m)-1 (4.81 days °C-1), respectively, in 1900 to 2.85 days (100 m)-1 (-4.75 days °C-1) and -2.84 day (100 m)-1 (4.73 day °C-1) in 2019. The long-term trend of the sensitivity of the modelled SGS date to elevation was -0.0037 day year-1 per 100 m, but the analogous trend in the case of the modelled EGS date was not significant. Despite the need for further studies to improve the generality and representativeness of the model, the development of degree-day phenology models in multiple, steep river basins will deepen our ecological understanding of the sensitivity of plant phenology to climate change.
气候变化对植物物候事件（如花、叶芽和叶落）的影响，在陡峭的河流流域可能比在国家和大陆的水平尺度上更大。这种可能性是由于温度对植物物候的影响以及垂直和水平温度敏感性梯度之间的差异。我们通过使用基于长期、连续、现场观测的度日物候模型，计算了位于日本中部山区的一个陡峭河流流域的生长季节开始日期（SGS）和结束日期（EGS）。我们通过在流域内多个点拍摄的物候事件、实时摄像机图像和高分辨率卫星观测来评估模型化的 SGS 和 EGS 日期的通用性和代表性。模型化的 SGS 和 EGS 日期对海拔的敏感性分别从 1900 年的 3.29 天（100 米）-1（-5.48 天 °C-1）和-2.89 天（100 米）-1（4.81 天 °C-1）变为 2019 年的 2.85 天（100 米）-1（-4.75 天 °C-1）和-2.84 天（100 米）-1（4.73 天 °C-1）。模型化的 SGS 日期对海拔的敏感性的长期趋势为-0.0037 天/年/每 100 米，但模型化的 EGS 日期的类似趋势并不显著。尽管需要进一步的研究来提高模型的通用性和代表性，但在多个陡峭的河流流域中开发度日物候模型将加深我们对植物物候对气候变化敏感性的生态理解。
