植物生态学报 ›› 2022, Vol. 46 ›› Issue (7): 753-765.DOI: 10.17521/cjpe.2021.0254

• 研究论文 • 上一篇    下一篇

中国北方树木秋季物候的过程模拟及其区域分异归因

陈奕竹, 郎伟光, 陈效逑()   

  1. 北京大学城市与环境学院, 地表过程分析与模拟教育部重点实验室, 北京 100871
  • 收稿日期:2021-07-07 接受日期:2021-09-27 出版日期:2022-07-20 发布日期:2021-12-16
  • 通讯作者: 陈效逑
  • 作者简介:* (cxq@pku.edu.cn)
  • 基金资助:
    国家自然科学基金(41771049);国家自然科学基金(41471033)

Process-based simulation of autumn phenology of trees and the regional differentiation attribution in northern China

CHEN Yi-Zhu, LANG Wei-Guang, CHEN Xiao-Qiu()   

  1. College of Urban and Environmental Sciences, Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing 100871, China
  • Received:2021-07-07 Accepted:2021-09-27 Online:2022-07-20 Published:2021-12-16
  • Contact: CHEN Xiao-Qiu
  • Supported by:
    National Natural Science Foundation of China(41771049);National Natural Science Foundation of China(41471033)

摘要:

揭示温带落叶树木秋季物候的发生机理对提高生态系统固碳量和植被生产力的预估精度具有重要意义。该研究利用低温和光周期乘积模型模拟了1981-2014年中国北方温带90余个站点6个树种的叶始变色期和落叶末期, 并对逐站点-物种的最优模型进行了模拟精度评价, 分析了最优模型模拟精度的时空差异及其随水分梯度的空间变化。主要结果如下: (1)在诱导叶片衰老方面, 光周期缩短的影响通常大于温度降低的影响。据此建立的叶始变色期和落叶末期最优模型模拟的平均均方根误差分别为6.9 d和6.0 d, 模拟与观测时间序列呈显著正相关关系的比例分别为71.4%和83.6%; (2)最优模型对区域平均和多年平均叶始变色期和落叶末期模拟的绝对误差小于2.4 d, 但模拟日期的时空变幅通常小于观测日期, 这与秋季物候发生日期的高度时间变异性密切相关; (3)水分条件在一定程度上影响叶片衰老诱导途径的选择, 表现为光周期缩短诱导叶片衰老的叶始变色期最优模型所占比例在干旱和半干旱区大于湿润和半湿润区, 而最优模型的模拟精度在湿润和半湿润区高于干旱和半干旱区。该研究验证了低温和光周期乘积模型在中国温带地区的适用性, 并揭示了水分条件对秋季物候发生机理和模拟精度的影响。

关键词: 秋季物候, 模拟, 低温和光周期乘积模型(TPM), 模拟效果的时空特征, 水分依赖性, 温带落叶树木

Abstract:

Aims Revealing occurrence mechanisms of autumn phenology in temperate deciduous trees is of vital importance for improving estimation accuracies of ecosystem carbon sequestration and vegetation productivity. This study aimed to uncover the mechanisms of leaf senescence in response to environmental changes and simulation accuracies of autumn phenology through process-based models, and further investigate impacts of water conditions on leaf senescence mechanisms and simulation accuracy of autumn phenology.

Methods We used the low temperature and photoperiod multiplicative model (TPM) to fit the first leaf coloration dates and leaf fall end dates of six tree species at more than 90 stations across the temperate zone of northern China from 1981 to 2014. The TPM contains two sub-models, i.e., photoperiod-initiated leaf senescence model (TPMp) and temperature-initiated leaf senescence model. We evaluated simulation accuracies and their spatiotemporal variations of station-species specific optimum models, and analyzed regional differentiation of proportions of two sub-models among optimum models and its spatial dependence on arid-humid gradient.

Important findings (1) Photoperiod shortening plays more important roles in initiating leaf senescence than temperature decrease. The simulated average root mean square errors of optimum models for first leaf coloration and leaf fall end dates are 6.9 d and 6.0 d, respectively. Proportions of significantly positive correlations between simulated and observed time series are 71.4% (first leaf coloration) and 83.6% (leaf fall end), respectively. (2) Simulated regional mean absolute errors and multi-year mean absolute errors of optimum models for first leaf coloration date and leaf fall end date are less than 2.4 d. However, amplitudes of temporal and spatial variations in simulated phenological dates are usually smaller than those in observed phenological dates, which are closely related to the high temporal variability of autumn phenological occurrence date. (3) Water conditions affect the selection of leaf senescence initiation pathways to a certain extent. This is mainly manifested in that proportions of TPMp among optimum models for first leaf coloration dates in arid and semi-arid regions are higher than those in humid and semi-humid regions, while simulation accuracies of optimum models in humid and semi-humid regions are higher than those in arid and semi-arid regions.

Key words: autumn phenology, simulation, low temperature and photoperiod multiplicative model (TPM), spatiotemporal characteristics of simulation effect, moisture dependence, temperate deciduous trees