Department of Biometeorological Applications, Czech Hydrometeorological Institute, Na Šabatce 17, Prague, Czech Republic.
Department of Agroecology and Plant Production, University of Life Sciences in Prague, Prague 6 - Suchdol, Czech Republic.
Int J Biometeorol. 2020 May;64(5):791-801. doi: 10.1007/s00484-020-01869-1. Epub 2020 Jan 31.
This paper analyzes a long-term (1991-2019) flowering period of birch in the Czech Republic. Temporal and spatial evaluation in timing of beginning and end of flowering (F and F) and flowering period (F) of Betula pendula were investigated in different zones of the Czech Republic. The field observations were carried out at 44 sites of the Czech Hydrometeorological Institute phenological network; the detailed analysis including growing degree days (GDD) evaluation to F and F onsets and time of flowering were made at 9 sites in different altitudes. The trends and Pearson's correlation coefficients between F (F) and GDDs were calculated as well. The timing of both phenological stages showed a significant advance to earlier onsets (e.g., - 7.0 d per decade at Měděnec station) and the time of flowering shortens (e.g., - 3.8 d per decade at Rokytnice station). Nevertheless, the most marked shift was observed for mountain area in the north-western and north-eastern part of the Czech Republic. In contrast, the smallest shift was found in the southern part of the Czech Republic. The shift of the GDD values fluctuates from negative to positive values. Pearson's correlation coefficients calculated for both phenophases and period of flowering of Betula pendula showed the highest values in F (e.g., 0.846 at Modrava station) and in F (e.g., 0.711 at Rokytnice station) as well. Thus, our results indicate due to global warming symptoms that birch pollen allergy may appear earlier in the year but for a shorter period.
本文分析了捷克共和国桦树的一个长期（1991-2019 年）花期。在捷克共和国的不同地区，研究了欧洲白桦（Betula pendula）的开花开始和结束时间（F 和 F）以及花期（F）的时空评估。实地观测在捷克水文气象研究所物候网络的 44 个地点进行；在不同海拔的 9 个地点进行了详细分析，包括对 F 和 F 开始和开花时间的生长度日（GDD）评估。还计算了 F（F）和 GDD 之间的趋势和皮尔逊相关系数。两个物候阶段的时间都显示出明显的提前，即每十年提前 7.0 天（例如，Měděnec 站），开花时间缩短（例如，Rokytnice 站每十年缩短 3.8 天）。然而，在捷克共和国西北部和东北部的山区观察到的变化最为显著。相比之下，在捷克共和国南部发现的变化最小。GDD 值的变化从负值波动到正值。为欧洲白桦的两个物候阶段和花期计算的皮尔逊相关系数显示出最高的值在 F（例如，Modrava 站为 0.846）和 F（例如，Rokytnice 站为 0.711）。因此，我们的结果表明，由于全球变暖的症状，桦树花粉过敏可能会更早出现，但持续时间更短。
