Growing seasons of Nordic mountain birch in northernmost Europe as indicated by long-term field studies and analyses of satellite images
Growing seasons of Nordic mountain birch in northernmost Europe as indicated by long-term field studies and analyses of satellite images
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DOI：
10.1007/s00484-006-0042-y
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发表时间：
2006-07
影响因子：
3.2
通讯作者：
E. Shutova;F. Wielgolaski;S. Karlsen;O. Makarova;N. Berlina;T. Filimonova;E. Haraldsson;P. Aspholm;L. Flø;K. Høgda
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文献类型：
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作者：
E. Shutova;F. Wielgolaski;S. Karlsen;O. Makarova;N. Berlina;T. Filimonova;E. Haraldsson;P. Aspholm;L. Flø;K. Høgda
在1964 - 2003年期间，在欧洲最北部科拉半岛的三个地点和1994 - 2003年期间在跨边界帕斯维克-埃纳雷地区的两个地点观察到北欧山地桦树（Betula pubescensssp. tortuosa，也称为B. p. ssp. czerepanovii）的物候期首次变绿（萌芽）和变黄。将实地观测结果与基于GIMMS-NDVI数据集的1982 - 2002年生长季节开始和结束时的卫星图像进行了比较。在40年期间，仅在一个地点（Kandalaksha）观察到第一次绿化推迟的趋势。这与卫星图像显示的该地点生长季节推迟的情况十分吻合。在整个研究期间，无论是实地观察还是卫星分析，都没有发现其他地点的绿化时间发生重大变化。这些结果与近几十年来欧洲其他地区普遍观察到的早春不同。在欧洲最寒冷的地区，例如北方高山和最北部的大陆地区，过去几十年来，由于北大西洋涛动普遍为正，降水量增加，往往会降雪。降雪量的增加可能会推迟生长季节的开始时间，尽管气温的升高通常会导致春季物候期提前。所有地点的桦树叶的秋季变黄倾向于较早的日期。由于Kandalaksha地区桦树变绿的时间较晚，变黄的时间较早，在观察到的几年里，那里的生长季节也明显缩短。在整个研究期间，显示田间黄化最严重的地点与1982 - 2002年卫星图像显示的生长季节提前结束的地区非常吻合。较早的黄化是高度相关的趋势，在秋季的网站，在研究期间，较早的空气温度下降，表明这个环境因素也是重要的秋季物候期。
The phenophases first greening (bud burst) and yellowing of Nordic mountain birch (Betula pubescensssp.tortuosa, also calledB.p. ssp.czerepanovii) were observed at three sites on the Kola Peninsula in northernmost Europe during the period 1964–2003, and at two sites in the trans-boundary Pasvik-Enare region during 1994–2003. The field observations were compared with satellite images based on the GIMMS-NDVI dataset covering 1982–2002 at the start and end of the growing season. A trend for a delay of first greening was observed at only one of the sites (Kandalaksha) over the 40 year period. This fits well with the delayed onset of the growing season for that site based on satellite images. No significant changes in time of greening at the other sites were found with either field observations or satellite analyses throughout the study period. These results differ from the earlier spring generally observed in other parts of Europe in recent decades. In the coldest regions of Europe, e.g. in northern high mountains and the northernmost continental areas, increased precipitation associated with the generally positive North Atlantic Oscillation in the last few decades has often fallen as snow. Increased snow may delay the time of onset of the growing season, although increased temperature generally causes earlier spring phenophases. Autumn yellowing of birch leaves tends towards an earlier date at all sites. Due to both later birch greening and earlier yellowing at the Kandalaksha site, the growing season there has also become significantly shorter during the years observed. The sites showing the most advanced yellowing in the field throughout the study period fit well with areas showing an earlier end of the growing season from satellite images covering 1982–2002. The earlier yellowing is highly correlated with a trend at the sites in autumn for earlier decreasing air temperature over the study period, indicating that this environmental factor is important also for autumn phenophases.