Modelling the impact of climate change on the occurrence of frost damage in Sitka spruce (Picea sitchensis) in Great Britain

Climate change is predicted to increase temperature and seasonal temperature variance in Great Britain (GB). Sitka spruce (Picea sitchensis (Bong.) Carr) is the most important tree species used in commercial plantations throughout Europe and GB. Frosts that occur outside the winter dormancy period can negatively affect trees, since they happen after dehardening. Damage can be especially severe at bud burst, before emerging needles mature and form protective barriers. Here, we modelled the impact of climate change on frost sensitivity in Sitka spruce with temperature data from the UKCP09 climate model HadRm3 that uses emission scenario SRESA1B for the years 2020-2099, the global and downscaled versions of the UKCP18 HadGem3 model that uses the emissions scenario RCP8.5, and the global model CMCC-CM for the RCP 4.5 and RCP 8.5 emissions scenarios, and compared the results with gridded historical data for the period 1960-2015. Three indicators that assessed the frost sensitivity of Sitka spruce were explored: the total number of frosts during the growing season (Index 1); the total number of frosts after bud burst (Index 2); the number of days with minimum temperatures below the resistance level (backlashes) during the growing year (Sep-Aug) (Index 3). The indices were validated with historical data for frost damage across GB, and Index 1-3 °C and Index 3 were shown to be significantly correlated. The frequency of all frosts and backlashes is expected to decrease with climate change, especially under higher emissions scenarios. Post bud burst frosts have been historically very rare in GB and remain so with climate change. Downscaled regional climate models detect geographic variability and improve prediction of overall trends in frost damage in comparison to global climate change models for GB.

Code and results available here.
The public datasets used to calculate these indices are available at the following links:
Climate change data:
http://catalogue.ceda.ac.uk/uuid/465ecd8a305ffb9df2bd8b54cada669f
http://catalogue.ceda.ac.uk/uuid/f1a2fc3c120f400396a92f5de84d596a
https://catalogue.ceda.ac.uk/uuid/589211abeb844070a95d061c8cc7f604
http://catalogue.ceda.ac.uk/uuid/87f43af9d02e42f483351d79b3d6162a
https://esgf-node.llnl.gov/search/cmip5/
Polygons that define shape of provenance region and seed zones:
https://data.gov.uk/dataset/ebc4fd45-27fc-499f-968e-ba4398f088fb/forest-reproductive-materials-sites-gb
Historical dataset: http://catalogue.ceda.ac.uk/uuid/87f43af9d02e42f483351d79b3d6162a

气候变化预计将导致英国（GB）气温上升及季节性温度变率的增加。西雅图云杉（Picea sitchensis (Bong.) Carr）是欧洲及英国商业人工林中最重要的树种。在冬季休眠期之外发生的霜冻会对树木产生负面影响，因为它们发生在树木脱硬之后。在芽萌发期，即新针叶成熟并形成保护屏障之前，损害可能尤为严重。本研究中，我们利用英国气候预测中心（UKCP09）气候模型HadRm3中的温度数据，该模型采用SRESA1B排放情景对2020-2099年的数据进行模拟，以及全球和降尺度后的UKCP18 HadGem3模型（采用RCP8.5排放情景）和CMCC-CM全球模型（针对RCP 4.5和RCP 8.5排放情景）的温度数据，对西雅图云杉的霜冻敏感性受到气候变化的影响进行了建模，并将结果与1960-2015年期间的历史网格化数据进行了比较。本研究探讨了三个评估西雅图云杉霜冻敏感性的指标：生长季节中霜冻的总次数（指标1）；芽萌发后霜冻的总次数（指标2）；生长年份（9月至次年8月）内最低温度低于抗性水平的日数（倒春寒）（指标3）。这些指标通过英国历史霜冻损害数据进行了验证，并显示指标1-3°C和指标3之间存在显著相关性。预计随着气候变化，所有霜冻和倒春寒的频率将下降，尤其是在高排放情景下。在英国，芽萌发后的霜冻历史上极为罕见，并且随着气候变化，这一情况仍然如此。与针对英国的全球气候变化模型相比，降尺度区域气候模型能够检测到地理变异性，并提高了对霜冻损害整体趋势的预测能力。

相关数据和结果可在此处获取。

用于计算这些指标的公共数据集可在以下链接找到：
气候变化数据：
http://catalogue.ceda.ac.uk/uuid/465ecd8a305ffb9df2bd8b54cada669f
http://catalogue.ceda.ac.uk/uuid/f1a2fc3c120f400396a92f5de84d596a
https://catalogue.ceda.ac.uk/uuid/589211abeb844070a95d061c8cc7f604
http://catalogue.ceda.ac.uk/uuid/87f43af9d02e42f483351d79b3d6162a
https://esgf-node.llnl.gov/search/cmip5/
定义产地区域和种子区域形状的多边形：
https://data.gov.uk/dataset/ebc4fd45-27fc-499f-968e-ba4398f088fb/forest-reproductive-materials-sites-gb
历史数据集：
http://catalogue.ceda.ac.uk/uuid/87f43af9d02e42f483351d79b3d6162a