From Intra-plant to Regional Scale: June Temperatures and Regional Climates Directly and Indirectly Control Betula nana Growth in Arctic Alaska
From Intra-plant to Regional Scale: June Temperatures and Regional Climates Directly and Indirectly Control Betula nana Growth in Arctic Alaska
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DOI：
10.1007/s10021-022-00771-8
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发表时间：
2022-06
期刊：
影响因子：
3.7
通讯作者：
A. Buchwal;M. Bret-Harte;H. Bailey;J. Welker
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文献类型：
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作者：
A. Buchwal;M. Bret-Harte;H. Bailey;J. Welker
苔原灌木的年轮宽度反映了气候敏感性，但组织特异性灌木年表的研究却很少。此外，仅在少数北极地区探索了对苔原灌木生长产生中尺度降水和温度影响的区域气候模式的相对重要性。在这里，我们研究了北极阿拉斯加邻近干燥石南和潮湿草丛苔原栖息地的桦木生长年轮与当地和区域气候的关系。使用地上和地下灌木器官的连续切片来分析平均灌木和五种组织特异性年轮宽度年表，每个地点有 30 种灌木，分别来自干燥和潮湿苔原的 161 和 104 个横截面。两个生境中的桦木生长年轮宽度主要与 6 月气温（1989-2014）有关。 “Branch2”年表与气温的关系最强（干燥地点：r= 0.78，6 月 16 日，DOY = 167；潮湿地点：r= 0.75，6 月 9 日，DOY = 160）。此外，潮湿地点的地下年表（“Root”和“Root2”）与前一个六月底的日平均气温呈正相关（“Root2”年表：r= 0.57，pDOY = 173）。大多数组织特定的年表与 6 月 8 日至 20 日期间的日平均气温表现出最强的相关性。结构方程模型表明，灌木生长通过与夏季海冰范围和气温的关系，与区域北极和太平洋年代际振荡（AO 和 PDO）气候指数间接相关。纳米桦的生长对生长季早期温度的强烈依赖表明，组织生长的资源分配高度协调，这可能会在快速变化的北极气候下增加其相对于其他灌木物种的竞争优势。
Tundra shrubs reflect climate sensitivities in their growth-ring widths, yet tissue-specific shrub chronologies are poorly studied. Further, the relative importance of regional climate patterns that exert mesoscale precipitation and temperature influences on tundra shrub growth has been explored in only a few Arctic locations. Here, we investigateBetula nanagrowth-ring chronologies from adjacent dry heath and moist tussock tundra habitats in arctic Alaska in relation to local and regional climate. Mean shrub and five tissue-specific ring width chronologies were analyzed using serial sectioning of above- and below-ground shrub organs, resulting in 30 shrubs per site with 161 and 104 cross sections from dry and moist tundra, respectively.Betula nanagrowth-ring widths in both habitats were primarily related to June air temperature (1989–2014). The strongest relationships with air temperature were found for ‘Branch2’ chronologies (dry site:r= 0.78, June 16, DOY = 167; moist site:r= 0.75, June 9, DOY = 160). Additionally, below-ground chronologies (‘Root’ and ‘Root2’) from the moist site were positively correlated with daily mean air temperatures in the previous late-June (‘Root2’ chronology:r= 0.57, pDOY = 173). Most tissue-specific chronologies exhibited the strongest correlations with daily mean air temperature during the period between 8 and 20 June. Structural equation modeling indicated that shrub growth is indirectly linked to regional Arctic and Pacific Decadal Oscillation (AO and PDO) climate indices through their relation to summer sea ice extent and air temperature. Strong dependence ofBetula nanagrowth on early growing season temperature indicates a highly coordinated allocation of resources to tissue growth, which might increase its competitive advantage over other shrub species under a rapidly changing Arctic climate.