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Abstract The Arctic is rapidly warming, and tundra vegetation community composition is changing from small, prostrate shrubs to taller, erect shrubs in some locations. Across much of the Arctic, the sensitivity of shrub secondary growth, as measured by growth ring width, to climate has changed with increased warming, but it is not fully understood how shrub age contributes to shifts in climate sensitivity.We studied Siberian alder,Alnus viridisssp.fruticosa, a large nitrogen‐fixing shrub that has responded to climate warming with northward range expansion over the last 50 years. We used serial sectioning of 26 individual shrubs and 94 cross‐sections to generate a 98‐year growth ring chronology, including one 142‐year‐old, Siberian alder in Northern Alaska. We tested how secondary growth sensitivity to climate has changed over the past century (1920–2017) and how shrub age affects climate sensitivity of alder growth through time.We found that over time, alder growth as expressed by the stand chronology became more sensitive to July mean monthly air temperature. Older shrubs displayed higher sensitivity to June and July temperature than younger alders. However, during the first 30 years of growth of any shrub, temperature sensitivity did not differ among individuals. In addition, the June temperature sensitivity of growth series from individual cross‐sections depended on the age of the attached shrub.Our results suggest that age contributes to climate sensitivity, likely through modifying internal shrub carbon budgets by changing size and reducing alder's dependence on N‐fixation over time. Older, more sensitive alder may enhance C and N‐cycling while having greater recruitment potential. Linking alder age to climate sensitivity, recruitment and total N‐inputs will enable us to better predict ecosystem carbon and nitrogen cycling in a warmer Arctic. Read the freePlain Language Summaryfor this article on the Journal blog.
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A nearly century long (1920-2017) Siberian alder (Alnus viridis ssp. fruticosa) secondary growth record near Sagwon Bluffs Alaska, USA
This data set contains measures of growth ring widths of Siberian alder (Alnus viridis ssp. fruticosa) from along the Sagwon Bluffs, Alaska, USA that was used to address how alder respond to temperature overtime and how plant age impacts their climate sensitivity. There are six individual files. One, the growth ring width data from each cross-section or part taken from an individual Siberian alder. Two, a data set of the detrended chronology with climate data over the period of 1920-2017. Three, a data set of individual detrended secondary growth with temperature and age data over the period of 1977-2016. Four, a data set relating individual alder's first 30 years of growth to temperature and the time period it started growth in. Five, a data set of detrended growth from cross-sections taken from each Siberian alder, age class information, and temperature. Finally, a data set containing the number of ramets, nodule biomass per area, and nitrogen fixation rate.
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- Award ID(s):
- 1936752
- PAR ID:
- 10520127
- Publisher / Repository:
- NSF Arctic Data Center
- Date Published:
- Subject(s) / Keyword(s):
- Secondary growth Growth rings Siberian alder Climate sensitivity Arctic Shrub growth
- Format(s):
- Medium: X Other: text/xml
- Sponsoring Org:
- National Science Foundation
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