10.5061/DRYAD.RH807JP
Huebner, Diane C.
University of Alaska Fairbanks
Bret-Harte, Marion S.
University of Alaska Fairbanks
Data from: Microsite conditions in retrogressive thaw slumps may
facilitate increased seedling recruitment in the Alaskan Low Arctic
Dryad
dataset
2020
Betula nana
thermokarst
Quaternary
Salix spp.
seedbank
microsite
retrogressive thaw slump (RTS)
National Science Foundation
https://ror.org/021nxhr62
DEB 1556481
2019-02-06T22:52:45Z
2019-02-06T22:52:45Z
en
https://doi.org/10.1002/ece3.4882
185014 bytes
2
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
In Low Arctic tundra, thermal erosion of ice-rich permafrost soils
(thermokarst) has increased in frequency since the 1980s. Retrogressive
thaw slumps (RTS) are thermokarst disturbances forming large open
depressions on hillslopes through soil wasting and vegetation
displacement. Tall (> 0.5 m) deciduous shrubs have been observed in
RTS a decade after disturbance. RTS may provide conditions suitable for
seedling recruitment, which may contribute to arctic shrub expansion. We
quantified in situ seedling abundance, and size and viability of soil
seedbanks in greenhouse trials for two RTS chronosequences near lakes on
Alaska’s North Slope. We hypothesized recent RTS provide microsites for
greater recruitment than mature RTS or undisturbed tundra. We also
hypothesized soil seedbanks demonstrate quantity-quality trade-offs:
younger seedbanks contain smaller numbers of mostly viable seed that
decrease in viability as seed accumulates over time. We found five times
as many seedlings in younger RTS as in older RTS, including birch and
willow, and no seedlings in undisturbed tundra. Higher seedling counts
were associated with bare soil, warmer soils, higher soil available
nitrogen, and less plant cover. Seedbank viability was unrelated to size.
Older seedbanks were larger at one chronosequence, with no difference in
percent germination. At the other chronosequence, germination was lower
from older seedbanks but seedbank size was not different. Seedbank
germination was positively associated with in situ seedling abundance at
one RTS chronosequence, suggesting post-disturbance revegetation from
seedbanks. Thermal erosion may be important for recruitment in tundra by
providing bare microsites that are warmer, more nutrient rich, and less
vegetated than in undisturbed conditions. Differences between two
chronosequences in seedbank size, viability, and species composition
suggest disturbance interacts with local conditions to form seedbanks. RTS
may act as seedling nurseries to benefit many arctic species as climate
changes, particularly those that do not produce persistent seed.
Seedling and seedbank dataEnvironmental characterization, seedling count
data, seedbank size and germination dataDCHuebner_data.xlsx
Alaskan Low Arctic