The role of summer precipitation and summer temperature in establishment and growth of dwarf shrub Betula nana in northeast Siberian tundra

Summary

It is widely believed that deciduous tundrashrub
dominance is increasing in the pan-Arctic region,
mainly due to rising temperature. We sampled dwarf birch
(Betula nana L.) at a northeastern Siberian tundra site and
used dendrochronological methods to explore the relationship
between climatic variables and local shrub dominance.
We found that establishment of shrub ramets was
positively related to summer precipitation, which implies
that the current high dominance of B. nana at our study site
could be related to high summer precipitation in the period
from 1960 to 1990. The results confirmed that early summer
temperature is most influential to annual growth rates
of B. nana. In addition, summer precipitation stimulated
shrub growth in years with warm summers, suggesting that
B. nana growth may be co-limited by summer moisture
supply. The dual controlling role of temperature and
summer precipitation on B. nana growth and establishment
is important to predict future climate-driven vegetation
dynamics in the Arctic tundra.