TITLE:
Changes in Environmental Parameters and Their Impact on Forest Growth in Northern Eurasia
AUTHORS:
Olga Khabarova, Igor Savin
KEYWORDS:
Climate Change, Forest Growth, Biomagnetism
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.5 No.2,
April
16,
2015
ABSTRACT: We performed an empirical investigation of forest growth for two types of
forests in northern Eurasia (larches and spruces) in order to show that the sensitivity
of trees to the variable climate and geomagnetic field can be seen even under the
large-scale average. The main purpose of this research was to model a forest growth
rate V for each forest type on the basis
of several environmental parameters influencing the tree growth in a high degree
and to find the differences and similarities of the larches and spruces’ response
to changing environment. We showed that V,
which is related to the annual tree-ring width, could be derived from the Normalized
Difference Vegetation Index (NDVI) data. Averaged yearly by species for 1982-2006,
it displayed a long-term decrease (most likely related to the global climate change)
as well as short-term variations with periods of 2.2, 4 and 8 years. A composite
function method was used for modeling. We selected several tree growth drivers (the
temperature, precipitation, insolation and the geomagnetic field intensity) that
were highly correlated with V, and a function
was modeled that described the behavior of V.
The correlation coefficients between the derived function and experimental time
series were 0.8 for larches and 0.9 for spruces. Compared with spruces, larches
demonstrated higher thermo-sensitivity. A loss of tree sensitivity to temperature
changes is puzzling for dendroclimatology, as a similar process might have occurred
during previous periods of sharp global climate changes (as observed currently).
Sensitivity of trees to geomagnetic field changes is confirmed both at long- and
short-timescales. Spruces are found to be more magnetosensitive than larches.