Аннотация:Summarized the results of long-term observations (2014-2018) of soil emissions and net CO2 fluxes
(2017-2018) in natural and human-modified (HM) ecosystems of Arctic tundra in archipelago of
Svalbard (78о04N, 14о13E). Factors associated with local land use, during the period of their active
impact may redouble the emissions of carbon dioxide from soil (0.111±0.021 > 0.064±0.011 gС m-2h
-
1
). During warm period the net C-balance at the sites with active land use was estimated as a source
to the atmosphere. Self-recovering after human influence plots (2) demonstrate intermediate values
of soil emissions of СО2 between unaffected tundra (1) and plots with active land use (3). With that
they demonstrate the greatest net C-sink within the observed range of Photosynthetically Active
Radiation as compared to (1) and (3). At the height of the vegetation period unaffected tundra
demonstrate a neutral net C-balance. The greatest contribution to soil emissions variance make
spatial factors (56-66% of variance), whereas temporal controls are responsible for 3.8-5.5% only.
Inter-annual fluctuations of key controls, among which the most important are the soil moisture and
temperature of the upper layer, both affect HM and natural ecosystems. Hence the spatial
differences between them remained constant from year to year. We conclude that HM arctic
ecosystems during periods of active land use with high probability become an additional net carbon
sources to the atmosphere. But if the human pressure is halted, under recovery they convert into a
sinks of C, which compensate for the first effect. The rate and degree of the compensation depends
on particular type of human footprint. This often leads to overcompensation and positive
atmospheric effects, but native plant communities are not restored, which is associated with
permafrost degradation. The study was supported by RFBR grant18-05-60279-Arctica, and state
assignments AAAA–A18–118052400130–7 and 0148-2017-0005 of Russia.