Acknowledgements

Dr. Gordon Jacoby, David Frank, Nicole Davi & Neil Pederson
Tree-Ring Lab, Lamont-Doherty Earth Observatory

Dr. Nikolai Lovelius
Botanic Institute of RAS

Prof. Oleg M. Raspopov
S. Petersburg Filial Institute of Terrestrial Magnetism, Ionosphere and Radiowaves Propagation SPbF IZMIRAN

Dr. Irina Ju. Kirtsidely
Botanical Institute RAS