Different climate response of three tree ring proxies of Pinus sylvestris from the Eastern Carpathians, Romania

The aim of this study was to compare the climatic responses of three tree rings proxies: tree ring width (TRW),
maximum latewood density (MXD), and blue intensity (BI). For this study, 20 cores of Pinus sylvestris covering
the period 1886–2015 were extracted from living non-damaged trees from the Eastern Carpathian Mountains
(Romania). Each chronology was compared to monthly and daily climate data. All tree ring proxies had a
stronger correlation with the daily climate data compared to monthly data. The highest correlation coefficient
was obtained between the MXD chronology and daily maximum temperature over the period beginning with the
end of July and ending in the middle of September (r=0.64). The optimal intervals for the temperature signature
were 01 Aug – 24 Sept for the MXD chronology, 05 Aug – 25 Aug for the BI chronology, and both 16 Nov
of the previous year – 16 March of the current year and 15 Apr – 05 May for the TRW chronology. The results
from our study indicate that MXD can be used as a proxy indicator for summer maximum temperature, while
TRW can be used as a proxy indicator for just March maximum temperature. The weak and unstable relationship
between BI and maximum temperature indicates that BI is not a good proxy indicator for climate reconstructions
over the analysed region.