Climate Influence in Dendrochronological Series of Araucaria angustifolia from Campos do Jordão, Brazil

A dendrochronological series of Araucaria angustifolia was analyzed for a better understanding of the climatic factors that operate in Campos do Jordão city, São Paulo state, Brazil. The dendroclimatic analysis was carried out using 45 samples from 16 Araucaria angustifolia trees to reconstruct the precipitation and the temperature over the 1803–2012 yearly interval. To this end, Pearson’s correlation was calculated between mean chronology and the climatic time series using a monthly temporal resolution to calibrate our models. We obtained correlations as high as r=0.22(α=0.1) for precipitation (February), and r=0.21(α=0.1) for temperature (March), both corresponding to the end of the summer season. Our results show evidence of temporal instabilities because the correlations for the halves of 1963–2012 were very different, as well as for the full period. To overcome this problem, the dendrochronological series and the climatic data were investigated using the wavelet techniques searching for time-dependent cause–effect relationships. From these analyses, we find a strong influence of the region’s precipitation and temperature on the growth of tree ring widths.

Assessment of Climate Change by Dendrochronological Methods in Polissya

Dendrochronological methods were used to study the response of Quercus robur L. to climate change in Polissya. Negative pointer years (1950, 1976, 1995, 1999, 2002, 2008, and 2011) resulted from the precipitation deficiency during the growing season, cold or extremely warm winters, and abnormal early-spring temperatures. Positive pointer years (1967, 1997, 2001, and 2007) had a favorable heat and moisture balance. Dendroclimatic analysis of oak regional tree-ring chronology showed that during the spring and summer terms of 1980 - 2013, as compared to the previous 1946–1979, there a decrease in the positive influence of temperatures on the oak radial growth. In the second period, the negative impact of precipitation during the cold period on radial growth increased. The adverse impact of April precipitation on radial growth for both periods was revealed as well as the positive influence of July precipitation in the first period and precipitation in June and July in the second one. The increased influence of temperatures and precipitation on the oak radial growth in 1980 - 2013, as compared to previous 1946-1979, indicates an increase in the tree sensitivity to climate change in the second period.

Effect of various climate databases on the results of dendroclimatic analysis

The paper deals with the comparison of the time series drawn from different climate databases. We compared the observed data with the modeled data of monthly and seasonal temperature means and precipitation totals. Reliable and longest available time series of such data represent the basic starting point of dendroclimatic analyses. We evaluated the differences in the growth response of spruce derived using different databases of the considered climatic variables. The stem cores used to derive the cross-correlation function were taken from Hårås locality situated in the boreal zone of the Swedish part of Lapland. We compared the observed records from the nearest weather stations situated 18, 40, 70 and 110 km away from the locality with the interpolated data from four modeled temperature databases and four modeled precipitation databases generated by KNMI Climate Explorer. The spatial resolution of the modeled databases was 0.5° × 0.5° of latitude and longitude or 1° × 1° respectively. The evaluation revealed that in all modeled databases systematic errors of different magnitudes occurred. We also found that the radial increments of spruce correlated more tightly with the temperature than with the precipitation in the area of interest. Hence, in the conditions of the boreal zone, temperature could be a more important factor with regard to tree-ring formation. Because of higher spatial variability seen in precipitation data when compared to temperature data, we conclude that the nearest weather station is the most suitable for dendroclimatic analysis leaning on precipitation. Drawing on these results we recommend that the modeled precipitation and temperature databases examined in our study are used for dendroclimatic analyses within areas featuring a sparse network of weather stations.

Silvicultural and dendroclimatic analysis of plantations Gmelin larch western part of the Putoran plateau

The results of the silvicultural analysis of characteristics and condition of Gmelin larch stands and other components phytocoenosis in various site conditions: Larch sphagnum-ledum (slopes of the northern and southern exposure) and Larch alder (intermontane site) in the upper reaches of Lama lake (Putorana plateau). In the surveyed stands dominated by trees 150-200 years old. Plantings on the northern slopes are in satisfactory sanitary condition, stable, perform basic environmental functions. Sanitary condition of stands on the slopes of southern exposure - is not satisfactory.