The frequency of site and zonal pointer years in Norway spruce in two altitudinal zones (500−900 m and 900−1370 m a.s.l.) in the Western Beskidy Mountains was analysed. In total, 32 tree stands were studied – 16 in each zone. In both zones number of negative site pointer years increased along with increase of number of positive site pointer years. Above 900 m a. s. l. number of site pointer years increased along with the altitude, while below 900 m a.s.l. their number decreased along with the altitude. We found no common pointer years for all 32 populations. In lower zone, short winter, early and very warm spring or high precipitation in June and July in a given year caused negative pointer years. In the upper one positive pointer years occurred after the warm autumn and in years with the warm growing season.
The aim of this study was to investigate differences in radial increment reaction of Norway spruces from the Beskidy Zachodnie Mountains (S Poland). Spruce stands were located at different altitudes and slope aspect. Two altitudinal zones were distinguished by a separating altitude of 900 m a.s.l. The den− drochronological belts, consistent in terms of radial increment, amount to 200−250 m in the lower zone, and narrow down to ca. 100 m in the upper one. Factor differentiating radial increment of spruces at vari− ous altitudes was temperature in September of previous year as well as precipitation in March and June of current year.
The study analysed short−term rhythm of radial increments of spruces from different elevations and their climate drivers. Two Norway spruce stands were chosen at the lower and upper montane forest belt in Roztoka Valley (DR) (1000−1050 m asl, 49°13′N, 20°04′E) and in Hala Gąsienicowa (HG) (1500−1550 m asl, 49°13′N, 20°04′E). 20 trees were sampled and one increment core was taken per tree. The sampled trees were dominant or co−dominant individuals without visible damage. To remove the age trend, the tree−ring widths values were standardized to annual sensitivity indices. Principal components analysis, bootstrapped correlation and pointer years analysis were used to classify sensitivity of investigated series and identify the climate factors, which determined annual variability of the radial increments. Pointer years were also determined by using interval trend method. The first principal component (PC1) accounts for 39% of the variance among all tree−ring series. The second component (PC2) accounts for 15% of the variance among the tree−ring series and divides the series into two groups. This grouping seems to express the lower and higher locations of the sites. The sensitivity series of spruces from both sites had different as well as similar features. These differences resulted from different tree's reaction to temperature in early spring and precipitation in spring and summer. The similarity of increment reactions of spruce from both sites was caused by their similar sensitivity to sunshine duration and precipitation in January, temperature in June and July, sunshine duration in June. Cluster analysis confirmed the impact of the climatic factors on differences of increment reactions of spruces. A number of the pointer years was higher at site located in the upper montane forest belt. Their chronology also consisted a stronger climatic signal. The climatic sensitivity which was specificity for a given climatic belt was recorded into individual tree series. For that reason, the tree−ring width series of trees are useful in the estimate of a climate−increment relationship. They can also be used to dividing dendroclimatic belts.
The aim of this study was to i) determine similarities and differences in the increment reaction of silver firs growing at different elevation, ii) identify climatic factors, which caused these response, and iii) determine dendroclimatic zones and identify a site, where a tree grew on the basis of tree−ring widths series. Studied stands were located in the Ustroń Forest District at the elevation of: 500−550 m a.s.l. (foothill zone, 18°59 E, 49°43 N) and 800−850 m a.s.l. (lower montane forest zone, 18°58 E, 49°43 N). In each stand 20 dominant firs were selected and one increment core per tree was taken. Tree−ring widths (fig. 1) were transformed into annual sensitivity index (fig. 2). Principal component analysis was used to reduce a number of original variables and classify the tree−ring series. Response function analysis was used to determine climate−radial increment relationships. The standardized series of firs on both sites were different in terms of the climate influence (fig. 3). The analysed trees responded differently to solar and thermal conditions in previous autumn and current summer as well as to pluvial conditions at the beginning of winter and in the second half of summer. The investigated firs had also common increment characteristics. The trees from both sites responded similarly to thermal, solar and pluvial conditions in February, solar and pluvial conditions in May and temperature in winter and summer (fig. 4). Climatic signal of each elevation zone was recorded by each tree and depended on the climatic conditions in given area. On the basis of standardized tree−ring series, dendroclimatic regionalization can be created and the stand, where a tree grew, can be identified.
The study evaluated the sensitivity of European larch (Larix decidua) of two provenances to thermo−pluvial conditions on the provenance plot located in Sękocin Stary (52°05‵ N, 20°51‵ E, 125 m a.s.l.). The studied larches originated from Pelplin (lowland, northern Poland, 50 m a.s.l.) and Szczytna (upland, southern Poland, 525 m a.s.l.). The trees of both provenances differed in terms of their quantitative and qualitative breeding characteristics. The trees originated from different climatic regions whose climate was also different from the climate of the provenance plot. Values of the size of the radial increments measured at cores extracted from the trees were the measure of their sensitivity to the climatic factor. The cluster and principal component analyses were used to classify the trees according to their features of the short−term rhythm of the radial increments. The response function and pointer years analyses were used to evaluate climate−growth relationships. The results of the study show the trees of both provenances have similar sensitivity to the thermo−pluvial conditions in the previous September, the temperature in March and the precipitation in May of the year of tree−ring formation. The larches of Pelplin provenance, in contrast to the trees of Szczytna provenance, were sensitive to the low temperature in February and the low precipitation in the growing season. These features could be one of the causes of the lower incremental abilities of the trees of Pelplin provenance. The larches of Szczytna provenance had higher frost tolerance in February and drought tolerance in summer.
The study analysed the causes of the annual variation of tree−ring widths of silver fir and white fir. The partial populations of both fir species has been growing for over 100 years in Rzepin (western Poland) in a fresh broadleaved forest site. We assumed that the year−to−year changes of the size of radial increment presents sensitivity of trees to local climate factor. The period from 1931 to 2015 was analysed. We found that the silver and white firs had high homogeneity of radial growth responses and sensitivity to year−to−year changes of weather conditions. Warm November of the previous year, short winter and high air temperature in August had positive influence on the size of their radial increment. Moreover, precipitation in February, April and July of the year of tree−ring formation contributed to wider tree−ring. The white fir was highly resistant to winter frost in contrast to the silver fir. In addition, this fir species preferred cold springs. Furthermore, the silver fir suffered from overabundant precipitation in August. The climate conditions of western lowland part of Poland were not a limiting factor for growth of both species because the studied populations achieved the highest site index class.