The purpose of the study is to find the effects of different growing site conditions on trees with the vessel features in the woods of Quercus ilex L. growing in different regions through Turkey under different site conditions, and to evaluate the results in respect of forestry. A total of 102 wood samples were collected from 102 sampling plots (as 20 m x 10 m plots) in 9 distribution areas in Turkey. Environmental, climate and stand data were obtained for each plot. Standard wood anatomical studies were performed. The results show that, while vessel element lengths are almost stable in all regions, the most changeable vessel element feature is the vessel frequency in different regions of Quercus Q. ilex. Hierarchical cluster analysis based on the mesomorphy and xeromorphy ratios revealed that a total of 15 sites fell into Group 1 (14.71%-very humid), 39 sites (38.24%-humid) into Group 2 and 48 sites (47.06%-dry) into Group 3. The ratios of dry sites are 29.63% in Black sea region, 45.71% in Marmara region and 60% in Aegean region; Black Sea Region promote more mesomorphic wood formation, those in the Aegean region force xeromorphic wood formation in general. The stands of Quercus Q. ilex mixed with Pinus brutia are drier and produce negative correlation with temperature and positive correlations with precipitation. Increasing tree cover, tree height and stem diameter promote wider vessel element diameters and lower number of vessels per square mm. In the individuals of Quercus Q. ilex growing on the mountain ridges of Muğla, Davutlar National Park and its around and on the shallow soils are the driest conditions, and safety is more prominent than efficiency in water transport. In the lower elevations and on the deep soils, efficiency in water transport becomes more prominent than safety. Due to its mesomorphic vessel features in lowland humid sites, Quercus Q. ilex may be planted in lowlands and humid sites through Turkey.

The Kızılırmak River is the longest inland river, has the second-largest basin, and is one of the most important water sources of Turkey. On the other hand, flow data in the basin are too short-term and discordant, with too many gaps to provide reliable information regarding variations in river runoff. In this research, we reconstructed the April–July total precipitation and mean April–August streamflow of Gökırmak River at one gauge in the lower Kızılırmak River Basin using seven regional tree-ring chronologies. Tree-ring chronologies were highly correlated with the precipitation from April to July and with the streamflow from April to August. Both reconstructions successfully explained total variance in instrumental records with 0.36 (precipitation) and 0.35 (streamflow) R2 values. We provided 210 years (1794–2003) of precipitation and streamflow reconstructions, which largely overlapped. Five extreme dry (1840, 1842, 1873, 1887, and 1947) and four extreme wet years (1829, 1837, 1814 and 1881) were determined. The longest consecutive drought and wet events were three years long, for the periods of 1926–1928 and 1835–1837, respectively. The 13-year low-pass filter values highlighted a 30-year-long (from 1843 to 1872) stationary period of April–August mean streamflow.