ИСТИНА

It is known that paleoclimatic information can be obtained from tree-ring records. These samples are usually collected around three regions: at the northern (highlatitude or arctic) timberline, at the southern (arid) timberline, and in the mountain regions along the altitude timberline. The general feature of these three regions is their enhanced sensitivity to the external forcing. Obviously there are some difficulties in data accessing from wood samples collected at middle latitudes. Therefore to obtain reliable climatic information from middle latitude dendrochronological data it is necessary to find trees with the greatest sensitivity. The more proper ones are trees growing at the limit of surviving around big polluted centres like Monchegorsk coppernickel enterprise (Severonikel; 67.9 N, 32.9 E) at Kola Peninsula. By now we’ve analyzed more than 30 tree-ring records (about 15 wood samples in each series) collected at different parts of Kola Peninsula. All samples were cross-dated and ring widths were measured using standard dendrochronological technicues and COFECHA and ARSTAN programs. It was obtained that the more clear response on external impacts (solar activity, volcanic eruptions, climatic changes) was observed in the last century only on tree-ring data collected in the vicinity of Severonikel plant. This heightened sensitivity of wood samples permitted us to suggest the 4th or "technogenic" timberline located around polluted areas, where climatic variations may be effectively studied. It is very important that global and regional climatic changes may be studied rather far from the usual timberline areas at middle latitudes where the industry concentration and pollution are maximal.