Dendroclimatology is focused on studying tree-ring formation in response to (changing) weather conditions. The calculation of climate-growth relationships enables the determination of those climate or climate-related factors (e.g. river discharge) that mainly influence the growth of trees of a certain species under specific site conditions.
Assessment of climate-growth relationships allows (1) evaluation of the effect of a changing climate on tree growth and forest development and (2) reconstruction of past climate conditions beyond the period where instrumental records are available by using tree-ring data as proxy (=indirect) data for climate variables. The longest tree-ring chronologies available are build up from sub-fossil oak and pine trees and potentially enable reconstruction of specific climate factors about 10.000 years back in time.