Journal Article drought Air Pollutants Bayesian inference CONECOFOR forest monitoring Fagus sylvatica ICP-Forests N critical loads N762921K75 Nitrogen Observational Study PLS regression Picea abies Research Support, Non-U.S. Gov't SPEI Soil Pollutants XAFS XANES XAS biotic disturbance carbon cycling data assimilation data processing ecosystem productivity extreme events growth and carbon sequestration insect-host system inverse modeling laboratory spectrometer model calibration