Abstract This paper reviews eight characteristic approaches for forest decline research in the Federal Republic of Germany (FRG) with their major results: (1) Monitoring of the pollution load in the atmosphere; (2) assessment of the atmogenic bioelement deposition to and of nutrient cycling in forest ecosystems; (3) ecophysiological studies; (4) the open top chamber approach; (5) growth measurements; (6) investigations on root dynamics; (7) case studies describing different disease phenomena; and (8) multidisciplinary experiments to test hypotheses about the interactions of stress factors. Several distinct types of disease or decline have been identified for several tree species, all of them leading to drastic foliage losses. The additional symptoms, however, as well as the sets of plausible stress factors associated with these disease types differ greatly. Until now, the significance of pollutants and acidic deposition, as one cause (among others) of “new type”; forest diseases in the FRG, has been identified only for the “high elevation”; decline of Norway spruce, which occurs over less than 10% of the total acreage for this species in the FRG. For other types of disease, either the contribution of pollution stress is unclear or the “new type”; character of the disease is in question. The so‐called “new type”; diseases occur on all types of parent rock, on all soil types, in widely variant climatic conditions, in stands with varying nutritional status and in landscapes where pollution and atmospheric deposition differ considerably. Therefore, it is unlikely that a distinct chemical soil milieu or a specific nutritional stress on the affected trees acts as a large‐scale uniform trigger for all forest disease phenomena over all of central Europe. On the contrary, the synchronization of different disease types in coniferous stands during the period 1980–85 is probably caused by large‐scale weather stress such as dry periods or frost phenomena or combinations of such events. These weather stresses trigger natural diseases as well as regional tree decline due to pollution and deposition. Infertile soils, inadequate nutrition, pollution‐caused atmospheric deposition and pathogens are not general, but local/regional or disease‐type‐specific stress factors, wherever they occur in force.