Balance of Chemicals in Pine and Spruce Forests of Karelia

Resumo

An equation of the balance of chemicals is proposed which makes it possible to estimate the changes in their quantity in the soil under a growing stand. When determining the sources of chemicals for forest soils, the measured data of their contents in atmospheric precipitation and estimated inputs of dieback are used. Sinks of elements are calculated from lysimetric data and their accumulation is determined for phytomass increase. Due to the insufficient study of element migration during transpiration, the influence of this process on the balance is evaluated for two options: with and without taking possible losses of chemicals as a result of biogenic evaporation into account. Growth increment and dieback phytomass are estimated differentially for the soil cover and the stand. We have documented the species-averaged contents of certain chemicals accumulating by growing phytomass and returning with dieback in pine and spruce stands and their soil covers. The accumulation of elements in soil cover rises due to precipitation falling through the forest canopy. The greatest increase is obtained in the input of potassium and calcium. Their contribution is the highest in the precipitation flux of all studied chemicals in the soil cover. However, the precipitation of potassium is comparable to its uptake by phytomass. Dieback is the dominant source of silicon, nitrogen, and total phosphorus for the forest soils. The balance model shows that the mature and old-growth stands support the accumulation of nutritional elements in the soils. Losses of silicon might be compensated by its soil storage.