Modification of the atmospheric load of elements during passage through foliaged canopies of five tree species of temperate zone forests

Atmospheric load is an important source of nutrients and pollutants to ecosystems. During the flux through forest canopies that deposition is intensively modified enriching in some elements and pooring in others. Both, atmospheric load and flux of elements through forest canopies, were investigated in the Kampinos National Park (central Poland) during vegetative seasons (April-October) of the years 1998 and 2000. Throughfall was compared with atmospheric deposition in five different forest ecosystems: pine, birch, locust tree, alder, and oak. Atmospheric deposition data was obtained from rain collectors equipped with artificial foliage of an area similar to the actual leaf surface area in a given ecosystem. Results showed that H[^+] and Pb[^2+] flowed passively through tree canopies. NO[3^-], PO[4^3-], SO[4^2-], NH[4^+], Na[^+], Cd[^2+], Zn[^2+] and Cu[^2+] were retained in the canopies (the process was the most intensive for ammonium - 58%, and phosphorus - 60% retained), whileCl[^-], Mg[^2+], K[^+] and Ca[^2+] were leached out of canopies (throughfall, in comparison to bulk precipitation, was enriched by up to 109% in case of potassium). These processes all occurred more vigorously in deciduous trees, like alder and oak, and less intensively or not at all in pine tree stands. Trees living in symbiosis with nitrogen-fixing microorganisms (alder and locust tree) were equally effective at trapping nitrogen from atmospheric loads, as at non-symbiotic tree species. The calendar day has no influence on the throughfall balance of elements with the only exception for calcium (only in alder forest also magnesium and chlorine), which was more intensively leached out during the autumn then on the beginning of vegetation season.