Altered Soil Chemistry Research Articles

Distribution of field layer species in Swedish deciduous forests in 1929-54 and 1979-88 as related to soil pH

Literature data on vascular plant distribution in deciduous forests were compared in 1929-54 and 1979-88. pH in the topsoil was related to the occurrence of 13 common vascular plants. The median of pH (H2O) was 5.2 for the old (n=105) and 4.4 for the new plots (n=132). New plots of pH>5 were scarce and soils of pH<4 were limited to the new plots. Comparison of the pH related frequency curves gave four patterns: (A) a displacement of frequency curves towards lower pHs for the new plots (Stellaria holostea, Milium effusum, Melica uniflora); (B) a widening of the frequency curves into lower pH for the new plots (Viola riviniana/reichenbachiana, Galium odoratum, Lamium galeobdolon, Oxalis acetosella, Maianthemum bifolium); (C) a raised frequency curve for the new plots at all pHs (Stellaria nemorum, Poa nemoralis, Rubus idaeus, Mercurialis perennis); (D) a lowered frequency curve for the new plots at all pHs (Deschampsia flexuosa). It is deduced, that the pH related frequency curves are not stable over long periods as e.g. the studied 40–60 years. The increased amounts of nitrogen and acidifying substances in deposition probably caused an altered soil chemistry and a change in competition among nitrogen favoured and acid tolerant species. As the soil in the new plots was more acidic, the total frequency was higher for many species. However, the frequency of most species decreases with soil pH, and if soil acidification continues without further plant adaptation to low soil pH, there will be a decrease of many species.

Elemental concentrations in tree rings by PIXE: statistical variability, mobility, and effects of altered soil chemistry

Concentrations of up to 14 elements were determined from increment cores by proton-induced X-ray emission for dated series of annual rings of plantation Liriodendrontulipifera L. All trees were treated in 1965 with 841, 224, and 280 kg/ha of elemental N, P, K, respectively, and with either 0, 1683, or 3366 kg/ha of elemental Ca applied as pulverized agricultural limestone. Intraring elemental concentrations were not significantly different between earlywood and late-wood. Statistical variability of proton-induced X-ray emission elemental determinations was greatest for Al, Si, Cl, Cu, and Zn; concentrations of P, K, Ca, Mn, and Sr were least variable. Estimated standard errors among cores within trees averaged less than those among trees on a uniform site. Element mobility was tested in xylem core samples taken in 1965 and 1986. Liming significantly increased P, S, K, Ca, and Zn and decreased Mn in pre-1965 xylem. Retroactive liming effects were not detected for Mg, Al, Fe, Sr, or Ba; liming responses of Si, Cl, and Cu were unclear. Significant differences in elemental concentration independent of liming were detected between the 1965 and 1986 sampling times for P, K, Ca, Mn, Zn, Sr, and Ba. Of these, differences in P, K, and Mn may be due largely to heartwood formation between sampling times. Exchangeable Ca and Mg, followed by pH, were the most important soil variables in significant regressions with xylem elemental concentrations; only weak relationships were found with foliar elemental concentrations. Concentrations of Al, Si, Fe, and Cu in L. tulipifera xylem could be useful biomonitors of soil chemical changes by virtue of their apparent immobility; other elements, particularly S and Sr, may also be useful. However, expected time trends, especially as they pertain to heartwood formation, should be taken into account for each element.

1982 Stockholm Conference on Acidification of the Environment

This article is a review and analysis of the 1982 Stockholm conference on acidification of the environment. At the conference, evidence was presented that strongly suggests that SO/sub 2/ is damaging trees and forests in a chronic manner; by stressing trees directly and by altering soil chemistry. Of the nations participating in the conference, only the US and Great Britain took the position that more research is needed. The other participants favored immediate implementation of control strategies for SO/sub 2/ emissions.

1982 Stockholm Conference on Acidification of the Environment

This article is a review and analysis of the 1982 Stockholm conference on acidification of the environment. At the conference, evidence was presented that strongly suggests that SO/sub 2/ is damaging trees and forests in a chronic manner; by stressing trees directly and by altering soil chemistry. Of the nations participating in the conference, only the US and Great Britain took the position that more research is needed. The other participants favored immediate implementation of control strategies for SO/sub 2/ emissions.