TITLE:
Linnebjer—A South Swedish Oak Forest and Meadow Area—Revisited after Half a Century
AUTHORS:
Folke O. Andersson, Bengt Nihlgård
KEYWORDS:
Oak Disease, Tree Vitality, Deposition of S and N, Soil Acidification, Soil C and N Accumulation, Increased Amounts of Ca and Mg
JOURNAL NAME:
Open Journal of Ecology,
Vol.6 No.2,
January
25,
2016
ABSTRACT: An oak forest and three wet meadows/fens were
reinvestigated after 50 years concerning tree vitality, biomass and
productivity, and soil chemistry. Sulphur and nitrogen deposition has changed
dramatically during these years, and the aim was to analyse the differences in
both the oak forest and the open field ecosystems. Trees were re-measured and
soil profiles were resampled. Important visible changes in the oak forest were
stated concerning the vitality of oaks. Aboveground there was a decrease in
tree biomass, production and litter fall, but a huge increase in standing dead
logs. During the years, the deposition of sulphur had decreased drastically,
but nitrogen deposition was still high. Soil acidification in the forest had
decreased, reflected in an increased base saturation in the forest, in spite of
slightly lowered pH-values. Strongly increased amounts of exchangeable Ca and
Mg now appeared in the forest soil, and a substantial transport of calcium and
magnesium had obviously taken place from the forest soil to the meadow and fens
during the years. However, the most important soil change was the accumulation
of organic matter. The increased accumulation of organic matter in turn meant
increased amounts of colloid particles and microsites for ion exchange in the
soil. This favoured 2-valence base cations, and especially Ca and Mg that
increased very much in all the studied ecosystems. Carbon as well as nitrogen
had strongly increased in the forest, meadow and fen soils. This was
interpreted as a natural result of increased vegetation growth due to high
nitrogen deposition, increased global annual temperature and increased carbon
dioxide concentration in air. It was concluded that the decreased deposition of
sulphur had had a positive effect on soil chemistry, and that the deposition of
nitrogen probably had stimulated vegetation growth in general, and contributed
to increased amount of organic matter in the soils. However, in this studied
oak forest, the decreased vitality and many killed trees were also suspected to
be a result of high nitrogen deposition. Obviously increased tree growth was
counteracted by decreased stress resistance, and increased appearance of
pathogens in the oak trees.