Linnebjer—a south swedish oak forest and meadow area—revisited after half a century

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 changeddramatically during these years, and the aim was to analyse the differences in both the oak forestand the open field ecosystems. Trees were re-measured and soil profiles were resampled. Importantvisible changes in the oak forest were stated concerning the vitality of oaks. Abovegroundthere was a decrease in tree biomass, production and litter fall, but a huge increase in standingdead logs. During the years, the deposition of sulphur had decreased drastically, but nitrogendeposition was still high. Soil acidification in the forest had decreased, reflected in an increasedbase saturation in the forest, in spite of slightly lowered pH-values. Strongly increased amounts ofexchangeable Ca and Mg now appeared in the forest soil, and a substantial transport of calciumand magnesium had obviously taken place from the forest soil to the meadow and fens during theyears. However, the most important soil change was the accumulation of organic matter. The increasedaccumulation of organic matter in turn meant increased amounts of colloid particles andmicrosites for ion exchange in the soil. This favoured 2-valence base cations, and especially Ca andMg that increased very much in all the studied ecosystems. Carbon as well as nitrogen had stronglyincreased in the forest, meadow and fen soils. This was interpreted as a natural result of increasedvegetation growth due to high nitrogen deposition, increased global annual temperature and increasedcarbon dioxide concentration in air. It was concluded that the decreased deposition ofsulphur had have a positive effect on soil chemistry, and that the deposition of nitrogen probablyhad stimulated vegetation growth in general, and contributed to increased amount of organicmatter in the soils. However, in this studied oak forest, the decreased vitality and many killedtrees were also suspected to be a result of high nitrogen deposition. Obviously increased treegrowth was counteracted by decreased stress resistance, and increased appearance of pathogensin the oak trees

Pathogenicity of Swedish isolates of Phytophthora quercina to Quercus robur in two different soils

Several studies have demonstrated the involvement of soil-borne Phytophthora species, especially Phytophthora quercina , in European oak decline. However, knowledge about the pathogenicity of P. quercina in natural forest soils is limited. The short-term effects of two south-Swedish isolates of P. quercina on root vitality of Quercus robur seedlings grown in two different soils, one high pH, nutrient-rich peat-sand mixture and one acid, nitrogen-rich but otherwise nutrient-poor forest soil are described. Pathogenicity of P. quercina was tested using a soil infestation method under a restricted mesic water regime without prolonged flooding of the seedlings. There was a significant difference in dead fine-root length between control seedlings and seedlings grown in soil infested with P. quercina . Trends were similar for both soil types and isolates, but there was a higher percentage of fine-root die-back and more severe damage on coarse roots in the acid forest soil. No effects on above-ground growth or leaf nutrient concentration between control seedlings and infected seedlings were found. The results confirm the pathogenicity of south-Swedish isolates of P. quercina in acid forest soils under restricted water availability. Stress-induced susceptibility of the seedlings and/or increased aggressiveness of the pathogen in the forest soil are discussed as key factors to explain the difference in root die-back between soil types

Biomass burning in eastern Europe during spring 2006 caused high deposition of ammonium in northern Fennoscandia

High air concentrations of ammonium were detected at low and high altitude sites in Sweden, Finland and Norway during the spring 2006, coinciding with polluted air from biomass burning in eastern Europe passing over central and northern Fennoscandia. Unusually high values for throughfall deposition of ammonium were detected at one low altitude site and several high altitude sites in north Sweden. The occurrence of the high ammonium in throughfall differed between the summer months 2006, most likely related to the timing of precipitation events. The ammonia dry deposition may have contributed to unusual visible injuries on the tree vegetation in northern Fennoscandia that occurred during 2006, in combination with high ozone concentrations. It is concluded that long-range transport of ammonium from large-scale biomass burning may contribute substantially to the nitrogen load at northern latitudes. (C) 2013 Elsevier Ltd. All rights reserved

Growth response of spruce saplings in relation to climatic conditions along a gradient of gap size

To evaluate the relative importance of climatic factors and the level of natural canopy disturbance on sapling growth rates, terminal shoot increment of Norway spruce (Picea abies (L.) Karst.) saplings was analyzed in old-growth Sphagnum-Myrtillus forests of the European southern boreal zone (Tver Region, Russia). For a 5-year period, terminal increments were retrospectively measured in 225 saplings in a range of naturally created canopy gaps. Climatic variability was estimated by Seljaninov hydrothermal coefficient. Variation in the growth rate was partitioned as (i) annual variation observed within a particular sapling over a 5-year period ("within-stem variation," WSV) and (ii) variation of 5-year cumulative height increments within a particular location ("within-location variation," WLV). Sapling growth was positively related to gap size and, except when under canopy location, with the height of the saplings. For the growth, differences in sapling location along a gradient of gap sizes were more important than annual dynamics of water availability. Impact of the annual climatic variability was less pronounced in large gap, compared with other locations. Absolute values of WSV and WLV were similar under an intact canopy. WSV had a tendency to decrease in greater gaps, whereas WLV variation increased

Slash pile burning at a Norway spruce clear-cut in southern Sweden

The effect of burning piles of slash on a Norway spruce clear-cut in southern Sweden was followed for 3 years. The vegetation cover, soil chemistry, soil water at a depth of 30 - 40 cm and runoff water were studied. The burnt plots were without vegetation for several months after burning, while the control plots were almost totally covered by Deschampsia flexuosa and Galium saxatile. The remaining mor horizon of the burnt plots had a pH of 6 compared with pH 4.4 in the control plots. This caused more intense nitrification of the burnt plots that, in turn, caused an acid push with high concentrations of hydrogen ions, nitrate and potassium in the soil water. After 1 year, a cover of D. flexuosa and G. saxatile had also developed on the burnt plots, and the soil water chemistry no longer indicated an elevated leakage of ions. Throughout the study period, no leaching effect was observed in the runoff water. This was explained by nutrient retention of a swamp forest with Betula pubescens on peat soil, surrounding the ditch collecting the runoff water. The increased risk of developing a nutrient imbalance in the next forest generation may strongly outweigh the short-term benefit of reduced competition between tree seedlings and forest floor vegetation, especially if the slash burning is not expected to be of any value for species conservation

Mapping critical loads for nitrogen based on biodiversity using ForSAFE-VEG: introducing the basic principles

This chapter describes the basic principles inside the VEG extension to the ForSAFE model system. It allows changes in ground vegetation to be calculated, an important part of biodiversity. In the VEG model, the basis for modelling ground vegetation dynamics is a competition strength model based on soil chemistry promoting and retarding factors, nutrients, water and light. The strength is used in a competition model to assign ground area to each plant type considered. The ForSAFE-VEG is freely available from the authors and is used for assessing critical loads for acidity and nitrogen in Europe and United Sates, based on biodiversity criteria

Inorganic constituents of well water in one acid and one alkaline area of south Sweden

Acid precipitation may lead to loss of essential elements and increase the concentrations of potentially toxic elements in drinking water. In this study 46 private wells from acid regions (pH < 6.5) were compared with 43 private wells from alkaline areas in southern Sweden. The concentrations of about 30 elements were analysed especially by inductively coupled plasma optical emission spectroscopy (ICP-OES). The concentrations of essential elements such as calcium, chromium, selenium and potassium were significantly lower in acid than in alkaline well water. On the other hand, the levels of potentially toxic metals such as cadmium and lead were significantly higher in acid well water. High copper concentrations, observed at pH around 6 in contrast to earlier findings, is to be considered as an acidification problem, as should the high fluoride values. The highest concentrations of a number of metals and ions, for example calcium, chromium, titanium and sulphate, appeared at pH 7.0-8.0, where the peak in concentrations occur due to leaching of metals from soil particles in acid soils and precipitation of carbonates and sulphates in more alkaline soils. The low levels of especially calcium and magnesium ions, and some micronutrients in the acid water, in combination with high concentrations of acid ions and toxic microelements, may cause nutritional imbalances. This should be regarded as risk factors with relation to effects on human health