Movement patterns of an avian generalist predator indicate functional heterogeneity in agricultural landscape

Landscape Ecology - Biodiversity is closely related to landscape heterogeneity, but both are difficult to evaluate directly. Apex predators, such as raptors, are potential surrogate indicators of...     

The nutrient status of Norway spruce in pure and in mixed-species stands

Atmospheric deposition of N and S appears to have caused nutrient imbalance in Norway spruce stands in southern Sweden. This calls for a change of forest management to procedures that promote nutrient balance. Studies have shown lower soil acidity in Norway spruce/deciduous mixed stands than in spruce monocultures, but the tree nutrient status in such mixtures has not been much investigated so far.

The nutrient status of Norway spruce foliage and top mineral soil chemistry in monocultures and in stands mixed with beech, birch, or oak was investigated through paired comparisons on 30 sites in southern Sweden (27 sites) and eastern Denmark (three sites). In total, 45 mixed stands and 34 pure stands were included in the study.

Spruce needles from mixed stands had higher concentrations and ratios to N of K, P, and Zn than needles from pure spruce stands. Among the mixed stands, the K status appeared to be positively correlated with the percentage of deciduous tree basal area. Soil samples from mixed stands had a higher Mg concentration, base saturation, and BC/Al ratio than soil samples from pure stands. The spruce needle nutrient status was comparable in pure stands on fertile sites and in mixed stands on poor sites. We did not detect any differences in spruce tree growth between pure and mixed stands.

This paper discusses possible reasons for a positive effect on the tree nutrient status in mixed-species stands and the possibility of using mixed-species stands as a forest management procedure to avoid nutrient imbalance.     

Leaching of nitrogen from a forest catchment at söder»sen in southern Sweden

Water balance and leaching of plant nutrients, with special reference to N, were described for a 46-ha catchment consisting mainly of coniferous forest (one third of it clear-cut) during the period January 1982-August 1988. The atmospheric N load in this region is high compared with most other parts of Scandinavia. On average, annual N leaching amounted to 9.5 kg ha^?1 in the form of NO₃-N (83%), org-N (15%) and NH₄-N (2%). The highest monthly rate of N transport observed was 3.9 kg ha^?1. The NO₃-N levels in groundwater in the 60-yr-old coniferous stand ranged from 0.5 to 3.1 mg L^?1. The effect of clear-cutting on groundwater-NO₃-N levels lasted 4 yr. The highest annual NO₃-N transport from the clear-cut area observed was 18 kg ha^?1. The groundwater in the spruce forest was very acidic (pH=4.3) in contrast to the stream water (pH=6.3). The relatively higher pH-value of the stream water was probably a result of chemical and biological processes occurring in the highly humified, periodically waterlogged peat soil (alder swamp) in the vicinity of the small stream.     

Mercury in the Swedish environment — Recent research on causes,consequences and corrective methods

During the last decade a new pattern of Hg pollution has been discerned, mostly in Scandinavia and North America. Fish from low productive lakes, even in remote areas, have been found to have a high Hg content. This pollution problem cannot be connected to single Hg discharges but is due to more widespread air pollution and long-range transport of pollutants. A large number of waters are affected and the problem is of a regional character. The national limits for Hg in fish are exceeded in a large number of lakes. In Sweden alone, it has been estimated that the total number of lakes exceeding the blacklisting limit of 1 mg Hg kg-1 in 1-kg pike is about 10 000. The content of Hg in fish has markedly increased in a large part of Sweden, exceeding the estimate background level by about a factor of 2 to 6. Only in the northernmost part of the country is the content in fish close to natural values. There is, however, a large variation of Hg content in fish within the same region, which is basically due to natural conditions such as the geological and hydrological properties of the drainage area. Higher concentrations in fish are mostly found in smaller lakes and in waters with a higher content of humic matter. Since only a small percentage of the total flow of Hg through a lake basin is transferred into the biological system, the bioavailability and the accumulation pattern of Hg in the food web is of importance for the Hg concentrations in top predators like pike. Especially, the transfer of Hg to low trophic levels seems to be a very important factor in determining the concentration in the food web. The fluxes of biomass through the fish community appear to be dominated by fluxes in the pelagic food web. The Hg in the lake water is therefore probably more important as a secondary source of Hg in pike than is the sediment via the benthic food chain. Different remedy actions to reduce Hg in fish have been tested. Improvements have been obtained by measures designed to reduce the transport of Hg to the lakes from the catchment area, eg. wetland liming and drainage area liming, to reduce the Hg flow via the pelagic nutrient chains, eg. intensive fishing, and to reduce the biologically available proportion of the total lake dose of Hg, eg. lake liming with different types of lime and additions of selenium. The length of time necessary before the remedy gives result is a central question, due to the long half-time of Hg in pike. In general it has been possible to reduce the Hg content in perch by 20 to 30% two years after treatments like lake liming, wetland liming, drainage area liming and intensive fishing. Selenium treatment is also effective, but before this method can be recommended, dosing problems and questions concerning the effects of selenium on other species must be evaluated. Regardless how essential these kind of remedial measures may be in a short-term perspective, the only satisfactory long-term alternative is to minimize the Hg contamination in air, soil and water. Internationally, the major sources of Hg emissions to the atmosphere are chlor-alkali factories, waste incineration plants, coal and peat combustion units and metal smelter industries. In the combustion processes without flue gas cleaning systems, probably about 20 to 60% of the Hg is emitted in divalent forms. In Sweden, large amounts of Hg were emitted to the atmosphere during the 50s and 60s, mainly from chlor-alkali plants and from metal production. In those years, the discharges from point sources were about 20 to 30 t yr 1. Since the end of the 60s, the emission of Hg has been reduced dramatically due to better emission control legislation, improved technology, and reduction of polluting industrial production. At present, the annual emissions of Hg to air are about 3.5 t from point sources in Sweden. In air, more than 95% of Hg is present as the elemental Hg form, HgO⁰. The remaining non-elemental (oxidized) form is partly associated to particles with a high wash-out ratio, and therefore more easily deposited to soils and surface waters by precipitation. The total Hg concentration in air is normally in the range 1 to 4 ng m-3. In oceanic regions in the southern hemisphere, the concentration is generally about 1 ng m^?3, while the corresponding figure for the northern hemisphere is about 2 ng m-3. In remote continental regions, the concentrations are mainly about 2 to 4 ng m^?3. In precipitation, Hg concentrations are generally found in the range 1 to 100 ng L^?1. In the Nordic countries, yearly mean values in rural areas are about 20 to 40 ng L^?1 in the southern and central parts, and about 10 ng L^?1 in the northern part. Accordingly, wet deposition is about 20 (10 to 35) g km^?2 yr^?1 in southern Scandinavia and 5 (2 to 7) in the northern part. Calculations of Hg deposition based on forest moss mapping techniques give similar values. The general pattern of atmospheric deposition of Hg with decreasing values from the southwest part of the country towards the north, strongly suggests that the deposition over Sweden is dominated by sources in other European countries. This conclusion is supported by analyses of air parcel back trajectories and findings of significant covariations between Hg and other long range transported pollutants in the precipitation. Apart from the long range transport of anthropogenic Hg, the deposition over Sweden may also be affected by an oxidation of elemental Hg in the atmosphere. Atmospheric Hg deposited on podzolic soils, the most common type of forest soil in Sweden, is effectively bound in the humus-rich upper parts of the forest soil. In the Tiveden area in southern Sweden, about 75 to 80% of the yearly deposition is retained in the humus layer, chemically bound to S or Se atoms in the humic structure. The amount of Hg found in the B horizon of the soils is probably only slightly influenced by anthropogenic emissions. In the deeper layers of the soil, hardly any accumulation of Hg takes place. The dominating horizontal flow in the soils takes place in the uppermost soil layers (0 to 20 cm) during periods of high precipitation and high groun water level in the soils. The yearly transport of Hg within the soils has been calculated to be about 5 to 6 g km^?2. The specific transport of total Hg from the soil system to running waters and lakes in Sweden is about 1 to 6 g km^?2 yr¹. The transport of Hg is closely related to the transport of humic matter in the water. The main factors influencing the Hg content and the transport of Hg in run-off waters from soils are therefore the Hg content in soils, the transport of humic matter from the soils and the humus content of the water. Other factors, for example acidification of soils and waters, are of secondary importance. Large peatlands and major lake basins in the catchment area reduce the out-transport of Hg from such areas. About 25 to 75% of the total load of Hg of lakes in southern and central Sweden originates from run-off from the catchment area. In lakes where the total load is high, the transport from run-off is the dominating pathway. The total Hg concentrations in soil solution are usually in the range 1 to 50, in ground water 0.5 to 15 and in run-off and lake water 2 to 12 ng L^?1, respectively. The variation is largely due to differences in the humus content of the waters. In deep ground water with a low content of humic substances, the Hg concentration is usually below 1 ng L^?1. The present amount and concentrations of Hg in the mor layer of forest soils are affected by the total anthropogenic emissions of Hg to the atmosphere, mainly during this century. Especially in the southern part of Sweden and in the central part along the Bothnian coast, the concentrations in the mor layer are markedly high. In southern areas the anthropogenic part of the total Hg content is about 70 to 90%. Here, the increased content in these soils is mainly caused by long-range transport and emissions from other European countries, while high level areas in the central parts are markedly affected by local historical emissions, mainly from the chlor-alkali industry. When comparing the input/output fluxes to watersheds it is evident that the present atmospheric deposition is much higher than the output via run-off waters, on average about 3 to 10 times higher, with the highest ration in the southern parts of Sweden. Obviously, Hg is accumulating in forest soils in Sweden at the present atmospheric deposition rate and, accordingly, the concentrations in forest soils are still increasing despite the fact that the emissions of Hg have drastically been reduced in Sweden during the last decades. The increased content of Hg in forest soils may have an effect on the organisms and the biological processes in the soils. Hg is by far the most toxic metal to microorganisms. In some regions in Sweden, the content of Hg in soils is already today at a level that has been proposed as a critical concentration. To obtain a general decrease in the Hg content in fish and in forest soils, the atmospheric deposition of Hg has to be reduced. The critical atmospheric load of Hg can be defined as the load where the input to the forest soils is less than the output and, consequently, where the Hg content in the top soil layers and the transport of Hg to the surface waters start to decrease. A reduction by about 80% of the present atmospheric wet deposition has to be obtained to reach the critical load for Scandinavia.     

Lysimeter study of effects of acid deposition on properties and leaching of gleyed dystric brunisolic soil in Norway

The effects of artificial rain of various acidities were studied in a lysimeter experiment. Lysimeters, 29 cm in diameter, and 40 cm deep contained a Gleyed Dystric Brunisol. Natural structure, stratification and original vegetation were maintained. Artificial rain was produced from groundwater with “high” concentrations of neutral salts and from rainwater with lower concentrations. pH levels of 6, 4, 3 and 2 were established by adding H₂SO₄. Effects of dilution with given amounts of acid were examined by comparing the effects of 50 mm “rain” month^?1 of pH 3 and pH 2 with 500 mm “rain” month^?1 of pH 4 and pH 3, respectively. The study continued for 5 yr. Totals of 1250 or 12500 mm “rain” were applied in addition to a natural input of 2773 mm. Increased input of SO₄ ^2? increased the output of SO₄ ^2? but, as concentration increased, sorption of SO₄ ^2? in the soil also increased. Concentrations of base cations in the leachate increased parallel to the output of SO₄ ^2?. However, significant effects on leaching of base cations and on the content of exchangeable cations in the soil, was only found in the pH 2 treatment with 1250 mm of “rain” and in the pH 4 and pH 3 treatment with 12500 mm of “rain”.     

Equal performance of TaqMan, MGB, molecular beacon, and SYBR green-based detection assays in detection and quantification of roundup ready soybean

We have tested and compared the performance of 12 different assays representing four different real-time polymerase chain reaction (PCR) chemistries in the context of genetically modified organism detection. Several different molecular beacon, SYBR Green, TaqMan, and MGB assays were designed for the event specific detection and quantification of the 3' integration junction of GTS 40-3-2 (Roundup Ready) soybean. Sensitivity as well as robustness in the presence of background DNA were tested. None of the PCR-based approaches appeared to be significantly better than any of the other, but the molecular beacon assays had the lowest efficiency and also seemed more sensitive to changes in experimental setup.     

Evidence of Lower Productivity in Long Term Limed Lakes as Compared to Unlimed Lakes of Similar pH

Ecosystem development in lime-treated waters in Sweden has been followed since 1989 in a programme for integrated studies of the effects of liming acidified waters (ISELAW). Observations after prolonged liming (>10 y) indicate a phosphorus depletion in the limed lakes which contrasts to the increased phosphorus supply often following within the initial years after lime treatment. After prolonged liming, the levels of total phosphorus are lower as compared to neutral reference lakes at identical TOC, and the phosphorus/TOC -ratio is consequently lower in limed lakes. Depletion of dissolved inorganic nitrogen during the summer is also lower in limed as compared to neutral reference lakes. Phytoplankton biomass and species number also lower in the limed lakes as compared to unlimed neutral references. Furthermore the bacterial number per unit TOC is lower in the long term limed lakes, possibly as a result of phosphorus limitation. As to the higher trophic levels, the benthic soft-bottom fauna of limed lakes (specifically the sublittoral fauna) is poorer in terms of species diversity and abundance. Also fish community composition indicates lower productivity in the limed lakes. Taken together there is thus evidence that the long term limed lakes have a lower trophic level than reference lakes.     

The Distribution of Soluble Copper- and Zinc-Binding Proteins in Liver and Kidney of Chronic Copper-Poisoned Goats

The distribution of copper and zinc among the soluble proteins in the liver and kidney from chronic copper-poisoned goats was examined after gel filtration of the proteins. The concentrations of copper in the liver and kidney cortex from five experimentally copper-poisoned goats were: 550–810 µg/g liver and 190–420 µg/g kidney cortex (wet weight). In general the copper-binding proteins from, both the liver and kidney samples were separated into two different fractions with approximate molecular weights (m.w.) of > 65,000 and 10,000, respectively. From the liver samples, varying amounts of copper were eluted in a fourth fraction with m.w. < 2,000. In the majority of kidney samples the dominating copper-binding protein fraction was the high molecular weight fraction. Absolute amounts of copper recovered in the metallothionein-like protein fraction were nearly the samt for all samples investigated. The distribution of zinc-binding proteins in both liver and kidney samples was nearly the same. The high molecular weight fraction dominated, and no zinc was bound to metallothionein-like proteins.     

The index herd with PMWS in Sweden: Presence of serum amyloid A,circovirus 2 viral load and antibody levels in healthy and PMWS-affected pigs

Background

Postweaning Multisystemic Wasting Syndrome (PMWS) is an emerging disease in pigs of multifactorial origin, but associated to porcine circovirus type 2 (PCV2) infection. PMWS was first diagnosed in Sweden at a progeny test station that received pigs aged five weeks from 19 different nucleus herds on the day after weaning. The objective of this study was to examine, for the first time in an index outbreak of PMWS, the relationship between PCV2 virus, antibodies to PCV2 and serum amyloid a (SAA) in sequentially collected serum samples from pigs with and without signs of PMWS.

Methods

Forty pigs of the last batch that entered the station at a mean age of 37.5 days were monitored for signs of PMWS during the first 55 days after arrival. Serum was collected on six occasions and analysed for presence of PCV2 DNA and antibodies to PCV2, as well as for levels of SAA.

Results

Four of the pigs (10%) were concluded to have developed PMWS, with necropsy confirmation in three of them. These pigs displayed low levels of maternal antibodies to PCV2, more than 10⁷ PCV2 viral DNA copies per ml serum and failed to mount a serological response to the virus. Starting between day 23 and 34 after arrival, an increase in PCV2 viral load was seen in all pigs, but PCV2 did not induce any SAA-response. Pigs that remained healthy seroconverted to PCV2 as the viral load was increased, regardless of initially having low or high levels of PCV2-antibodies.

Conclusion

In this index case of PMWS in Sweden, pigs affected by PMWS were not able to mount a relevant serum antibody response which contributed to the disease progression. The maximal PCV2 virus load was significantly higher and was also detected at an earlier stage in PMWS-affected pigs than in healthy pigs. However, a viral load above 10⁷ PCV2 DNA copies per ml serum was also recorded in 18 out of 34 pigs without any clinical signs of PMWS, suggesting that these pigs were able to initiate a protective immune response to PCV2.     

Segment-based coancestry,additive relationship and genetic variance within and between the Norwegian and the Swedish Fjord horse populations

ABSTRACT

The Fjord horse originates from Norway but forms a global population due to several small populations in foreign countries. There exists no information about the additive relationship and the genetic variance between these subpopulations. By collecting blood samples from Norwegian and Swedish Fjord horses, a sample of 311 Norwegian and 102 Swedish horses gave 485,918 SNPs available for analysis. Their inbreeding coefficients were calculated and compared to the pairwise coancestry and the shared genomic segments. The effective population size was almost similar with the two methods in the Norwegian Fjord horse population (63 and 71), but very different in the Swedish population (269 and 1136) and unprecise due to a much smaller number of observations. The study showed that coancestry from shared genomic segments can be used to estimate additive genetic relationship and genetic variation within and between the global populations of the Fjord horse.