The full list of projects contains the entire database hosted on this portal, across the available directories. The projects and activities (across all directories/catalogs) are also available by country of origin, by geographical region, or by directory.
The aim is to monitor the Lake Myvatn and the river Laxá ecosystem for (1) detecting trends, (2) detecting background variability in the system, (3) assess the efficiency of management measures, (4) observe perturbations in order to generate hypotheses about causal relationships.
Persistent organic pollution is a global problem. This fact is especially apparent in the Arctic where pesticides currently used in distant environments accumulate, in some cases to higher levels than those observed in the source region. This pollution threatens the well-being of the aboriginal inhabitants of these regions. Most of the traditionally harvested animals in the Arctic are long-lived and from the higher trophic levels of the food chain, thereby providing an opportunity for considerable bioaccumulation and biomagnification of persistent contaminants. This has prompted a growing concern by the Alaska Inupiat that pollutants in the environment might be contributing to their unique morbidity and mortality rates, especially of their children. Our studies are currently focused on two specific organic pollutants found in the Arctic environment; 1}hexachlorobenzene (HCB), a byproduct during manufacture of several different chlorinated compounds and consistently detected in the Arctic and, 2} dichlorodiphenyl dichloroethylene (p,p’-DDE), a chlorinated environmental breakdown product measured in the Arctic population at significantly higher concentrations than the parent pesticide, DDT. We hypothesize that mammalian embryonic cell exposure to these chemicals, individually or as mixtures at environmentally relevant concentrations and ratios, will alter the cell cycle and/or cause death by apoptosis, rather than by necrosis. We also predict synergistic cytotoxicity of the chemical mixture because of an accumulation of deleterious effects at different cellular target sites by each chemical. We further hypothesize that while some chemicals target non-genetic cellular components (such as a cell membrane or cytosolic component), other chemical effects will occur primarily at the genetic level, directly or indirectly. Our experiments have been designed as a set of sensitive cellular and molecular assays to compare levels and types of cytotoxic and genotoxic activity of the above chemicals (individual and mixture), at environmentally relevant concentrations, upon embryonic cells in culture. Our experimental evidence thus far is that these chemicals, separately or as a mixture at concentrations and molar ratios relevant to that measured in the Arctic environment, do have cytotoxic and/or genotoxic effects that could result in profound consequences to exposed tissues of a developing embryo or fetus. We have further experimental evidence that exposure to both chemicals at environmentally relevant concentrations is more toxic to the cell than the sum of effects by exposure to the individual chemicals. Experimental results indicate this is due to different cellular target sites for each chemical (Appendix A: Preliminary Results).
Biological materials obtained in the central Arctic Ocean at the FSU “North Pole stations” in 1975-1981 have shown that the multi-year ice and ice/water interface is of rich and diverse biotop inhabited by the large number of diatoms and invertebrate animals. Two main matter fluxes in the sea ice ecosystem may be distinguished: (1) the inflow of biogenous elements from water into the ice interior where they are assimilated by the microflora during photosynthesis (summer stage), and (2) the outflow – from ice to water - of the organic matter accumulated in the summer due to photosynthesis (winter stage). Accumulation of organic matter within the sea ice interior during the process of photosynthesis may be considered as an energy depot for organisms of the whole trophic network of the arctic sea ice ecosystem. Recent data from the SHEBA Ice Camp drifted within the Beaufort Gyre 1997-1998 have shown that: (1) sea ice diatoms are very scarce by species and numbers; (2) fresh water green algae are dominated by numbers and distributed within the whole sea ice thickness; (3) invertebrate animals within the sea ice interior are not indicated; (4) invertebrate animals from the ice/water interface are scarce by species and numbers; (5) concentrations of chlorophyll and nutrients in the sea ice are significantly lower of the average concentrations measured before in this region for the same period of time. Remarkable accumulation of the organic mater within the sea ice interior were not indicated.
Ecology of bacterioplankton and bacterioneuston in the polar seas, distribution, number, in situ heterotrophic activity, involvement in natural purification processes from oil pollution.
Oil pollution and oil biodegradation in the inner part of Kandalaksha Bay and adjacent areas.
The objectives of the project are to assess: 1) the present biodiversity of benthos in Arctic coastal ecosystems (White Sea, southern Barents Sea, Pechora Sea), and indicators for changes caused by disturbances; 2) the adaptations to the Arctic climate for some benthic key-species, the additional influence of disturbance and the sensitivity of the key-species to additional stress from disturbances; 3) the geochemical background of the regions Research activities: Annual missions by ship for sampling water, sediments and macrobenthos. Biodiversity analysis of macrobenthos in sediments in laboratories in Murmansk (MMBI) and Tromsø (Akvaplan-Niva), ecophysiological analyses in laboratories of St. Petersburg (ZISP), Yerseke (NIOO-CEMO) and Pisa (UN), analyses of pollutants in laboratories in Moscow (MSU), Nantes(UN) and Pisa (UP), geochemical analyses of water and sediment in laboratories of Moscow (MSU) and Barcelona (UB). Training of 3 PhD students
The overall objective is to assess the influence of increased UV radiation and temperature on photosynthesis, nutrient uptake and primary production of microphytes. In order to do this, the existence and nature of strategies against potential UV damage in marine macrophytes of different climatic regions will be investigated. Research activities Measurement of photosynthesis using oxygen exchange and variable fluorescence (PAM); determination of oxidative stress (Gluthation, SOD, CLSM) and nutrient uptake under different UV-regimes
The aim of this international project is to measure and model arctic UV-radiation and assess the effects on freshwater planktonic organisms and foodwebs. The fieldwork and experiments are conducted at Ny-Alesund, Spitsbergen. The specific aim of our participation is to study the food web effects of UV-B stress by means of in-situ enclosure studies. In the laboratory we found that UV-B stressed algal cells may increase in volume and form a thicker cell wall. These changes in the algal cells may reduce their digestibility by zooplankton. Further the role of photopigments (like melanin and carotenoids), present in some zooplankters, will be studied in relation to the survival of these animals at high UV-B exposure. Research activities Grazing experiments with Daphnia pulex (melanic and hyaline) are performed in in-situ enclosures (under different UV exposures) in the Brandal Lagune during July. The green alga Chlamydomonas will be incubated in-situ under different UV exposures to assess the potential use of this alga as a biodosimeter for UV-B. Further the survival of melanic and hyaline daphnids will be tested in-situ.
Besides some beneficial effects of UV exposure, i.e. skin tanning and vitamin D production, UV ex-posure can have deleterious effects on human health. Deleterious effects are a.o. skin cancer, skin aging, wrinkling, cataract, snow blindness, and effects on the immune system. The objectives of this project are especially aimed at the detection of UV effects on the human immune system and as a consequence of the UV induced immunomodulation effects on the resistance to infections and tumors. Research activities Research activities are focussed at laboratory animal studies, studies with human volunteers, epidemiology and mathematical modelling.
The 'NAR-2000' expedition was performed during August-September 2000. The overall programme of work includes: - monitoring of pollution in air, waters and bottom sediments of freshwater lakes, soils and terrestrial vegetation - soil/botanical studies - visual and remote sensing (aerial photos and video surveys) studies of damage to soil and vegetation cover. Samples of river water and bottom sediments from 25 freshwater bodies and samples from 16 terrestrial sites in the area of the Varandey and Toravey oil fields were taken for chemical analyses.
I. Objectives: I.1. To determine the normal range of values (natural variability due to time of year, age, gender) for basic nutritional and health parameters (blubber characteristics, essential and non-essential elements, structure of basic tissues) in the bowhead whale. a. Blubber thickness (depth and girth), chemical composition (lipids, water, calories), and tissue structure (light microscopy and special stains) will be assessed. b. Essential and non-essential elements (heavy metals) will be measured in liver and kidney. c. Tissue structure (light microscopy) characteristics obviously related to nutritional status in liver (glycogen, lipid and lipofuscin stores), pancreas (zymogen granules), and intestine (mucosal microvilli) and any evidence of inactivity/atrophy will be examined. d. Documentation of "normal" structure of basic tissues and evaluation for evidence of disease will also be conducted. I.2. Using data from Objective 1 to identify the parameters most important in assaying the health status of other mysticetes residing in the Bering Sea or Western Arctic that are harvested or stranded. I.3. Using data from Objective 1 to help determine the role of the bowhead whale as an indicator of ecosystem health and development of an optimized protocol for assessing mysticete health for the Bering Sea and Western Arctic, and other regions.
To monitor levels of pollutants in merlin by analysis of POPs and heavy metals in eggs and feathers. /Feathers and addled eggs of merlin were collected in 1992, 1993, 1994, 1999 and 2000 for chemical analysis of POPs and heavy metals. Comparisons with eggs from museum collections show that there has been a significant shell thinning in eggs of Norwegian merlins. From 1947 up to 1990 the eggs were on average ca. 15% thinner than normal and after 1990 the thinning has been ca. 10%. There are still high concentrations of DDE to reduce reproductive output in some cases. The PCB levels are low compared to the DDE levels and the concentrations of other chlorinated hydrocarbons are also low. Results from mercury analyses indicate possible effects on breeding performance in some adults.
The first part of the present study evaluated tissue concentrations of twelve essential and non-essential elements in four arctic marine mammal species important as subsistence resources to indigenous Alaskans. Species sampled included: bowhead whales, beluga whales, ringed seals, and polar bears. Concentrations of As, Cd, Co, Cu, Pb, Mg, Mn, Hg, Mo, Se, Ag, and Zn, were analyzed in liver, kidney, muscle, blubber, and epidermis (the latter in cetaceans only). Elements that were identified as having tissue concentrations, which in domesticated species would have been considered higher than normal and/or even toxic, were Cd, Hg, Ag, and Se. However, the concentrations of these elements were consistent with previous reports for arctic marine mammals. Remaining elements were at concentrations within normal ranges for domesticated species, although Cu was found frequently at concentrations that would be considered marginal or deficient in terrestrial domesticated animals. Across-species comparisons revealed that Cd was highest in kidney, followed by liver in all four species. Its concentrations were frequently correlated with Cu, Zn, Hg, and Se. Cadmium accumulated with age in bowhead and beluga whales, especially in liver and kidney. The relationships between Cd and Hg, and between Cd and Se were believed to be due to mutual accretion with age, although direct interactions could not be ruled out, especially with respect to Cd and Se. Associations between Cd and Cu, and Cd and Zn were potentially attributable to mutual binding with the inducible protein, metallothionein. This assumption was supported by the observation that Cd:Zn ratios in liver and kidney displayed a significant linear relationship to age and that this ratio either increased slightly (in kidney and liver of bowheads) or remained constant (in kidney and liver of belugas) with age. In general, Se was highest in liver and kidney of all four species, where it was frequently at concentrations that would have been deemed elevated or toxic for domesticated species, although within ranges previously reported for arctic marine mammals. Selenium increased with age indices, and was highly correlated with Hg, and often with Cd as well. Mercury also increased with age, and liver contained the highest tissue concentration in the cetacean and pinniped species. The pattern of Se accumulation in polar bears differed, with highest concentrations found in kidney, which suggested that this tissue may be the primary site for Hg detoxification in this species, as is the case for terrestrial mammals. Compared to the other three species, bowhead whales had very low Hg concentrations in all tissues. The highly significant linear relationship between Hg and Se noted in various tissues (particularly liver) of all four species was presumed due to binding of these two elements to each other following demethylation of MHg. This assumption was supported by the observations that while Se and Hg both accumulated with age, the fraction of total Hg that was composed of MHg decreased with age. The quantity that represented the difference between total Hg measured directly and calculated total Hg [i.e., SHg = Hg(II) + MHg], also increased with age in beluga liver. This connoted that a portion of the total Hg present was in an organic form other than MHg, and that this form accumulated with age. Alternatively, this portion, which was apparently not measured by either the Hg(II) or MHg procedures, may have been lost during extraction. Species in this study had mean hepatic Hg:Se molar ratios that were below unity. This implies that Hg concentrations may have been below some threshold level, after which subsequent accumulation proceeds in a 1:1 molar ratio fashion with Se. Alternatively, it might suggest that a 1:1 Hg:Se molar ratio is not a prerequisite for protection from Hg toxcosis among marine mammals, because none of the animals in the present study exhibited lesions typically associated with Hg toxicosis. In beluga liver, concentrations of Ag were elevated when compared to domesticated species. The only element that showed a significant linear association to Ag was Cu—a relationship that was observed in all four species. This suggested that Ag and Cu may be associated through a common ligand, possibly metallothionein. The association between Ag and Se in beluga liver was less strong than that between Hg and Se; moreover, Ag did not increase with age. These findings indicate that Ag probably does not compete with Hg for Se binding, and therefore is unlikely to substantially inhibit detoxification of Hg in beluga whales. In the second portion of this research, tissues from bowhead whales, beluga whales and ringed seals were examined at both the gross and light microscopic level. The purpose of this evaluation was three-fold: to describe the normal histologic appearance of tissues; to perform a routine histologic survey of tissues that would contribute to a general health assessment, and; to scrutinize tissues for lesions that might support a diagnosis of toxicosis caused by Cd, Hg, Ag, or Se. Tissues examined were chosen on the basis of their propensity to be targets for toxicologic injury from the specified elements (with the exception of brain) and included, but were not limited to, the tissues analyzed chemically. Special stains were used to identify particular pigments or tissue components. Overall, the bowhead whales evaluated appeared healthy and had low parasite burdens. The most common lesion, which was observed in all bowheads, was a non-inflammatory chronic renal periglomerular and interstitial fibrosis. This lesion was not typical of Cd-induced nephropathy, and it did not appear to be associated with renal Cd burdens. Nevertheless, thresholds of Cd-induced renal injury are not known for cetacean species, and more whales need to be examined histologically in conjunction with analysis of tissue Cd residues. Acute myodegeneration was observed in cardiac and/or skeletal muscle of a few bowheads, and was presumed to reflect a hunting-induced exertional myopathy. The beluga whales examined were generally in good body condition and appeared healthy grossly, but they had much higher parasite burdens than bowhead whales. In particular, prevalence in belugas of pulmonary nematodiasis was high, being especially common among whales obtained from Pt. Hope compared to those from Pt. Lay. Grossly, firm, caseous nodules were associated with lungworms, while histologically, the associated pulmonary changes ranged from mild chronic inflammation and focal granuloma formation to catarrhal granulomatous and eosinophilic verminous bronchopneumonia. Another change observed in some belugas and believed to be associated with lungworm infection, was multifocal pulmonary arterial medial hypertrophy and degeneration. Beluga whales harvested at Pt. Lay (summer) frequently showed evidence of hepatic and pancreatic atrophy, while whales taken at Pt. Hope (spring) did not. This was believed to result from anorexia during migration—a supposition corroborated by the lack of stomach contents among Pt. Lay whales. Another prominent histologic finding among belugas was hepatic telangectasia, which occurred with significantly greater frequency and severity in Pt. Hope belugas than in those from Pt. Lay. The etiology and significance of this lesion could be not be ascertained, although it was not believed to be associated with any of the elements analyzed in this study. Mild thickening of Bowman’s capsule was seen frequently in belugas. However, this lesion was not typical of Hg or Cd-induced nephropathies, and did not appear correlated with kidney concentrations of these metals. This lesion was believed to be a normal consequence of aging in belugas, although a metal etiology for it could not be excluded irrefutably. In general, ringed seals were in good body condition and appeared healthy on gross examination. Among seals evaluated histologically, the most common finding was a mild, chronic, focal or periportal hepatitis, with focal hepatocellular necrosis sometimes apparent. Although a metal etiology for this lesion could not be definitively ruled out, in the absence of other lesions that would support a diagnosis of metal toxicosis, an infectious etiology was considered more credible. Two out of sixteen seals had embryologic remnants (an epidermoid cyst and an ultimobranchial cyst)—lesions that are usually considered incidental. While no toxic (metal or otherwise) etiology could be ascertained for these lesions, the incidence of retained embryologic remnants seemed high. A number of xenobiotics are known to be endocrine-disruptors, and the potential for such an etiology among these seals should be examined further. Lipofuscin deposition was ubiquitous among all three species examined histologically. Lipofuscin was most prevalent in hepatocytes, but also commonly was observed in various other tissue and cell types, especially in cardiac and skeletal myocytes, and in uriniferous tubular epithelial cells. The third portion of this study employed autometallographic (AMG) development of light microscopic tissue sections to amplify and localize deposition of inorganic Hg in liver and kidney of beluga and bowhead whales. No staining occurred among bowhead tissues, confirming the extremely low concentration of Hg determined through chemical analyses. In beluga kidney sections, AMG granules were seen throughout the uriniferous tubular epithelium, showing that Hg deposits throughout the nephric tubule, and not solely in the proximal tubular epithelium. In liver tissue, AMG granules were deposited primarily in periportal regions among whales with lower hepatic Hg burdens. In addition to periportal deposition, AMG granules were observed in pericentral and mid-zonal regions in the belugas sampled that had higher liver Hg concentrations (generally older animals). Granules were densely concentrated in stellate macrophages, especially near portal triads. Granules also were distributed in hepatocellular cytoplasm, generally concentrated toward the bile cannalicular domain of the cell. Granules were discrete, potentially indicating that Hg was confined within lysosomes. These observations suggested that inorganic Hg deposits initially in periportal regions of young animals, with subsequent accumulation occurring pericentrally, and finally, midzonally as the whales age. Computer-assisted densitometric analysis was used for semi-quantitative evaluation of AMG staining intensities. These AMG staining intensities were well correlated with concentrations of Hg determined via chemical analysis. Areas with AMG-staining were identified and compared with location of lipofuscin in the same field, visualized with fluorescent microscopy. While AMG granules and lipofuscin deposits sometimes were co-localized, they more often were not. In addition, abundant lipofuscin deposition was seen in livers of younger belugas with little to no Hg-catalyzed AMG staining. Also, lipofuscin concentrated predominantly in pericentral regions. These observations suggested that in the healthy marine mammals of this study, marked hepatic lipofuscin deposition most often occurred independently of Hg accumulation. Consequently, hepatic lipofuscin is likely to be a poor indicator of Hg-induced damage in belugas. The abundant lipofuscin deposition in livers of marine mammals was interpreted as most likely denoting a heightened exposure to oxidative stress that is probably inherent to a marine mammalian existence. These oxidative stressors may include a diet high in polyunsaturated fatty acids (PUFAs), alternating hypoxia and abundant oxygenation, and periodic bouts of anorexia associated with migration.
Establish a benchmark to gauge the efficacy of legislation restricting the use of marine antifoulants containing TBT on the Pacific coast of the US
The present project includes one pilot study of wild adult glaucous gull (Larus hyperboreus) and one experimental study of glaucous gull chicks raised in captivity. The pilot study of adult gulls gave us enough blood and tissue samples to develop the methods needed for immune system analysis in the laboratory experiment. In the experimental study a total of 39 glaucous gull chicks were hatched and raised in captivity in Svalbard, Norway. The chicks were divided into two groups. One experimental group (20 chicks) was given food that mimicked the “natural” food found in the marine environment. The control group (19 chicks) was given “clean” food. After 56 days the chicks were sacrificed in order to collect samples for analyses of organochlorines (OCs) and immunocompetence measurements. The experimental group had 2.8, 3.9, 5.0, and 6.1 time’s higher concentrations of HCB, Oxychlordane, ?DDT, and ?PCB, respectively, compared to the control group at day 56. All chicks used in the experiment were immunised with various vaccines and sera in order to test their ability to respond against foreign antigens. The experimental chicks produced low levels of virus neutralising antibodies when tested against the herpes virus and reovirus. They produced higher levels of neutralising antibodies when tested to tetanus toxoid. There was, however, no difference between the experimental groups with regard to the mean antibody titres. The chicks in both groups also responded to the influenza virus by increasing the production of specific antibodies. However, the mean antibody titre in the exposed group was significantly lower than in the control group. The mitogen-induced response of blood lymphocytes to PHA and LPS was significantly higher in the exposed group compared to the control group. The specific response of blood lymphocytes to Con A, PWM, KLH, TET, and PPD was higher in the exposed group compared to the control group. However, do to high variance in the exposed group there was no significant difference between groups with regard to the lymphocyte response to these mitogens. The results from the present study indicate a toxic effect of OCs on the glaucous gull chicks, which induced a systematic activation of the immune system. Further work on data will be performed.
Population monitoring of Gyrfalcon, Golden Eagle, Willow Grouse and Passerine birds
The aim of the project is to monitor forest health in the border areas between Norway and Russia. The impact on the forest ecosystems in the border areas is varying. In the areas close to the nickel smelter (in Nikel), the damage is serious, while the damage on the Norwegian areas are much less. Here the damage is mostly related to lack of lichen vegetation on birch stems. The moss vegetation in the bottom layer is also influenced. In some cases, when certain weather conditions fell together with high emissions of sulphur dioxide, visible damage has been developed on leaves of shrubs and trees, even on Norwegian territory. Even the emission normally does not cause visible damage on Norwegian territory; chemical influenced is traced over large Norwegian areas
The aim of the project Intensive monitoring of forest ecosystem in an air pollution gradient from Nikel and westwards, running in the period 1994-1998/99, has been to develop and perform environmental monitoring in the border areas between Norway and Russia. The project is a contribution to the joint Norwegian/Russian Environmental Co-operation. Russian scientists have established and performed analyses at four monitoring sites in Russia, while Norwegian scientists have done similar monitoring at adjacent Norwegian areas. The scientists have worked together in two workshops and in the field. The collaboration has been efficient carried out by extensive use of e-mail. An important result for of the project has been harmonised field methodology, which has been put into practice by means of common fieldwork. The impact on the forest ecosystems in the border areas is varying. In the areas close to the nickel smelter (in Nikel), the damage is serious, while the damage on the Norwegian areas are much less. Here the damage is mostly related to lack of lichen vegetation on birch stems. The moss vegetation in the bottom layer is also influenced. In some cases, when certain weather conditions fell together with high emissions of sulphur dioxide, visible damage has been developed on leaves of shrubs and trees, even on Norwegian territory. Even the emission normally does not cause visible damage on Norwegian territory; chemical influenced is traced over large Norwegian areas
In 1990, the Directorate for Nature Management (DN) established an area for integrated monitoring within Børgefjell National Park, Røyrvik, N Trøndelag. Studies of vegetation-environment relationships in the area was performed by NINA. The area includes both subalpine birch forest and low alpine heath. The new established vegetation investigation included all together 80 different species. This material was processed numerically by using multivariate methods. Indirect gradient analyses were performed using Detrended Correspondence Analysis (DCA) and Local Nonmetric Multidimentional Scaling (LNMDS). Direct gradient analyses were performed by using rescaled hybrid Canonical Correspondence Analysis (CCA). Non-parametric correlation analyses, Kendall’s , were performed between environmental parameters and DCA axis values. The results of the numerical and statistical processing were used partly to provide a description of the vegetational structure in the material and partly to quantify how much each ecological parameters contributed to determination of vegetational structure. This work shows the species distribution along various complex gradients; moisture, nutrient conditions, light etc. The investigation is primarily designed to study vegetation dynamics along these gradients and whether changes in the number of species can be related to changes in physical, biotic and, not least, chemical parameters. Variance analysis was performed to assess to what extent the sample plots tends move in a determined direction from 1990 to 1995. The variation between the years were not significant along the primary complex gradients, but there were a significant displacement of species along the following gradients. The most important species were: Vaccinium vitis-idaea, Melampyrum sylvaticum and Hylocomium splendens), which showed an increase and some cryptogams like Brachythecium reflexum, B. salebrosum and Cladonia ecmocyna which declined.
In 1993, the Directorate for Nature Management (DN) established a new area for the monitoring of terrestrial ecosystems in Dividalen National Park in Troms County. This report presents the reanalysis of vegetation and soil from this terrestrial monitoring area. The area in Dividalen is located in the northern boreal birch forest, in a relatively continental section where the dominant type of vegetation is bilberry-mountain crowberry birch forest (A4c). The structure of the vegetation is analysed by multivariate methods (ordination). In Dividalen all together 131 species were found; 75 vascular plants, 18 mosses, 14 liverworts and 24 lichens. This is a decrease from the number of species recorded in 1993 when 141 species were found in the same mesoplots: 74 vascular plants, 24 mosses, 18 liverworts and 25 lichens. The decrease was not significant for the total number of species or for the total number of vascular plants. However the total number of cryptogames showed a slight significant decrease in number between 1993 and 1998. This may be due to increased cover of several ericoid species. In Dividalen we found no significant changes in vegetation composition for the periode 1993 – 1998 along the first four ordination axes. However, there were changes in mesoplots with high DCA1 values. The changes were in the direction towards lower species richness. Species like Myosotis decumbens, Poa alpina, Solidago virgaurea, Cerastium fontanum and Rumex acetosa ssp. lapponicus showed the largest decrease in these mesoplots. Species that showed the largest increase were Vaccinium vitis-idaea, Mnium spinosum and Polytrichum juniperinum. We have found no relations between these changes and acidification due to deposition of pollutans. Lack of disturbance factors in the area in the last years, which favours an increase in ericoid vegetation, is the probable explanation for the changes.