Spatial and temporal variability of algal and lichen epiphytes on trees in relation to pollutant deposition in Sweden

Green algae on Norway spruce needles and lichens on Scots pine and birch bark have been monitored for four and ten years, respectively, within the National Swedish Environmental Monitoring Program (PMK). Their spatial and temporal patterns in Sweden were analyzed. Algal colony thickness and colonization rate on needles increased from north to south and from east to west, but also with length of growing season and amount of atmospheric N and S deposition. However, no clear temporal trend was found over the 10 yr monitoring period. In general, patterns for sensitive lichens were opposite to those observed for the algae. Weighted Mean Sensitivity (WMS) of lichens was determined to be the best index of air quality among three indices evaluated. WMS increased from south to north, from west to east, and decreased with increasing deposition of N and S. The observed geographic, pollutional and biological variables were highly correlated with each other. Therefore, the relationships between biological and environmental factors cannot be clarified at the present time.     

Accumulation of aluminum inHypogymnia physodes in the surroundings of a finnish sulphite-cellulose factory

Atomic absorption analyses were performed on an epiphytic lichenHypogymnia physodes growing at different distances from a sulphite-cellulose and paper plant in Mänttä, southern Finland. Lichen samples were taken from the bark of pine, birch and spruce. The mean Al-content of the lichen was 3-fold and 7.5-fold higher than those in other studies in southern and northern Finland. The accumulation of Al mainly orginated from the dust emission of the pulp and paper mill and its power plant which were the biggest single source of dust pollutants in Finland. Road dust and other local sources also increase Al-content of the lichens. Fe-concentrations ofHphysodes correlated with those of Al. Hg- and Cu-levels were also slightly elevated. Zn was at about the same and Cd at an even lower level than afore mentioned background values. With Zn, the contents were higher in lichens growing on birch than on coniferous trees.     

Mercury concentration in tree rings of black spruce (Picea mariana Mill. B.S.P.) in boreal Quebec,Canada

Black spruce from boreal forests located in northeastern Canada (Quebec) were sampled during the summer of 1990, at two stations located at 6° latitude from one another. The objective of the study was to compare the temporal and spatial evolution of mercury in the tree rings of sites with differing degrees of mercury contamination in their soils. Mean mercury tree ring contents ranged from 13 to 37 ng/g, and were more concentrated in the southern than in the northern station. No evident relationship was found between annual growth and corresponding mercury concentrations. The difference in tree ring mercury content associated with geographic orientation of the disks indicates that daily exposure to sunlight as well as temperature may affect mercury uptake, and that the mercury observed in the tree rings must be deposited from the atmosphere onto the tree surface.     

Temporal and Spatial Changes in Spruce Bark Acidity at the Scale of the Czech Republic in the Last Two Decades,and the Current Abundance of Epiphytic Lichen <Emphasis Type="Italic">Hypogymnia physodes</Emphasis>

Two large-scale national monitoring campaigns investigating changes in spruce bark extract acidity and long-term monitoring of bark acidity along elevation transects have been carried out in the Czech Republic. The investigations have revealed significant average changes in the pH values of bark extracts (4 g: 16 ml) from 2.35 to 2.60 between 1989 and 1995, and from 2.60 to 3.25 between 1995 and 2005. In comparison with 1990, the H⁺ concentrations in bark extracts had decreased by 10–15% in 1995 and by 70% in 2005. National emissions of acidic compounds were reduced by about 58% (1995) and 62% (2005), and the mean annual H⁺ deposition was reduced by about 60% (1995) and by about 80% (2005). However, neither inventoried current absolute amounts nor specific regional amounts of emitted acidic pollutants correlated significantly with bark acidity in 1995 and 2005. Bark acidity was not significantly affected by the elevation of the sampling plots or by the average tree defoliation. Along the altitudinal transects, considerably defoliated trees near the top of mountain ridges showed permanently lower bark acidity than trees lower down the mountain slopes. Significant differences in average bark acidity were found between defined mountain, highland and lowland elevation zones. In 2005, the epiphytic lichen Hypogymnia physodes was found at almost all sampling plots, with the exception of the most industrialised areas of two coal basins. The abundance of the lichen correlated significantly and negatively with spruce bark acidity and with total nitrogen and copper concentrations in moss growing at the bark sampling plots in 2005.     

Field Photosynthesis Measurements on Black Spruce (Picea mariana): Does Needle Age Matter?

Black spruce (Picea mariana) trees have needles that persist for a number of years, and it is not clear which age class should be evaluated for photosynthesis to best understand physiological responses. Moreover, the impact of sampling current versus older foliage is rarely acknowledged in published literature, even though it may influence the interpretation of results. We compared the photosynthesis rate of current and 1-year-old foliage of black spruce natural regeneration during three growing seasons. The photosynthesis rate was consistently greater for 1-year-old needles compared to current-year needles at the beginning of each growing season; however, after about 1 month, rates were similar between the two age classes. This same pattern was repeated every season and was independent of light availability induced by different harvesting treatments. We suggest that photosynthesis measurements of black spruce should be performed on 1-year-old needles instead of current-year foliage to ensure more uniform photosynthesis values throughout the season.     

Evaluation of black spruce (Picea mariana) as a bioindicator of aluminum contamination

The aim of this work is to evaluate black spruce (Picea mariana) as an indicator of environmental aluminum contamination. The territory studied extends to a radius of 100 km around the Alcan aluminum refinery in Jonquiere, Quebec, Canada. Samples of wood were taken from the trunks of trees at 26 sites at distances of 5, 10, 20, 30, 40, 50 and 100 km from the refinery. Five trees were sampled at each site. Each sample was cut into 25 pieces corresponding to 50 yr growth. These were analyzed for aluminum by neutron activation. Soil samples taken near the bases of the trees were also analyzed and significant variations in exchangeable aluminum were observed as a function of direction from the refinery and distance. The pH of organic and mineral horizons show no significant difference. Exchangeable aluminum increased with soil acidity. The most contaminated sites showed important correlations (r²=0.73) between exchangeable aluminum in soil and aluminum in bark. We observed greater aluminum concentrations in tree rings corresponding to the last 20 yr, especially at sites directly exposed to environmental contamination along prevailing winds. In conclusion, black spruce appears to be a better spatial than chronological indicator of aluminum contamination.     

The concentrations of K,Rb and Cs in spruce needles (Picea abies Karst.) and in the associated soils

The elemental concentrations of K, Rb and Cs were determined in needles from individual spruce trees as a function of the needle age class. The concentrations are highest in current year's needles and decrease smoothly in older needles, approaching a constant value. Rb and Cs show similar behaviour, whereas that of K differs in so far as its relative decrease with time is less pronounced. Intra- and intersite variation of the needle concentrations are largest for Cs and smallest for K. Individual trees show a highly significant correlation between the log (Cs) and log (Rb) values. Total soil concentrations were determined at 9 sites with different parent material. Intra- and intersite variations of K are comparable for soils and for needles, whereas those for Rb and Cs are much smaller for soils than for needles. All three elements are correlated in soil samples. There is no close connection between soil and needle concentrations at the various sites. However, the results suggest that needle concentrations of Rb and Cs, but not of K, are strongly dependent on the sorption properties of the associated soils.     

Mercury Cycling in Lake Gordon and Lake Pedder,Tasmania (Australia). I: In-lake Processes

The processes affecting the concentrations of total mercury (total Hg) and methylmercury (MeHg) in a freshwater system comprising two connected reservoirs in southwest Tasmania were investigated. Surface concentrations of total mercury (total Hg)were temporally and spatially uniform in both Lake Gordon (2.3±0.4 ng L^-1, n = 27) and Lake Pedder (2.3±0.3 ng L^-1, n = 11). The surface concentrations of MeHg in Lake Gordon (0.35±0.39 ng L^-1, n = 25) were more variable than total Hg and MeHg typically comprised 10–20% of total Hg. The relatively high amount of total mercury present as MeHg in Lake Gordon was attributed to the high proportion of wetlandsin the upper catchment (50% of total area) and in-lake contributions (ca. 40% of total MeHg). Despite the close proximity of the two lakes, MeHg concentrations in Lake Pedder were consistently lower than in Lake Gordon. This phenomenon canbe explained in part by the greater contribution of direct rainfall to Lake Pedder leading to the dilution of MeHg. Water column MeHg concentrations were higher in warmer months in bothlakes, reflecting increased net methylation of inorganic mercury.Unlike previous studies of seasonally anoxic lakes, depth profiles of total mercury and MeHg in Lake Gordon were uniform and were not affected by water column stratification occurringin the summer months, and oxygen depletion with depth. This suggests that redox cycling and accumulation of MeHg in the hypolimnion following seasonally-induced anoxia is not a significant part of the mercury cycle in Lake Gordon. The primary location of MeHg production within the lake's water column is not conspicuous. Mercury speciation measurements made above and below the lake system over a period of 19 months indicates that after 20 yr of impoundment, the reservoirs are not significantly affecting MeHg concentrations in the downstreamriverine environment.     

Spatial Variation and Correlations of Mercury Levels in the Terrestrial and Aquatic Components of a Wetland Dominated Ecosystem: Kejimkujik Park,Nova Scotia,Canada

This study investigates the ranges and spatial variation ofmercury in various media in the wetland ecosystems ofKejimkujik Park, Nova Scotia. Mercury concentrations infive-year-old yellow perch (age based on regression analysesof existing data) ranged from 0.12–0.72 μgg^-1(wet weight basis) in 24 lakes. Mercury concentrations inred maple ranged from 5 to 41 ng g^-1 and levels inwhite pine ranged from 5 to 58 ng g^-1, dry weight.Concentrations of total mercury were found to besignificantly higher in epiphytic lichens (maximum of 660 ngg^-1) and in feather mosses (maximum of 395 ng g^-1)compared to vascular species. The soil Ah horizon exhibitsthe highest concentrations for both mercury and gold, withmaximum values of 466 and 42.8 ng g^-1 respectively;whereas the C-horizon appears to host the most Zn (maximum209.9 μg g^-1). Lake water pH and dissolved organic carbon (DOC) were thevariables most highly correlated with mercury in lake watersand yellow perch. No correlations were observed betweenmercury in terrestrial components and mercury in yellowperch; however, mercury in yellow perch was correlated withP in leaf tissues of both red maple and white pine. Theimportance of understanding linkages between terrestrial andaquatic ecosystems is emphasized through this study.     

Foliar symptoms on norway spruce and relationships to magnesium deficiencies

Crown symptoms, foliar and soil nutrient status, disease and insect presence in Norway spruce (Picea abies [L.] Karst.) were evaluated in twelve plantations across West Virginia, Pennsylvania, New York and New Hampshire during 1987 to 1988. The most obvious crown symptoms observed under plantation conditions were thinning and chlorosis. These symptoms were similar to those observed on this species throughout the past decade in central Europe and specifically in the Black Forest of the Federal Republic of Germany. A crown vigor index (CVI) was calculated for each tree to classify health status. Of the 180 trees sampled, 247 were healthy; 517 were intermediate, and 257 had severe crown symptoms. The symptoms varied from state to state, plantation to plantation, and from tree to tree. The most severe symptoms were noted on trees at Plantation 12, near Davis, WV. Severe symptoms were also noted on trees within Plantations 4 and 5 in the Tug Hill Plateau region, NY, and within Plantation 3 near Donegal, PA. Two entire branches were removed from the top crown and mid-live crown, respectively, of each sampled tree. Based on laboratory observations, the most common needle symptom was a uniform chlorosis. Chlorotic spots on needle surfaces were the second most common symptom. Thirteen major and trace foliar nutrient elements were determined. Average foliar Mg concentrations of symptomatic trees within several plantations ranged from 0.022 to 0.0637; levels less than the accepted deficiency threshold value. There were significant (negative) correlations between the mean foliar Mg concentrations for the trees and their corresponding CVI and mean discoloration indices of needles. Corresponding soil pH, available P, exchangeable cations, 7 saturation of K, Mg, and Ca of soils were determined for each tree. Soil pH, exchangeable Mg and 7 saturation of Mg were significantly lower in the more symptomatic Norway spruce.     

Lead Exclusion and Copper Translocation in Black Spruce Needles

Current-year, 1-year-old, and 2-year-old needles were collected separately on 37 black spruce (Picea mariana Mill. B.S.P.) trees located on a heavy metal contamination gradient around the smelter in Murdochville, Québec (Canada). Needles were analyzed separately by year for the concentrations of Pb and Cu, a nonessential and an essential metal, respectively. Lead concentrations increased significantly with needle age in the highly contaminated area near the smelter. In contrast, Cu concentrations decreased with needle age in the same area. Our results support the hypothesis that the passive sequestration of toxic metals in the senescing foliage is a detoxification process contrasting with the active translocation of essential metals in the nonsenescent part of the foliage.     

The use of moss,lichen and pine bark in the nationwide monitoring of atmospheric heavy metal deposition in Finland

Mosses, lichens and pine bark were compared as indicators of atmospheric heavy metal deposition in Finland. The samples were collected from the nationwide sampling network systematically covering the country as a whole. All three bioindicators showed a fairly similar result concerning heavy metal deposition. The major emission sources and the areas affected were reflected in the metal concentrations in the samples. However, there were differences between the accumulation of metals. The correlation between concentrations in mosses and lichens was generally higher than that between mosses and bark or lichens and bark. Concentrations in lichens were the highest and lichens reflected the regional differences in background areas as well as the local emission sources. The concentrations in the mosses were slightly lower than those in lichens and also the mosses pinpointed the emission sources and the extend of the areas polluted. Bark had the lowest concentrations and bark did not generally reveal regional differences as well as mosses and lichens. In spite of the differences, all three bioindicators proved to be suitable for monitoring atmospheric heavy metal deposition.     

Response of blue spruce (Picea pungens) to manganese pollution from MMT

The use of methylcyclopentadienyl manganese tricarbonyl (MMT) in unleaded gasoline has become a source of manganese (Mn) contamination to which urban ecosystems are exposed. The potential of coniferous trees as spatial and chronological indicators of Mn pollutation was investigated. Manganese concentrations in xylem from blue spruce (Picea pungens) growing near (high-exposure site) and far (low-exposure site) from a road were measured as a function of the year of wood formation. Exchangeable Mn content, which is the soil fraction most readily available for uptake by trees, was also measured in the soils of both sectors. The results of the soil analysis show that exchangeable Mn concentrations are about 10 times higher in soils exposed to contamination (p<0.0005), in=" comparison=" with=" the=" concentrations=" found=" in=" soils=" weakly=" exposed.=" however,=" the=" mn=" concentrations=" in=" the=" trees=" near=" the=" road=" were=" not=" significantly=" different=" from=" those=" in=" the=" reference=" trees=" (p=">0.05). Therefore, it appears that blue spruce is not sensitive to soil Mn contamination arising from the use of MMT in gasoline.     

Temporal variation of mercury in vegetation

Temporal changes in the Hg content of balsam fir needles (Abies balsamea) and white spruce needles (Picea glauca) were monitored at a control site over two growing seasons. Results indicated a significant increase in the Hg content of needles of both species over the course of a growing season and from one year to the next. The Hg content of new foliage more than doubled within each growing season, and was 5–10 ng g^?1 higher in the 1990 growing season than in the previous year. These results indicate that temporal variation is a potential source of error when mapping the spatial variation of Hg concentrations in vegetation. To minimize this source of error, field surveys should be completed as quickly as possible (i.e., within two or three weeks).     

Mineral element composition of declining and healthy stands of red spruce in western Massachusetts

Abstract

Concentrations of N, P, K, Ca, Mg, and Mn were determined in one‐, two‐, and five‐year‐old needles from upper and lower crowns of declining and healthy red spruce (Picea rubens Sarg.) to assess nutritional deficiencies as causes of severe defoliation in upper‐elevation forests in western Massachusetts. Concentrations of N and K did not differ between stands or positions in crowns but decreased with leaf age. In declining stands, mean Ca concentrations were the same in the upper and lower crowns (3.2 mg g^‐1), whereas in healthy stands, Ca was higher in the lower crown (4.8 mg g^‐1) than in the upper crown (3.9 mg g^‐1). Five‐year‐old needles of healthy trees had higher Ca than those of declining trees (6.0 and 3.8 mg g^‐1, respectively). Mean concentrations of P and Mg in declining trees were 0.9 and 0.5 mg g^‐1, respectively, with each element being at threshold levels of sufficiency. Mean concentrations of P and Mg, respectively, were 0.3 mg g^‐1 and 0.2 mg g^‐1 lower in needles of declining trees than in healthy trees. Five‐year‐old needles of declining trees were lower in P and Mg than those from healthy trees. Mean Mn concentrations were lower in needles of declining trees than in healthy trees (0.4 vs 1.3 mg g^‐1). The results suggest that low P, Mg, and possibly Ca concentrations in needles of declining trees may contribute to the decline.     

Crown Condition and Nutrient Status of Red Spruce (Picea Rubens Sarg.) in West Virginia

The appearance, foliar nutrient status, and soil nutrient availability were determined for 9 trees in each of 39 red spruce stands in West Viginia. Visual evaluation of crown conditions for all 351 trees sampled resulted in median values of 5% for discoloration and 10% for defoliation. The most common symptom of discoloration was needle chlorosis, found on the upper surface of collected branches. Defoliation generally occurred beginning with the older year-classes of needles and progressed outward toward the branch tips. The levels of discoloration and defoliation varied to such an extent among stands, plots, and trees within a plot that a single causal agent was not likely responsible for the observed symptoms. Foliar nutrient levels were compared to observed crown condition but were inconclusive in proving a definite relationship between crown condition and any individual nutrient; levels of foliar N and P were negatively correlated to defoliation, but not to discoloration or live crown ratio; yet, foliar K was negatively correlated to both discoloration and defoliation and positively correlated to live crown ration. While individual sample trees exhibited symptoms of reduced health and vigor, the majority of red spruce sampled during the course of this study appeared healthy.     

Mineral supply of healthy and declining trees of a young spruce stand

Two subsamples of healthy and declining trees of the same spruce stand were studied for their biomass and mineral content. Calcium and Mg content of the stand was found to be of the same order of magnitude as the total amount of these elements on the exchangeable capacity of the soil. This result shows that on poor soils fast growth of young stands is a powerful factor influencing soil impoverishment and acidification. The difference between the Ca and Mg content of yellow and green trees is equal to the amount of these elements which is taken up by the green trees during a 2 yr period.This suggests that this difference is the result of a rather long term trend of inadequate nutrient uptake.The evolution of Ca and Mg concentrations in relation to age of needles shows that declining trees support their growth by concentrating their Ca and Mg supply into the growing organs.     

Mineral supply of healthy and declining trees of a young spruce stand

Two subsamples of healthy and declining trees of the same spruce stand were studied for their biomass and mineral content. Calcium and Mg content of the stand was found to be of the same order of magnitude as the total amount of these elements on the exchangeable capacity of the soil. This result shows that on poor soils fast growth of young stands is a powerful factor influencing soil impoverishment and acidification. The difference between the Ca and Mg content of yellow and green trees is equal to the amount of these elements which is taken up by the green trees during a 2 yr period. This suggests that this difference is the result of a rather long term trend of inadequate nutrient uptake. The evolution of Ca and Mg concentrations in relation to age of needles shows that declining trees support their growth by concentrating their Ca and Mg supply into the growing organs.     

Determination of stress bioindicators in three norway spruce stands in northern Germany

At three sites in northern Germany (Witzenhausen, Egge-Mountains and Hamburg-Eißendorf) biochemical stress bioindicators (chlorophyll, starch, proline and acid phosphatase and peroxidase activity) were determined in the needles of healthy and damaged Norway spruce (Picea abies L. Karst.). Peroxidase activity was higher in 1 and 2 yr old needles of damaged Norway spruce at the Witzenhausen and Hamburg-Eißendorf sites. Phosphatase activity was significantly higher in needles of damaged trees in all needle ages at the Egge-mountains site in 1983, and at the Witzenhausen site in current and 1 yr old needles. At the Hamburg-Eißendorf site lower phosphatase activity in needles of damaged trees was determined. At the Witzenhausen site lower levels of chlorophyll were determined in the 1 and 2 yr old needles of damaged trees, whereas at the Hamburg-Eißendorf and Egge-mountains sites lower chlorophyll levels were found in current needles. Thus between healthy and damaged trees at a specific site differences in the stress bioindicators could be found, however no common pattern between the sites could be determined. The study indicates that these biochemical bioindicators may be used to show a general stress, but it is difficult to relate them to a specific stress factor.     

Schwermetall- und Nährelementgehalte von Pflanzen und Bodenproben schwermetallhaltiger Halden im Raum Bleiberg in Kärnten (Österreich). II. Holzpflanzen

Heavy metal- and nutrient contents of plants and soil samples from metalliferous waste dumps in Bleiberg (Carinthia, Austria). II. Woody plants Needles, stem- and root-samples from coniferous trees (Norway spruce and Scots pine), taken from a waste dump habitat and an offmine-site in Bleiberg (Carinthia) were analysed on their macronutrient-and heavy metal-contents. No significant age dependent differences in N-and P-content of the two species were observed. The highest potassium levels occured in the youngest needle age group. The needles of the trees from the mining dump site show increasing Ca- and Fe- concentrations with increasing needle age. The Mn-contents of needles collected in offmine-sites were higher than those from the waste dump. The Mg-levels in the needles from both sites are remarkably low, a symptom of undersupplement. High Pb- and Zn-concentrations were determined in older needles of waste-dump-trees. Because of rather high Pb- and Zn-levels in the roots of the trees from this site a physiological transport barrier is assumed, which partly inhibits the upward lead transport; on the other hand lead is partly deposited in stem-wood of the two species. The heavy metal contents of roots from mining dump site are interpreted as an effect of high metal stress in the fine fraction of soil material.