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.     

Plant species richness and composition in managed grasslands: The relative importance of field management and environmental factors

Decline of grassland diversity throughout Europe within the last decades is threatening biological diversity and is a major conservation problem. There is an urgent need to determine the underlying factors that control vascular plant species richness and composition in managed grasslands. In this study, 117 grasslands were sampled using standardised methods. Explanatory variables were recorded for each grassland site, reflecting the local field management, site-specific environmental conditions and large-scale spatial trends. Using variation partitioning methods, we determined the pure and shared effects of these three sets of explanatory variables on the plant species richness and composition in grasslands. Most of the explained variation in plant species richness was related to the joint effect of local field management and environmental variables. However, the applied variation partitioning approach revealed that the pure effect of spatial variables contributed relatively little to explaining variation in both the plant species richness and species composition. The largest fractions of explained variation in plant species composition were accounted for by the pure effects of environmental and local field management variables. Moreover, the results revealed that the main mechanisms by which these sets of explanatory variables affect plant species vary according to the type of management regime under study. From our findings we could conclude that particularly a reduction of nitrogen fertilisation on meadows and grazing at a low stocking rate on pastures can help to conserve biodiversity.     

The Impact of Atmospheric Deposition of Non-Acidifying Substances on the Quality of European Forest Soils and the North Sea

In the pilot study ESQUAD the impact of atmospheric deposition of three heavy metals (cadmium, copper and lead) and two persistent organic pollutants (benzo(a)-pyrene and lindane) on the quality of European soils and seawater has been calculated. Calculations have been made of atmospheric transport and deposition using a detailed emissions database for Europe. This enabled deposition maps to be produced to a resolution of approximately 50 km. The distribution of pollutant concentrations in forest soils was calculated for each grid cell using a database of soil property parameters in Europe. For the North Sea, a model was used to map long-term concentrations in water and sediment, which are due to atmospheric deposition and other, non-atmospheric sources. The model calculations allowed detailed comparisons of deposition fluxes and concentrations of the substances studied with critical loads and environmental quality threshold values, including critical loads. Although significant uncertainties were identified, the study gives insight in how threshold exceedance rates in Europe relate to pollutant type, threshold type, environmental compartment and chemophysical phase (adsorbed, dissolved). For all pollutants and for all compartments exceedances were calculated for at least some of the quality thresholds that were chosen.     

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.     

西安市污染气象特征和大气环境容量分析

利用2010年西安市环境监测资料及同期气象资料,分析了3种主要污染物(SO2,NO2,PM10)的时空分布特征以及各种气象条件对城市大气污染的影响;采用A—P值法计算大气环境容量。结果表明:(1)西安市区低空大气全年以较稳定—稳定为主,污染物浓度随稳定度频率的增大而增大;(2)风速对污染物浓度的影响非常显著。随风速增大各污染物浓度相应减小;而在春季大风沙尘天气里,PM10浓度随风速增大而增大;(3)降水对污染物的稀释作用很强,降水量小于1mm时浓度不降反增,大于10mm时稀释作用却相对减弱;(4)受气象条件的综合影响,污染物排放造成环境容量的利用率高甚至出现超负荷现象。     

Investigation of lichens using molecular techniques and associated mineral accumulations on a basaltic flow in a Mediterranean environment

The role of lichens in the breakdown of rocks in various environments is well documented. We investigated the formation of secondary minerals under 13 different fungal species growing on a basaltic flow in Sanliurfa (Turkey) to understand the influence of lichen species on the transformation of minerals in a Mediterranean environment. We used molecular technique (rDNA sequence) to identify 13 different species of lichens (7 crustose, 5 foliose and 1 pathogenic). X-ray diffraction and scanning electron microscopy were used to determine the composition of mineral accumulations. The formation of quartz and 2:1 phyllosilicates in various layers (top, brown and white) of the weathered basaltic flows under all the lichen colonies may be the result of precipitated silica alone (quartz) or in combination with aluminum (2:1 clays) released as a by-product during the breakdown/weathering of primary silicate minerals present in the basalt. However, aeolian deposition may also be a possible source of these mineral species. Whewellite, a calcium oxalate mineral, accumulates in the weathered basalt underneath all the species of lichens. We believe that the formation of whewellite was due to organic acids excreted by fungal hyphae to dissolve primary minerals (e.g., olivine and feldspars); this lichen-mediated process released enough calcium and generated oxalate necessary for the formation of whewellite.     

辽河流域水稻主产区土壤重金属元素地球化学特征及空间变异研究——以盘锦市为例

以辽河流域水稻主产区—盘锦市为研究区,采用传统统计学和地统计学方法,在GIS技术支持下对研究区耕地表层土壤重金属元素(As、Cr、Cd、Pb、Hg)地球化学特征及空间变异进行了初步研究。研究结果表明:盘锦市耕地土壤重金属元素整体水平较低,土壤环境质量良好,对农田环境质量基本不构成影响,98%以上土壤为一至二级,只有Cd单元素出现少量三级和超三级土壤。     

稀土元素Ce对爪哇伪枝藻盐胁迫耐受性的影响

荒漠藻类广泛分布于干旱区环境,盐胁迫是影响荒漠藻类生存的重要环境因子,稀土农用及其引起的生态环境问题亦受到广泛关注,为此以一种从荒漠结皮中分离的典型蓝藻——爪哇伪枝藻为材料,在实验室条件下研究盐胁迫和外源稀土元素铈对伪枝藻生理生化特性和细胞结构的影响。试验处理时,先进行铈效应浓度的筛选,然后设置NaCl浓度分别为0（对照）、0.05、0.3 mol.L^-1进行盐胁迫和Ce、Ce＋0.05 mol.L^-1 NaCl、Ce＋0.3 mol.L^-1 NaCl处理,分别测定各种处理下的藻生物量（以叶绿素a表示）、光合活性（Fv/Fm）、藻蓝蛋白含量、胞外多糖含量、膜脂过氧化产物丙二醛含量和伪枝藻素含量以及超微结构的变化。研究结果表明,与对照处理相比,盐胁迫导致伪枝藻生物量和光合活性的显著降低,胞外多糖出现大量积累,藻蓝蛋白和伪枝藻素含量呈现明显下降,同时导致伪枝藻膜脂丙二醛含量的大量增加和藻细胞超微结构的破坏。添加外源铈的盐胁迫处理发现,铈能够促进伪枝藻细胞的生长活性,并对藻细胞的内部结构具有一定的保护作用,而对藻细胞的藻蓝蛋白、伪枝藻素和胞外多糖的影响并不明显。这表明稀土元素铈对于伪枝藻的生长可能具有一定的调节作用,但对于提高伪枝藻的盐胁迫耐受性作用并不显著。研究结果为更好地理解稀土元素对荒漠藻类的生物学效应提供了有意义的参考,可为稀土在荒漠结皮培植中的应用提供指导。     

Does forest continuity matter in conservation? - A study of epiphytic lichens and bryophytes in beech forests of southern Sweden

The effects of forest continuity at local scale for red-listed and indicator species of epiphytic lichens and bryophytes were investigated in 150 Fagus sylvatica stands in southern Sweden. Stands having forest continuity (n = 106) had continuous forest cover more than 350 years, whereas stands lacking continuity (n = 44) had forest cover less than 160 years. Forest continuity was identified by comparing a sequence of historical maps with a modern survey of beech forests. In the field woody beech substrates were searched for the epiphytes of interest. A number of environmental and spatial variables were inventoried and compiled for each stand. In all 64 species (51 lichens, 13 bryophytes) were found in the stands having continuity, and 21 (14 lichens, 7 bryophytes) in the stands lacking continuity. Controlling for the different number of surveyed stands, stands having continuity had significantly more species of lichens, but not of bryophytes. In the stands lacking continuity we did not find lichens associated with the very late succession stage. The quantity of substrates, stand age and forest continuity were the three most important factors explaining species richness as well as composition of studied epiphytes. The effect of continuity was probably due to a combination of a higher substrate quality, mainly old beeches, and a longer time available for colonization. Also, we found strong positive correlations between number of indicator and red-listed epiphyte species. In short-term conservation old stands having continuity, containing suitable substrates and indicator species are target areas.     

Atmospheric models and acidification: Summary and conclusions of the Warsaw II meeting on atmospheric computations to assess acidification in Europe

Three topics are discussed in this report: sensitivity/uncertainty analysis of long range transport models, the interface between atmospheric models of different scales, and linkage between atmospheric and ecological models. In separate analyses of long range transport models, it was found that uncertainty of annual S deposition was mostly affected by uncertainty of wind velocity, mixing height and wet deposition parameterization. Uncertain parameters collectively caused S deposition errors of around 10–25% (coefficient of variation) in the models examined. The effect of interannual meteorological variability on computed annual S deposition was relatively small. Different methods were presented for combining models of regional and interregional scale. It was found to be more important to include interregional information in regional-scale models for annual computations compared to episodic computations. A variety of linkage problems were noted between atmospheric and ecological models. The vertical distribution of pollutants and ‘forest fittering’ of pollutant deposition were found to be important in ecological impact calculations but lacking in the output of most interregional atmospheric models.