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PubMed2000

Spatial genetic structure in a Neolitsea sericea population (Lauraceae).

Neolitsea sericea (Bl.) Koidz. (Lauraceae) is a dioecious, insect-pollinated, and broad-leaved evergreen tree with bird-dispersed seeds. We used allozyme loci, F-statistics, and spatial autocorrelation statistics (Moran's I ) to examine the changes in genetic structure among five age classes within a study population (60 m x 100 m area) in southern Korea. No significant differences in expected heterozygosity were found among the age classes. The mean F-values averaged over loci were similar among age classes and showed overall conformance of heterozygosities with Hardy-Weinberg proportions. Differences in allelic frequencies among age classes were small (mean G(ST)=0.012), and statistically significant only for one locus (Pgd-2). The mean Moran's I-values for each of five age classes indicated essentially random spatial distribution. The homogeneity of genetic structure and genetic diversity among the five age classes may reflect the occurrence of similar reproductive events, year after year. The results may reflect the attractive red drupes of N. sericea in that they cause various frugivorous birds to disperse the seed long distances and independently, which in turn may help N. sericea maintain higher levels of genetic diversity within populations.

Animals↗

PubMed2001

Two-dimensional imaging of electronic wavefunctions in carbon nanotubes.

The drive towards the development of molecular electronics is placing increasing demands on the level of control that must be exerted on the electronic structure of materials. Proposed device architectures ultimately rely on tuning the interactions between individual electronic states, which amounts to controlling the detailed spatial structure of the electronic wavefunctions in the constituent molecules. Few experimental tools are available to probe this spatial structure directly, and the shapes of molecular wavefunctions are usually only known from theoretical investigations. Here we present scanning tunnelling spectroscopy measurements of the two-dimensional structure of individual wavefunctions in metallic single-walled carbon nanotubes; these measurements reveal spatial patterns that can be directly understood from the electronic structure of a single graphite sheet, and which represent an elegant illustration of Bloch's theorem at the level of individual wavefunctions. We also observe energy-dependent interference patterns in the wavefunctions and exploit these to directly measure the linear electronic dispersion relation of the metallic single-walled carbon nanotube.

Journal Article↗

PubMed2001

Anatomical analysis of Saccharomyces cerevisiae stalk-like structures reveals spatial organization and cell specialization.

Recently we reported an unusual multicellular organization in yeast that we termed stalk-like structures. These structures are tall (0.5 to 3 cm long) and narrow (1 to 3 mm in diameter). They are formed in response to UV radiation of cultures spread on high agar concentrations. Here we present an anatomical analysis of the stalks. Microscopic inspection of cross sections taken from stalks revealed that stalks are composed of an inner core in which cells are dense and vital and a layer of cells (four to six rows) that surrounds the core. This outer layer is physically separated from the core and contains many dead cells. The outer layer may form a protective shell for the core cells. Through electron microscopy analysis we observed three types of cells within the stalk population: (i) cells containing many unusual vesicles, which might be undergoing some kind of cell death; (ii) cells containing spores (usually one or two spores only); and (iii) familiar rounded cells. We suggest that stalk cells are not only spatially organized but may undergo processes that induce a certain degree of cell specialization. We also show that high agar concentration alone, although not sufficient to induce stalk formation, induces dramatic changes in a colony's morphology. Most striking among the agar effects is the induction of growth into the agar, forming peg-like structures. Colonies grown on 4% agar or higher are reminiscent of stalks in some aspects. The agar concentration effects are mediated in part by the Ras pathway and are related to the invasive-growth phenomenon.

Culture Media↗

PubMed2005

Bayesian spatio-temporal modelling of national milk-recording data of seasonal-calving New Zealand dairy herds.

A spatio-temporal analysis was undertaken with the aim of identifying the dynamics of herd mean individual cow SCCs (MICSCC) in seasonally calving New Zealand dairy herds. Two datasets were extracted from the Livestock Improvement Corporation's extensive national dairy recording database: (1) milk-recording data aggregated at the herd-level and (2) sales questionnaire data containing information on the size, location and infrastructure of each farm. A Bayesian spatio-temporal modelling approach was applied to the analysis. The data were aggregated by 10 km(2) grid cells and linear regression models were developed with spatially structured and unstructured random effects, a linear temporal trend random effect and spatial-temporal interactions for log-transformed median MISCC (ln(median MISCC)). Significant associations were found between ln(median MISCC) and milk yield, milk fat, milk protein, farm area and number of cups in the dairy. This led us to suggest that SCCs should be adjusted for volume and constituents prior to determining a threshold MISCC for identification of subclinical mastitis (SCM) problem herds. Part, or all, of the temporal trend in MISCC in the spatio-temporal model was accounted for by inclusion of yield and milk constituents as independent variables. This supports the hypothesis of a dilution effect with potential consequences for misdiagnosis of SCM, particularly in late lactation. Unmeasured covariates were similarly likely to be spatially structured and unstructured.

Animals↗

PubMed2003

Resistance may be futile: dispersal scales and selection for disease resistance in competing plants.

If a host species shares a pathogen with competing species, the disease may provide a net benefit. Selection for resistance will depend on the trade-off between the damage done by the disease and the positive effects resulting from infection of competitors. This paper presents a simple, spatially explicit model of a plant that shares a disease with a superior competitor. The phenotypic evolution of cost-free resistance is studied by using the method of pair approximation to analyse the small-scale spatial structure of the interacting populations. Selection favors lower resistance when disease transmission is spatially local and the damage to the competitor is sufficient to outweigh the direct effects of infection. This suggests that local spatial structure may be critical in determining the coevolution of host-host-pathogen systems.

Competitive Behavior↗

PubMed1994

Three-dimensional structure of (1-71)bacterioopsin solubilized in methanol/chloroform and SDS micelles determined by 15N-1H heteronuclear NMR spectroscopy.

Spatial structures of a chymotryptic fragment C2 (residues 1-71) of bacterioopsin from Halobacterium halobium, solubilized in a mixture of methanol/chloroform (1:1, by vol.) and 0.1 M 2HCO2NH4, or in perdeuterated sodium (2H)dodecyl sulfate (SDS) micelles in the presence of perdeuterated (2,2,2-2H)trifluoroethanol, were determined by two-dimensional and three-dimensional heteronuclear 15N-1H NMR techniques. The influence of (2,2,2-2H)trifluoroethanol on the conformational dynamics of C2 in micelles and the effect of the salt (organic mixture) were studied. Under the best conditions, 1H and 15N resonances of 15N-uniformly enriched protein were assigned in both milieus by homonuclear two-dimensional NOE (NOESY) and two-dimensional total-correlated (TOCSY) spectra and heteronuclear three-dimensional NOESY-multiple-quantum-correlation (HMQC) and TOCSY-HMQC spectra. 651 (organic mixture) and 520 (micelles) interproton-distance constraints, derived from volumes of cross-peaks in two-dimensional NOESY and three-dimensional NOESY-HMQC spectra, along with deuterium exchange rates of amide groups measured in both milieus and 51 HN-C alpha H coupling constants obtained in the case of the organic mixture, were used in the construction of C2 spatial structures. Obtained structures are similar in both milieus and have two right-handed alpha-helical regions stretching from Pro8 to Met32 and Phe42 to Tyr64 (organic mixture), and from Pro8 to Met32 and Ala39 to Leu62 (micelles). In micelles, the second alpha helix is terminated by C-cap Gly63, adopting a conformation characteristic of a left-handed helix. Residues Gly65 to Thr67 from the turn of a right-handed helix. In the isotropic medium of the organic mixture, the C-terminal region of residues 65-71 lacks an ordered structure. Torsion angles chi 1 were unequivocally determined for 18 alpha-helical residues in both milieus. In the isotropic organic mixture and anisotropic micellar system, C2 remains a compact structure with a characteristic size of 3.0-3.5 nm. C2 seems to be present in at least two conformational states, packed and unpacked. Using NMR data, along with the electron cryomicroscopy model of bacteriorhodopsin [Henderson, R., Baldwin, J. M., Ceska, T. A., Zemlin, F., Beckman, E. & Downing, K. H. (1990) J. Mol. Biol. 213, 899-929], we suggested a model for the conformation of C2 in this putative close-packed state. However, no NOE contact between alpha helices was found in either milieu.

Amino Acid Sequence↗

PubMed1992

[Approach to studying natural oligopeptides in the area of structure relationship to function].

Structure and structure-function relations of naturally occurring oligopeptides and peptide receptors are discussed. An approach to inferring function of low-molecular peptides in the direction from their structure is postulated. Diverse biological activities of oligopeptides supposedly arise from a limited number of preferable spatial structures which may exist under physiological conditions. Each particular function of an oligopeptide is connected with a definite spatial structure, belonging to the set of the low-energy conformations. A method is suggested for constructing a synthetic analogue with a predetermined physiologically active conformation, prior to all chemical and biological tests.

Oligopeptides↗

PubMed2003

Metapopulation dynamics with quasi-local competition.

Stepping-stone models for the ecological dynamics of metapopulations are often used to address general questions about the effects of spatial structure on the nature and complexity of population fluctuations. Such models describe an ensemble of local and spatially isolated habitat patches that are connected through dispersal. Reproduction and hence the dynamics in a given local population depend on the density of that local population, and a fraction of every local population disperses to neighboring patches. In such models, interesting dynamic phenomena, e.g. the persistence of locally unstable predator-prey interactions, are only observed if the local dynamics in an isolated patch exhibit non-equilibrium behavior. Therefore, the scope of these models is limited. Here we extend these models by making the biologically plausible assumption that reproductive success in a given local habitat not only depends on the density of the local population living in that habitat, but also on the densities of neighboring local populations. This would occur if competition for resources occurs between neighboring populations, e.g. due to foraging in neighboring habitats. With this assumption of quasi-local competition the dynamics of the model change completely. The main difference is that even if the dynamics of the local populations have a stable equilibrium in isolation, the spatially uniform equilibrium in which all local populations are at their carrying capacity becomes unstable if the strength of quasi-local competition reaches a critical level, which can be calculated analytically. In this case the metapopulation reaches a new stable state, which is, however, not spatially uniform anymore and instead results in an irregular spatial pattern of local population abundance. For large metapopulations, a huge number of different, spatially non-uniform equilibrium states coexist as attractors of the metapopulation dynamics, so that the final state of the system depends critically on the initial conditions. The existence of a large number of attractors has important consequences when environmental noise is introduced into the model. Then the metapopulation performs a random walk in the space of all attractors. This leads to large and complicated population fluctuations whose power spectrum obeys a red-shifted power law. Our theory reiterates the potential importance of spatial structure for ecological processes and proposes new mechanisms for the emergence of non-uniform spatial patterns of abundance and for the persistence of complicated temporal population fluctuations.

Competitive Behavior↗

PubMed1992

Three-dimensional structure of (1-36)bacterioopsin in methanol-chloroform mixture and SDS micelles determined by 2D 1H-NMR spectroscopy.

Spatial structures of proteolytic segment A (sA) of bacterioopsin of H. halobium (residues 1-36) solubilized in a mixture of methanol-chloroform (1:1), 0.1 M LiClO4 organic mixture, or in perdeuterated sodium dodecyl sulfate (SDS) micelles, were determined by 2D 1H-NMR techniques. 324 and 400 NOESY cross-peak volumes were measured in NOESY spectra of sA in organic mixture and SDS micelles, respectively. The sA spatial structures were determined by local structure analysis, distance geometry calculation with program DIANA and systematic search for energetically allowed side chain rotamers consistent with NOESY cross-peak volumes. The structures of sA are similar in both milieus and have the right-handed alpha-helical region from Pro8 to Met32 with root mean square deviation (RMSD) of 0.25 A between backbone heavy atoms and fit well with Pro8 to Met32 alpha-helical region in electron cryo-microscopy model of bacteriorhodopsin. The N-terminal region Ala2-Gly6 of sA in organic mixture has a fixed structure of two consecutive gamma-turns as 2 * 2(7)-helix (RMSD of 0.25 A) stabilized by the Thr5 NH...O = C Gln3 and Ile4 NH...O = C Ala2 hydrogen bonds while this region in SDS micelles has disordered structure with RMSD of 1.44 A for backbone heavy atoms. The C-terminal region Gly33-Asp36 of sA is disordered in both milieus. Torsion angles chi 1 of sA were unequivocally determined for 13 (SDS) and 11 (organic mixture) of alpha-helical residues and are identical in both milieus.

Amino Acid Sequence↗

PubMed1999

Spatio-temporal dynamics of resident and immigrating populations of Carcinops pumilio (Coleoptera: Histeridae) in high-rise poultry facilities.

The histerid beetle Carcinops pumilio (Erichson) is an important natural predator of the house fly, Musca domestica L., in accumulated poultry house manure. We examined the spatio-temporal dynamics of establishing adult C. pumilio in high-rise poultry facilities using conventional and geostatistical approaches. The growth curves of resident and immigrating populations followed logistic and exponential equations, respectively, and their rates of establishment were statistically the same. Frequency distributions for both populations were strongly positively skewed, and approximately 53% of sampling intervals were significantly modeled by the negative binomial. Taylor's power law indicated both populations to be aggregated, and gave excellent least squares regression fits to both populations. Correlograms, a geostatistical tool, suggested little local spatial structure (e.g., 2nd order effects) for either population. The resident population was 'randomly' aggregated: beetles were clustered around randomly distributed aggregations of house fly immatures. The immigrating population exhibited significant spatial trends (e.g., 1st order effects) consistently seen at all sampling intervals. C. pumilio spatial structure was represented primarily by this spatial trend; thus, immigration of C. pumilio may have been either a singular event in time, or initiating at 1 or multiple times from a singular location.

Animal Husbandry↗

PubMed2003

Spatio-temporal patterns of soil available nutrients following experimental disturbance in a pine forest.

Although disturbance is known to alter soil nutrient heterogeneity, it remains unclear whether spatial patterns in soil nutrients after disturbance follow predictable temporal changes that reflect underlying processes. This study examined the effects of tree harvesting and girdling on overall variability, geostatistical patterns, and resource congruence of soil available nutrients in a mature Pinus elliottii Engelm. forest. The two disturbances led to different patterns of vegetation removal, forest floor redistribution, and revegetation, but showed similar post-disturbance changes in overall soil nutrient variability. Soil nutrient variability increased after both disturbances by more than 5-fold, and then decreased, returning to the undisturbed level in 4 years. Spatial structures assessed using geostatistics did not show predictable temporal trends. However, girdled plots showed more persistent spatial structures in soil nutrients than harvested plots, and had semivariogram ranges mostly equal to or less than 10 m, reflecting effects of persistent and spatially stable patches of undisturbed hardwoods that had an average patch size of 10 m. Resource congruence examined with Spearman rank correlations was nil before disturbance, increased after disturbance and then became nil again by the 4th year post-disturbance. The timing of the increase was related to treatment, occurring in the 1st year after disturbance in the girdled plots, but not until the 2nd year in the harvested plots. These two patterns of congruence were potentially caused by different rates of nutrient patch formation and resource uptake by plants during early succession. Although temporal changes in soil heterogeneity have been documented previously, the present study indicates that temporal trends in nutrient variability after disturbance may be predictable, and that the marked changes in spatio-temporal patterns of soil nutrients as a result of disturbance are ephemeral.

Ecosystem↗

PubMed2000

Structural and spatial organisation of brain parenchymal vessels in the lizard, Podarcis sicula: a light, transmission and scanning electron microscopy study.

The structure and 3-dimensional pattern of the intraparenchymal microvessels in the brain of the lizard, Podarcis sicula, were studied by a combination of light and transmission electron microscopy as well as scanning electron microscopy of vascular corrosion casts. The angioarchitecture pattern consists of narrow hairpin-shaped microvascular loops of different length originating from the meningeal surface. In each loop, descending and ascending vessels are closely apposed to one another throughout their length and are connected by a narrow U-shaped terminal loop at their tips. The 2 limbs of the vessel pairs show a slightly different diameter but lack other structural differences. While some paired vessels give rise to a secondary hairpin-shaped loop with 2 possible branching patterns, there are no anastomotic intraparenchymal connections with analogous neighbouring structures. The cerebral vascular pattern of Podarcis sicula resembles that found in a few representatives of other vertebrate classes. All cerebral vessels structurally appear to be capillaries. Also the observations carried out on semithin and thin sections strongly support the capillary loop model in the Podarcis brain vasculature and, in accordance with studies carried out on various vertebrates, the general submicroscopic features of the brain capillary wall suggest the presence of an endothelial type blood-brain barrier.

Animals↗

PubMed2001

Spatial-temporal structures of human alpha rhythms: theory, microcurrent sources, multiscale measurements, and global binding of local networks.

A theoretical framework supporting experimental measures of dynamic properties of human EEG is proposed with emphasis on distinct alpha rhythms. Robust relationships between measured dynamics and cognitive or behavioral conditions are reviewed, and proposed physiological bases for EEG at cellular levels are considered. Classical EEG data are interpreted in the context of a conceptual framework that distinguishes between locally and globally dominated dynamic processes, as estimated with coherence or other measures of phase synchronization. Macroscopic (scalp) potentials generated by cortical current sources are described at three spatial scales, taking advantage of the columnar structure of neocortex. New EEG data demonstrate that both globally coherent and locally dominated behavior can occur within the alpha band, depending on narrow band frequency, spatial measurement scale, and brain state. Quasi-stable alpha phase structures consistent with global standing waves are observed. At the same time, alpha and theta phase locking between cortical regions during mental calculations is demonstrated, consistent with neural network formation. The brain-binding problem is considered in the context of EEG dynamic behavior that generally exhibits both of these local and global aspects. But specific experimental designs and data analysis methods may severely bias physiological interpretations in either local or global directions.

Alpha Rhythm↗

PubMed1985

Spatial Distribution, Structure, Biomass, and Physiology of Microbial Assemblages across the Southern Ocean Frontal Zones during the Late Austral Winter.

We examined the spatial distributions of picoplankton, nanoplankton, and microplankton biomass and physiological state relative to the hydrography of the Southern Ocean along 90 degrees W longitude and across the Drake Passage in the late austral winter. The eastern South Pacific Ocean showed some large-scale biogeographical differences and size class variability. Microbial ATP biomass was greatest in euphotic surface waters. The horizontal distributions of microbial biomass and physiological state (adenylate energy charge ratio) coincided with internal currents (fronts) of the Antarctic Circumpolar Current. In the Drake Passage, the biological scales in the euphotic and aphotic zones were complex, and ATP, total adenylate, and adenylate energy charge ratio isopleths were compressed due to the extension of the sea ice from Antarctica and constriction of the Circumpolar Current through the narrow passage. The physiological state of microbial assemblages and biomass were much higher in the Drake Passage than in the eastern South Pacific Ocean. The temperature of Antarctic waters, not dissolved organic carbon, was the major variable controlling picoplankton growth. Estimates of picoplankton production based on ATP increments with time suggest that production under reduced predation pressure was 1 to 10 mug of carbon per liter per day. Our results demonstrate the influence of large-scale hydrographic processes on the distribution and structure of microplankton, nanoplankton, and picoplankton across the Southern Ocean.

Journal Article↗

PubMed2001

Genetic structure of spatial and verbal working memory.

Working memory (WM) encompasses both short-term memory (storage) and executive functions that play an essential role in all forms of cognition. In this study, the genetic structure of storage and executive functions engaged in both a spatial and verbal WM span task is investigated using a twin sample. The sample consists of 143 monozygotic (MZ) and 93 dizygotic (DZ) Japanese twin pairs, ages 16 to 29 years. In 155 (87 MZ, 62 DZ) of these pairs, cognitive ability scores from the Kyodai Japanese IQ test are also obtained. The phenotypic relationship between WM and cognitive ability is confirmed (r = 0.26-0.44). Individual differences in WM storage and executive functions are found to be significantly influenced by genes, with heritability estimates all moderately high (43%-49%), and estimates for cognitive ability comparable to previous studies (65%). A large part of the genetic variance in storage and executive functions in both spatial and verbal modalities is due to a common genetic factor that accounts for 11% to 43% of the variance. In the reduced sample, this common genetic factor accounts for 64% and 26% of the variance in spatial and verbal cognitive ability, respectively. Additional genetic variance in WM (7%-30%) is due to modality specific factors (spatial and verbal) and a storage specific factor that may be particularly important for the verbal modality. None of the variance in cognitive ability is accounted for by the modality and storage genetic factors, suggesting these may be specific to WM.

Adult↗

PubMed2006

Neural adjustments to chromatic blur.

The perception of blur in images can be strongly affected by prior adaptation to blurry images or by spatial induction from blurred surrounds. These contextual effects may play a role in calibrating visual responses for the spatial structure of luminance variations in images. We asked whether similar adjustments might also calibrate the visual system for spatial variations in color. Observers adjusted the amplitude spectra of luminance or chromatic images until they appeared correctly focused, and repeated these measurements either before or after adaptation to blurred or sharpened images or in the presence of blurred or sharpened surrounds. Prior adaptation induced large and distinct changes in perceived focus for both luminance and chromatic patterns, suggesting that luminance and chromatic mechanisms are both able to adjust to changes in the level of blur. However, judgments of focus were more variable for color, and unlike luminance there was little effect of surrounding spatial context on perceived blur. In additional measurements we explored the effects of adaptation on threshold contrast sensitivity for luminance and color. Adaptation to filtered noise with a 1/f spectrum characteristic of natural images strongly and selectively elevated thresholds at low spatial frequencies for both luminance and color, thus transforming the chromatic contrast sensitivity function from lowpass to nearly bandpass. These threshold changes were found to reflect interactions between different spatial scales that bias sensitivity against the lowest spatial grain in the image, and may reflect adaptation to different stimulus attributes than the attributes underlying judgments of image focus. Our results suggest that spatial sensitivity for variations in color can be strongly shaped by adaptation to the spatial structure of the stimulus, but point to dissociations in these visual adjustments both between luminance and color and different measures of spatial sensitivity.

Adaptation, Ocular↗

PubMedDate not supplied

[Conformational aspects of biological activity of functional fragments of the p21ras oncoproteins. 3. Fragment 34-46 of the native oncoprotein and the decapeptide corresponding to its 35-44 sequence].

Theoretical conformational analysis was used to study the spatial structure of a putative binding site responsible for binding of p21 oncoproteins to other oncoproteins. Conformational properties of the isolated address sequence localized in fragment 34-46 of native p21 and of the decapeptide molecule corresponding to the 35-44 sequence in the primary structure of oncoproteins of this family were revealed. Our calculations demonstrated a similarity between the spatial structures of the peptides, which confirms the hypothesis on the identity of their biological functions.

Models, Molecular↗

PubMed2005

Time series of metals in mosses and their correlation with selected sampling site-specific and ecoregional characteristics in Germany.

GOAL, SCOPE AND BACKGROUND: The UNECE Heavy Metals in Mosses Surveys provide exposure data (Predicted Environmental Concentrations--PEC) for ecotoxicological risk assessments by measuring the accumulation of several metals in naturally growing mosses throughout Europe. Germany took part in the monitoring campaigns 1990, 1995 and 2000. The article deals with the description and application of the extensive methodical design developed to investigate the following three hypotheses: 1. The metal accumulation in mosses measured at up to 1000 sites may be geostatistically extrapolated from the sampling sites to ecoregions in order to transform the site-specific PEC values to surface PEC values. 2. The metal specific measurement values may be aggregated to metals integrating accumulation indices. 3. The ecoregional situation as well as sampling site-specific topographical features such as altitude, slope gradient or direction influence the accumulation of metals in mosses. METHODS: The methodical design integrates several data sources as well as statistical analysis and GIS techniques: The site-specific data on metal accumulation are geostatistically transformed to valid surface data on metal accumulation. The sampling site-specific measurement data and the estimated surface data on the accumulation of As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Sb, Ti, V and Zn are aggregated to integrative metal accumulation indices by means of percentile statistics. The metal-specific estimated data and the metals integrating accumulation indices are correlated with site-specific data on altitude, slope gradient and direction as well as with the ecoregional conditions derived from a multivariate ecoregionalisation. The mean multi-metal accumulation index for the whole of Germany over the ten year period from 1990 to 2000 was related to the accumulation indices within each of the ecoregions and each of the monitoring campaigns 1990, 1995 and 2000. In addition to this ecoregionalisation of the temporal trends of metal accumulation, the hot spots of accumulation are mapped. RESULTS AND DISCUSSION: The Heavy Metals in Mosses Survey 2000 reveals low metal concentrations in most European countries. In Germany, all metals decreased about 22% (Cu) to 64% (Pb) from 1990 to 2000. Mapping concentrations as dot maps deliver the most unbiased and detailed picture of the spatial structure of the metal accumulation in mosses. This information, detailed with respect to metal species and sampling site, is spatially generalized by means of geostatistical estimation. According to the cross-validation, the precision of the geostatistical estimation is quite good so that the extrapolation does not bias the spatial structure, but helps to clarify it. By percentile statistics, an ordinally scaled multi-metal accumulation index is calculated and spatially differentiated over time in terms of ecoregions which were calculated by means of Classification and Regression Trees (CART). The integrative statistical analysis reveals declinations of up to 80% of the multi-metal accumulation in some of Germany's ecoregions from 1990 to 2000. CONCLUSION: The monitoring of heavy metal bioaccumulation by means of mosses is an effective and cheap method for the analysis of the environmental concentrations of metals accumulated in terrestrial ecosystems. Geostatistics, percentile statistics, cross-tabulations and ecoregionalisation serve well to clarify the spatial and temporal trends in the large data sets coming out of the UNECE Heavy Metals in Mosses Surveys: By combining these statistical methods and integrating them into a geographical information system (GIS), they allow to detect and map the spatial-temporal trends of metal accumulation, to calculate metal-integrating accumulation indices, to describe temporal trends of metal accumulation within ecoregions, and to detect and map hot spots. RECOMMENDATION AND PERSPECTIVE: The spatial and temporal trends of metal accumulation in mosses should be linked with deposition data and data on the vitality of forest ecosystems, as well as with data on human health. Statistical valid interspecies calibration is needed. The integrated methodology of data evaluation presented in the article at hand should be implemented in the future UNECE Heavy Metals in Mosses Surveys. The hot spot areas should be investigated with special care in the 2005 survey to prove if the PEC values of the metals exceed the Predicted no Effect Concentrations (PNEC values). In addition to the metals, the 2005 survey should monitor the nitrogen accumulation in mosses.

Bryophyta↗