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PubMed2005

Ground-based and remotely sensed nutrient availability across a tropical landscape.

Tropical soils often are assumed to be highly weathered and thus nutrient-depleted, but this prediction applies primarily to geomorphically stable surfaces. Topography complicates the assumption of nutrient depletion, because erosion can enhance the supply of nutrients to tropical ecosystems. Consequently, understanding nutrient availability across landscapes requires a spatially explicit assessment of the relative strength of depletion and enhancement. We document the relationship between foliar nutrients and topographic position across a 20-km(2), 4- to 5-million-year-old eroded landscape in Kaua'i, Hawai'i, and use this relationship to build a bottom-up map of predicted nutrient availability across this landscape. Only approximately 17% of the landscape is nutrient-poor, mostly on stable uplands; nutrient availability on slopes and valley bottoms is much higher, in some cases similar to the most fertile montane forests in the Hawaiian Islands. This pattern was corroborated by top-down remote sensing of area-integrated canopy phosphorus concentrations.

Ecosystem↗

PubMed2004

Oviposition of the invasive two-spotted leafhopper on an endemic tree: effects of an alien weed, foliar pubescence, and habitat humidity.

The two-spotted leafhopper, Sophonia rufofascia (Kuoh and Kuoh), is an exotic pest from South-East Asia that attacks a wide variety of plant species in Hawaii. Myrica faya Aiton is an aggressive exotic weed that displaces and excludes native plants in Hawaiian forests. It has been argued that because of the high nutritional quality of its foliage, M. faya might facilitate leafhopper invasion of native Hawaiian ecosystems that were originally dominated by the endemic tree Metrosideros polymorpha (Gaudichaud). In the present study, we quantified suitability of M. faya and M. polymorpha as ovipositional hosts for S. rufofascia. Overall, leafhoppers preferred to deposit their eggs into the foliage of M. faya. M. faya presence in the area did not affect leafhopper oviposition on M. polymorpha. Foliar pubescence provided good protection of hirsute morphotypes of M. polymorpha. At the same time, glabrous M. polymorpha morphotypes were quite suitable for leafhopper oviposition. There was no difference in the abundance of leafhopper eggs along a precipitation gradient. Our results confirm that invasion of native Hawaiian forests by the weed M. faya will facilitate their invasion by S. rufofascia. Because of the broad host range characteristic of the two-spotted leafhopper, this build-up may adversely affect a number of endemic plant species growing in native forests.

Animals↗

PubMed2005

Excellence in evidence-based practice: organizational and unit exemplars.

The University of Iowa Hospitals and Clinics is a recognized leader in evidence-based practice. Creating organizational excellence in evidence-based practice takes leadership and a committed effort at all levels. Building the capacity, culture, and vision at the organizational and unit levels is needed to promote use of evidence in practice. Practical approaches that have been effective in promoting development of an evidence-based practice program and project are outlined. An exemplar describing development and adoption of an evidence-based project to improve sedation management led to improvements in patient care processes and outcomes.

Algorithms↗

PubMed2005

Space-efficient whole genome comparisons with Burrows-Wheeler transforms.

The starting point for any alignment of mammalian genomes is the computation of exact matches satisfying various criteria. Time-efficient, O(n), data structures for this computation, such as the suffix tree, require O(n log(n)) space, several times the space of the genomes themselves. Thus, any reasonable whole-genome comparative project finds itself requiring tens of Gigabytes of RAM to maintain time-efficiency. This is beyond most modern workstations. With a new data structure, the compressed suffix array (CSA) implemented via the Burrows-Wheeler transform, we can trade time-efficiency for space-efficiency, taking O(n log(n)) time, but running in O(n) space, typically in total space less than or equal to that of the genomes themselves. If space is more expensive than time, this is an appropriate approach to consider. The most space-efficient implementation of this data structure requires 5 bits per nucleotide character to build on-line, in the worst case, and 2.5 bits per character to store once built. We present a description of this data structure and how it is used to obtain matches. An implementation (called bbbwt) is demonstrated by aligning two mammalian genomes on a modest workstation equipped with under 2 GB of free RAM in time superior to that of the implementations of other data structures.

Animals↗

PubMed2005

Why modelling a complex intervention is an important precursor to trial design: lessons from studying an intervention to reduce falls-related injuries in older people.

OBJECTIVES: To develop a cost-effectiveness model of a complex intervention from pilot study data in order to inform the viability and design of a subsequent falls prevention trial. METHODS: We used two models; the first estimated the probability of falling over a 12-month period based on a probability tree; the second used Markov simulation to assess the impact of the programme over time. RESULTS: The first model indicated that our intervention would reduce the proportion falling by only 2.8% over a 12-month period. The major reason for this small effect was that less than a quarter of older people at risk of falling were assessed using our screening tool. Even if policy-makers were willing to spend 30,000 pounds per quality-adjusted life-year gained, there is only a 40% chance that the intervention would be cost-effective. Sensitivity analyses showed that the only scenarios that produced a substantial increase in the effect of the intervention were those in which all older people are assessed. CONCLUSIONS: The model-building approach described in this paper is vital when designing complex trials and where a trial is not possible. Information from the modelling can be used to re-design the intervention. The effectiveness of our proposed intervention appears very small due to its inability to reach those at risk of falling. It is most likely not to be cost-effective. If inability to reach the target group is a weakness common to other similar interventions, this suggests an area for further research.

Accidental Falls↗

PubMed2004

Live-wires using path-graphs.

OBJECTIVES: This article discusses our new Path-Graph approach for the interactive Live-Wire segmentation method in 2D applied to pre-segmented data. Furthermore, we examine whether or not the Live-Lane extension provides advantages in combination with pre-segmentation. METHODS: We automatically over-segment the image data in a preprocessing step, using region growing with an automatic seed point generation. The Live-Wire algorithm is applied on this mosaic data by using the outlines of the homogeneous regions as the basis for graph building. We present a new definition of this underlying graph where the edges of the standard graphs are turning into vertices and the vertices of the new graph are defined by the edge connectivity in the standard graph. For better differentiation we name our new graph Path-Graph and the original defined graph Node-Graph. RESULTS: The quality evaluation is done by comparing our segmentation results with existing model data. We show that using the Path-Graph as basis for the Live-Wire algorithm instead of the Node-Graph allows for a finer segmentation. We achieve a reduction of incorrectly classified pixels by 20.66 per cent and a decrease of the mean boundary deviation by 11.61 per cent. Since savings on cost tree calculations are compensated by additional computation time required to compute the Live-Lanes, a performance loss of 2.41 per cent is measured. CONCLUSIONS: Our redefinition of the underlying graph increases the quality of the Live-Wire segmentation. The Live-Lane extension in combination with pre-segmentation is not justified for our data.

Algorithms↗

PubMed2000

Molecular evolution of apoptotic pathways: cloning of key domains from sponges (Bcl-2 homology domains and death domains) and their phylogenetic relationships.

Cells from metazoan organisms are eliminated in a variety of physiological and pathophysiological processes by apoptosis. In this report, we describe the cloning and characterization of molecules from the marine sponges Geodia cydonium and Suberites domuncula, whose domains show a high similarity to those that are found in molecules of the vertebrate Bcl-2 superfamily and of the death receptors. The Bcl-2 proteins contain up to four Bcl-2 homology regions (BH). Two Bcl-2-related molecules have been identified from sponges that are provided with two of those regions, BH1 and BH2, and are termed Bcl-2 homology proteins (BHP). The G. cydonium molecule, BHP1_GC, has a putative size of 28,164, while the related sequence from S. domuncula, BHP1_SD, has a M(r) of 24,187. Phylogenetic analyses of the entire two sponge BHPs revealed a high similarity to members of the mammalian Bcl-2 superfamilies and to the Caenorhabditis elegans Ced-9. When the two domains, BH1 and BH2, are analyzed separately, again the highest similarity was found to the members of the Bcl-2 superfamily, but a clearly lower relationship to the C. elegans BH1 and BH2 domains in Ced-9. In unrooted phylogenetic trees the sponge BH1 and BH2 are grouped among the mammalian sequences and are only distantly related to the C. elegans BH domains. The analysis of the gene structure of the G. cydonium BHP showed that the single intron present is located within the BH2 domain at the same position as in C. elegans and rat Bcl-x(L). In addition, a sponge molecule comprising two death domains has been characterized from G. cydonium. The two death domains of the potential proapoptotic molecule GC_DD2, M(r) 24,970, share a high similarity with the Fas-FADD/MORT1 domains. A death domain-containing molecule has not been identified in the C. elegans genome. The phylogenetic analysis revealed that the sponge domain originated from an ankyrin building block from which the mammalian Fas-FADD/MORT1 evolved. It is suggested that the apoptotic pathways that involve members of the Bcl-2 superfamily and of the death receptors are already present in the lowest metazoan phylum, the Porifera.

Amino Acid Sequence↗

PubMed2005

Cyanobacteria from Brazilian building walls are distant relatives of aquatic genera.

The 16S-rDNA from 22 cyanobacteria isolated from biofilms on walls of modern and historic buildings in Brazil was partially sequenced (approximately 350 bp) using specific primers. The cyanobacteria with the closest matching sequences were found using the BLAST tool. The sequences were combined with 52 other cyanobacterial sequences already deposited in public data banks and a dendrogram constructed, after deletion from each sequence of one of the variable 16S rDNA regions (VI). The newly sequenced organisms fitted well within their respective families, but their similarities to other members of the groups were generally low, less than 96%. Close matches were found only with one other terrestrial (hot dry desert) cyanobacterium, Microcoleus sociatus, and with Anabaena variabilis. Phylogenetic analysis suggested that the deletion of the hypervariable regions in the RNA structure is essential for meaningful evolutionary studies. The results support the standard phylogenetic tree based on morphology, but suggest that these terrestrial cyanobacteria are distant relatives of their equivalent aquatic genera and are, indeed, a distinct population.

Algorithms↗

PubMed2005

Bayesian coestimation of phylogeny and sequence alignment.

BACKGROUND: Two central problems in computational biology are the determination of the alignment and phylogeny of a set of biological sequences. The traditional approach to this problem is to first build a multiple alignment of these sequences, followed by a phylogenetic reconstruction step based on this multiple alignment. However, alignment and phylogenetic inference are fundamentally interdependent, and ignoring this fact leads to biased and overconfident estimations. Whether the main interest be in sequence alignment or phylogeny, a major goal of computational biology is the co-estimation of both. RESULTS: We developed a fully Bayesian Markov chain Monte Carlo method for coestimating phylogeny and sequence alignment, under the Thorne-Kishino-Felsenstein model of substitution and single nucleotide insertion-deletion (indel) events. In our earlier work, we introduced a novel and efficient algorithm, termed the "indel peeling algorithm", which includes indels as phylogenetically informative evolutionary events, and resembles Felsenstein's peeling algorithm for substitutions on a phylogenetic tree. For a fixed alignment, our extension analytically integrates out both substitution and indel events within a proper statistical model, without the need for data augmentation at internal tree nodes, allowing for efficient sampling of tree topologies and edge lengths. To additionally sample multiple alignments, we here introduce an efficient partial Metropolized independence sampler for alignments, and combine these two algorithms into a fully Bayesian co-estimation procedure for the alignment and phylogeny problem. Our approach results in estimates for the posterior distribution of evolutionary rate parameters, for the maximum a-posteriori (MAP) phylogenetic tree, and for the posterior decoding alignment. Estimates for the evolutionary tree and multiple alignment are augmented with confidence estimates for each node height and alignment column. Our results indicate that the patterns in reliability broadly correspond to structural features of the proteins, and thus provides biologically meaningful information which is not existent in the usual point-estimate of the alignment. Our methods can handle input data of moderate size (10-20 protein sequences, each 100-200 bp), which we analyzed overnight on a standard 2 GHz personal computer. CONCLUSION: Joint analysis of multiple sequence alignment, evolutionary trees and additional evolutionary parameters can be now done within a single coherent statistical framework.

Algorithms↗

PubMed1989

[Charles Ledger and the Cinchona].

Reading "The life of Charles Ledger", the book written by Gabriele Grammiccia, one notices immediately, what an extraordinary personality Ledger was. He was typically British and belonged to that generation for which, as he wrote himself, "the fact of being a British subject is in itself a reason of pride, including as such a definite obligation to serve the country." This blinding patriotism of even modest British people all over the world, gave the City, as well as the British Empire, a remarkable place in the world trade. The history of Ledger's life, derived from the most authorized sources, is a real adventure novel. At the age of eighteen, he goes to Lima (Peru), in order to find a job. It takes him but a few years to build up his own import-export business. In Tacna, in the very South of Peru, near the Chilean and Bolivian borders (the region where he lived), alpaca wool and quinquina bark are some of the most traded goods. These two products will determine his further life. The principles of his commercial policy were as follows: to buy first quality products, and pack the goods in such a way that they reach the British or European customers in perfect condition, thereby always giving a preferential treatment to the Commonwealth. The quinquina bark trade is hampered by the fact that there is a very great quantity of varieties, each having a different concentration of alkaloids in its bark. To buy the best species, Cinchona calisaya, one needs a perfect knowledge of these trees. The expertise is only to be obtained by visiting the regions where the quinquina tree grows and finding one's way with the help of willing "cascarilleros", the Indians collecting the quinquina bark. During one of his exploration trips, Ledger was fortunate enough to enjoy the service of a Bolivian called Manuel, who faithfully assisted him and his family for years. Together they ranged, at great pains, across every possible region, even the most remote ones; they succeeded in identifying the richest collections of quinquina trees and signing buying contracts on the spot. The most beautiful trees are usually unsuitable for any form of exploitation. In order to understand the special atmosphere that made the solving of the quinquina problems so arduous in the course of time, it seems best to place them in a historical perspective.(ABSTRACT TRUNCATED AT 400 WORDS)

Cinchona↗

PubMed2000

Machine learning for survival analysis: a case study on recurrence of prostate cancer.

Machine learning techniques have recently received considerable attention, especially when used for the construction of prediction models from data. Despite their potential advantages over standard statistical methods, like their ability to model non-linear relationships and construct symbolic and interpretable models, their applications to survival analysis are at best rare, primarily because of the difficulty to appropriately handle censored data. In this paper we propose a schema that enables the use of classification methods--including machine learning classifiers--for survival analysis. To appropriately consider the follow-up time and censoring, we propose a technique that, for the patients for which the event did not occur and have short follow-up times, estimates their probability of event and assigns them a distribution of outcome accordingly. Since most machine learning techniques do not deal with outcome distributions, the schema is implemented using weighted examples. To show the utility of the proposed technique, we investigate a particular problem of building prognostic models for prostate cancer recurrence, where the sole prediction of the probability of event (and not its probability dependency on time) is of interest. A case study on preoperative and postoperative prostate cancer recurrence prediction shows that by incorporating this weighting technique the machine learning tools stand beside modern statistical methods and may, by inducing symbolic recurrence models, provide further insight to relationships within the modeled data.

Artificial Intelligence↗

PubMed1993

Two visual systems in one brain: neuropils serving the principal eyes of the spider Cupiennius salei.

Principal (anterior median) eyes of the wandering spider Cupiennius are served by three successive neuropils, the organization of which is distinct from those serving secondary eyes. Photoreceptors terminate in the first optic neuropil amongst second order neurons with overlapping dendritic fields. Second order neurons terminate at various depths in anterior median eye medulla where they are visited by bush-like dendritic trees of third order projection neurons. These supply tracts which extend into the "central body." This crescent-shaped neuropil lies midsagittally in the rear of the brain near its dorsal surface. It is organized into columns and it supplies both columnar and tangential efferents to other brain centers. The supply to and organization of the "central body" neuropil is reminiscent of retinotopic neuropils supplying the lobula of insects. Channels to the "central body" comprise one of two concurrent visual pathways, the other provided by the secondary eyes supplying the "mushroom body." We suggest that principal eye pathways may be involved in form and texture perception whereas secondary eyes detect motion, as is known for jumping spiders. Our data do not support Hanström's classical view that the "central body" is specifically associated with web-building, nor that it is homologous to its namesake in insect brains.

Afferent Pathways↗

PubMed2006

TaxMan: a taxonomic database manager.

BACKGROUND: Phylogenetic analysis of large, multiple-gene datasets, assembled from public sequence databases, is rapidly becoming a popular way to approach difficult phylogenetic problems. Supermatrices (concatenated multiple sequence alignments of multiple genes) can yield more phylogenetic signal than individual genes. However, manually assembling such datasets for a large taxonomic group is time-consuming and error-prone. Additionally, sequence curation, alignment and assessment of the results of phylogenetic analysis are made particularly difficult by the potential for a given gene in a given species to be unrepresented, or to be represented by multiple or partial sequences. We have developed a software package, TaxMan, that largely automates the processes of sequence acquisition, consensus building, alignment and taxon selection to facilitate this type of phylogenetic study. RESULTS: TaxMan uses freely available tools to allow rapid assembly, storage and analysis of large, aligned DNA and protein sequence datasets for user-defined sets of species and genes. The user provides GenBank format files and a list of gene names and synonyms for the loci to analyse. Sequences are extracted from the GenBank files on the basis of annotation and sequence similarity. Consensus sequences are built automatically. Alignment is carried out (where possible, at the protein level) and aligned sequences are stored in a database. TaxMan can automatically determine the best subset of taxa to examine phylogeny at a given taxonomic level. By using the stored aligned sequences, large concatenated multiple sequence alignments can be generated rapidly for a subset and output in analysis-ready file formats. Trees resulting from phylogenetic analysis can be stored and compared with a reference taxonomy. CONCLUSION: TaxMan allows rapid automated assembly of a multigene datasets of aligned sequences for large taxonomic groups. By extracting sequences on the basis of both annotation and BLAST similarity, it ensures that all available sequence data can be brought to bear on a phylogenetic problem, but remains fast enough to cope with many thousands of records. By automatically assisting in the selection of the best subset of taxa to address a particular phylogenetic problem, TaxMan greatly speeds up the process of generating multiple sequence alignments for phylogenetic analysis. Our results indicate that an automated phylogenetic workbench can be a useful tool when correctly guided by user knowledge.

Database Management Systems↗

PubMed2001

Bridging the "beech-gap": New Zealand invertebrate phylogeography implicates Pleistocene glaciation and Pliocene isolation.

The existence of areas of lower endemism and disjunction of New Zealand biota is typified by Nothofagus beech trees (hence "beech-gap") and have been attributed to a variety of causes ranging from ancient fault-mediated displacement (20-25 million years ago) to Pleistocene glacial extirpation (< 1.8 million years ago). We used cytochrome oxidase I and 12S mtDNA sequence data from a suite of endemic invertebrates to explore phylogeographic depth and patterns in South Island, New Zealand, where the "beech-gap" occurs. Phylogeographic structure and genetic distance data are not consistent with ancient vicariant processes as a source of observed pattern. However, we also find that phylogeographic patterns are not entirely congruent and appear to reflect disparate responses to fragmentation, which we term "gap," "colonization," and "regional." Radiations among congenerics, and in at least one instance within a species, probably took place in the Pliocene (2-7 million years ago), possibly under the influence of the onset of mountain building. This orogenic phase may have had a considerable impact on the development of the biota generally. Some of the taxa that we studied do not appear to have suffered range reduction during Pleistocene glaciation, consistent with their survival throughout that epoch in alpine habitats to which they are adapted. Other taxa have colonized the beech-gap recently (i.e., after glaciation), whereas few among our sample retain evidence of extirpation in the most heavily glaciated zone.

Animals↗

PubMed2005

Long-term potentiation is impaired in middle-aged rats: regional specificity and reversal by adenosine receptor antagonists.

Memory loss in humans begins early in adult life and progresses thereafter. It is not known whether these losses reflect the failure of cellular processes that encode memory or disturbances in events that retrieve it. Here, we report that impairments in hippocampal long-term potentiation (LTP), a form of synaptic plasticity associated with memory, are present by middle age in rats but only in select portions of pyramidal cell dendritic trees. Specifically, LTP induced with theta-burst stimulation in basal dendrites of hippocampal field CA1 decayed rapidly in slices prepared from 7- to 10-month-old rats but not in slices from young adults. There were no evident age-related differences in LTP in the apical dendrites. Both the adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine and a positive AMPA receptor modulator (ampakine) offset age-related LTP deficits. Adenosine produced greater depression of synaptic responses in middle-aged versus young adult slices and in basal versus apical dendrites. These results were not associated with variations in A1 receptor densities and may instead reflect regional and age-related differences in adenosine clearance. Pertinent to this, brief applications of A1 receptor antagonists immediately after theta stimulation fully restored LTP in middle-aged rats. We hypothesize that the build-up of extracellular adenosine during theta activity persists into the postinduction period in the basal dendrites of middle-aged slices and thereby activates the A1 receptor-dependent LTP reversal effect. Regardless of the underlying mechanism, the present results provide a candidate explanation for memory losses during normal aging and indicate that, with regard to plasticity, different segments of pyramidal neurons age at different rates.

Aging↗

PubMed1993

Convergent evolution of similar enzymatic function on different protein folds: the hexokinase, ribokinase, and galactokinase families of sugar kinases.

Kinases that catalyze phosphorylation of sugars, called here sugar kinases, can be divided into at least three distinct nonhomologous families. The first is the hexokinase family, which contains many prokaryotic and eukaryotic sugar kinases with diverse specificities, including a new member, rhamnokinase from Salmonella typhimurium. The three-dimensional structure of hexokinase is known and can be used to build models of functionally important regions of other kinases in this family. The second is the ribokinase family, of unknown three-dimensional structure, and comprises pro- and eukaryotic ribokinases, bacterial fructokinases, the minor 6-phosphofructokinase 2 from Escherichia coli, 6-phosphotagatokinase, 1-phosphofructokinase, and, possibly, inosine-guanosine kinase. The third family, also of unknown three-dimensional structure, contains several bacterial and yeast galactokinases and eukaryotic mevalonate and phosphomevalonate kinases and may have a substrate binding region in common with homoserine kinases. Each of the three families of sugar kinases appears to have a distinct three-dimensional fold, since conserved sequence patterns are strikingly different for the three families. Yet each catalyzes chemically equivalent reactions on similar or identical substrates. The enzymatic function of sugar phosphorylation appears to have evolved independently on the three distinct structural frameworks, by convergent evolution. In addition, evolutionary trees reveal that (1) fructokinase specificity has evolved independently in both the hexokinase and ribokinase families and (2) glucose specificity has evolved independently in different branches of the hexokinase family. These are examples of independent Darwinian adaptation of a structure to the same substrate at different evolutionary times. The flexible combination of active sites and three-dimensional folds observed in nature can be exploited by protein engineers in designing and optimizing enzymatic function.

Amino Acid Sequence↗

PubMed2002

Twenty years of lichen cover change in a tropical habitat (Costa Rica) and its relation with air pollution.

We report lichen cover change over a 20 years period for the Costa Rican capitol city. Foliaceous lichen cover was measured with a 10 x 10 cm template positioned 1.5 m above ground on the south, east, north and west sides of ten phorophytic trees per station (11 stations) from 1976 through 1997. Results were compared with previous measurements along an urban transect (at three heights above ground) and in a rural station. Lichen cover was correlated with traffic density and varied between stations and years. Mean lichen cover was 23% in 1976, 12% in 1986, 9% in 1990 and 22% in 1997. Most stations suffered a large cover reduction after 1976 but improved after 1990, possibly reflecting improved traffic regulations and elimination of lead (Pb) from gasoline. Cover values by cardinal orientation were: west 17%, east 14%, north 13% and south 12%. Sidewalks of streets with more traffic had lower cover values. In the rural station, cover was lower than expected (possibly because of climate), and was not correlated with height above ground or cardinal orientation, in contrast with temperate regions. In polluted cities human activity should concentrate above the first floor of buildings (particularly in hospitals or schools) because pollution was found to concentrate in the first 2 m above ground.

Air Pollutants↗

PubMed2004

Spatial analysis and indicator building for metal accumulation in mosses.

Mosses are used as passive accumulation monitors for metal accumulation in terrestrial ecosystems. Under leadership of the Federal Agency for Environmental Protection Germany took part in the previous European-wide moss monitoring campaigns 1990, 1995 and 2000. The investigations accomplished thereby cannot be presented completely in this article. The remarks rather concentrate on methodical aspects of the statistical data analysis. In Chapter 2 the design of data collection is summarized. Chapter 3 treats the geostatistical analysis and transformation of point data to areal information. Chapter 4 describes the aggregation of the element-specific metal concentrations in mosses to a spatially and temporally differentiated indicator of metal accumulation by means of descriptive and multivariate statistics. The work presented is only a small part of geostatistics and multivariate statistics which fit for analysis of moss monitoring data. Taking the results presented here as a basis, the following steps would further be of great importance: cluster-analytic evaluation of the results of the Moss Monitoring 1990 and 1995, detailing the cluster results using additional empirical and location describing information (e.g. moss species, ecoregions, site and species specific variability of metal accumulation) as well as optimizing the indicator buildung by testing of multivariate statistical regression models (e.g. Classification and Regression Trees).

Bryophyta↗