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Pollen Morphological Inter- and Intraspecific Variability in Selected Species of Rubus L. (Rosaceae)
Pollen morphology is one of the important vehicles in resolving some taxonomic problems on the family, genera or species level and has become part of the many disciplines and collaborative approaches in plant systematics and evolution. Palynological studies on the large and taxonomically highly complex genus Rubus L. have been limited, particularly concerning pollen variability. The aim of current study was to investigate the scope of inter- and intraspecific variability of the studied species based on pollen morphology, as well as verify taxonomic usefulness of pollen traits in distinguishing the studied taxa. The sixteen native Poland and Europe Rubus species were studied. Over a dozen quantitative and qualitative features of 2100 pollen (70 samples of 30 pollen each) were analyzed. Exine ornamentation and pollen size proved to be most useful pollen traits in the assessment of variability in the studied Rubus species. Pollen traits did not confirm the currently adopted taxonomical division of the genus Rubus into subgenera, sections and series. The greatest interspecific variability was found for traits P, E, Le and d, while variability was lowest in the case of Exp, Exe, P/E, Le/P, d/E, Exp/P and Exe/E. Intraspecific variability was determined by the following features ordered from those least to most variable: P, E, d, Le, d/E, Exp/P, Exp, P/E and Le/P.
How Do Pollen Grains of Convallaria majalis L. Respond to Different Habitat Conditions?
To date, the effect of habitat conditions on the characteristics of pollen has not been extensively investigated; however, it needs to be remembered that it may be highly significant for the quality of their generative reproduction success. It was decided to conduct the analyses on Convallaria majalis as a common species, naturally found in many different forest habitats. Moreover, the investigations covered pollen morphology and for the first time also the variability of pollen grains in this species. The plant material came from 98 natural sites located in Poland, in nine differing forest habitats. In total, 2940 pollen grains were analyzed in terms of five quantitative features (i.e., the length of the longest and shortest polar axes–LA and SA, exine thickness–Ex, the LA/SA and Ex/LA ratios) as well as the following qualitative ones: pollen outline and shape, sulcus type and exine ornamentation. Our studies revealed that the most important pollen characteristics in C. majalis included sulcus type, exine ornamentation, distribution and size of perforations, LA and pollen shape. The study showed the response of pollen to different habitat conditions found in the nine investigated habitats. The Ex/LA ratio and Ex were these pollen characteristics, which exhibited the most marked response to the different habitat conditions. Pollen from two habitats, moist mixed coniferous forest and upland mesic broadleaved forest, exhibited the most distinct characteristics.
×Sorbaronia ′Mitschurinii′ - an overlooked alien shrub rapidly expands in temperate Scots pine forests
Abstract Biological invasions are one of the most important threats to biodiversity. However, spread mechanisms have been described in detail only for some widespread taxa. Here, we aim to characterize the unique phenomenon of ×Sorbaronia ′Mitschurinii′ (Rosaceae) spread into temperate Scots pine forests. We assessed the surroundings of an abandoned ×Sorbaronia ′Mitschurinii′ plantation, established in 1986 near Ośno Lubuskie (W Poland). Around the plantation we established 66 study plots in 30 m intervals along eight transects, in a systematic design. Using generalized linear mixed-effects models we analysed how the distance from the propagule source (i.e. abandoned plantation), maximum age of ×Sorbaronia shrubs assessed using dendrochronological techniques, and light availability determined the density and biomass of the studied plant. We found that its mean aboveground biomass in the plantation was 7.22 ± 0.66 Mg ha−1, and decreased with distance from the propagule source: 6.83 Mg ha−1 30 m from the abandoned plantation, 1.38 Mg ha−1 at a distance of 90 m, and 0.11 Mg ha−1 at a distance of 180 m, almost disappearing at further distances (but present at the maximum distance of 450 m). The density and aboveground biomass of ×Sorbaronia ′Mitschurinii′ increased with increasing maximal age of the studied plant and its light availability. The ×Sorbaronia ′Mitschurinii′ plantation acted as a strong propagule source, as it reached a density of 100 ind. 100 m−2 after five years, forming a dense shrub layer, capable of reproducing. We conclude that alien species planted at high density and left with no management control might transform into invasion hotspots under favourable circumstances. The study highlights the importance of scientific awareness of similar cases of overlooked invasion sources, as management to limit their spread is still possible.
Invasive × Sorbaronia fallax nothosubsp. mitschurinii affects temperate Scots pine forest biodiversity and functioning
Comparison of Pearson’s and Spearman’s correlation coefficients for selected traits of Pinus sylvestris L.
Abstract The Spearman rank correlation coefficient is a non-parametric (distribution-free) rank statistic proposed by Charles Spearman as a measure of the strength of the relationship between two variables. It is a measure of a monotonic relationship that is used when the distribution of the data makes Pearson’s correlation coefficient undesirable or misleading. The Spearman coefficient is not a measure of the linear relationship between two variables. It assesses how well an arbitrary monotonic function can describe the relationship between two variables, without making any assumptions about the frequency distribution of the variables. Unlike Pearson’s product-moment (linear) correlation coefficient, it does not require the assumption that the relationship between variables is linear, nor does it require that the variables be measured on interval scales; it can be applied to variables measured at the ordinal level. The purpose of this study is to compare the values of Pearson’s product-moment correlation coefficient and Spearman’s rank correlation coefficient and their statistical significance for six morpho-anatomical traits of Pinus sylvestris L. (original – for Pearson’s coefficient, and ranked – for Spearman’s coefficient) estimated from all observations, object means (for trees), and medians. The results show that the linear and rank correlation coefficients are consistent (as to direction and strength). In cases of divergence in the direction of correlation, the correlation coefficients were not statistically significant, which does not imply consistency in decision-making. Estimation of correlation coefficients based on medians is robust to outlier observations and factors that linear correlation is then very similar to rank correlation.
Pollen morphology and variability of native and alien, including invasive, species of the genus Spiraea L. (Rosaceae) in Poland
The pollen morphology was studied in 25 taxa of the genusSpiraeaL. The aims of this study were to describe the pollen morphology and variability and to determine whether the pollen features of alien, expansive or invasiveSpiraeaspecies differ from those of other taxa. The species ofSpiraeawere analysed for nine quantitative pollen traits as well as the following qualitative traits: the outline, shape and exine ornamentation. In total, 750 pollen grains were measured. Based on the pollen key exine ornamentation features, then individualSpiraeaspecies were distinguished, while the other species formed groups of usually 2–3, up to 8 species. The most important pollen features included length, width and course of grooves and striae, presence or absence of perforations, as well as their number and diameter. The most variable taxa for all the nine biometric traits jointly wereS.×billardii,S.veitchii,S.nipponicaandS.cana. The pollen of the invasiveS.tomentosadiffered from the other taxa studied, unlike the other invasive species (S.douglasiiandS.japonica).
Comparison of Pearson’s and Spearman’s correlation coefficients values for selected traits of Pinus sylvestris L.
The Spearman rank correlation coefficient is a non-parametric (distribution-free) rank statistic proposed by Charles Spearman as a measure of the strength of the relationship between two variables. It is a measure of a monotonic relationship that is used when the distribution of the data makes Pearson's correlation coefficient undesirable or misleading. The Spearman coefficient is not a measure of the linear relationship between two variables. It assesses how well an arbitrary monotonic function can describe the relationship between two variables, without making any assumptions about the frequency distribution of the variables. Unlike Pearson's product-moment (linear) correlation coefficient, it does not require the assumption that the relationship between variables is linear, nor does it require that the variables be measured on interval scales; it can be applied to variables measured at the ordinal level. The purpose of this study is to compare the values of Pearson's product-moment correlation coefficient (treating the data in a quantitative way) and Spearman's rank correlation coefficient (treating the same data in a somewhat "qualitative" way) and their statistical significance for six Pinus sylvestris L. traits (original – for Pearson's coefficient and ranked – for Spearman's coefficient) estimated from all observations, object means (for trees) and medians. The results show that the linear and rank correlation coefficients are consistent (as to direction and strength). In cases of divergence in the direction of correlation, the correlation coefficients were not statistically significant, which does not imply consistency in decision-making. Estimation of correlation coefficients based on medians is robust to outlier observations and factors that linear correlation is then very similar to rank correlation.
The effect of soil physicochemical properties on intraspecific variability of pollen morphology in Staphylea pinnata L.
Intra- and interspecific pollen morphology variation of invasive Reynoutria taxa (Polygonaceae) in their response to different habitat conditions
Although understanding the relationship between the reproductive mode and mass-dispersal potential of plants is crucial for studying invasion phenomena, the morphological features of invasive species’ pollen are not well understood. This study examined the pollen morphology and variability of three Reynoutria (knotweed) taxa (R. japonica, R. sachalinensis, R. × bohemica) invasive in Europe, and their reaction to different habitat conditions within seven distinguished habitat types. The pollen was sourced from 95 sites from the taxa’s invasive range in Central Europe. In total, 2850 pollen grains were measured and analysed for 11 quantitative and qualitative features. The pollen of R. sachalinensis was distinguished from that of the other two taxa (reticulate perforate) based on its rugulate and fossulate perforate exine ornamentation. The pollen’s response to various habitat conditions, which was most marked in R. × bohemica, was reflected by pollen size and exine thickness. Our research indicates that pollen availability is not a limiting factor for the sexual reproduction of knotweeds in Central Europe, including Reynoutria japonica, long considered male sterile. The observed presence of male-fertile specimens of R. japonica may enhance the efficiency of generative reproduction in this species throughout its invaded ranges. This finding should be considered when planning actions to control the population of these transformer plant species.
The effect of herbicides on morphological features of pollen grains in Prunus serotina Ehrh. in the context of elimination of this invasive species from European forests
AbstractPrunus serotinaEhrh. is an alien invasive neophyte widespread in European forests. So far, no effective methods of its elimination have been developed. For this reason, the aim of our study was to determine how herbicides affect the morphological characteristics of pollen grains. This knowledge may be crucial to control this invasive species. The current study was carried out in a research area of 2.7 ha located in the Zielonka Forest near Poznań, Poland (N 52°31′58.016″, E 17°05′55.588″). We tested morphological differences among ten features ofP. serotinapollen, based on the samples collected from 15 control trees compared to the 50 trees treated with five different herbicides. In total 1950 pollen grains were measured. We confirmed the adopted hypotheses of long-term herbicide influence onP. serotinapollen. Pollen grains from the control trees had a longer equatorial axis, were more elongated in shape and had the largest range of exine thickness compared to the pollen from the herbicide-treated samples. Exine thickness in the control sample was on average 0.74 µm, ranging from 0.42 to 1.19 µm. The average values and the ranges of this trait in the samples treated with herbicides were larger (e.g. average exine thickness was from 0.90 to 0.95 µm). There were differences in the P/E ranges of variability between the control and herbicide-treated samples. In the control sample the P/E ratio was 1.32–2.04 and elongated forms of pollen shapes prevailed, while in the herbicide-treated samples it ranged from 1.03 to 1.47. The share of deformed pollen grains in the herbicide-treated samples was lower than expected, ranging from 8.7 to 25.3%, while in the control samples it was 6%. Logo and Mustang turned out to be the most effective among the herbicides used in the described research. The two used application methods were found to have an effect on pollen quality.