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The investigations of structure of the genets and populations of Iris sibirica L. were carried out in the period 1999–2002. The studies were conducted in Molinietum caeruleae patches localized in Southern Poland. The patch labelled MW (“more wet”) measured 5,600 m² and was chracterised by presence of large depressions filled with stagnant water, concentrated chiefly in the central part of the site. In this locality species with a high competitive potential (like Phagmites australis Trin., Chamanerion angustifolium (L.) Scop., Epilobium hirsutum L., Filipendula ulmaria (L.) Maxim. and others) prevailed. The patch called LW (“less wet”) measured 1,800 m² and was characterised by small number of depressions scattered throughout the site. In this locality dominated the plants of minor competitive abilities (like Lathyrus pratensis L., Lotus corniculatus L. and others). The spatial pattern of populations was described on the basis of the locations of all ramet clusters in 100 m² square plots. Each ramet cluster was attributed to a developmental stage. The differences in height of ramets between stages was estimated on the basis of lenght of the tallest leaf and generative shoot measured in all genets and ramet clusters in both populations (30 leaves and all generative shoots in 5 clusters of ramet at generative and senile stages and 4 – at fragmentation phase in both populations). In study year 2000 Iris sibirica population in LW locality was consisted of 26 ramet clusters and showed an aggregation structure, while population growing in MW site was consisted of 502 ramet clusters and presented the group-aggregation spatial structure constituted by groups of dozen or so ramet clusters, forming large aggregations. Both populations showed signs of senility in effect of absence of genets in prereproductive stages. In 2001 and 2002 the seedlings and juvenile genets appeared only in artificially made gaps. The genets in initial stage are much lower (about 40 %) than older ones and the ramet in MW locality reached greather height (6 to 23%) than in LW site. The evaluation of structure of populations taken as indicator of their vitality, show that the population from less wet locality was in better condition despite of low abundance. Domination of ramet cluster at generative stage and vicinity of plants with low competitive potential enables longer existence of Iris sibirica in occupied site. In more wet locality the I. sibirica population is worse equiped to survive. Advanced senility and the vicinity of plants with high competitive potential might inhibit the proliferation of I. sibirica ramet clusters, accelerate their fragmentation or even eliminate from occupied site.
Long-lived clonal plants provide an optimal place for the natural storage of seeds as a ‘non-soil seed bank’. We tested the hypothesis that the size and species diversity of a non-soil seed bank deposited within the clonal plant Carex cespitosa depends mainly on the plant's size. To verify this hypothesis, an experiment was conducted on an unmown meadow in the Białowieża National Park. The emerging seedlings of different species originating from C. cespitosa tussocks of different size (large and small) were observed under greenhouse conditions for four years. The size of a non-soil seed bank was evaluated based on the number of seedlings. Significant differences in the seedling number were found between large and small sedge tussocks (Mann-Whitney test Z = 3.96, P < 0.001). However, the number of recorded species was independent of tussock size. Both types of tussocks were dominated by meadow, forest and swamp species (in decreasing order). Some of these species are no longer present in the studied area, or their occurrence is limited to small groups at the meadow's edges. A non-soil seed bank within the tussock cores of C. cespitosamay be, similar to a soil seed bank, a tool for studying the changes occurring in plant communities.
The investigations of the impact of disturbance severity on recruitment of clonal plant species were preformed in three Molinietum caeruleae patches dominated by small meadow species (MC), or prevailed by tall grasses (GR) or overgrown by willows (SA). The meadows were located in Vistula valley close to Kraków agglomeration, southern Poland. In above menntionned patches ten permanent experimental plots were randomly arranged. Each plot was divided in four subplots measured 900 cm² represented undisturbed control, low level of disturbance (the litter and the moss layer removal), intermediate level of disturbance (the litter, moss and above-ground vegetation removal), high level of disturbance (the litter, moss and the plants removal as well as top soil raking). The colonization of gaps was observed in the years 2008–2010. Irrespective of patch character, the greatest species richness and seedling abundance were observed in gaps, which occurred in result of intermediate disturbances. Weaker recruitment rates were recorded in openings left after disturbances of low- and high severity, while in fully compact herb layer no seedlings were found. In MC patch, regardless of treatment in all openings similar spectra of life history traits were observed. In seedling pool of all subplots appeared taxa creating below ground organs of clonal growth. In all subplots dominated species with intermediate values of lateral spread, numerous vegetative descendants, short-lasting stems and no persistent genet integration. In sites GR and SA in openings left after weak disturbances appeared species with below- and aboveground organs of clonal growth. The majority of them characterized by slight lateral spread, low number of vegetative offsprings, long lifespan of shoots and persistent genet integration. The abundance of taxa creating underground clonal growth organs, with considerable vegetative spread, high production of daughter ramets, short lifespan of shoots and not enduring genet integration increased gradually and significantly with disturbance gradient. Although the greatest recruitment rates were found in gaps left after removal of litter, moss and above-ground parts of plants, the most effective way for conservation of Molinietum caeruleae meadows appeared to be creation of different severity disturbances. Such treatment contributes to maintenance of heterogeneity of clonal species composition, especially in patches in advanced successional stages.
In plants, biomass allocation and rhizome morphological plasticity reflect different strategies of adaptation to the environment. The aims of this study were to explore the patterns of allocation to different components of the belowground system, and to evaluate the effects of environmental factors on the plasticity of biomass allocation and rhizome morphology. We conducted a survey of the clonal plant, Scirpus planiculmis, in the Momoge wetland in northeastern China. Samples were collected at three sites. Site I is the washland of a seasonal lake. Site II is a permanent lake. Site III belongs to the bank of a recessive river. The average number of sampled plants was 686.25±91.61 per site. We determined the biomass of different plant parts (aboveground part, root, tuber, rhizome) and measured parameters of rhizome morphology (specific rhizome length, average rhizome diameter). Edaphic factors (soil moisture content, organic matter, available phosphorus, available potassium, pH, electrical conductivity) were included as environmental variables. Differences in biomass allocation patterns were analyzed and multiple regression analyses were used to construct a model. The results showed that the structure of the belowground system varied significantly among the three sites. (1) The tubers accounted for the largest share of biomass in plants at site I; (2) plants at site III showed significantly longer rhizomes than those of plants at site II, while the plants at site II showed larger rhizome diameter; (3) pH was the crucial factor affecting biomass allocation and rhizome morphology, and was negatively correlated with root biomass of S. planiculmis. Based on these results, we concluded that: (1) greater resource allocation to the storage organ (tuber) reflects a conservative strategy to avoid damage and to maintain the potential for recolonization in a frequently disturbed habitat; (2) the morphological plasticity of the rhizome increases the ability of the clone to acquire resources. Shorter rhizomes enable rapid colonization of the habitat and efficient resource use under strong competition pressure, while longer rhizomes are useful to explore new habitats when local resources are insufficient. Our results suggest that ecological niche of S. planiculmis should be reconsidered. It may be more appropriate to classify S. planiculmis as a facultative salt-alkali plant, although a degree of tolerance to salinity and alkalinity is important for the initial formation of a population.
This study examined the anatomical and morphological variability of 10 needle traits in isozymatically identified clones of three peatbog populations of Pinus mugo, focusing on variation within and between clones, and the relation between isozyme variation and morpho-anatomical characters of needles. In each peatbog there were clones exhibiting high and low plasticity of the anatomical and morphological traits studied. In general, three types of variation within clones were distinguished: (1) clones with ramets very similar to each other, (2) clones with extensive intra-clone variability, and (3) clones with intermediate variability. The differences in phenotypic variability within clones may be explained by differences in the reaction norm of ramets in particular clones and by somatic mutations. In respect to anatomical, morphological and isozymatic traits, clones from the same peatbog showed more similarity to each other than to clones from other peatbogs.
Aquatic ecosystems are receivers for various pollutants, for instance, Chromium (Cr, one of the toxic heavy metals) and phosphorus (one of the biggest causes of water eutrophication). Such contaminants have brought serious impact on health and security of aquatic ecosystems. Physiological integration between the integrated ramets of clonal plants can increase their tolerance to environmental stress. It is hypothesized that physiological integration and phosphorus could facilitate the expansion of amphibious clonal plants from soil to Cr-polluted aquatic habitats. This study was conducted to primarily examine how physiological integration and phosphorus affected the effects of Cr on plant growth and population expansion. An amphibious clonal herbaceous plant Alternanthera philoxeroides was used to simulate the spread process by induced stolon connection or disconnection, Cr pollution and different levels of phosphorus in aquatic habitats. We found that Cr pollution deployed to apical ramets directly decreased the growth and photosynthetic parameters of the apical ramets that lacked connections to the basal ramets, but these effects could be mitigated by stolon connections. Cr pollution had no effects on these disconnected basal ramets, but the transmission of Cr from the apical parts via connected stolons negatively affected the growth of the basal ramets. Increasing the phosphorus not only increased the growth but also decreased the levels of Cr that accumulated in the plant tissues and the bioactivity of Cr. These results indicated that increasing the phosphorus could benefit the population expansion and establishment of A. philoxeroides through physiological integration from terrestrial to Cr-polluted aquatic habitats.
The two populations of Paris quadrifolia L. were studied in isolated habitats in a currently fragmented landscape. Both populations were located in deciduous forests, the first (A) – on fresh mineral and acidic soil, and the second (B) – on wet organogenic, less acidic and more fertile soil. We hypothesized that genetic variation should be higher within population of more fecund plants, and that genetic distance between the two populations that occupy different isolated habitats in a fragmented landscape should be high. Demographic characteristics of populations were studied in the 2000–2005 period. In patches of both populations, 22 permanent plots measuring 1m² each were designated. For molecular testing 41 samples from both populations were selected. The share of generative shoots was higher in the population A than population B (0.35 and 0.20, respectively). However, the fecundity of ramets expressed as the number of seeds in the ripe fruit was lower in A than in the B population (15 versus 21 seeds). The germination ability was significantly higher for the seeds from A than from the B population (79% versus 44%). The survival of the juveniles was high in both populations (54 and 76%). The Random Amplified Polymorphic DNA (RAPD) analysis with the application of five primers permitted identifying 91 loci. The estimation of genetic diversity was based on polymorphic loci, the share of which was average 44%. Nei’s gene diversity (h) was higher in the A than B population (0.28 versus 0.22). The genetic diversity between the populations was not large (GST = 0.14). Clonal diversity was very high, G/N ratio = 1, and cluster analysis showed intermingling between samples from both the populations. There were quite a small genetic distance (D = 0.10), and a rather high level of gene flow (Nm = 1.51) between the populations from currently isolated habitats. The obtained results indicate that the genetic diversity was lower within population of more fecund plants from more productive habitat.
Blackberries growing in forests regenerate mainly in a vegetative way; however, detailed studies have shown substantial variability in performance of Rubus individuals. The main problem is if the differences among plants are genetically based, or are due to site heterogeneity? This study was aimed at determining 1) how large are the differences in performance of individual plants and how persistent they are during consecutive years, 2) how much of that variability can be explained by the local environmental conditions, especially the intensity of competition among plants, and whether the performance of individual plants is related to their genetic characteristics. In a partially cut mature beech forest in Western Carpathians 35 randomly chosen individuals of Rubus hirtus (Waldst. & Kitt.) were tagged and measured each year for 9 years. Ten largest and ten smallest individuals were selected for genetic analysis. Mean size of individual plants differed between consecutive growing seasons, but the overall size ranking was quite consistent throughout the entire period of study. Analysis of environmental variables: relative light intensity and local abundance of potential competitors explained about 24% of the differences in individual plant performance. In the genetic analysis the five primers were applied to analyse all 20 samples. The five primers produced 10 polymorphic bands, showing a high variability. Only a few samples displayed identical band patterns, indicating either vegetative propagation or apomictic origin. Distribution of the results of Spearman’s rank correlation of plant size among genetically related individuals did not differ significantly from the distribution of rank correlation coefficients in the entire sample. In the analysed population genetical affinity did not seem to correlate with the performance of Rubus hirtus.
The aim of the study was to compare some life strategy traits of individuals of Purple Loosestrife Lythrum salicaria within three meadow populations existing under various habitat conditions. The study attempted to answer the following questions: Do different habitat conditions affect the biomass allocation between particular organs of individuals? Can the individuals belonging to different populations of the same species realise their own unique reproductive strategy, in other words, can their reproductive effort represent various levels? In the case of L. salicaria the reproductive effort, measured by the participation of inflorescence biomass in the biomass of aboveground parts of genets, exhibits similar values (14.2-15.1%) in all the study populations, despite their habitat conditions. This fact proves that at the population level, the reproductive effort is relatively stable. Great differences are visible in the case of particular individuals within each of the populations. Specific genets in a population, depending on the habitat microstructure and the biotic relations with other individuals both of their own and other species, may realise their own reproductive strategies, being a part of their life strategies.
Leymus chinensis (Trin.) Tzvel., a perennial grass, is a dominant species from arid to semi-arid steppes in northern China and eastern Mongolia. Phragmites communis Trin. is also a perennial grass, and is distributed widely in the world. In the natural grasslands of northeastern China, both species always co-exist as co-dominating species due to their common characteristics such as propagation both by seeds and vegetative reproduction. Replacement series experiments were used to test the effects of nutrient availability and competitive interaction on the growth performance of two clonal plant species. The experimental treatments included five nutrient levels (3.6, 7.2, 10.8, 14.4 and 18.0 kg organic matter per pot, 20 cm diameter and 15 cm deep) and five species proportions (20:0, 16:4, 10:10, 4:16 and 0:20 for L. chinensis and P. communis, respectively) with twenty tillers in total per pot. Each treatment had 10 replications. Growth characteristics including tiller height, tiller number, plant biomass, rhizome length and bud number of plants in monoculture and mixture culture were recorded and compared to examine the effects of nutrient and competitive interaction on the plant performance. The growth of L. chinensis and P. communis in mixture was influenced by the nutrient availability and competition, which depended on the combination between nutrient level and species proportion. The results implied that the intensity of competition should be lower in nutrient-poor habitats when the co-existing species demanded on the same limiting resource. P. communis benefited from coexisting with L. chinensis, especially under nutrient-rich conditions. The aboveground relative yield (RYabove) expressed in units of tiller height, dry biomass and daughter tiller number was recommended as an effective and simple index to predict the relative competitive ability for clonal plants. It was based on the regression for RY above and RYbelow (the belowground relative yield) against RY (relative yield), measured as yield in mixture divided by that in monoculture.
Cliffs are the primary habitat of many rare and endangered plant species, but few studies have investigated the genetic diversity of these species. Taihangia rupestris Yu et Li (Rosaceae) is the only species of the genus Taihangia, which occurs exclusively in small crevices on the faces of north-facing vertical cliffs at altitudes ranging from 600 to 1500 m above sea level. It is a perennial herb endemic to the southern part of the Taihang Mountains in northern China. We sampled fresh leaves from 11 to 38 individuals of T. rupestris in each of eight cliff-face populations located in the provinces of Hebei, Shanxi and Henan in China. The leaves were dried by silica gel and DNA was extracted. We then assessed the genetic variability within and among the eight populations of T. rupestris using random amplified polymorphic DNA (RAPD). Within the 150 plants sampled, 81.2% of the 117 RAPD markers detected were polymorphic, and Nei’s diversity (H) was on average 0.21 in the eight populations and 0.28 in the species as a whole. The grouping of the eight populations by clustering analysis agreed with their pattern of geographical distribution and with the separation of the species into two varieties (T. rupestris var. ciliata and T. rupestris var. rupestris). Genetic distances (Φst) were significantly correlated with geographic distances. Although significant genetic differentiation existed between groups (varieties) and among populations, a high proportion (65.4%) of the total genetic variation was maintained within populations. Therefore, high genetic diversity is preserved in the cliffdwelling populations, and in situ protection of T. rupestris should focus on the protection of the habitat of both varieties, which may be of particular importance for the long-term survival of this species.
Clonal plants combine sexual and clonal reproduction, which contribute differently to plant fitness. We investigated the consequence of natural selection on the two reproductive modes and the ecological factors that affect the reproductive modes of Eremosparton songoricum (Litv.) Vass. in order to understand the reproductive strategies of a clonal plant and the relationship between sexual and clonal reproduction. Morphological characteristics and biomass allocation patterns were m easured and compared at the clonal fragment level in two natural populations (riverside population A and hinterland population B) in the Gurbantunggut Desert, China. The flowering plant ratio, inflorescence number per plant, flower number per raceme, fruit number, mass of 100 seeds, root biomass, fruit biomass and ramet height were significantly higher, whereas fruit set, ramet density, rhizome biomass and length, and root number were significantly lower, in population A compared with those in population B. We estimated that the importance of clonal reproduction varies in two populations of E. songoricum, and the investment adjustment in the two reproductive modes may be based on cost required for each new plant to generate the more survival progeny in the plant life time.
In order to analyze changes in biomass allocation patterns across genetically structured populations where plants are competing for access to light, we performed glasshouse experiment with controlled genetic identity of competitors. Clonal replicates of 17 Lamium maculatum (L.) genotypes were grown in three treatments: control (low competition for light availability), intraclonal and interclonal competition. It was shown that competition between genetically unrelated individuals (interclonal treatment) was the most stressful environment for Spotted Dead Nettle. Results of allometry analyses, based on standardized major axis (SMA) mathematical procedure, have shown the smallest differences in relative investment to sexual reproduction between larger and smaller individuals when competing with unrelated plants. Our results indicate that allometric relationships between vegetative and reproductive traits could be strongly affected by genetic relatedness of competing plants.
A systematic knowledge of clonal integration is an important step in understanding the ecological implication of clonality. This study focuses on the performance of rhizomatous clonal plants under different situations and we proposed a hypothesis that clonal integration will significantly improve the disturbance and drought resistance ability and the competitive ability of Eremosparton songoricum. In 2009, the experiments were carried out in two natural populations. Rhizome was either severed (S) or not (I) in four treatments that include control (C), drought (D), disturbance (E), and competition (F). The biomass and the root-shoot ratio were compared in different experimental treatments. Under drought and disturbance treatments, the biomass of ramet with severed rhizome was significantly less than that of intact ramets, and both were lower than the samples under the control treatment. The differences in root-shoot ratio were opposite to the biomass in drought and disturbance treatments. The ramet biomass under the competition treatment had the same result as that under the drought and disturbance treatments. However, th e root-shoot ratio was highest in FS (competition treatment with severed rhizome) and lowest in FI (competition treatment with intact rhizome) under competition and control treatments. Our results suggest that clonal integration enhances the disturbance and drought resistance ability rather than the competitive ability of Eremosparton songoricum. This may be one of the various reasons why E. songoricum is distributed in sand dunes of droughty conditions with more disturbances but less competition. Integration proved to be important for the species occupying adverse patches. For E. songoricum, the existence of rhizome reduces the impact of environmental stress and improves the fitness in association with its location at the dune.
Prunus mume is one of the most popular landscape plants In China and Japan. A successful in vitro propagation system for six cultivars of Prunus mume has been developed by in vitro culture of nodal segments from seedling and mature plants. High multiplication rates (from 2.5 to 5.5) were achieved using modified MS media and WPM basic media supplemented with TDZ, BA, IBA, 2,4-D or NAA at concentrations adjusted for each cultivar. All the studied cultivars could be proliferated efficiently on WPM media supplemented with 2.2 µM TDZ, 2.2 µM BA and 2.5 µM IBA. Shoots were rooted on agar-gelled 1/2 MS or WPM basic media containing 2.5 or 5.0 µM IBA, and plantlets were transferred to pots after they had grown more than 3 roots and at least one root was more than 10 mm long. The effects of TDZ, media composition and different genotypes on shoot multiplication and growth were studied in detail. The genetic fidelity of the micropropagated plants from the ’Xuemei’ cultivar was examined using PCR-ISSR markers, and the results demonstrated complete genetic stability in the cloned plants.
Two populations of Iris sibirica, a clonal species protected by law in Poland, occurring in patches of Molinietum caeruleae, of similar floristic composition although with different dominant species, were studied. In the Stanisławice locality, species with a high competitive potential prevailed, contrary to the Opatkowice locality, where the species of low competitive potential dominated. It was established that vegetative propagation ensures the continued presence of populations in both localities, although the proximity of plants with high competitive potential limits the vegetative propagation of ramet clusters of Iris sibirica. Despite the high level of seed production, the recruitment of seedlings in both patches is possible only in artificially created gaps. The field observations support the conclusion that creating gaps allowing for germination of seeds and development of seedlings, as well as eliminating expansive neighbours allowing proliferation of ramet clusters of Iris sibirica, is an affective way of protecting populations of this species.
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