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Gaku Kudo - One of the best experts on this subject based on the ideXlab platform.
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Variations in Ramet performance and the dynamics of an alpine evergreen herb, Gentiana nipponica, in different snowmelt conditions.
American journal of botany, 2018Co-Authors: Yuka Kawai, Gaku KudoAbstract:Variation in demographic paRameters reflects the life-history strategies of plants in response to specific environments. We aimed to investigate the intraspecific variation in life-history traits of a clonal alpine herb, Gentiana nipponica, in various snowmelt conditions. Individual Ramets within genets accumulate leaves for 7-9 yr without shedding, and die after reproduction. We tested the physiological function of accumulated leaves for reproduction and monitored the Ramet demography in early, intermediate, and late snowmelt populations over 3 yr. Then, we simulated Ramet dynamics using the demographic paRameters. Old leaves had a carbon storage function, and the initiation of reproduction depended on the amount of Ramet leaves. Growth and reproductive performance were highest in the population with an intermediate snowmelt period. The early snowmelt population showed short persistence periods due to restricted growth and high mortality of the Ramets. The late snowmelt populations showed slow growth, but high survival rate of the Ramets, in which the Ramet size at reproduction was smallest and fruit formation was often suppressed by the short growing period. Limiting factors dictating the distribution of G. nipponica differed between the early and late snowmelt habitats. High mortality and restricted growth, because of the harsh environment, determine the distribution limit toward earlier snowmelt locations. By contrast, late snowmelt strongly limited fecundity because of the short period for fruit maturation. The difference in snowmelt time provides a clear gradient of selective forces that may promote local adaptation among neighboring populations. © 2018 Botanical Society of America.
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variations in Ramet performance and the dynamics of an alpine evergreen herb gentiana nipponica in different snowmelt conditions
American Journal of Botany, 2018Co-Authors: Yuka Kawai, Gaku KudoAbstract:PREMISE OF THE STUDY Variation in demographic paRameters reflects the life-history strategies of plants in response to specific environments. We aimed to investigate the intraspecific variation in life-history traits of a clonal alpine herb, Gentiana nipponica, in various snowmelt conditions. METHODS Individual Ramets within genets accumulate leaves for 7-9 yr without shedding, and die after reproduction. We tested the physiological function of accumulated leaves for reproduction and monitored the Ramet demography in early, intermediate, and late snowmelt populations over 3 yr. Then, we simulated Ramet dynamics using the demographic paRameters. KEY RESULTS Old leaves had a carbon storage function, and the initiation of reproduction depended on the amount of Ramet leaves. Growth and reproductive performance were highest in the population with an intermediate snowmelt period. The early snowmelt population showed short persistence periods due to restricted growth and high mortality of the Ramets. The late snowmelt populations showed slow growth, but high survival rate of the Ramets, in which the Ramet size at reproduction was smallest and fruit formation was often suppressed by the short growing period. CONCLUSIONS Limiting factors dictating the distribution of G. nipponica differed between the early and late snowmelt habitats. High mortality and restricted growth, because of the harsh environment, determine the distribution limit toward earlier snowmelt locations. By contrast, late snowmelt strongly limited fecundity because of the short period for fruit maturation. The difference in snowmelt time provides a clear gradient of selective forces that may promote local adaptation among neighboring populations.
Tomáš Herben - One of the best experts on this subject based on the ideXlab platform.
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Effects of neighbourhood structure and tussock dynamics on genet demography of Festuca rubra in a mountain meadow
Journal of Ecology, 2006Co-Authors: Jun-ichirou Suzuki, František Krahulec, Tomáš Herben, Helena Štorchová, Toshihiko HaraAbstract:Summary 1 We examined whether genet demography in the clonal grass Festuca rubra in a mountain grassland in the Krkono s e Mountains (Czech Republic) changes in response to local environment. The data were also used to compare genet recruitment with estimates of genet mortality. 2 We sampled F. rubra from four permanent plots in which Ramet densities of all species have been recorded at a fine scale for a decade. Identities of 224 Ramets were assessed by means of RAPD, yielding 145 different genets, of which most (68%) were found only once. The genet with the highest number of sampled Ramets was recorded nine times. 3 By assuming that the probability that two Ramets are genetically identical is a function of distance between Ramets, we estimated that successful seedling recruitment rates were between 0.15 and 16 genets m − 2 yr − 1 depending on the plot. Genet mortality was estimated from Ramet mortality using the assumption that Ramet mortality was uncorrelated over space. In three of the four plots, genet mortalities fell into the same range as the genet recruitment rates. 4 The total number of genets per unit area must be known to enable determination of per capita recruitment and mortality rates. We developed an estimation technique involving simulation of the sampling process, which yielded values of 231‐968 genets m − 2 . Genet turnover was therefore low (0.1‐1% annually) and the high genet diversity is maintained by a very low recruitment. 5 Spatial analysis showed that two Ramets were more likely to be genetically identical when they came from a microhabitat where Festuca Ramet density had recently increased; patches in which Festuca Ramet density had decreased were more likely to contain Ramets from several genets. Expanding tussocks are thus more likely to be composed of Ramets of one genet only. Density and biomass of other species in the neighbourhood showed little correlation with the genet structure of Festuca rubra. 6 Although Ramets of Festuca rubra intermingle with other species at a fine scale, the population biology of its genets is driven mainly by the dynamics of its own Ramets. Interactions with other species and response to local environments have little effect on genet structure.
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Ecological benefits of integration of Calamagrostis epigejos Ramets under field conditions
Flora - Morphology Distribution Functional Ecology of Plants, 2006Co-Authors: Stanislav Březina, Zuzana Münzbergová, Tomáš Koubek, Tomáš HerbenAbstract:Abstract We established two independent experiments to estimate the ecological consequences of artificial severing on Ramets of the competitively strong perennial grass Calamagrostis epigejos. We compared the responses of mature Ramets of different size growing in different environments. Finally, we tested whether the response of young Ramets to the severing depends on the density of surrounding vegetation. Severing decreased biomass and number of rhizomes of young Ramets but did not affect their competitive tolerance. It decreased survival of mature Ramets (probably due to traumata caused by cutting attached rhizomes) but did not influence total biomass of survived Ramets. The response of total biomass of mature Ramets to severing changed with size of the Ramets. Further, biomass allocation to rhizomes changed differently after Ramet severing in the two environments. The results suggest that field grown young Ramets of Calamagrostis benefit from physiological integration. In contrast, mature Ramets seem to be independent units according to the resource economy. Ecological benefits of integration depended on size of Ramet clumps: Ramets in clump had larger survival probability than control Ramets. They also depended on environmental conditions: severing increased formation of new rhizomes at a sand dune subsrate, but it had a negative effect on plants in the forest experimental site. This intra-specific variation should be taken into account when trying to explain ecological patterns of integration benefits of clonal plants.
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Ramet performance in two tussock plants do the tussock level paRameters matter
Flora, 2005Co-Authors: Tomáš Herben, Zuzana Münzbergová, Anna Bucharova, Martin Kr Ivanek, Vlasta Juklic KovaAbstract:Abstract Studies in plant demography are primarily done at the level of Ramets and typically collect Ramet-related paRameters such as Ramet size, type and history. This approach ignores possible effects of factors associated with higher levels, such as genet or tussock. This is particularly important in perennial resprouting herbs with persistent root that consists of many Ramets as interaction between Ramets, both by competition and by resource sharing, are likely to be intense in these plants. This study investigates effects of tussock-level paRameters (age, size and Ramet position within tussock and Ramet density) on performance of individual Ramets in two tussock-forming resprouting herbs ( Tanacetum vulgare and Centaurea jacea ). The results show that position of a Ramet within tussock did not affect Ramet growth, but had significant effects on flowering and survival in both species. The direction of the effect differed between the two species; marginal Ramets were more successful in T. vulgare , while central Ramets were more successful in C. jacea . In addition, tussock age had a significant effect on Ramet flowering and survival in T. vulgare . Both these effects are likely to be due to the more competitive life form of T. vulgare , which is restricted to temporary habitats with intense competition. C. jacea is a species of mown or grazed grasslands with lower productivity, which are more stable and where competition is weaker. The effects of the number of neighboring Ramets and of the tussock size were significant, but often locality-specific. The results indicate that although many important effects of tussock-related paRameters exist, their direction and magnitude differ between species or even populations and are thus not easily predictable. Neglecting these effects, however, is likely to make the demographic models weaker.
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Ramet performance in two tussock plants — Do the tussock-level paRameters matter?
Flora - Morphology Distribution Functional Ecology of Plants, 2005Co-Authors: Zuzana Münzbergová, Martin Kr˘ivánek, Anna Bucharova, Vlasta Juklíc˘ková, Tomáš HerbenAbstract:Abstract Studies in plant demography are primarily done at the level of Ramets and typically collect Ramet-related paRameters such as Ramet size, type and history. This approach ignores possible effects of factors associated with higher levels, such as genet or tussock. This is particularly important in perennial resprouting herbs with persistent root that consists of many Ramets as interaction between Ramets, both by competition and by resource sharing, are likely to be intense in these plants. This study investigates effects of tussock-level paRameters (age, size and Ramet position within tussock and Ramet density) on performance of individual Ramets in two tussock-forming resprouting herbs ( Tanacetum vulgare and Centaurea jacea ). The results show that position of a Ramet within tussock did not affect Ramet growth, but had significant effects on flowering and survival in both species. The direction of the effect differed between the two species; marginal Ramets were more successful in T. vulgare , while central Ramets were more successful in C. jacea . In addition, tussock age had a significant effect on Ramet flowering and survival in T. vulgare . Both these effects are likely to be due to the more competitive life form of T. vulgare , which is restricted to temporary habitats with intense competition. C. jacea is a species of mown or grazed grasslands with lower productivity, which are more stable and where competition is weaker. The effects of the number of neighboring Ramets and of the tussock size were significant, but often locality-specific. The results indicate that although many important effects of tussock-related paRameters exist, their direction and magnitude differ between species or even populations and are thus not easily predictable. Neglecting these effects, however, is likely to make the demographic models weaker.
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Plant clonality: Biology and diversity
Folia Geobotanica, 1994Co-Authors: Tomáš Herben, Toshihiko Hara, Chris Marshall, Lenka SoukupováAbstract:The current approaches to the study of clonal plants are reviewed. Most studies concentrate at the level of the Ramet and clonal fragment exploring the “microscopic” view of clonal plants, dealing with the translocation of resources, clonal integration, plasticity of growth etc. The information gained, by this approach can be used in the understanding of higher levels of organization within the clonal system either with the help of spatially explicit modelling techniques, or by using means and distributions of size within a population instead of studying individual Ramets separately. Plant scientists use the term clone with two meanings, viz. (a) a set of physiologically connected, but potentially independent Ramets, and (b) a set of genetically identical, but potentially physically separated individuals. The overlap of these terms differs between individual plant species, depending on the extent of physical separation of the Ramets and the degree of physiological integration between the Ramets; the lower the frequency of Ramet separation, the closer are the physiological and genetic concepts of the clone. Three critical areas seem to be neglected in clonal plant research: (a) the interrelationship between hierarchical levels in clonal plants, (b) the particular spatial structure of their environment, and (c) the importance of clonal plants in different ecological communities.
Yunfei Yang - One of the best experts on this subject based on the ideXlab platform.
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Phenotypic Plasticity in Sexual Reproduction Based on Nutrients Supplied From Vegetative Ramets in a Leymus chinensis Population.
Frontiers in plant science, 2020Co-Authors: Jian Guo, Yunfei YangAbstract:Phenotypic plasticity is considered a major mechanism that allows plants to adapt to heterogeneous environments. The physiological integration between the interconnected rhizomes or stolons of clonal plants influences the plasticity of such plants in heterogeneous environments. However, the determinants of plasticity of reproductive Ramets in clonal plants in homogeneous environments are unclear. Here, we chose Leymus chinensis, a perennial rhizomatous grass, and conducted a series of field experiments in situ, including grading sampling of reproductive Ramets and different connection forms of vegetative Ramets labeled with 15N at four reproductive stages. Reproductive Ramet biomass, inflorescence biomass, seed number, seed-setting percentage, reproductive allocation, and reallocation significantly increased with an increase in the number of vegetative Ramets connected to tillering nodes, and the plasticity indexes of these six phenotypic characteristics showed similar increasing trends. The amount of nutrients supplied from the connected vegetative Ramets to the reproductive Ramets was significantly affected by the transfer direction, reproductive stage, and position order of the vegetative Ramets. Throughout the sexual reproduction stage, nutrients were preferentially transferred to the acropetal reproductive Ramet in L. chinensis populations. The amount of nutrients supplied from the connected vegetative Ramets to the reproductive Ramets at the milk-ripe stage, when sexual reproduction was most vigorous, was significantly larger than that at other reproductive stages. The amount of nutrients supplied from the spacer vegetative Ramet to the acropetal reproductive Ramet was significantly larger than that to the basipetal reproductive Ramet. The closer the vegetative Ramet was to the reproductive Ramet, the more nutrients were supplied; the amount of nutrients supplied was significantly negatively related to the position order of the vegetative Ramet. We identified the determinant of plasticity in sexual reproduction in clonal plants in a homogeneous environment: physiological integration between Ramets within clones. Our results are vital for better understanding the adaptation of populations and even the evolution of species of clonal plants.
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Age structure and growth analysis of Ramets of Chamaedaphne calyculata populations in a mire of the Xiaoxing'an Mountains
Journal of Northeast Normal University, 2004Co-Authors: Yunfei Yang, Huiqing LangAbstract:As a clonal evergreen dwarf shrub, Chamaedaphne calyculata is mainly distributed in oligotrophic mires. By virtue of observing a great deal of samples, classified age structure of Ramets of Chamaedaphne calyculata clonal populations by way of counting bud scale traces on the Ramets. In a mire of Xiaoxing'an Mountains in the middle of growing season, the Ramets were classified as 8 age classes and showed a declining age structure. Both mean biomass and mean height per Ramet in the center was lower than those in the margin. Different condition of nutrients was main factor to affect the differences of the age structure, growth characteristics of biomass and height and their ecological plasticity of Chamaedaphne calyculata Ramets in the two habitats. Oligotrophic condition limited the biomass accumulation and height increment. Heterogenous environmental conditions determined ecological plasticity of Ramet biomass and length in Chamaedaphne calyculata populations.
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Biomass allocation and growth analysis on the Ramets of Phragmites communis populations in different habitats in the Songnen Plains of China
Ying yong sheng tai xue bao = The journal of applied ecology, 2003Co-Authors: Yunfei YangAbstract:In the Songnen Plains of China, the reeds grow fastest in middle August. In this experiment, four research plots were chosen in the arid habitats. The first plot was dominated by reed, and in which, there was some stagnant water in July and August. The Ramets of reeds grew singly, and most of them could turn into reproductive growth. Its community coverage was more than 95% after the fast growing season of July. The second plot was Leymus chinensis + Phragmites communis community, where soil was alkaline meadow with stagnant water for a short time or not. Its community coverage was more than 90%. Two or three Ramets grew in a tuft, while most of them couldn't turn to reproductive growth, so reeds were used to make hay stored in winter every year. The third plot was on Aeolian sandy soil with good permeability and drainage on a grassland of artificial forest edge on sand dune. Its community coverage was about 50%, and two or three Ramets grew in a tuft. The last plot was alkaline bareground patches, where top soil was lost completely. Soil was hard and permeability was poor. On some alkaline patches, there could form a micro-community dominated by reed, and eight to twenty Ramets could grow in a tuft. Ramets were all slender and creeping stems. Its community coverage was from 20% to 40%. The results showed that four mentioned habitats, the growth and productivity of the Ramets of the populations were the largest in the lowland and the smallest in the alkaline patch. The height of Ramets differed 2.8 times, and the biomass differed 4.4 times in the two habitats. There were also significant difference between the other two habitats, sand soil and mixed-grass community. The integrated condition of habitat were the major factor that affected the height of the Ramets of the population. Moreover, the growth condition of interior habitat was the major factor that affected the Ramet biomass of the population in lowland and alkaline patch, while the integrated habitat conditions had much more effects on the Ramet biomass of the population in sand land and meadow. The height of Ramet was much lower in ecological plasticity than the biomass in every population. The variations of biomass allocation of the Ramet in different habitat conditions indicated important strategies in the growth regulation and biomass allocation. More biomass of Ramets was allocated to leaves preferentially in the four habitants, especially on sand dune. Reeds in alkaline patch had small Ramets and enough growth spaces. There were 63.04% and 53.61% biomass allocated to leaves, and only 14.82% and 19.92% to the stems, although 58.31% was allocated to leaves and only 19.05% to stems to ensure the full material product in the meadow, because of the interspecific competition. But, in the lowland with better conditions where had a higher density and large coverage, only 42.1% were allocated to leaves, while 37.52% were allocated to stem to elongation of stem in order to improve the individual competition for space and light. The leaf sheath/biomass ratio of the Ramets was 20.38%-26.47%, which was nearly, at the same level in four habitats. There was the same regulation of the heterogeneous speed growth by power function, either in the increased height and weight of the Ramets, or in the relative increased weight of the stems, leaves and the Ramets of the populations in four different habitat conditions.
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Growth strategies of different age classes of Ramets in Kalimeris integrifolia population at the Songnen Plains of China
Ying yong sheng tai xue bao = The journal of applied ecology, 2003Co-Authors: Yunfei YangAbstract:As a perennial forage, Kalimeris integrifolia Turcz. Ex DC is a species of Compositea clone plant, which has a high potential in vegetative propagation by root crowns. Its population was constructed by three age classes of Ramets. In the Songnen Plains the middle ten days of June is the more vigorous vegetative growth period of the clone Ramets. The results showed that the capabilities of Ramet growth and production were the lowest in the 1st age class and heightened in the 2nd and 3rd age classes. Biomass allocations were the most in stem, more in leaves, and the least in tapoot of three age classes of Ramets. The biomass allocation in leaves was the most in the 1st age class, more in the 2nd age class, and the least in the 3rd age class, but those in stem and in taproot were all the least in the 1st age class lesser in the 2nd age class, and the most in the 3rd age class. The relationships between total weight and height, leaf weight and stem weight, and taproot weight and shoot weight of clone Ramets were all power function, but the biomass allocation in taproot was linearly decreased with height increase in three age classes. The strategies of growth and biomass allocation of the population Ramets were: 1) the biomass allocation in leaves was more in the young period to ensure the productive organ constructed continuously, and hence, more productive material was gradually allocated in stem and taproot with the growth of Ramets, 2) the energy allocation of Ramets was less in taproot, but the biomass allocation in taproot was relatively more in young period, and then, the prorate decreased with Ramet growth, and the ratio kept relatively steady.
Yuka Kawai - One of the best experts on this subject based on the ideXlab platform.
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Variations in Ramet performance and the dynamics of an alpine evergreen herb, Gentiana nipponica, in different snowmelt conditions.
American journal of botany, 2018Co-Authors: Yuka Kawai, Gaku KudoAbstract:Variation in demographic paRameters reflects the life-history strategies of plants in response to specific environments. We aimed to investigate the intraspecific variation in life-history traits of a clonal alpine herb, Gentiana nipponica, in various snowmelt conditions. Individual Ramets within genets accumulate leaves for 7-9 yr without shedding, and die after reproduction. We tested the physiological function of accumulated leaves for reproduction and monitored the Ramet demography in early, intermediate, and late snowmelt populations over 3 yr. Then, we simulated Ramet dynamics using the demographic paRameters. Old leaves had a carbon storage function, and the initiation of reproduction depended on the amount of Ramet leaves. Growth and reproductive performance were highest in the population with an intermediate snowmelt period. The early snowmelt population showed short persistence periods due to restricted growth and high mortality of the Ramets. The late snowmelt populations showed slow growth, but high survival rate of the Ramets, in which the Ramet size at reproduction was smallest and fruit formation was often suppressed by the short growing period. Limiting factors dictating the distribution of G. nipponica differed between the early and late snowmelt habitats. High mortality and restricted growth, because of the harsh environment, determine the distribution limit toward earlier snowmelt locations. By contrast, late snowmelt strongly limited fecundity because of the short period for fruit maturation. The difference in snowmelt time provides a clear gradient of selective forces that may promote local adaptation among neighboring populations. © 2018 Botanical Society of America.
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variations in Ramet performance and the dynamics of an alpine evergreen herb gentiana nipponica in different snowmelt conditions
American Journal of Botany, 2018Co-Authors: Yuka Kawai, Gaku KudoAbstract:PREMISE OF THE STUDY Variation in demographic paRameters reflects the life-history strategies of plants in response to specific environments. We aimed to investigate the intraspecific variation in life-history traits of a clonal alpine herb, Gentiana nipponica, in various snowmelt conditions. METHODS Individual Ramets within genets accumulate leaves for 7-9 yr without shedding, and die after reproduction. We tested the physiological function of accumulated leaves for reproduction and monitored the Ramet demography in early, intermediate, and late snowmelt populations over 3 yr. Then, we simulated Ramet dynamics using the demographic paRameters. KEY RESULTS Old leaves had a carbon storage function, and the initiation of reproduction depended on the amount of Ramet leaves. Growth and reproductive performance were highest in the population with an intermediate snowmelt period. The early snowmelt population showed short persistence periods due to restricted growth and high mortality of the Ramets. The late snowmelt populations showed slow growth, but high survival rate of the Ramets, in which the Ramet size at reproduction was smallest and fruit formation was often suppressed by the short growing period. CONCLUSIONS Limiting factors dictating the distribution of G. nipponica differed between the early and late snowmelt habitats. High mortality and restricted growth, because of the harsh environment, determine the distribution limit toward earlier snowmelt locations. By contrast, late snowmelt strongly limited fecundity because of the short period for fruit maturation. The difference in snowmelt time provides a clear gradient of selective forces that may promote local adaptation among neighboring populations.
Zuzana Münzbergová - One of the best experts on this subject based on the ideXlab platform.
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Ecological benefits of integration of Calamagrostis epigejos Ramets under field conditions
Flora - Morphology Distribution Functional Ecology of Plants, 2006Co-Authors: Stanislav Březina, Zuzana Münzbergová, Tomáš Koubek, Tomáš HerbenAbstract:Abstract We established two independent experiments to estimate the ecological consequences of artificial severing on Ramets of the competitively strong perennial grass Calamagrostis epigejos. We compared the responses of mature Ramets of different size growing in different environments. Finally, we tested whether the response of young Ramets to the severing depends on the density of surrounding vegetation. Severing decreased biomass and number of rhizomes of young Ramets but did not affect their competitive tolerance. It decreased survival of mature Ramets (probably due to traumata caused by cutting attached rhizomes) but did not influence total biomass of survived Ramets. The response of total biomass of mature Ramets to severing changed with size of the Ramets. Further, biomass allocation to rhizomes changed differently after Ramet severing in the two environments. The results suggest that field grown young Ramets of Calamagrostis benefit from physiological integration. In contrast, mature Ramets seem to be independent units according to the resource economy. Ecological benefits of integration depended on size of Ramet clumps: Ramets in clump had larger survival probability than control Ramets. They also depended on environmental conditions: severing increased formation of new rhizomes at a sand dune subsrate, but it had a negative effect on plants in the forest experimental site. This intra-specific variation should be taken into account when trying to explain ecological patterns of integration benefits of clonal plants.
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Ramet performance in two tussock plants do the tussock level paRameters matter
Flora, 2005Co-Authors: Tomáš Herben, Zuzana Münzbergová, Anna Bucharova, Martin Kr Ivanek, Vlasta Juklic KovaAbstract:Abstract Studies in plant demography are primarily done at the level of Ramets and typically collect Ramet-related paRameters such as Ramet size, type and history. This approach ignores possible effects of factors associated with higher levels, such as genet or tussock. This is particularly important in perennial resprouting herbs with persistent root that consists of many Ramets as interaction between Ramets, both by competition and by resource sharing, are likely to be intense in these plants. This study investigates effects of tussock-level paRameters (age, size and Ramet position within tussock and Ramet density) on performance of individual Ramets in two tussock-forming resprouting herbs ( Tanacetum vulgare and Centaurea jacea ). The results show that position of a Ramet within tussock did not affect Ramet growth, but had significant effects on flowering and survival in both species. The direction of the effect differed between the two species; marginal Ramets were more successful in T. vulgare , while central Ramets were more successful in C. jacea . In addition, tussock age had a significant effect on Ramet flowering and survival in T. vulgare . Both these effects are likely to be due to the more competitive life form of T. vulgare , which is restricted to temporary habitats with intense competition. C. jacea is a species of mown or grazed grasslands with lower productivity, which are more stable and where competition is weaker. The effects of the number of neighboring Ramets and of the tussock size were significant, but often locality-specific. The results indicate that although many important effects of tussock-related paRameters exist, their direction and magnitude differ between species or even populations and are thus not easily predictable. Neglecting these effects, however, is likely to make the demographic models weaker.
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Ramet performance in two tussock plants — Do the tussock-level paRameters matter?
Flora - Morphology Distribution Functional Ecology of Plants, 2005Co-Authors: Zuzana Münzbergová, Martin Kr˘ivánek, Anna Bucharova, Vlasta Juklíc˘ková, Tomáš HerbenAbstract:Abstract Studies in plant demography are primarily done at the level of Ramets and typically collect Ramet-related paRameters such as Ramet size, type and history. This approach ignores possible effects of factors associated with higher levels, such as genet or tussock. This is particularly important in perennial resprouting herbs with persistent root that consists of many Ramets as interaction between Ramets, both by competition and by resource sharing, are likely to be intense in these plants. This study investigates effects of tussock-level paRameters (age, size and Ramet position within tussock and Ramet density) on performance of individual Ramets in two tussock-forming resprouting herbs ( Tanacetum vulgare and Centaurea jacea ). The results show that position of a Ramet within tussock did not affect Ramet growth, but had significant effects on flowering and survival in both species. The direction of the effect differed between the two species; marginal Ramets were more successful in T. vulgare , while central Ramets were more successful in C. jacea . In addition, tussock age had a significant effect on Ramet flowering and survival in T. vulgare . Both these effects are likely to be due to the more competitive life form of T. vulgare , which is restricted to temporary habitats with intense competition. C. jacea is a species of mown or grazed grasslands with lower productivity, which are more stable and where competition is weaker. The effects of the number of neighboring Ramets and of the tussock size were significant, but often locality-specific. The results indicate that although many important effects of tussock-related paRameters exist, their direction and magnitude differ between species or even populations and are thus not easily predictable. Neglecting these effects, however, is likely to make the demographic models weaker.
