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1

Adaptive significance of and factors affecting plasticity of biomass allocation and rhizome morphology; a case study of the clonal plant Scirpus planiculmis (Cyperaceae)

Ning Y., Zhang Z. X., Cui L. J., Zou C. L.

Polish Journal of Ecology

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2014

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Vol. 62, nr 1

77--88

EN

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.

2

Variation of sexual and clonal reproduction in Eremosparton songoricum (Litv.) (Fabaceae) on drought in arid regions : an experimental approach

Wang J., Shi X., Yin L., Zhang D.

Polish Journal of Ecology

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2012

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Vol. 60, nr 1

145-152

EN

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.

3

Role of clonal integration in life strategy of sandy dune plant, Eremosparton songoricum (Litv.) Vass (Fab aceae) : experimental

Wang J., Shi X., Yin L., Zhang D.

Polish Journal of Ecology

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2011

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Vol. 59, nr 3

455-461

EN

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, the 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.

4

High genetic diversity in the naturally rare plant Taihangia rupestris Yu et Li (Rosaceae) dwelling only cliff faces

Tang M., Yu F., Jin X., Ge S.

Polish Journal of Ecology

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2010

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Vol. 58, nr 2

241-248

EN

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 ([Phi]st) 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.

5

Population structure of a clonal endangered plant species Iris sibirica L. in different habitat conditions

Kostrakiewicz K.

Polish Journal of Ecology

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2008

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Vol. 56, nr 4

581-592

EN

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 m[^2] 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 m[^2] 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 m[^2] 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.

6

Effects of nutrient availability and competition between two grass species Leymus chinensis (Trin) Tzvel. and Phragmites communis Trin. on the plant performance

Ba L., Xiao N., Xu W., Wang D.

Polish Journal of Ecology

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2008

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Vol. 56, nr 3

453-462

EN

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 (RY[above]) 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 RY[above] (the belowground relative yield) against RY (relative yield), measured as yield in mixture divided by that in monoculture.