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Biomass Allocation, Compensatory Growth and Internal C/N Balance of Lolium perenne in Response to Defoliation and Light Treatments

Wang L., Wang J., Liu W., Gan Y., Wu Y.

Polish Journal of Ecology

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2016

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Vol. 64, nr 4

485--499

EN

Light environments can have a considerable influence on how plants respond to defoliation through influencing the biomass allocation patterns and internal C/N ratio. Seedlings of Lolium perenne, a common perennial grass species, were grown for eight weeks under three different light environments (natural light, red light and shading) and two different defoliation treatments (no defoliation versus 50% aboveground biomass removal). This study was conducted to examine (1) the effects of light regimes and defoliation on biomass accumulation, biomass allocation and internal C/N ratio status in plants; (2) how the light regimes influence the pattern of compensatory growth after defoliation; and (3) the relationship between compensatory growth and the internal C/N ratio status. We found that red light altered the shoot-to-root allometry, enhanced the leaf C concentrations and induced N deficiency. By contrast, the leaf N concentrations of L. perenne were greater during shading treatment, which simultaneously enhanced shoot growth and stopped root growth. Under defoliation, red light increased shoot growth, not at the expense of root growth, which was not the same as in natural light and shading treatment. Moreover, regardless of the unclipped (no defoliation) and defoliation conditions, the L. perenne biomass partitioning between roots and shoots was significantly correlated with the leaf N concentrations and C/N ratio, indicating that allometric biomass allocation can be largely modulated by signals related to the C and N status of the plants. These results demonstrated that the leaf C and N status would be an appropriate indicator of compensatory growth after defoliation.

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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.

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Biomass dynamics in young silver birch stands on post-agricultural lands in central Poland

Zasada M., Bijak S., Bronisz K., Bronisz A., Gawęda T.

Drewno : prace naukowe, doniesienia, komunikaty

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2014

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vol. 57, nr 192

29--39

EN

The paper analyses the production and allocation of biomass in young, spontaneous silver birch afforestation occurring on post-agricultural lands in the Mazowsze region (central Poland). We investigated 114 sample plots of age varying from 1 to 19 years. During the first 15 years after their establishment on abandoned farmland, the naturally regenerated silver birch stands produced on average approximately 75 tons of dry biomass per hectare. The major (50–70%) part of this biomass was stored in the tree stems and this share increased with age. The fractions of biomass in the foliage and roots decreased over time, while the share of biomass in the branches remained rather constant. The significant age-dependency of the allometric relationships suggested the need to use age-sensitive biomass expansion factors to estimate the biomass from the stem volume.

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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.

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Life history strategy influences biomass allocation in response to limiting nutrients and water in an arid system

Mao W., Allington G., Li Y., Zhang T., Zhao X., Wang S.

Polish Journal of Ecology

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2012

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Vol. 60, nr 3

545-557

EN

The optimal partitioning theory (OPT) predicts that a plant should allocate relatively more biomass to the organs that acquire the most limiting resource. However, variation in biomass allocation among plant parts can also occur as a plant grows in size. As an alternative approach, allometric biomass partitioning theory (APT) asserts that plants should trade off their biomass between roots, stems and leaves, and this approach can minimize bias when comparing biomass allocation patterns by accounting for plant size in the analysis. We analyzed the biomass allocation strategy of the two species: annual Setaria viridis (L.) Beauv and perennial Pennisetum centrasiaticum Tzvel from the Horqin Sandy Land of northern China by treating them with different availabilities of soil nutrient and water (added in summer and winter), and hypothesized that the two species have different patterns of biomass allocation strategy in response to different soil water content and soil nitrogen content. After taking plant size into account, the biomass allocation strategy of S. viridis and P. centrasiaticum differed in response to nitrogen and water; leaves and root:shoot ratio (RTS) of S. viridis were "true" in response to various soil nitrogen contents. The plasticity of roots was also "true" in response to fluctuation in soil water content. However, P. centrasiaticum showed a different pattern with no shift of biomass allocation strategy in response to nitrogen and water. Adjustment in organs biomass allocation pattern of S. viridis in response to nitrogen and water limitation was dramatic, this suggested that S. viridis support optimal partitioning theory (OPT). P. centrasiaticum has better tolerance to varied environments and more likely support the allometric biomass partitioning theory (APT), this characteristic may allow P. centrasiaticum to keep dominance in fragile habitats.