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2 Polish Journal of Ecology

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Effects of contrasting habitats on the phenology, seasonal growth and drymass allocation pattern of two bulbous geophytes (Alliaceae) with partly different geographic ranges

Duchoslav M.

Polish Journal of Ecology

2009

Vol. 57, nr 1

15-32

Allium oleraceum L. and A. vineale L. are two related bulbous geophytes with an annual storage organ that coexist in a wide range of habitats but show both partly different geographic ranges and habitat preferences in Europe. To explore whether ecological and distributional differences between species can be related to expected variation in some key life-history traits between them, research was undertaken to compare the phenology, seasonal growth, and dry-mass allocation of vegetative and reproductive plants of the species at successional gradient comprising three sites with contrasting environmental conditions (steppe, scrub, forest), where populations of the study species coexist (the Czech Republic). The results showed, in general, partly different timing of phenophases between species and different responses of species to contrasting environmental conditions. A. vineale displayed an annual life cycle similar to that observed in many Mediterranean geophytes, i.e. regularly sprouting above ground before the arrival of winter, its growth was concentrated into early and mid-spring and started to wither after a temperature increase and several short-term drought events in early summer, though its flowering was delayed until late June. A. oleraceum showed high year-on-year variation in the onset of shoot elongation above-ground; its growth was concentrated into mid- and late spring and its flowering was delayed until July. The patterns of phenology observed between the study species thus partly reflect selection under different environmental conditions of their origin. The total duration of the green above-ground period of reproductive plants in both species continued about 1.5-2 months beyond that of the vegetative ones. Over main growth period, mean relative growth rates (RGR) of A. oleraceum and A. vineale ranged from 20 to 22 and from 6 to 28 mg g[^-1]dw day[^-1], respectively. A. vineale showed significantly higher RGR than A. oleraceum only in steppe conditions while at shaded sites the reverse pattern was found. The RGR of both vegetative and reproductive plants of A. oleraceum did not differ from one site to another. On the other hand, both vegetative and reproductive A. vineale plants showed lower RGR at shaded sites than at steppe one. Shading increased allocation into leaves in both species, caused complete abortion of developing scapes in A. vineale but only reduced reproductive allocation in A. oleraceum. A. oleraceum was able to maintain fitnessrelated traits more stably across the environments studied than A. vineale that fit well into the pattern of habitat differentiation observed between them in Central Europe. Data concerning growth of and allocation into new bulb in both species also support the hypothesis that allocating reserves for the coming year is the first priority in geophytes with an annual storage organ.

Carbohydrate reserve changes in below-ground biomass of subalpine grasslands as a result of different snow conditions (Hruby Jesenik Mts., Czech Republic)

Zeidler M., Banas M., Duchoslav M.

Polish Journal of Ecology

2008

Vol. 56, nr 1

75-83

Carbohydrate concentration changes in below-ground biomass of subalpine tall grasslands with Calamagrostis villosa (Chaix) J.F. Gmelin were monitored during one year on the slope of Petrovy kameny Mt. (Hruby Jesenik Mts., Czech Republic). Stands of the community with natural snow conditions were compared with stands on a ski piste. Soil temperature development and snow melting times were also observed in the territory concerned. The difference was stated between mean annual temperature on control stands (4.21 [degree] C) and ski piste (3.95 [degree] C) in the upper 5 cm of soil. At the average, snow melted on the ski piste two weeks later than that on the natural stands. The natural stands and the stands on the ski piste differ significantly from each other in terms of development of carbohydrate accumulation in the below-ground biomass. Consumption of reserve carbohydrates by the plants at both the ski piste and in the natural stands was nearly similar during the winter. At the beginning of the growing season (July), significant difference in carbohydrate concentration in below-ground organs between stands on the ski piste and natural stands was observed. It was caused by late melting of the snow cover and subsequent delay of the phenologic development and assimilation of the vegetation in the ski piste. Later in season (August, October), the differences in carbohydrate concentration between stands at the ski piste and natural stands disappeared. The mean annual amount of carbohydrates in the upper (0-5 cm) and lower (5-10 cm) soil horizons in natural stands and ski piste stands do not differ fundamentally, except for the significant difference in July. The results obtained are discussed in view of abiotic environmental conditions, the plant physiology and strategy of the dominant species.