Abstract form

Using propagule mimics to model seed bank formation in salinized
soils
G. MATUS* 1 , O. VALKÓ 1,2 , P. TÖRÖK 2 , M. PAPP. 1 , E. VIDA 1,2 , A. KELEMEN 2 , T.
MIGLÉCZ 2 , B. TATÁR 1 , S. KÉKI 3 , T. TÓTH 4
1 Dept. of Botany, 2 Dept. of Ecology, 3 Dept. of Applied Chemistry, University of
Debrecen; 4 Research Institute for Soil Science and Agricultural Chemistry, HAS
Studying soil seed banks is among the research highlights in plant ecology, especially in
ecological restoration. Several attempts were made to reveal correlation between size
and shape vs. vertical distribution of seeds in the soil. Based on empirical data from
natural seed banks, the generally accepted assumption among plant ecologists is that
species with small and spherical seeds are more likely to build up dense and deeply
penetrating soil seed banks than species with large and flattened seeds. It was, however,
not known how long does it take for a seed to travel to certain depths in the soil.
Without this information the vertical distribution and seed age can hardly be compared.
The aim of our study was to provide a reference by giving statistical description of the
movement of non-decomposing propagule mimics, the size and density of which falls
into the range of naturally occurring Central-European plant species. Granules made of
high-density polyethylene (HDPE, specific gravity ρ=0.95) and of different sizes and
shapes were applied as propagule mimics. The selected study sites are located in the
Bihar Plain in the vicinity of Derecske (East-Hungary). on meadow solonetz soils of
silty loam texture covered with differently degraded stands of traditionally managed
pastures (Achilleo-Festucetum pseudovinae and Cynodonti-Poetum angustifoliae). The
impact of grazing (cattle and/or sheep) on vertical and horizontal dispersal of propagule
mimics is to be assessed by comparing fenced and unfenced plots. Results collected on
the sodic soils are compared to a similar dataset on non salt-affected soils in order to
show how special physical conditions of sodic soils affect seed bank formation.
Basic soil characteristics in the uppermost 10 cm of the studied soils have been
analyzed (particle size distribution, sum of exchangeable cations and CEC values, pH-
H 2 O, soil organic matter, CaCO 3 , AL(ammonium-lactate extractable)-Ca, AL-K 2 O, AL-
P 2 O 5 , NH 4 -N, NO 3 -N, exchangeable Al, Ca, Fe, Mg, Mn, Na and K). Movement of
granules is also to be correlated with penetration resistance determined by a drop
hammer penetrometer.
Altogether 160,000 granules were placed to 400 spots in October 2008. In the project
(OTKA 67748) planned for 5 years, recollection of small soil monoliths (15x15x7.5
cm) is scheduled twice a year (April, October) in five replicates per plot in each date.
Granules resting on soil surface are collected first then monoliths are cut into slices of
12.5 mm width. Granules are separated through soaking in water then washing over a
series of sieves. Coinciding with former observations, our first results suggest that
smaller granules traveled to deeper layers in a larger portion.
Key words: soil seed banks, propagule size, propagule shape, physical soil type, grazing
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