caa a22 4500 475750977 CHVBK 20180406123523.0 cr unu---uuuuu 170329e20000701xx s 000 0 eng 10.1023/A:1009850706843 doi (NATIONALLICENCE)springer-10.1023/A:1009850706843 Spatial distribution of soil seed banks of three African savanna woody species at two contrasting sites [Elektronische Daten] [E.T.F. Witkowski, R.D. Garner] In southern African savannas, bush encroachment is a major problem for range managers. However, little is understood of the actual regeneration processes leading to it, and in particular the role of soil seed banks. The horizontal (between microsites) and vertical (with depth in litter and soil) distribution of soil seed banks of the microphyllous woody species, Acacia tortilis, A. nilotica and Dichrostachys cinerea (all legumes of the Mimosoideae), were quantified in an area with low intensity grazing (reserve), and a bordering cattle farm with high intensity grazing (farm). Species differed in seed bank densities between microsites and sites. Seed densities for all species were highest below parent tree canopies and decreased with distance beyond the canopy, and with soil depth. D. cinerea had the smallest seed bank associated with parent trees, particularly on the farm (8 vs. 1643 seeds/tree on the reserve), A. tortilis had the largest (6357, 31910), with A. nilotica intermediate (1789, 1906). The proportion of current (recently fallen) versus old (≥1year old) seeds differed between species and sites. These species form at least short-term persistent seed banks with the old seeds largely representing the persistent seed bank. Seed densities in the open (inter-canopy) and those dispersed under either of the other two (non-parental) study species were much lower than those associated with parent trees. The latter were mostly found under the acacias (single-stemmed) rather than D. cinerea (multistemmed). Total seed store per parent plant increased with plant size (best fits were mostly power curves of canopy area). A large proportion of intact seeds were viable, namely 81-84% for A. tortilis, 68-77% for A. nilotica and 63-78% for D. cinerea, with no differences between sites. Viability tended to increase with depth of burial, except for A. nilotica seeds at the 3-5cm depths on the farm. At the landscape scale there were 1.5 million and 140 000 A. tortilis seeds/ha on the reserve and farm respectively, with corresponding values of 2000 and 31 000 for D. cinerea, and 23 000 and 86 000 for A. nilotica. Kluwer Academic Publishers, 2000 Disturbance nationallicence Grazing nationallicence Landscape nationallicence Seed dispersal nationallicence Spatially explicit nationallicence Witkowski E.T.F. Restoration and Conservation Biology Research Group, Department of Animal, Plant and Environmental Sciences, University of the Witwatersrand, P.O. Wits 2050, Johannesburg, Gauteng, South Africa aut Garner R.D. Restoration and Conservation Biology Research Group, Department of Animal, Plant and Environmental Sciences, University of the Witwatersrand, P.O. Wits 2050, Johannesburg, Gauteng, South Africa aut Plant Ecology Kluwer Academic Publishers 149/1(2000-07-01), 91-106 1385-0237 149:1<91 2000 149 11258 https://doi.org/10.1023/A:1009850706843 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1009850706843 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Witkowski E.T.F. Restoration and Conservation Biology Research Group, Department of Animal, Plant and Environmental Sciences, University of the Witwatersrand, P.O. Wits 2050, Johannesburg, Gauteng, South Africa aut NATIONALLICENCE 700 1- Garner R.D. Restoration and Conservation Biology Research Group, Department of Animal, Plant and Environmental Sciences, University of the Witwatersrand, P.O. Wits 2050, Johannesburg, Gauteng, South Africa aut NATIONALLICENCE 773 0- Plant Ecology Kluwer Academic Publishers 149/1(2000-07-01), 91-106 1385-0237 149:1<91 2000 149 11258 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer