Variation in vegetation cover and seedling performance of tree species in a forest-savanna ecotone release_7hwjmw5tcvdmrayx7v4ae27vum [as of editgroup_72n3lehyjvdi5nronfaphjnhau]

Abstract

<jats:title>Abstract</jats:title>Differential tree seedling recruitment across forest-savanna ecotones is poorly understood, but hypothesized to be influenced by vegetation cover and associated factors. In a 3-y-long field transplant experiment in the forest-savanna ecotone of Ghana, we assessed performance and root allocation of 864 seedlings for two forest (<jats:italic>Khaya ivorensis</jats:italic> and <jats:italic>Terminalia superba</jats:italic>) and two savanna (<jats:italic>Khaya senegalensis</jats:italic> and <jats:italic>Terminalia macroptera</jats:italic>) species in savanna woodland, closed-woodland and forest. Herbaceous vegetation biomass was significantly higher in savanna woodland (1.0 ± 0.4 kg m<jats:sup>−2</jats:sup> vs 0.2 ± 0.1 kg m<jats:sup>−2</jats:sup> in forest) and hence expected fire intensities, while some soil properties were improved in forest. Regardless, seedling survival declined significantly in the first-year dry-season for all species with huge declines for the forest species (50% vs 6% for <jats:italic>Khaya</jats:italic> and 16% vs 2% for <jats:italic>Terminalia</jats:italic>) by year 2. After 3 y, only savanna species survived in savanna woodland. However, best performance for savanna <jats:italic>Khaya</jats:italic> was in forest, but in savanna woodland for savanna <jats:italic>Terminalia</jats:italic> which also had the highest biomass fraction (0.8 ± 0.1 g g<jats:sup>−1</jats:sup> vs 0.6 ± 0.1 g g<jats:sup>−1</jats:sup> and 0.4 ± 0.1 g g<jats:sup>−1</jats:sup>) and starch concentration (27% ± 10% vs 15% ± 7% and 10% ± 4%) in roots relative to savanna and forest <jats:italic>Khaya</jats:italic> respectively. Our results demonstrate that tree cover variation has species-specific effects on tree seedling recruitment which is related to root storage functions.
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