The Seed and Fern Spore Bank of a Recovering African Tropical Forest

Abstract

Seed banks contribute to forest regeneration after disturbance, but less is known about fern spore banks, particularly in a paleotropical context. We sampled the buried seed and fern spore bank in Mabira Forest, a 300 km 2 forest in central Uganda, to explore the effect of time since disturbance. Soil cores (5 cm depth) were taken from 39 plots across three different classes of 'recovery': (1) not disturbed since 1950; (2) logged between 1950 and 1980; and (3) cleared for agriculture between 1970 and 1990 but reforested since. Plant emergence was monitored in a glasshouse. We predicted that the seed bank would reflect time since disturbance, with more pioneer species in recently disturbed stands, and that the fern spore bank would reflect stand age less closely due to greater dispersal capacity. We recorded a median 752 seeds per square meter, most of which were trees; the most abundant species was the invasive tree Broussonetia papyrifera. The fern spore bank was twice as dense, but 95 percent of fern spores were of one species, Christella parasitica. Tree seed density was significantly affected by time since disturbance with fewer seeds in the older stands. Herb seed density, fern spore density, and species richness for all groups were not significantly affected by time since disturbance. Neither seed bank nor fern spore bank closely resembled the aboveground vegetation. We compared our results to existing literature on seed banks in tropical forests, finding that our densities are relatively high for African forests, but low compared to the Neotropics and Australia.Abstract in French is available in the online version of this article.

The role of the peat seed bank in plant community dynamics of a fire‐prone New Zealand restiad bog

“…These patterns may be due to the fern's reproduction mode. Viable 'spore banks' have been identified for at least some fern species (Penrod & Mccormick 1996;Ram ırez-Trejo et al 2004;Esaete et al 2014), and it is possible that Gleichenia gametophytes were overlooked, especially as they look superficially similar to liverworts which were present. However, seed/spore bank recovery is much more common in angiosperms, and it is more likely that Gleichenia relies solely on resprouting for early regeneration as other studies have suggested (Walker & Boneta 1995;Clarkson 1997;Mcqueen & Forester 2000).…”