Seed bank dynamics and restoration of Ibodi monkey forest reserve, Southwestern Nigeria

Abstract

Ibodi Monkey forest reserve (IBMFR) is known for its rich flora and fauna, mainly contributed by regrowth forest species. However, intensive anthropogenic interferences such as agriculture, illegal mining and selective exploitation over a large extent of these ecosystems in the past years have led to a serious depletion of forest's diversity. Consequently, restoration of IBMFR has become a high priority for ecological management of forest. The distribution of soil seed bank in three different physiognomies, (natural regrowth forest, cocoa plantation and tree fallow) at Ibodi monkey forest were investigated. Six sample plots, each 25 m x 25 m, from each physiognomy were chosen for this investigation. Seasonal variation of seed bank density at various soil depths were carried out by using soil auger to bring soil samples out from 0-15 cm (topsoil) and 15-30 cm (subsoil) and seedling emergence monitored. The total seed density at 0-15 cm depth was significantly (p < 0.05) higher than the seed bank density at 15 -30 cm depth in both seasons. Seed density varied from 288 seeds/m² to 768 seeds/m² in rainy season and 288 seeds/m² to 1287 seeds/m² in the dry season. Seed bank density was significantly (p<0.05) higher in dry season compared with rainy season in regrowth forest and tree fallow physiognomies. This study revealed seeds are more concentrated in the upper soil layer than the lower soil layer in the three physiognomies, with relatively large number of herbaceous species compared with woody species. The seedbank may not be sufficient to restore the forest reserve. Additional management actions, such as active seed sowing of target species, may be necessary.

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Keywords: Disturbance, physiognomy, seed, season