TITLE:
Soil Seed Bank Characteristics in Congolese Rainforests and Implications for Post-Logging Plots Reforestation
AUTHORS:
Chauvelin Douh, Belvina Chardène Mabengo, Jean de Dieu Nzila, Larisa Mbouchi Malonga, Gilbert Nsongola, Jean Joël Loumeto, François Mankessi, Saint Fédriche Ndzaï, Félix Koubouana
KEYWORDS:
Soil Seed Bank, Natural Regeneration, Logging, Commercial Tree Species, Central African Rainforests
JOURNAL NAME:
Open Journal of Forestry,
Vol.13 No.3,
July
5,
2023
ABSTRACT: The soil seed bank is considered as an important mechanism for the
natural regeneration, resilience and conservation of the forests after
disturbances. This study evaluates the
characteristics of the soil seed bank in two post-logging plots of
Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and
another exploited in 2021. In each study plot, 40 samples were collected per
soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth).
The species diversity and abundance of the soil seed bank were estimated after
soil samples were brought to germination. The results demonstrated that 347
seedlings belonging to 37 species in the plot exploited in 2008 and 418
seedlings belonging to 27 species in that exploited in 2021 germinated during
20 weeks of monitoring.The total densities of the seedlings identified were respectively 1446
seedlings/m2 and 1742 seedlings/m2.The plot exploited in 2021 presented a higher proportion of herbaceous
species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer
species were recorded in the plot exploited in 2008.These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga
cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to
20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer
demonstrated important proportions in woody species (9%), these are in
particular Rubiaceae sp.4 and Nauclea diderrichii.While
that exploited in 2021, presented 19% of woody species, namely the species of
Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly
exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species
recorded with densities of 108 seedlings/m2 and 4 seedlings/m2,
respectively in the plot exploited in 2008 and that exploited in 2021.
Commercial tree species are poorly represented in the soil seed bank. Consequently,
the study suggests that to improve the natural regeneration of the commercial
species, silvicultural interventions based on planting techniques in the
exploited plots should be more effective in order to sustainably manage these
production forests.