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Open Journal of Forestry 2019年第4期9卷 341-354页

作者： Koubouana Félix Atsoumpari Ngakabi Létycia Adeline Ndzai Saint Fédriche Ifo Suspense Averti Laboratoire de Géomatique et d’Ecologie Tropicale Appliquée (lgeta) ENSAF Brazzaville Congo Laboratoire de Géomatique et d’Ecologie Tropicale Appliquée (lgeta) ENS Brazzaville Congo

The factors influencing the distribution of forests and their development are important in order to better understand the bio-functioning of tropicals ecosystems forests. The Republic of the Congo has an important forest area of 23.5 million ha subdivided into three large massifs with different forest units from the north until the south of the country. The present study proposes to highlight the relationship between the edaphic and pedological factors and the distribution of the floristic species of some tropical forests of the Congo. To achieve this aim, a principal component analysis (PCA) was to identify similarities or oppositions between variables and to locate the most correlated variables. Also, the indices of biodiversities were used to assess the biodiversity between forest plot and forest sites. A total of 238 species distributed in 46 families were counted. We noted a CS similarity between Mbomo-Kellé and FMU Mokabi-Dzanga of 50%. However, there was considerable variability between the forests of the Impfondo-Dongou axis and of the forest of other localities. The main component analysis carried out showed that the distribution of floristic species in the studied forests is determined by the edaphic factors.

关键词： Tropical Forest Congo Biodiversity’s Indices Principal Component Analysis Environmental Factors Similarity Coefficient

Soil Seed Bank of the Marantaceae Forests of Ouesso Forest Industry (IFO), Republic of Congo

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Open Journal of Applied Sciences 2023年第11期13卷 1935-1950页

作者： Stevy Endurance Nkellankela Chauvelin Douh Christian Moussoumbou Belvina Chardène Mabengo Larisa Mbouchi Malonga Saint Fédriche Ndzaï Félix Koubouana Laboratory of Geomatics and Applied Tropical Ecology (lgeta) Superior National School of Agronomy and Forestry (ENSAF) Marien N’GOUABI University Brazzaville Congo Department of Forest Ecology National Forestry Research Institute (IRF) Brazzaville Congo

The soil seed bank is a key indicator of natural regeneration and/or forests resilience after disturbances. This study evaluates the soil seed bank characteristics in two Marantaceae forests plots of Ouesso Forest Industry (IFO) in north of the Republic of Congo. In each plot, 12 samples were taken per soil layers (0 - 5 cm, 5 - 10 cm, 10 - 15 cm and 15 - 20 cm deep). Diversity and abundance seed were estimated after germination of soil samples. The results revealed 101 seedlings belonging to 17 species for plot 1 and 129 seedlings belonging to 15 species for plot 2. The average densities of germinated seeds were respectively 281 seedling/m2 and 358 seedling/m2. There were no significant differences (p > 0.05) between the mean densities of the two plots. Herbaceous species dominated with percentages of 71% and 73%, respectively in plot 1 and plot 2. Both plots showed potential of regeneration from the soil seed bank. However, this potential seems higher in plot 2. Pioneer taxa were more abundant in the soil seed bank of plot 1 (4 woody pioneer species) than in plot 2 (1 woody pioneer species). The highest species richness was obtained in the first two soil layers (0 - 5 cm and 5 - 10 cm depth) while 25% of species were exclusively found in the deepest layer (15 - 20 cm) in plot 2. The study suggests silvicultural interventions based on planting or enrichment techniques for contribute to sustainable management of Marantaceae forests that could prevent the growth and development of seedlings.

关键词： Soil Seed Bank Seedlings Marantaceae Forests Natural Regeneration Forest Resilience Republic of Congo

Regeneration Potential of Woody Species at the Side of Secondary Roads Post-Logging of Loundoungou-Toukoulaka Forest Management Unit, Republic of the Congo

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Natural Resources 2023年第7期14卷 102-120页

作者： Chauvelin Douh Larisa Mbouchi Malonga Donatien N’zala Belvina Chardène Mabengo Christian Moussoumbou Saint Fédriche Ndzaï Félix Koubouana Marien N’Gouabi University Superior National School of Agronomy and Forestry (ENSAF) Laboratory of Geomatics and Applied Tropical Ecology (LGETA) Brazzaville Republic of the Congo National Forestry Research Institute (IRF) Department of Forest Ecology Scientific City of Brazzaville Brazzaville Republic of the Congo

Natural regeneration is the basis of a dynamic and demographic balance of plant populations. The objective of this study was to assess the natural regeneration potential of woody species along secondary roads post-logging abandoned since 2008 and 2018. In the two Annual Allowable Cuts (AAC 2008 and AAC 2018), 24 regenerating sub-plots (i.e. 12 sub-plots for AAC 2008 and 12 sub-plots for AAC 2018) with a unit area of 5 m × 5 m were delimited with a total area of 0.06 ha (i.e. 0.03 ha for each AAC). The abundance and diversity of woody species were respectively inventoried and estimated. Two estimators of the specific richness were used to estimate the floristic diversity of each Annual Allowable Cuts (AAC). The results reveal globally 88 woody species in the AAC 2008 and 241 woody species in the AAC 2018, with respective average densities of 2933 stem/ha and 8033 stem/ha. There was a very highly significant difference between the mean densities of the two AAC (Kruskal-Wallis test;H = 2.36, p-value < 0.000). The results also highlight a great diversity and a relatively high abundance of woody species in the 2018 AAC compared to the 2008 AAC. Also, the spatial structuring of the sub-plots on the basis of Principal Component Analysis (PCA) demonstrates that the floristic composition of the two AAC is globally different. The study suggests silvicultural interventions and the long-term assessment of regenerating woody species along abandoned secondary roads in order to guarantee the sustainable management of their population.

关键词： Regeneration Dynamics Woody Species Abandoned Secondary Roads Forest Management Unit

Changes in Chemical Composition of Soluble Organic Chemical Compounds during Litters Decomposition into Tropical Forest of Milletia laurentii De Wild

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Open Journal of Forestry 2019年第1期9卷 70-87页

作者： Gouolaly Tsiba Mavoungou Naiving Flovique Rosère Edzonga Josianne Milandou Matoko Jodhry Préféré Malonga Urielle Marini Madingou Parfait Noé Binsangou Stoffenne Ifo Suspense Averti National Institute for Research in Health Science Department of Pharmacopeia and Folk Medicine ChemistryOrganic Biomolecules and Pharmacodynamics LaboratoryBrazzavilleRepublic of Congo Sciences and Technologies Faculty Marien Ngouabi UniversityBrazzavilleRepublic of Congo lgeta ENSMarien Ngouabi UniversityBrazzavilleRepublic of Congo ENSAF Marien Ngouabi UniversityBrazzavilleRepublic of Congo

Recent publication attested that in the urban forest of Brazzaville, litter decomposition is faster with almost 45% of initial weight loss than in the dry season, where an average loss of 26% in initial litter weight is noted (Ifo et al., 2018). This study was carried out in the urban forest of Brazzaville to follow the decomposition of some organic compounds/secondary metabolites (reducing Sugars, total Flavonoid and Polyphenols) of the leaves litters of two tropical species Antiaris toxicaria Lesch and Millettia laurentii De Wild. Thin-layer chromatography and spectrophotometric assay of these metabolites were used on the samples of litters collected in the field on various dates of follow-up of the decomposition (0 d, 14 d, 28 d, 42 d, 56 d, 72 d and 84 d). The chromatographic profile of initial litters shows a series of spots on yellow florescence materializing presence of flavonoids, green fluorescence revealing the presence of the acids phenols derived from the cinnamic acid. But the chromatographic profile of the two litters in decomposition after two weeks remains without structural information, being able to characterize the decomposition of the chemical families highlighted in the initial litters. Also, the analysis of quantitative total reducing sugar in the initial litters, gives average concentrations of 64.4, 58.6, 57.5 g EG/kg Ms respectively for the litters of Millettia laurentii De Wild, Antiaris toxicaria Lesch and the mixed litters (Millettia laurentii and Antiaris toxicaria). Comparatively with the other types of litters, the initial average concentrations in phenolic compounds (polyphenols and flavonoids totals) were the highest for the litters of Antiaris toxicaria Lesch (27.3 g EAG/kg Ms and 13.07 g EC/kg Ms) (P = 0.001). The losses of organic chemical compounds are more significant during the first two weeks of experiment than after this period. Antiaris toxicaria Lesch loses on average 43.8 g EG/kg Ms of reducing Sugars, 12.21 g EC/kg Ms of

关键词： Tropical Urban Forest Litter Decomposition Organic Chemical Compounds

Soil Seed Bank Characteristics of the Mbe and Nguela Shrub Savannas, and Implications for the Reforestation, Republic of Congo

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Open Journal of Ecology 2023年第7期13卷 435-453页

作者： Chauvelin Douh Christian Moussoumbou Belvina Chardène Mabengo Larisa Mbouchi Malonga Gilbert Nsongola Tite Miafouna Aimé Judicaël Mahoua Saint Fédriche Ndzaï Félix Koubouana Laboratory of Geomatics and Applied Tropical Ecology (lgeta) Superior National School of Agronomy and Forestry (ENSAF) Marien N’GOUABI University Brazzaville Republic of Congo National Forestry Research Institute (IRF) Department of Forest Ecology Scientific City of Brazzaville Brazzaville Republic of Congo Institute of Research in Exact and Natural Sciences (IRSEN) Scientific City of Brazzaville Brazzaville Republic of Congo

The soil seed bank is an important source of restoration and resilience of disturbed ecosystems. This study evaluates the regeneration potential through the soil seed bank of the shrub savannas of Nguela and Mbe in order to predict the eventual dynamics. Three plots of 0.25 ha subdivided into four sub-plots of 0.015 ha have been installed in each savannah. In total, 48 samples of each savannah, i.e. 96 samples of both savannas, have been taken from the soil layers, 0 - 5 cm, 5 - 10 cm, 10 - 15 cm and 15 - 20 cm. Species diversity and abundance of the soil seed bank have been assessed after germination. The results reveal 167 seedlings belonging to 23 species in the Mbe savannah and 144 seedlings belonging to 14 species in the Nguela savannah. The total densities of the germinated seeds were respectively 463.63 seeds/m2 and 400 seeds/m2. Nevertheless, the 20 cm deep layers have illustrated themselves compared to the superficial layers with densities of 16.29 seeds/m2 and 21.66 seeds/m2, respectively, in the savannas of Mbe and Nguela. Herbaceous species largely dominated, with percentages of 91% and 100%, respectively, in the savannas of Mbe and Nguela. Alone, the Trema orientalis (L.) Blume species has been identified as woody species in the Mbe savannah. The greatest specific richness has been obtained in the first five centimeters of soil, with 21.73% and 28.57% of exclusive species, respectively, in the savannas of Mbe and Nguela. The results reveal that restoration through the soil seed bank would be limited to a single woody species found (T. orientalis). Consequently, the study suggests silvicultural interventions based on planting or enrichment techniques for sustainably managed savannas exposed to anthropogenic disturbances.

关键词： Soil Seed Bank Shrub Savannas Restoration Anthropogenic Disturbances Republic of Congo

Soil Seed Bank Characteristics in Congolese Rainforests and Implications for Post-Logging Plots Reforestation

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Open Journal of Forestry 2023年第3期13卷 294-314页

作者： Chauvelin Douh Belvina Chardène Mabengo Jean de Dieu Nzila Larisa Mbouchi Malonga Gilbert Nsongola Jean Joël Loumeto François Mankessi Saint Fédriche Ndzaï Félix Koubouana Laboratory of Geomatics and Applied Tropical Ecology (lgeta) Superior National School of Agronomy and Forestry (ENSAF) Marien N’GOUABI University Brazzaville Republic of the Congo National Forestry Research Institute (IRF) Department of Forest Ecology Scientific City of Brazzaville Brazzaville Republic of the Congo Higher Teacher Training College (ENS) Marien N’GOUABI University Brazzaville Republic of the Congo Institute of Research in Exact and Natural Sciences (IRSEN) Scientific City of Brazzaville Brazzaville Republic of the Congo Biodiversity Laboratory Management of Ecosystems and the Environment Sciences and Techniques Faculty (FST) Marien N’GOUABI University Brazzaville Republic of the Congo

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 explo

关键词： Soil Seed Bank Natural Regeneration Logging Commercial Tree Species Central African Rainforests