Article How Tightly Linked Are Pericopsis elata (Fabaceae) Patches to Anthropogenic Disturbances in Southeastern Cameroon? (original) (raw)
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Ecology of Pericopsis elata (Fabaceae), an Endangered Timber Species in Southeastern Cameroon
Biotropica, 2012
Pericopsis elata (Fabaceae) is a tall tree of high commercial value of the moist semi-deciduous African forests. As a result of decades of logging it is now considered as threatened and listed on the IUCN Red List and CITES Appendix II, even though essential biological parameters controlling its population dynamics remain unknown. This study aims at improving the knowledge of the species' ecological parameters, and at assessing the impact of selective logging on its populations in an 118,052 ha forest in Cameroon. After inventorying the species in 1432 ha, mortality and growth were assessed over continuous 5-and 2-yr periods in unlogged and logged areas, respectively. Phenology was monitored in the unlogged forest during 5 yr. The population structure shows high relative abundance of trees in medium size categories. Mean annual diameter increments in both environments did not differ significantly between unlogged and logged areas. P. elata is a deciduous species that flowers at the end of the main dry season. The minimum reproduction and effective flowering diameters were 32 and 37 cm, respectively. Fruit maturation took place during 7 mo. With a minimum logging diameter of 90 cm, the recovery rate computed over a 30-yr period was > 100 percent. Selective logging harvested only 12.1 percent of the total number of seed trees and had little influence on the species' biological parameters. Securing sufficient regeneration as a post-logging action is probably the most important consideration for achieving long-term sustainability.
Open Journal of Soil Science, 2018
One of the problems limiting high survival rates of Pericopsis elata (afrormosia, assamela), a high value timber species, is lack of data on its pedological requirements. A study was conducted in the East Region of Cameroon to identify possible soil properties favoring its spatial distribution. Two test areas, in and out of a Pericopsis elata natural forest stand were identified and in each sampling units of 50 × 50 m delineated. Thirty eight and sixteen quadrats in and out of the stands were respectively sampled for soil physico-chemical properties, number of stems and diameter at breast height. Soil samples in each quadrat were analyzed following standard laboratory procedures. Soil properties were tested for normality and compared for the two sites using Student's t-test. Principal component analysis and correlation analysis were performed on tree and soil data to identify soil factors responsible for spatial distribution. From our findings, key soil indicators favouring Pericopsis elata distribution appear to be acidity (soil pH and exchangeable acidity), base status (base saturation and exchangeable bases) and texture (clay content). More specifically, optimal soil conditions for growth and survival of Pericopsis elata are: pH (4.1-5.0), exchangeable acidity (<4.67 cmolc•kg −1), base saturation (6.2%-17.8%), and clay content (24.0%-49.0%), which should be considered in site selection for reforestation with Pericopsis elata.
Ecology and management of Pericopsis elata (Harms) Meeuwen (Fabaceae) populations: a review
Pericopsis elata (Fabaceae) is a valuable timber species occurring in moist semi-deciduous African forests. While it is at present substantially reduced, the tree's natural distribution previously covered several distinct areas from Côte d'Ivoire to the Democratic Republic of Congo. This species has been logged since the second half of the 20 th century. Because it suffers from a lack of regeneration, P. elata is now included in CITES Appendix II and is recorded as "Endangered A1cd" on the IUCN Red List. As with other long-lived light-demanding species, the survival of P. elata may have been favored by important disturbances that occurred in the Congo Basin during the last millennia. While both international trade and industrial uses of the wood of P. elata are well documented, information about its ecology are very sparse or contradictory, and even absent in some cases (e.g., regarding its effective flowering diameter). Furthermore, data describing the management of P. elata are scarce, including potential solutions to compensate for the deficit of natural regeneration. Along the same lines, genetic studies still remain at an early stage and only vague hypotheses have been offered to explain the origins of the tree's populations. We emphasize the need for new research on those topics. Further studies would be useful in deciding whether P. elata populations can continue to be logged without the species being threatened with extinction. Finally, such research needs to target effective and inexpensive management procedures that could secure the future of the species in a logging context.
Pericopsis elata (Harms) van Meeuwen is a tropical Africa's timber of high economic value. In many countries its low natural regeneration rate does not favor the replacement of harvested populations, thus CITES and IUCN recommended a total protection of the species. This survey aimed to characterize the early growth stages and natural regeneration of P. elata through the determination of seedlings distribution and structure. Squared plots of 2500 m² were installed around stumps and seed-bearing trees respectively in the logged and unlogged forest concessions at Ouesso, near Yokadouma, South-East Cameroon. Stumps, seed-bearing trees and seedlings were counted and their structural parameters (diameter and height) were recorded. A total of 56 plots corresponding to 14 ha were surveyed and 1069 seedlings were recorded. The rate of regeneration was 56% around stumps and 24.13% around seed-bearing trees. The spatial distribution of seedlings appears to be aggregated. Germination and seedling growth have shown that early growth stages of Pericopsis elata are not representing a relevant limiting factor for the evolution of population. However, the limited number of saplings and the lack of poles suggest that light could play an important role in the evolution of the early stages.
Growth and productivity of Pericopsis elata (Harms) Meeuwen in some forest plantations of Cameroon
Forest Science and Technology, 2012
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Plant Ecology and Evolution, 2014
Background and aims – Prior to European colonisation of Central Africa, human populations were dispersed through the forests, where they practiced slash-and-burn cultivation. From the 19th century they were progressively concentrated in villages along roads, leaving large areas of forest derelict. In south-western Cameroon, and elsewhere in Central Africa, forest canopy is dominated by long-lived light-demanding tree species, suggesting a possible role of human disturbance. The aim of this study was to bring new insights into the possible effect of historical human disturbances in terms of timing and spatial extent on the current forest composition. Location – Wet evergreen littoral forest in south-western Cameroon. Methods and key results – A combined vegetation sampling and archaeobotanical survey were conducted. Potsherds, oil-palm endocarps, and charcoal were found throughout the study area, suggesting generalised human occupation and anthropogenic fire. Human occupancy occurred in two periods: between 2200 and 1500 BP, and, more recently, beginning three centuries ago. High frequency of fire and the presence of Elaeis guineensis both dated recently (between 260 and 145 BP) suggest slash-and-burn shifting cultivation practices. These human-induced disturbances may coincide with the age of the current emergent light-demanding species, the age of which can be estimated around 200 years, or with the phases of drying climate recorded in the Central African forest in the early 18th century. Conclusions – These results support the idea that historical human disturbances are one of the major factors that shaped the current forest composition in Central Africa.
International journal of innovation and scientific research, 2021
Three silvicultural experiments with Pericopsis elata were carried out in the Deng-Deng Forest Reserve in 1974 to understand the silviculture of this specie. However, this work has not yet yielded its full results. The objective of the present study is to construct productivity curves and evaluate the effect of silvicultural method and planting type on the height growth of Pericopsis elata. The data collected for this study came from 9 stem analyses carried out in the plantations. A fit to the Johnson-Schumacher model was performed. The variability of productivity curves between the three plantations indicates that there is a consistent relationship between silvicultural methods, planting types and Assamela fertility indices. Three levels of fertility were identified for each plantation at 40 years (H40): 18 m, 22 m and 26 m for P741; 12 m, 15 m and 18 m for P745 and 15 m, 20 m and 25 m for P746. The open field method shows the best growth performance in height (18 m ≤ Ht ≤ 26 m) regardless of plant type, compared to the layered method. Following the large layered silvicultural method, short stumps show better height growth (15 m ≤ Ht ≤ 25 m) than bagged seedlings (12 m ≤ Ht ≤ 18 m).
Early succession in the tropical forest in southern Cameroon, Central Africa
Tropical Plant Research, 2020
Every year in tropical regions, large areas of forest are converted into agricultural field crops by the means of slash and burn. After two or three year's cultivation when the yields decline, the field is abandoned and the farmer clears another portion of forest to plant crops. Following a synchronic approach, early forest succession was studied in southern Cameroon in 70 square plots of 400m² each from former field crops aged between one and five years. In these plots, floristic inventory was done by recording all plant species while a Braun-Blanquet cover abundance index was assigned to each. Quantitative data involved the counting of all tree and shrub individuals of at least 5 cm diameter at breast height (DBH). For each plot the age, the type of vegetation cleared before the last cropping season, the vegetation around the fallow and the number of farming cycles in the same plot were considered as environmental data. The type of crops planted in his former field was also taken into consideration. Data were analyzed using PC-Ord 5.19. Five clusters were discriminated in relation with crops planted and land management. Thickets of Chromolaena odorata developed on fallows frequently reconverted into field crops whereas forest fallows were subjected to light disturbance. In Chromolaena thickets, forest recovery is slower than in forest fallows.