Wild populations of the Afromontane forest tree Prunus africana (Rosaceae), known as the African Cherry or Red Stinkwood (sometimes called Pygeum africanum) are currently the sole source of bark and bark extract exported from Africa and Madagascar to Europe. This trade has taken place for nearly 30 years, for production of at least 19 different herbal preparations sold by 23 companies based primarily in Europe, but also in North and South America. These are used to treat benign prostatic hypertrophy (BPH), a common disease in older men. This account provides an interesting case-study of a medicinal species which is in transition from wild harvest to cultivated sources of supply. It also illustrates the ‘ecological footprint’ of Europe on African forests, and upon a medicinal resource within them. Bark exploitation has caused serious damage to wild populations of Prunus africana, including trees inside forests of high conservation value in Madagascar and Cameroon. Because of the difficulty of implementing and enforcing conservation measures or developing local institutions to do so, sustainable bark harvesting of remaining wild stocks by local communities is considered unlikely in Cameroon and in Madagascar. For these reasons, cultivation has been suggested as an alternative source of bark production. This study investigated the economic feasibility of different planting systems (enrichment planting, small-scale farming and plantations) for Prunus africana cultivation. As part of this process, we investigated Prunus Africana bark production and growth rates, finding statistically significant correlations between bark thickness, diameter at breast height (dbh) and tree height. Prunus africana showed rapid growth, reaching 14m high and 37cm dbh in 18 years. Results of a comparison between the flow of costs and benefits from small-scale production of Prunus africana and Eucalyptus camaldulensis show that Eucalyptus camaldulensis cultivation is 30% more profitable than Prunus Africana production. But there are reasons why farmers might rather invest in Prunus africana instead of, or in addition to, Eucalyptus trees: Prunus africana is highly valued as an ingredient in many local medicinal treatments, it is used in making tools such as hoes and axes, and it is a good source of poles and firewood. Moreover, farmers and field observation indicated that with the possible exception of maize, crop yield is not much affected by the presence of Prunus africana in the fields. This contrasts with the depressive effect of Eucalyptus trees on crop yields. In North West Province, Cameroon, at least 3,500 farmers are already planting Prunus africana. Bark price is affected by moisture content, distance from the factory and the monopoly, which the company has had on export of bark and bark extract. This study determined bark moisture content to be 42-50%. In rural Cameroon, intermediaries only pay 70 FCFA (0.14 US$) per kg of Prunus africana bark, equivalent to about US$ 142 per ton of fresh bark. At the factory gate, bark sells for 104-270 FCFA francs per kg (in 1994, 1 US$ = 490 CFA), depending on bark moisture content and quality, equivalent to US$ 212 – 551 per ton. Higher prices were paid for bark in Cameroon in 1994, when an Italian company paid 250 FCFA francs/kg, regardless of bark moisture content (US$510 per ton of fresh bark). In Kenya, the price paid to the exporter was considerably higher (11 French francs (US$ 2) per kg). This is equivalent to a price of US$ 2,000 per ton of fresh bark. By comparison, the price for fresh bark of the black wattle, Acacia mearnsii, which is cultivated for its tannin- rich bark, was US$ 94 per ton. On the basis of this study, we recommend clarification of Cameroon forestry law to enable farmers to sell bark from Prunus africana trees they cultivate, that information on the best methods for Prunus africana cultivation from seed be provided to farmers, more competitive bark prices that reflect the international market value of this product, and the initiation of an out-grower scheme with the involvement of the pharmaceutical company that buys the bark and has a monopoly on the export of bark extract.
Tag: flooding
Farm level evaluation of drainage technology for mungbeans grown prior to lowland rice
There is substantial potential to expand the area planted to pre-rice upland crops on rainfed lowland ricelands if practical surface drainage methods can be used to reduce waterlogging during the early rains. Previous agronomic research Found substantial yield advantages in pre-rice mungbean performance with simple ridging technology. We conducted studies in cooperation with farmers from 1987 to 1990 to evaluate these tractor-ridging and animal-ridging methods on a field scale. Heavy rainfall caused natural surface flooding on 7 to 25 days in broadcast-seeded plots. Tractor-ridging elevated the upper root zone 11 cm above the soil surface, and maintained free-water levels below the ridge surface. The ridge height with animal ridging was half that obtained with tractor-ridging, and protection from surface flooding was intermediate. Grain yields were significantly higher across farms (n=7) with tractor ridging compared to broadcast-seeding (360 kg/ha vs 166 kg/ha). Comparativenet returns with ridging were 215O/ha vsrn49/ha. In a season without waterlogging. Yields among planting systems were comparable (672 kg/ha vs 602 kg/ha). The greatest advantages of ridging were exhibited in fields subject to moderate waterlogging stress. Simple surface drainage techniques tend to stabilize yields, and enable expanded pre-rice mungbean production on waterlog-prone ricelands.
Flooding tolerance of four tropical peatland tree species in a nursery trial
In order to facilitate hydrological restoration, initiatives have been conducted to promote tree growth in degraded and rewetted peatlands in Indonesia. For these initiatives to be successful, tree seedlings need to be able to survive flooding episodes, with or without shade. We investigated the survival rates and the formation of adventitious roots in the case of four tree species exposed to combinations of different shading and water levels under controlled conditions in a nursery, with artificial rainwater and with peat soil as the medium. The research focused on the following questions (i) whether trees can grow on flooded peat soils; and (ii) which plant traits allow plants to cope with inundation, with or without shade. The four tree species compared (Shorea balangeran, Cratoxylum arborescens, Nephelium lappaceum and Durio zibethinus) include two natural pioneer and two farmer-preferred fruit trees. The experiment used a split-split plot design with 48 treatment combinations and at least 13 tree-level replicates. The study found that S. balangeran and C. arborescens had relatively high survival rates and tolerated saturated condition for 13 weeks, while N. lappaceum and D. zibethinus required non-saturated peat conditions. S. balangeran and C. arborescens developed adventitious roots to adapt to the inundated conditions. D. zibethinus, S. balangeran and N. lappaceum grew best under moderate (30%) shading levels, while C. arborescent grew best in full sunlight.
Population dynamics of Hippophae rhamnoides shrub in response of sea-level rise and insect outbreaks
The coastal vegetation of islands is expected to be affected by future sea-level rise and other anthropogenic impacts. The biodiverse coastal vegetation on the eastern part of the Dutch Wadden Island of Ameland has experienced land subsidence caused by gas extraction since 1986. This subsidence mimics future sea-level rising through increased flooding and raising groundwater levels. We studied the effects of this relative sea-level rise and other environmental factors (i.e. insect outbreaks, temperature and precipitation) on the population dynamics (i.e. cover and age structure and annual growth) of the shrub seabuckthorn (Hippophae rhamnoides L.) in young (formed after 1950) and old (formed before 1950) dune areas over a period of 56 years (1959–2015). We found an increase in seabuckthorn cover in the young dune areas since 1959, while over time the population in the old dunes decreased due to successional replacement by other species. With the increasing age of the young dunes, we found also a decrease in sea-buckthorn after 2009. However the sharp decrease indicated that other environmental factors were also involved. The most important determinant of annual shrub growth appeared to be five outbreaks of the brown-tail moth (Euproctis chrysorrhoea L.), in the last decade. Relative sea-level rise caused more frequent flooding and reduced growth at lower elevations due to inundation or soil water saturation. This study clearly indicates that sea-buckthorn is affected by relative sea-level rise, but that other ecological events better explain its variation in growth. Although shrub distribution and growth can be monitored with robust methods, future predictions of vegetation dynamics are complicated by unpredictable extreme events caused by (a)biotic stressors such as insect outbreaks.