Pathogenicity of Malaysian Phytophthora palmivora on cocoa,durian, rubber and oil palm determines the threat of bud rot disease

The epidemic of bud rot disease affecting oil palm in Colombia is primarily caused by Phytophthora palmivora. The pathogen has a cosmopolitan presence that includes Southeast Asia, but to date, bud rot has not been reported in this region. This study provides an overview of the potential risk of Malaysian P. palmivora isolates cross‐infecting other host species, including cocoa, durian, rubber and Malaysian oil palm planting materials (Dura × Pisifera, D × P). On cocoa pods, the durian isolate PP7 caused dark brown necrotic lesions. Detached leaf bioassays showed that P. palmivora isolates PP3 and PP7 infected different hosts, except rubber foliage without wounding. Inoculation tests on cocoa, durian and rubber seedlings caused brown necrotic lesions when stems were wounded, with 10% mortality in cocoa and durian at 17 days post‐inoculation (dpi). However, no further infection was observed, and lesions closed within 14–28 dpi on the non‐wounded seedlings. Pathogenicity tests of oil palm seedlings inoculated with isolates PP3 and PP7 indicated that Malaysian P. palmivora isolates were not pathogenic to oil palms based on localized infection observed only through wounding. Overall, the work demonstrated that Malaysian P. palmivora isolates were able to cross‐infect multiple hosts but did not show severe infections on oil palms.     

Afforestation of savannah with cocoa agroforestry systems: a small-farmer innovation in central Cameroon

Cocoa cultivation is generally considered to foster deforestation. Contrary to this view, in the forest–savannah interface area in Cameroon, farmers have planted cocoa agroforestry systems on Imperata cylindrica grasslands, a soil-climate zone generally considered unsuitable for cocoa cultivation. We undertook a survey to understand the agricultural and ecological bases of this innovation. Age, cropping history and marketable cocoa yield were assessed in a sample of 157 cocoa plantations established on grasslands and 182 cocoa plantations established in gallery forests. In a sub-sample of 47 grassland cocoa plantations, we inventoried tree species associated with cocoa trees and measured soil organic matter levels. Marketable cocoa yields were similar for the two types of cocoa plantations, regardless of their age: 321?kg?ha^?1 in cocoa plantations on grasslands and 354?kg?ha^?1 in cocoa plantations in gallery forests. Two strategies were used by farmers to eliminate I. cylindrica prior to the establishment of cocoa plantations, i.e., cropping oil palms in dense stands and planting annual crops. Farmers then planted cocoa trees and fruit tree species, while preserving specific forest trees. The fruit tree and forest tree densities respectively averaged 223 and 68 trees?ha^?1 in plantations under 10?years old, and 44 and 27 trees?ha^?1 in plantations over 40?years old, whereas the cocoa tree density remained stable at 1,315 trees?ha^?1. The Shannon–Weaver index increased from 1.97 to 2.26 over the same period although the difference was not statistically significant. The soil organic matter level was 3.13?% in old cocoa plantations, as compared to 1.7?% in grasslands. In conclusion, our results show that the occupation of grasslands by cocoa agroforestry systems is both an important example of ecological intensification and a significant farmer innovation in the history of cocoa growing.     

Removal of Acacia mangium overstorey increased growth of underplanted Anisoptera marginata (Dipterocarpaceae) on an Imperata cylindrica grassland site in South Kalimantan,Indonesia

Effect of removing Acacia mangium overstorey on the growth of underplanted Anisoptera marginata saplings was studied in a mixed tree plantation established on an Imperata cylindrica dominated grassland site in South-Kalimantan, Indonesia. At the time of overstorey removal the Acacia mangium trees were 80 months old (average height 21 m and DBH 20 cm) and the underplanted Anisoptera marginata saplings 68 months old (average height 4.2 m and DBH 3.1~cm), and the spacing of both species was 2 m × 4 m with such an arrangement that the saplings were located within the same lines as the nurse trees. Eight plots of 192 m² in size were randomly designated to overstorey removal (canopy gap) and no removal (closed canopy) treatments. Removal of Acacia mangium overstorey was carried out by girdling and later cutting down the dead trees. The Imperata grass did not show regrowth in canopy gaps. The mean annual increment for height and DBH of Anisoptera marginata within 22 months after the treatment were higher in canopy gaps (1.3 m a^-1 and 1.4 cm a^-1) than under closed canopy (0.7 m a^-1 and 0.7 cm a^-1). Results indicate good prospects for diversifying the composition of fast-growing forest plantations on grasslands and integrating slow-growing valuable species in plantation programs. Studies on other establishment methods, such as planting in gaps or lines, and further management practices as well as their effect on available light, moisture and nutrients are needed.     

Cacao-fruit tree intercropping effects on cocoa yield, plant vigour and light interception in Côte d’Ivoire

A major challenge for cocoa producers in Côte d’Ivoire is to seek alternative shade trees or crop associations to adapt their planting devices and techniques to the shortage of forests. The recent tendency developed by farmers is to plant simplified orchards combining cacao and fruit trees. An on-farm trial was set up in a 5-year-old cocoa farm to compare a cacao monocrop planted at densities of 1,115 trees ha^?1 with cacao intercropped with orange or avocado trees, both at 44 trees ha^?1. Observations were done on incident light received by the cacao, vigour, growth and cocoa yields. On average, the cacaos received 100 % light in the monocrop, 89.6 % under orange trees and 80.6 % of incident light under avocado trees. They yielded 64.0 pods tree^?1 year^?1 in the monocrop (equivalent to 2.54 kg dry cocoa beans tree^?1), 30.3 pods tree^?1 when combined with orange trees and 28.3 pods tree^?1 with avocado trees. The two combinations allowed cocoa yields equivalent to those observed in the region (0.58 kg dry cocoa beans tree^?1). Vigour and yield were very highly correlated with the incident light received. Both the yield and the incident light are a logistic function of the planting distance from the shade tree. The inflexion point of the logistic functions corresponds to the minimum planting distance between the cacao and the intercropped fruit trees. On this basis, we suggest that the cacaos should not be planted closer than 6.50 ± 0.2 m to the orange or avocado trees.     

Semi-wild palm groves reveal agricultural change in the forest region of Guinea

In West Africa, natural regeneration of oil palms (Elaeis guineensis Jacq.) can be favoured by agricultural practices. The structure of palm groves may thus reflect the history of land use. In this study, we examined the connection between biophysical factors, land use and the structure and dynamics of semi-wild palm groves in the village of Nienh, in the forest region of Guinea (Forest Guinea), in order to determine to what extent semi-wild palm groves could be considered as an ecological indicator of the history of regional landscapes. Grove management strategies of farmers were also determined and related to farm characteristics. In Nienh, semi-wild palm groves were found in three cropping systems with differing characteristics in each. Palms were scarce in lowland agricultural areas (8 palms ha⁻¹), while they were significantly taller (15.8 m on average) and less dense (36 palms ha⁻¹) in agroforests than in slash-and-burn cropping systems (9.4 m and 55 palms ha⁻¹ respectively). Interviews with farmers showed that it was possible for a farmer to have a global strategy of semi-wild palm grove densification combined with oil palm elimination on a plot scale. The lack of regeneration of palms in agroforests resulted from the almost systematic elimination of young palms by farmers. Conversely, in slash-and-burn cropping systems, young palms were often preserved. As the structure of semi-wild palm groves was partly explained by agricultural practices, it could be used as an ecological indicator of changes in practice in relation to socio-economic context.     

Combination of cacao with other plantation crops: an agroforestry system in Southeast Bahia,Brazil

Brazil accounts for about 20% of the world production of cocoa, and about 95% of cocoa produced in Brazil is from the southeastern part of Bahia State. Traditionally, cacao is grown in monoculture (though under the shade of various other species). But various crop combinations involving cacao have recently been undertaken by the farmers with encouragement from Brazilian government.As a part of the crop diversification programme in the traditional cacao growing areas and their surroundings, extensive areas are being planted to other plantation crops, mainly clove and rubber and, to some extent, coconut too. Crop combinations have been adopted in some of these new plantings and cacao is an important component of most of such combinations. Whereas several other crops are combined with clove trees, cacao is usually the only species grown with mature rubber trees. Young rubber trees are, however, interplanted with a number of other species. Productive coconut areas are found mostly in sandy soils along the coast so that there is little intercropping. However, scattered farms are found where coconuts are underplanted with guarana, black pepper, cacao, cashew, etc. as done commonly in other parts of Northeast Brazil.     

The effect of Maya traditional harvesting on the leaf production, and demographic parameters of Sabal palm in the Yucatán Peninsula, Mexico

Palm leaves are an important resource for family households. The effect of harvest on leaf production, growth and fecundity of wild individual palm trees has been studied, but little is known about palm harvest in agro-forestry systems. In the Maya area of the Yucatán Peninsula, Mexico, leaves of the xa’an palm (Sabal yapa, and Sabal mexicana) have been used since pre-Hispanic days for thatching the roofs of traditional Maya houses. The Maya have introduced xa’an palms in homegardens and the care they provide them improves their growth. Maya householders agree on what they consider to be the best harvest intensity for xa’an, recommending one or two harvest events per year, and leaving one or two leaves in each event; however, there is not ecological information documenting whether the traditional harvesting practices are the most adequate to maintain or increase leaf production, and their effect on the growth and fecundity of the palm trees. In Maxcanú, Yucatán, we studied eight family homegardens with S. yapa and S. mexicana. The selected individuals from each homegarden (n = 252) underwent six harvest treatments for 2 years C: control, no harvest, Al: annual harvest, leaving three leaves on the palm, Am: annual harvest leaving two leaves, Ah: annual harvest leaving one leaf, Sl: two harvests per year leaving three leaves, Sm: two harvests per year leaving two leaves. Treatments Ah and Sm simulated the traditional harvest method, and the remaining treatments simulated higher or lower harvest intensities and frequencies. Leaf production was higher in individual palms under higher harvest intensities and frequencies (Ah, Sl and Sm), but palm growth and leaf size were not affected by harvest. Number of inflorescences per palm differed between treatments and between homegardens during the first year only, but we could not find a clear pattern of variation. Production of new leaves was affected by initial palm size and initial leaf number. Removing mature leaves while leaving the young ones, as well as the intensity and frequency, with which traditional harvest is practiced, stimulate palms to compensate the defoliation effects by producing new leaves. This practice is based on empirical Maya knowledge that enables the manipulation of micro-environmental conditions and the development of sustainable harvesting strategies for the xa’an palm in traditional agro-forestry systems.     

Extractable sugar contents of trunks from fruiting and nonfruiting oil palms of different ages

Oil palm trunks (OPTs) are a potential source of sugars for bioethanol production, and so we determined the glucose, fructose, and sucrose contents of hot water extracts from OPTs. Samples of OPTs were obtained from different regions of the trunk, from trunks of palms of different ages (31-, 19-, and 15-year-old), and from fruiting and nonfruiting palms. The extractable sugar contents of the whole OPT and the upper and lower regions of each OPT were calculated. Our results indicated that the upper parts of OPTs should be used for bioethanol production because they yield higher concentrations of sugars than the lower parts do. To produce a highly concentrated glucose solution for bioethanol production, OPTs should be harvested as soon as production of palm oil has been completed and when new male flowers have appeared. If these suggestions are followed, then the estimated ethanol concentration after fermentation is 3.2% and the estimated ethanol production per harvested area is 3.5 kl/ha.     

The role of complex agroforestry systems in the conservation of forest tree diversity and structure in southeastern Ghana

The role of different agroforestry systems in the conservation of plant diversity and forest structure has not been directly compared in many agricultural dominated landscapes. In this study, we investigated tree diversity and forest structure in a complex agroforestry landscape traditionally grown for cocoa and mixed food crops and compared these to the natural forest in southeastern Ghana. The study was carried out using 36 25 m × 25 m plots. There was significant difference [95% Confidence Interval (95% CI)] in the native forest/non-crop tree species richness between the natural forest and the agroforest farmlands but species richness was similar between the cocoa and mixed food crops agroforests. The density of native forest/non-crop trees was significantly higher (P < 0.05) in the natural forest but similar between cocoa and mixed food crops agroforest. Similarly, the basal area of native forest/non-crop trees was significantly higher (P < 0.05) in the natural forest but comparable between cocoa and food crops agroforest. Of the 20 most abundant native forest/non-crop trees recorded, 12 of them showed significant responses (P < 0.05) to land use change with nine of the species significantly abundant in the natural forest relative to the agroforest systems. Eighteen native forest/non-crop trees species in the agroforestry systems were commonly recorded as being used; 100% of them being used as fuel wood with 83.3 and 77.8%, respectively, used as medicines and materials. The findings of this study suggests that although complex agroforestry systems are a poor substitute for the natural forest the heterogeneous mosaic landscape in which complex agroforestry forms part can be strategically managed to maximize the benefits of both sustainable agriculture production and conservation of plant diversity by acting as buffer between protected areas and intensively managed areas.     

Botanical composition and models of metabolizable energy availability from undergrowth in oil palm plantations for ruminant production

The availability of undergrowth is essential for integrating ruminant animals into oil palm plantations. This is because undergrowth can be used as a feed resource for ruminants. This type of production system has the advantage of diversifying income and controlling weeds in the plantation. At least fve botanical groups of herbage can be found in oil palm plantations, namely, grasses, broad leaved plants, legumes, ferns and palms. Grasses were found in abundant through all palm ages. Most grasses are tolerant to higher light intensity and some are shade-tolerant. This study showed that in the early stages of oil palm crop development, sun-loving species tend to dominate the field, mostly broad leaves and legumes, but they will gradually be replaced by shade-tolerant plants when the canopies close. Concentration of metabolizable energy in herbage on offer was 4.6 to 7.0 MJ/kg dry matter. Crude protein content of grasses, broad leaves, legumes, ferns and palms are 11.5%, 15.4%, 16.3%, 12.5% and 12.0%, respectively. Ruminant animals preferred broad leaved plants more than other botanical groups found in oil palm plantation. This paper showed that metabolizable energy available (MEA) models can be used for predicting available energy (MJ/ha/day) from the system for grazing ruminants. This is because MEA model was developed based on both quality and quantity of herbage present in the ecosystem.     

The conservation value of oil palm plantation estates, smallholdings and logged peat swamp forest for birds

The expansion of industrial oil palm cultivation threatens tropical biodiversity globally, especially in developing countries. Driven by plans to generate economic revenue, large-scale plantations are emerging in Southeast Asia, Africa and Brazilian Amazon. However, the ecological impacts of the sector are poorly studied with respect to oil palm management system, and recommended conservation measures are based on limited data. We studied avifauna in oil palm landscapes in Peninsular Malaysia under different management systems (large plantation estates versus smallholdings) and age classes (uniform age versus mixed-age stands). We sampled 41 large plantation estates and 14 smallholdings, as well as 20 sites in an extensively logged peat swamp forest, the type of natural forest prior to conversion to oil palms. Compared with logged peat swamp forest, our results showed that forest conversion to oil palm cultivation may have eliminated 48-60% of bird species. We also found: (i) plantation estates and smallholdings supported similar bird assemblages but the latter supported significantly more species (P = 0.007); and (ii) despite reduced species richness in oil palm landscapes, we found high abundance of some individual bird species in specific types of stands including some forest, migratory, and wetland species. Conversion of natural forest to oil palm landscapes should not occur in the future through clearing of primary or secondary native forests. To complement conventional conservation approaches (e.g. the establishment of protected areas) in palm oil-producing countries, existing plantation estates and smallholdings should be managed in ways to promote improved conservation outcomes, although oil palm landscapes maintained a fraction of the original forest biodiversity. Managing habitat heterogeneity at both a local and a landscape-level is highly recommended in oil palm landscapes to maintain and/or enhance avian biodiversity.     

Response of cocoa trees (<Emphasis Type="Italic">Theobroma cacao</Emphasis>) to a 13-month desiccation period in Sulawesi,Indonesia

In South-east Asia, ENSO-related droughts represent irregularly occurring hazards for agroforestry systems containing cocoa which are predicted to increase in severity with expected climate warming. To characterize the drought response of mature cocoa trees, we conducted the Sulawesi Throughfall Displacement Experiment in a shaded (Gliricidia sepium) cocoa agroforestry system in Central Sulawesi, Indonesia. Three large sub-canopy roofs were installed to reduce throughfall by about 80% over a 13-month period to test the hypotheses that (i) cocoa trees are sensitive to drought due to their shallow fine root system, and (ii) bean yield is more sensitive to drought than leaf or stem growth. As 83% of fine root (diameter <2 mm) and 86% of coarse root biomass (>2 mm) was located in the upper 40 cm of the soil, the cocoa trees examined had a very shallow root system. Cocoa and Gliricidia differed in their vertical rooting patterns, thereby reducing competition for water. Despite being exposed for several months to soil water contents close to the conventional wilting point, cocoa trees showed no significant decreases in leaf biomass, stem and branch wood production or fine root biomass. Possible causes are active osmotic adjustment in roots, mitigation of drought stress by shading from Gliricidia or other factors. By contrast, production of cocoa beans was significantly reduced in the roof plots, supporting reports of substantial reductions in bean yields during ENSO-related drought events in the region. We conclude that cocoa possesses traits related to drought tolerance which enable it to maintain biomass production during extended dry periods, whereas bean yield appears to be particularly drought sensitive.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Palms in Indigenous and Settler Communities in Southeastern Ecuador: Farmers’ Perceptions and Cultivation Practices

Most palms used in agroforestry systems are exploited from wild stands or are only occasionally cultivated, while only a few palms have been domesticated. In this study we investigated how socio-economic factors and people's perceptions of changes in palm use and availability, influenced palm cultivation among indigenous Shuar and mestizo settlers in south-eastern Ecuador. We also looked at how different uses of palms influenced which species they cultivated. Our results showed that perceptions of declining palm availability in combination with heavy reliance on palm products was positively related to palm cultivation. Hence, cultivation was more common in more remote villages where alternative products were hard to get. In addition, palm cultivation was more common among wealthier people and among indigenous people than among recent settlers. This points to a limiting role of assets such as land and to the importance of history and culture with regard to cultivation. It was not possible to identify any single palm use as the primary reason for cultivating a species, but the more uses a species had, the more likely it was to be cultivated. These findings have important implications for development projects that promote cultivation of palms and other long-lived tree crops. They illustrate how market access and lack of necessary assets may undermine cultivation of native species even though these are regarded as important resources.     

两种培育模式下闽楠生长及生物量研究

在福建宁化国有林场开展了混交(马尾松:闽楠混交比例分别为1:1和2:1)和马尾松间伐后林下套种(25%和40%间伐强度)2种培育模式下闽楠生长、材积及生物量的研究。结果表明,造林后第1年,马尾松林下套种的闽楠成活率高于马尾松+闽楠混交林;造林后1-4年,闽楠树高、胸径和材积在马尾松林下套种和马尾松+闽楠混交林中没有显著差异;造林后7-9年,马尾松+闽楠1:1混交林中闽楠胸径、树高、单株材积和单株生物量均显著高于马尾松+闽楠2:1混交林;40%间伐处理后林下套种的闽楠胸径、树高、单株材积和单株生物量大于25%间伐处理。总体上,造林7年后混交林中闽楠生长量和生物量显著高于林下套种。因此,闽楠与马尾松营造混交林比在马尾松林下套种更有利于其生长,但确定适宜的混交比例和加强后期的抚育管理(如间伐)对于闽楠人工林培育仍是十分重要的。     

Carbon storage and density dynamics of associated trees in three contrasting Theobroma cacao agroforests of Central Cameroon

In Central Cameroon cocoa is mainly produced by household farming systems based on complex associations between cocoa and companion trees. Setup either on native/remnant forest or savannah, these agroforestry systems (AFS) are managed according their geographical position and local pedoclimatic conditions. In this paper, we investigated the effects of local management strategies on carbon (C) storage of live trees in three different cocoa production zones of Central Cameroon. In the 58 fields studied, 8,996 cocoa trees and 1,258 companions were surveyed. Tree sampling was non-destructive and to estimate C storage we used allometric models for above- and belowground biomasses. We measured abundance, height, diameter at breast height and determined species of companion trees. We distinguished between four cocoa plantation age categories (immature, young, mature and senescent) and three preceding systems (forest, forest gallery and savannah). We surveyed farmers’ use of each associated tree, allocated it to a functional category and asked if it had been introduced or conserved. Total C content of live trees was on average close to 70 t ha^?1. We found that it mostly relied on associated trees—cocoa trees contribution being ac. 2–12 % of live trees total C. The level of contribution to C storage of companions from different use categories differed between sites—trees producing food had contributed most in Bokito and Obala while trees used for shading or fertility contributed most in Ngomedzap. Dynamics of C storage in live trees was found to be independent from cocoa trees growth and age. When aging, AFS continuously lost companion trees and especially conserved ones putatively because of farmers’ selective logging. Yet, AFS apparently maintained equivalent C storage abilities with time. Hence, even if cocoa do not contribute significantly to C storage in our study, the systems into which they are included are able to significantly store C and may also contribute to other ecological services such as conservation.     

Production and harvest of fibers from Aphandra natalia (Palmae) in Ecuador

Aphandra natalia (Balslev & Henderson) Barfod is native to the western Amazon. It is exploited commercially for its leaf sheath and petiole fibers, which are used for brooms. Data from a 2 year study on production and harvest of fibers in the province of Morona-Santiago in Ecuador shows correlations to exist between the degree of the palm's exposure to light and leaf production, and between exposure to light and petiole length (maximum fiber length), while correlation is absent between exposure to light and fiber load per leaf. A linear relation was found between time and leaf production, with an overall average of 5.5 leaves produced per palm per year. No difference in leaf production of male and female palms was found among palms growing at low light intensities, while among palms in open, light-exposed areas, males were found to produce significantly more leaves than females. An average of 8.5 leaves are cut per palm per harvest, yielding 3.4 kg of fibers, while 6.9 leaves are left untouched. Average harvest time per palm is 33 min. Under optimal conditions (high densities of easy accessible palms), one harvester may harvest and clean about 20 kg of fibers in 1 day, selling at US$1.1 kg⁻¹. One hectare with high, but natural, densities of the palm may produce fibers worth US$460 per year, which can be harvested and prepared in 22 work days. Exploitation of the edible fruits may be combined with fiber extraction if female palms are left to produce fruits, while male palms are exploited for fibers, or if harvest frequency of fibers from female palms is lowered considerably below the average of once every 1.55 years. The exploitation practised in the study area appears sustainable.     

Yields of cocoa/kola intercrops in Nigeria

The yields of two intercropped cocoa/kola plots at the Cocoa Research Institute of Nigeria, Ibadan, (W8/1 and C3/1), were compared with the yields of monoculture plots (N4/A and W1/2). It was found that 1.75 ha of monoculture plot gave the same crop yield (kg/ha) as 1.00 ha of mixed crop. The cocoa component started fruiting earlier than kola and also continued to yield annuall so there was no crop failure in any year.     

Community assessment of agroforestry opportunities in GaMothiba,South Africa

The sustainability of cocoa growing systems in the humid tropics is debatable. Socio-economic and technical data were obtained from 1,171 cocoa farmers and 1,638 cocoa plantations to assess the long-term dynamics of cocoa agroforests in central Cameroon since the beginning of the twentieth century. On-site, we estimated the age of the cocoa trees and measured their density in a sub-sample of 402 cocoa plantations. We inventoried associated woody species in 45 cocoa plantations from this sub-sample. Our results revealed a high Shannon index for the cocoa plantations (2.6) and showed that an average of 25 tree species per cocoa plantation had been planted with the cocoa trees at a density of 120 trees ha⁻¹. Surveys indicated that there had been no mineral fertilization. Nearly 70% of the cocoa agroforests were over 40 years old, and all farmers continuously regenerated their cocoa tree stands. Irrespective of the cocoa plantation age, the cocoa tree density remained over 1,000 plants ha⁻¹, and fermented dried cocoa yields were 255 kg ha⁻¹ on average. Cocoa agroforests occupied 60% of the cultivated area on farms and cocoa sales accounted for 75% of total farm income. Almost a third of the farmers were from the area and under 40 years old. In conclusion, our results show that the farmers’ agroforestry practices, in addition to the fact that the cocoa tree stands were continuously regenerated and passed down between generations of farmers, could explain the long-term dynamics of cocoa agroforests in central Cameroon.     

棕榈在孟加拉乡村传统利用——一种可持续的生物多样性管理手段(英文)

采用多级采样的方法研究了孟加拉国农村耕作区内棕榈树的传统利用模式和当地的管理经验。农民管理棕榈主要为获取树液产品,生产以糖为主的次生品。树液可直接用作饮料,也可加工成糖蜜或酒精饮料。7块不同地块为棕榈提供生长环境,20.40%的棕榈种植在果园内。尽管中等级的农民拥有多数棕榈(33%),但是主要管理棕榈的是没有土地的农民,他们靠棕榈维持生计。这些农民将自己的智慧应用到棕榈管理当中,从种植到开孔取树液再到产品加工。如果能更科学地管理棕榈,加上农民的智慧,棕榈业将会对当地经济发展起到重要作用,也会丰富当地生物多样性。