Article

Firewood yield and profitability of a traditional Daniellia oliveri short-rotation coppice on fallow lands in Benin

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Abstract

Sub-Saharan Africa has a great diversity of local coppicing species which are exploited in traditional short coppice systems for firewood. Biomass yield and profitability of these systems as well as their responses to silvicultural improvement are little known. This study evaluated the firewood yield and the profitability of a traditional Daniellia oliveri short-rotation coppice on fallow lands in central Benin. Two weed management options were considered: (1) the weedy option, usually practiced by locals, which experienced grass competition and bushfires, and (2) the weed-free option, which consisted in periodic removal of grasses and other species. Destructive measurements and allometric equations were used to estimate biomass yield in 12 plots over 42 months. A cost-benefit analysis model based on the net present value and the benefit-cost ratio was used to compare the profitability of the two management options. Biomass accumulation rate averaged 1.080.20 tonnes of dry matter ha�1 year�1 (t DM ha�1 year�1) in weedy conditions. Weed removal improved 3.5 times this rate in weed-free plots (3.83 � 0.47 t DM ha�1 year�1). After 42 months, total biomass reached 3.67 � 0.65 t DM ha�1 in weedy plots and 11.63 � 0.76 t DM ha�1 in weed-free plots. Most of the biomass (�88%) was marketable in local markets. Coppice exploitation was profitable after 24 months for both management options. Weed removal improved the profits three times. A sensitivity analysis showed that both options were still profitable with up to 25% increase of labour and transport costs, 25% decrease of biomass price and 12% increase of the discount rate.

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... A coppice cycle in a woodland where firewood is continuously harvested maintains links with traditional practices because for rural people, firewood is still the major source of cooking energy in the communal areas, as it was in years gone by (Mason and MacDonald, 2002). As a result of the ongoing high demand for firewood, collection consists of cutting even the green coppice of a previously harvested tree stump (Avohou et al., 2011). This reduces the overall productivity of an ecosystem that supplies the bulk of coppices (Avohou et al., 2011). ...
... As a result of the ongoing high demand for firewood, collection consists of cutting even the green coppice of a previously harvested tree stump (Avohou et al., 2011). This reduces the overall productivity of an ecosystem that supplies the bulk of coppices (Avohou et al., 2011). Rotational harvesting strategies can thus be implemented that maintain the community structure, ensuring that the removal of excess production will not alter the production and sustainability of the ecosystem (Shackleton, 1993). ...
Thesis
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The growth and recovery of trees from disturbances such as fire and browsing is driven by the intensity of the disturbances and the availability of resources. In savannas, resprouting has become recognized as a key functional trait in plant ecology over the past decade. Although this may indeed be the case, there is still limited information about the physiology and growth strategies of resprouting trees. Available information about the influence of disturbance comes from ecosystems that are in many ways different from tropical and sub-tropical savannas. Therefore it is important to know and understand post-disturbance tree responses and limitations so as to establish sustainable use and management practices. This thesis reports the findings of a study, conducted in the Mpumalanga province of South Africa, aimed at achieving a better understanding of the influences of resource availability (water and nutrients) and disturbances (herbivory and repeated cutting) on the coppicing of a widely distributed savanna tree species that is both ecologically and economically important; Terminalia sericea. To investigate the effects of resource availability, cut trees were exposed to different levels of water and nutrient (nitrogen and phosphorus) supplementation over a period of two years in a factorial experimental design. A number of coppice regrowth variables (e.g. shoot production, resprout shoot diameter and shoot length) were measured monthly, while the phenological responses (e.g. timing of leaf discolouration and fruit presence) were monitored every two weeks. The effects of disturbances were investigated in two separate experiments, in which cut trees were exposed to a five month browsing period and different cutting frequencies, respectively. Coppice regrowth variables were monitored for 12 months in trees exposed to browsing and for five months in trees exposed to different cutting frequencies. The effect of multiple cutting cycles on total non-structural carbohydrates and leaf chemistry (carbon, nitrogen and phosphorus) was measured. There was evidence of self-thinning of coppice shoots within cut trees in all experiments in the second year of growth, with supplemented trees also recording lower shoot numbers. With shoot production higher in trees that received no resource addition, water and nutrients interacted synergistically, doubling shoot diameter and iii shoot length for supplemented trees after 12-months of addition. The majority of the phenophases monitored peaked in the wet growing season. Supplemented trees changed colour from the typical green to senescent yellow later in the growing season than unsupplemented trees. Fruit presence occurred in the second year after cutting for supplemented trees. Shoot length and shoot diameter for unbrowsed trees were twice those for browsed trees, with leaf nitrogen and phosphorus content significantly higher for browsed trees compared to unbrowsed trees. Trees subjected to multiple cutting cycles recorded half the TNC levels, and half the resprout shoot diameter and shoot length of trees cut only once. Results from this study demonstrate that self-thinning (i.e., negative change in shoot number) is not primarily under resource control. By contrast, the findings suggest that shoot growth characteristics, the timing and duration of phenological stages in coppicing trees are resource-limited in savannas. Browsing induces an initial compensatory response through higher shoot production in browsed trees and should be kept minimal because, in the long run, browsed cut trees would take longer to recover lost biomass compared to unbrowsed cut trees. Repeated cutting significantly depleted non-structural carbohydrate reserves in stems, implying that repeatedly cut trees rely heavily on non-structural carbohydrate reserves for regrowth. The significantly lower shoot diameter and shoot length in repeatedly cut trees imply that the coppicing ability of a tree reduces as the cutting frequencies increase. Such information can be vital in establishing the competitive growth ability of T. sericea in a multiple-species ecosystem affected by changes in resource availability as well as natural disturbances. With reference to multiple cut trees, a form of cutting or harvesting strategy should be in place that allows for sustainable regeneration of the study species. A threshold in terms of number of cutting cycles a tree can tolerate based on either maximum or minimum levels of reserve carbohydrates should also be established, as this has a direct effect on the coppice growth and survival.
... Still regarding the calculation of economic evaluation criteria, one must also include the sale price of the products, which is usually the price found during the project formulation (e.g. Manzone et al., 2009;Avohou et al., 2011). However, in practice, sales will occur several years after the beginning of the project (time taken for trees to reach the cutting age) and the final price may or may not be the same as previously set. ...
... Another common process in economic studies is the use of sensitivity analysis (e.g. Avohou et al., 2011;Rode et al., 2014). The technique, however, does not incorporate the risk calculation, that is, it does not assign probability levels to the values resulting from the economic evaluation criteria (Hildebrandt and Knoke, 2011). ...
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Reliable estimates of price and wood yield as well as the calculation of economic criteria that include uncertainty are necessary to make the decision-making process more robust when analysing a long-term activity such as forestry. Through extreme value theory EVT combined with Bayesian inference it is possible to predict probability densities for inputs used in economic evaluation criteria like wood yield and prices. With it, uncertainties regarding the inputs can be taken into account in the economic analysis, improving the way they are obtained. Therefore, this study aimed to use Bayesian approach and EVT to estimate future price and yield to carry out an economic evaluation of a forestry project. Yield, maximum and minimum price were estimated in the form of probability density. Considering 95% of probability, the NPV calculated for the minimum price situation ranged from R$ 2050.11 to R$ 5409.07 ha−1, with a mean of R$ 3771.60 ha−1. The NPV calculated for the maximum price situation ranged from R$ 7766.77 to R$ 9070.29 ha−1, with a mean of R$ 8398.13 ha−1. These results serve as best and worst-case scenarios for managers in the case of a eucalyptus plantation established in 2017 under an outgrower scheme in Brazil. The presented methodology provided good results when estimating the variables of interest. It incorporates probability levels and/or prior information. With it, the economic performance of the project and its risks are better visualized and understood by researchers and managers.
... The absence of statistically significant differences between the yields of the various tree species may be due to the fact that most of the studies examined calculated on the basis of average yields per country, which have mostly been derived from test plots. Strauss et al. [33], Buchholz and Volk [13], Avohou et al. [36], Styles et al. [9] and Ericsson et al. [24] affirmed that SRC yield strongly depends on site characteristics, in particular on water supply. If water on site is scarce, urban or industrial waterif available nearbyis a cheap and efficient way of irrigation which leads to increased yields, and therewith increased profitability of SRC [76]. ...
... If the yield level is tolerable, a longer cultivation time can be economically interesting, because the cultivation costs decrease in proportion to the lifetime of an investment. Rosenqvist and Dawson [26], Avohou et al. [36] and Londo et al. [37] stated that the total cultivation time is a very important factor for the economic viability of SRC. In their evaluation, [26] estimated the necessary minimum cultivation time to reach a positive Net Present Value at 16 years. ...
Article
Since economic profitability is the most important factor for the adoption of short rotation coppice (SRC) for energy from biomass, our objective was to analyze and summarize published knowledge about the economic evaluation of SRC. Of 37 studies, 43% reported economic viability of SRC in comparison to a reference system; whereas 19% stated economic disadvantages of SRC, and 38% reported mixed results, depending on the underlying assumptions. We found a wide variety of underlying assumptions, underlying costs, process chains and methods used to evaluate SRC systems. Of the 37 studies, 8% used static approaches of capital budgeting ,84% used dynamic approaches and 8% applied approaches in which uncertainties were taken into account. Due to the long-term nature of investment in SRC, and therewith, the uncertain development of sensitive assumptions, approaches which consider uncertain- ties were best suited for economic evaluation. The profitability of SRC was found to be most sensitive to the price for biomass and biomass yield, but site-specific biomass data was lacking. Despite the wide variation within each cost unit,costs for land rent, harvesting, chipping, and establishment consistently made up the largest proportion of overall costs, and should therefore, be chosen carefully. We close with suggestions for improving the economic evaluation of SRC and enhancing trace ability and comparability of calculations.
... The absence of statistically significant differences between the yields of the various tree species may be due to the fact that most of the studies examined calculated on the basis of average yields per country, which have mostly been derived from test plots. Strauss et al. [33], Buchholz and Volk [13], Avohou et al. [36], Styles et al. [9] and Ericsson et al. [24] affirmed that SRC yield strongly depends on site characteristics, in particular on water supply. If water on site is scarce, urban or industrial waterif available nearbyis a cheap and efficient way of irrigation which leads to increased yields, and therewith increased profitability of SRC [76]. ...
... If the yield level is tolerable, a longer cultivation time can be economically interesting, because the cultivation costs decrease in proportion to the lifetime of an investment. Rosenqvist and Dawson [26], Avohou et al. [36] and Londo et al. [37] stated that the total cultivation time is a very important factor for the economic viability of SRC. In their evaluation, [26] estimated the necessary minimum cultivation time to reach a positive Net Present Value at 16 years. ...
Article
Since economicprofitability isthemostimportantfactorfortheadoptionofshortrotationcoppice(SRC) for energyfrombiomass,ourobjectivewastoanalyzeandsummarizepublishedknowledgeaboutthe economic evaluationofSRC.Of37studies,43%reportedeconomicviabilityofSRCincomparisontoa referencesystem;whereas19%statedeconomicdisadvantagesofSRC,and38%reportedmixedresults, depending ontheunderlyingassumptions.Wefoundawidevarietyofunderlyingassumptions, underlyingcosts,processchainsandmethodsusedtoevaluateSRCsystems.Ofthe37studies,8%used static approachesofcapitalbudgeting,84%useddynamicapproachesand8%appliedapproachesin which uncertaintiesweretakenintoaccount.Duetothelong-termnatureofinvestmentinSRC,and therewith,theuncertaindevelopmentofsensitiveassumptions,approacheswhichconsideruncertain- ties werebestsuitedforeconomicevaluation.Theprofitability ofSRCwasfoundtobemostsensitiveto the priceforbiomassandbiomassyield,butsite-specific biomassdatawaslacking.Despitethewide variationwithineachcostunit,costsforlandrent,harvesting,chipping,andestablishmentconsistently made upthelargestproportionofoverallcosts,andshouldtherefore,bechosencarefully.Weclosewith suggestions forimprovingtheeconomicevaluationofSRCandenhancingtraceabilityandcomparability of calculations.
... Eq (2) where AGM is the annual gross margin, NPV is net present value, r is the discount rate and k corresponds to the lifecycle of each crop. According to this financial indicator, higher will be its value greater will be the profitability of a crop and, accordingly, more convenient will be the investment for farmer (Avohou et al., 2011;Gasol et al., 2010). Finally, given that the profitability of SRCs is very sensitive to the market price and yield (Hauk et al., 2014) and that biomass and food markets are closely related to each other , as well as in other papers (Blanc et al., 2019;Kantavichai et al., 2014) a sensitivity analysis for each surveyed crops has been performed. ...
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The increase of renewable energy production worldwide, occurred in the last years, is also attributable to some agroforestry species cultivated according to the short rotation coppice technique. Although these species are able of enhancing abandoned or marginal land leading to numerous environmental benefits, an increasing number of farmers are introducing them in place of agricultural crops. Therefore, since for a farmer economic sustainability is one of the main factors to introduce a biomass crop, the study aimed at evaluating the profitability of Paulownia, a species that has been spreading in recent years. In particular, an economic analysis has been carried out in a Southern Italian farm in which Paulownia has recently replaced a vineyard, by adopting a discounted cash flow approach. The results show that the Paulownia for both timber and woodchip production, with an annual gross margin equal to 357.91 € ha⁻¹, can represent a valid alternative compared to wine grape (237.41 € ha⁻¹), while Paulownia for exclusively biomass production has almost zero profitability (4.22 € ha⁻¹). However, the profitability depends not only on the product typology but also on the future market price fluctuations, on the subsidies or incentives, as well as on adequate choices by entrepreneurs for the creation of sustainable supply chains also from an environmental and social point of view.
... In fact, the competition between land area for short rotation coppice plantations and food products has discouraged this first option (Glithero et al. 2013), leaving natural forests with coppicing species as a more desirable solution (Spinelli et al. 2017). However, shrubland management is one of the least studied topics in forest sciences, and therefore, local information becomes relevant to achieving sustainable solid biofuel production from these natural woody communities (Avohou et al. 2010). ...
Article
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Forest biomass with energy purpose is gaining importance. Although there is a lot of information about afforestation for energy purpose, native resource management for biofuel production is a less studied topic. Consequently, generating information about management of local forest types that have potential for providing biomass for energy, such as resprouting shrublands, becomes a priority objective. We evaluated the effects of harvesting intensity on coppice growth in three resprouting shrublands with contrasting site conditions in northern Patagonia (Argentina). At each site, three harvesting treatments in strips of increasing width were randomly assigned to six permanent plots of 31.5 × 45 m during 2013–2014. Four years after, we measured resprouts (number and size of stems) of the five native dominant species. We found that almost all species responded to harvesting intensity by enhancing the coppice growth rates. Nonetheless, species showed different strategies for resource obtention. When analyzing at the community level, the response to harvesting intensity was consistent among the hillside sites, but conservative in the valley bottom site with the worst environmental conditions. Due to the high response of these species to harvesting intensity, we conclude that intense shrubland management for biomass commercialization could be a viable option depending on site conditions.
... An understanding of how disturbances and resource availability interact will have further management implications for the long-term productivity and sustainability of woody vegetation (Neke 2004;Neke, Owen-Smith & Witkowski 2006;Pote et al. 2006). As a result of exposure to disturbances, coppicing (resprouting) may be central to the survival and resilience of trees in disturbance-prone systems (Avohou et al. 2011). Coppicing can be defined as the production of vegetative shoots at the base of the stem or sprouts arising from a stump, resulting in the emergence of new shoots from the stump or roots (Hardesty 1984;Laureysens et al. 2003;Van Wyk & Van Wyk 1997). ...
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The ability of a woody plant to coppice and remain vigorous largely depends on the severity of disturbances, resource availability and the mobilisation of stored reserves. There is limited information about the role played by resource limitation on the recovery of cut trees. This study investigated the effects of water and nutrient supplementation on coppice growth responses of resprouting cut trees in a semi-arid savannah in South Africa. Cut trees were exposed to different levels of water and nutrient (nitrogen and phosphorus) supplementation over a period of 2 years in a factorial experimental design. We hypothesised that adding water and nutrients would result in an increased coppice growth response and replenishment of stored structural reserves. Adding water and nutrients significantly increased shoot diameter, shoot length and resprouting ratio for the initial 12 months after cutting but not stored structural reserves. Such a response pattern suggests that the initial growth of resprouting shoots may be strongly resource-limited, while resources are concentrated on supporting fewer resprouting shoots compared to a higher number. Conservation implications: If practicing rotational tree harvesting, trees resprouting in resource-poor locations need a longer resting period to recover stored reserves and to also recover lost height after cutting.
... Financial analysis was performed by means of discounted cash flow (DCF) method [56][57][58][59][60] and in order to compare pluriennal crops with annual ones, as well as in other studies [61][62][63][64], annual gross margin (AGM) was determined, converting positive and negative cash flows to an average annual value. ...
... Au plan économique, les plantations forestières jouent un rôle important dans les stratégies de développement. Nombreuses sont les études qui ont montré les revenus positifs qu'elles génèrent (Siregar et al., 2007 ;Avohou et al., 2011). Les retombées économiques concernent également les emplois créés, les valeurs ajoutées et les revenus générés grâce aux activités de transformation et de distribution en aval de la production (Kaplinsky et al., 2003 ;Aoudji et al., 2012). ...
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Description of the subject. The present study deals with the production of the seedlings of teak (Tectona grandis L.f.), a species used in forest plantations in southern Benin. Objectives. The aim of the study was to evaluate the techniques and the profitability of teak seedling production in the community nurseries of southern Benin. Method. A survey was carried out in 55 community nurseries selected in the –Atlantique department, based on the snowball sampling method. Semi-structured interviews were conducted with nursery holders to collect data on activity organization, techniques of production, costs, and sales revenues. Results. Two types of community nursery were found to be operating: individual nurseries and collective nurseries. Seedling production methods varied widely across the nurseries. The collection of tout venant seeds, and the use of inadequate polyethylene containers might affect seedling quality. A financial analysis showed that nursery holders were receiving a positive return from their activity. The average net revenue from the production of 1,000 seedlings ranged between FCFA 20,603 and 26,649. Conclusions. Improved performance of community nurseries will require the provision of assistance to nursery holders in accessing good quality seeds, and the implementation of further retraining on production techniques. © 2015, FAC UNIV SCIENCES AGRONOMIQUES GEMBLOUX. All rights reserved.
... Au plan économique, les plantations forestières jouent un rôle important dans les stratégies de développement. Nombreuses sont les études qui ont montré les revenus positifs qu'elles génèrent (Siregar et al., 2007 ;Avohou et al., 2011). Les retombées économiques concernent également les emplois créés, les valeurs ajoutées et les revenus générés grâce aux activités de transformation et de distribution en aval de la production (Kaplinsky et al., 2003 ;Aoudji et al., 2012). ...
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Full-text available
Description of the subject. The present study deals with the production of the seedlings of teak (Tectona grandis L.f.), a species used in forest plantations in southern Benin. Objectives. The aim of the study was to evaluate the techniques and the profitability of teak seedling production in the community nurseries of southern Benin. Method. A survey was carried out in 55community nurseries selected in the Atlantique department, based on the snowball sampling method. Semi-structured interviews were conducted with nursery holders to collect data on activity organization, techniques of production, costs, and sales revenues. Results. Two types of community nursery were found to be operating: individual nurseries and collective nurseries. Seedling production methods varied widely across the nurseries. The collection of tout venant seeds, and the use of inadequate polyethylene containers might affect seedling quality. A financial analysis showed that nursery holders were receiving a positive return from their activity. The average net revenue from the production of 1,000 seedlings ranged between FCFA 20,603 and 26,649. Conclusions. Improved performance of community nurseries will require the provision of assistance to nursery holders in accessing good quality seeds, and the implementation of further retraining on production techniques.
... Additionally, SRC systems of woody crops have the potential to at least partially counterbalance the ever increasing global demand from wood and wood products (Abbot and Lowore, 1999). In the context of the search for alternatives and sustainable energy sources in Sub-Saharan Africa, SRC has been shown to be a promising option to increase firewood supply on agricultural (Abbot and Lowore, 1999;Shackleton, 2001) and fallow lands (Avohou et al., 2011). SRC management has the objectives to obtain a maximum output (i.e. ...
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Ensuring increased and sustainable biomass production is critical for European countries. Short-rotation coppice (SRC) plantations on agricultural lands have a great potential to increase biomass supply for biofuels, bioenergy, and bioproducts. In Italy, SRC is based on the use of fast growing species, high planting density, and short harvesting cycles. In this study, the performance of new genotypes to be used in SRC plantations for biomass production was evaluated after three biennial rotations. At the trial plantation in Mira (Northern Italy), six different poplar (Populus) genotypes, belonging to different interspecific hybrids were studied. This plantation provided the opportunity to study the relationships between survival, biomass production and other growth parameters over multiple rotations and for a wide genotypic range. Biomass production differed significantly among rotations starting from 16 Mg ha−1 year−1 in the first, peaking at 20 Mg ha−1 year−1 in the second, and decreasing to 17 Mg ha−1 year−1 in the third rotation. At the end of each rotation, significant differences among genotypes were observed in number of shoots per stool and per ha, stem diameter, tree height, and biomass production. Mean survival rates became significantly different from the other rotations only in the third rotation during which survival rate ranged from 95% for (P. × generosa) × P. nigra ‘Monviso’ to 75% for (P. × generosa) × P. nigra ‘AF6’, but non-significant difference was observed among genotypes. Skewness and inequality of shoot size distributions were genotype-dependent and increased with rotations. Highest biomass production was found for genotypes P. × canadensis ‘83.148.041’, ‘Monviso’ and (P. × generosa) × P. trichocarpa ‘AF8’ with mean annual dry mass production of 21.7, 19.5 and 19.3 Mg ha−1 year−1, respectively. Genotype × rotation interactions were significant on shoot size, diameter and number, but not on survival and biomass production highlighting that genotypes behaved differently over rotations. Moisture and ash content, wood specific gravity, and higher heating value were determined at the end of the third biennial rotation, and significant differences among genotypes were found. This study is critical for investigating the behavior of novel poplar genotypes with potential for commercial biomass production over multiple coppice rotations.
... The principal tree species used in short rotation crops worldwide are few in number, and are limited mainly to eucalypts, poplars, willows, Robinia and Acacia (Verwijst 2003). Locally other woody species may also be important (refer, for example, to work by Pereira and Pereira 1994; Dalianis et al. 1996;Shackleton 2001;Sims et al. 2001;Rédei 2003;Fang et al. 2004Fang et al. , 2011Geyer 2006;Buchholz and Volk 2007;Noh et al. 2007;Seebauer 2008;Avohou et al. 2011). The main species used for short rotation coppice in Europe are poplar and willow, and within Europe there are regional differences. ...
Chapter
Trees cultivated on agricultural land are playing an ever more significant role in rural development while at the same time also providing a range of ecosystem services such as soil protection, biodiversity conservation and greater carbon sequestration. All over the world, at the interface between forestry and agriculture, a wide variety of agroforestry systems are being implemented as a means to provide much needed wood of different dimensions and qualities, other non-timber forest products as well as animal and agricultural crop produce. An overview of some of the main agroforestry approaches making a contribution to rural development globally are presented, including innovative examples of modern agroforestry. Subsequently, another land use system flanking forestry and agriculture that has been growing in importance internationally in recent years is presented, namely short rotation coppice management. Distinct from traditional agroforestry systems in that in most cases wood is the only production goal, short rotation coppice plantations are a highly productive form of agricultural land use providing farmers with a great deal of flexibility, potentially high yields and certain ecosystem services
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Woody growth at five sites, covering a range of precipitation (620–785mm) and soil conditions in North Sudan zone in Burkina Faso was investigated 5–14 years after clear-cutting. Woody growth ranged from 0.7 to 1.7Mgha−1 per year, corresponding to 1.0–2.4m3ha−1 per year in terms of green volume when species-specific basic densities were applied. Trunks (girth more than 10cm), branches and stemlets made up about a third each of the yield and about one-third of the trunk was bark. Thus, the actual trunk wood production ranged from 0.2 to 0.7Mgha−1 per year corresponding to 0.3–0.9m3ha−1 per year. Woodfuel yield was reduced to about a fourth of the total yield, when excluding small dimensions and trunk-bark, species with low calorific value or multiple use, e.g. fruit bearing or forage. Each site was dominated by some few species in terms of percentage of dry mass: Sclerocarya birrea (13%), Anogeissus leiocarpus (57%), Acacia seyal (38%), Combretum glutinosum (17%) and Combretum nigricans (37%). Mean stool growth per site ranged from 0.5 to 1.7kg per year. Largest stool growth was recorded for S. birrea and A. leiocarpus with 4.1 and 3.6kg per stool per year, respectively.
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Large-scale field trials of short-rotation coppice with willow and poplar have been studied since the mid-1980s in the UK. The information and results gained from these trials are presented, particularly with respect to operations, productivity and costs. Current methods for site selection, establishment, management practice, pests and diseases, harvesting and storage of short-rotation coppice crops are described and discussed. In the UK, the ability of short-rotation coppice to compete with conventional agricultural crops is still heavily dependent on the subsidies available for short-rotation coppice and the crop in question. Analysis of a wide range of data from field trials in Europe and North America showed that average levels of productivity ranged from 2 to 13.5odt/ha/year. The assumption that short-rotation coppice productivity increases from the first to second and subsequent rotations is not borne out in practice. Productivity levels may be increased in future through improved management practice and clonal materials, but it is unlikely that the predictions made in the early 1980s will be achieved in practice.
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The accumulation of biomass and nutrients by three tree fallows planted in a previously cultivated ferruginous soil in the Sudanian zone of Cameroon were compared with that of a natural grazed herbaceous fallow and a natural ungrazed herbaceous fallow. The planted tree fallows, that were protected against fire and grazing, included: Acacia polyacantha, Senna siamea, and Eucalyptus camaldulensis. After 5 years of fallow, mean aerial woody biomass production rates ranged from 5.30 t ha(-1) per year for Acacia and 5.73 t ha(-1) per year for Eucalyptus to 3.81 t ha(-1) per year for Senna; furthermore, the total dry matter (DM) accumulation (root, shoot and litter) of tree fallows represented 2.5-4 times that of the herbaceous fallows. Regarding root mass, these proportions are increased to 5-7 times for the three tree species studied. Acacia had higher N and Mg contents in total DM than the other treatments while Eucalyptus had the greatest accumulation of Ca. Acacia and Eucalyptus had similar accumulation of total DM, P and K. Senna was not so productive as the other tree species but it accumulated a large quantity of K. Over a 7-year period, Acacia, a N-fixing species, accumulated in its total DM, 340 and 412 kg N ha(-1) more than Eucalyptus and Senna (non-N-fixing species) did, respectively. In the context of intensive harvest of aerial biomass, the accumulation of nutrients in the belowground components is a process of high importance. The N accumulation in the Acacia root mass (342 kg ha(-1)) represented roughly the total N accumulation in Eucalyptus or Senna stands. In Eucalyptus the root system accounted for only 18-27% of the accumulation of total DM and nutrients, while much greater proportions were found under Senna (39-52%) and Acacia (32-47%). Thus, the harvesting methods of the aerial biomass will play an important part in the conservation of the nutrients of the system, especially in the case of Eucalyptus. Nutrient removal by harvesting under different logging scenarios was evaluated. For Eucalyptus, the technique of de-barking on-site reduced the removal of Ca and Mg by 70 and 43%, respectively. Furthermore, the results show that in the long term, in comparison to removal of timber at the end of the rotation, annual harvesting of grass for fodder in tree fallows in the Sudanian zone of Africa, would be an equally important or even a more serious risk to site fertility. (C) 2003 Elsevier B.V. All rights reserved.
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Leafing, flowering and fruiting of the 24 most representative species of trees and shrubs in Sudanian savannas and fallows near Bondoukuy (Burkina Faso) were studied for 2 y (May 1992 to June 1994). The period of defoliation was generally brief, and leaf flushing, flowering and fruiting occurred mostly in the dry season. The phenological behaviour varied nonetheless across species and individuals. A classification taking into account synchrony/asynchrony and duration in foliation, flowering, fruit ripening and seed dispersal phases allowed comparison of species' phenological plasticity. Species were distributed along a scale of increasing plasticity, from trees to shrubs. Along this scale, species of the Leguminosae appeared to be separated from those of the Combretaceae, the latter being generally considered as characterising fallow farming systems. These results provide new evidence about the effect of phylogenetic constraints on the phenological behaviour of the woody species of the Sudanian savannas.
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The regeneration of natural vegetation (fallowing) is a traditional practice for restoring fertility of agricultural land in many parts in the tropics. As a result of increasing human population and insufficient fertilizer inputs, the ecosystem fertility functions of traditional fallows must now be improved upon via the use of managed fallows. Interactions between vegetation and soil determine nutrient losses and gains in crop—fallow systems and are influenced by fallow species, patterns and rates of biomass allocation, and crop and fallow management. Nutrient losses occur through offtake in crop harvests during the cropping phase and through leaching, runoff, and erosion in the cropping phase and the initial stage of fallows $#x2014; when nutrient availability exceeds nutrient demand by vegetation. Gains in nutrient stocks in later stages of fallow are generally more rapid on soils with high than low base status due to greater quantities of weatherable minerals and lack of constraints to N2 fixation, deep rooting, and retrieval of subsoil nutrients by fallow vegetation. On low base status soils (exchangeable Ca < 1 cmolc kg–1), N2 fixation and atmospheric inputs are likely to be the main sources of nutrient additions. On high base status soils limited by N, gains in N stocks by inputs from N2 fixation and retrieval of subsoil nitrate can occur relatively rapidly; hence short-term fallows can often improve crop performance. Large losses of Ca associated with soil organic matter (SOM) mineralization and soil acidification during cropping and fallow establishment, combined with chemical barriers to root penetration, suggest that long-duration fallows (> 5 yr) are needed for recovery of cation stocks and crop performance on low base status soils. On both soils, however, residual benefits of fallows on crop yields usually last less than three crops.
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This paper addresses the need for appropriate forest technology as a solution to the rural fuelwood shortage in developing countries. Many such solutions are proposed with little reference to existing local needs and resources. Complex wood harvesting technologies require a long time to diffuse through a population. Therefore, increases in productivity can be better achieved through focusing on the improved maintenance and deployment of proper hand tools. Evidence from Kenya is used to demonstrate the improvements that can be made in hand-tool production and maintenance. Most fuelwood users currently manage trees to produce firewood in the form of fuelwood sticks, not large logs. Appropriate fuelwood production systems should be developed, based on the principles of coppicing and pollarding, short rotation periods, and producing small diameter fuelwood sticks. A hypothetical fuelstick project is discussed to show that not only are such systems possible, but they can be economically superior to conventional solutions.
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The central area of the Mare aux Hippopotames Biosphere Reserve is located in the western part of Burkina Faso. Local populations have a close relationship with the reserve, from which they get much of their needs in food products, medicine, energy, arts and crafts. The use of resources has consequences for the biodiversity, ecosystem and environment of the reserve. The discussions held during ethnobotanical inquiries have permitted us to establish the main uses of woody plants and to pick out the repercussions of this usage. From this it emerges that the reserve has an important floristic richness and a biodiversity unknown to both locals and authorities.
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Most African savannas are subjected to harvesting of wood, especially for fuelwood, charcoal and construction timber. A key attribute of the resilience and productivity of savannas is the ability of damaged trees to regrow from the remaining stump. Survival of the cut stem and growth rate of the resultant coppice shoots is influenced by several factors, including size of the tree, cutting height and the root/shoot ratio after felling. Some of these can be manipulated to maximise subsequent regrowth, but this is little understood for most African savanna species. This study investigated the influence of original tree size, height of cut and post-harvest pruning on regrowth of Terminalia sericea. Regrowth was monitored as the number of coppice shoots, the mean coppice shoot length and the cumulative coppice shoot length per cut stump over four growing seasons. There was a positive relationship between cutting height and number of coppice shoots, but height of cut did not significantly affect mean or cumulative coppice shoot length. Larger stems produced more coppice and had greater mean and cumulative coppice shoot lengths than smaller stems. Post-harvest pruning increased the mean shoot length, but not the cumulative shoot length. After four growing seasons mean shoot length for the single shoot pruning treatment (one shoot left) was 54% greater than for the no prune treatment, whilst the double shoot pruning (two shoots left) was 40% greater. Extrapolated harvest intervals for fuelwood poles were 3–4 years for large stems, 4–5 years for medium-sized stems, and 4–9 years for small stems.
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Fuel characteristics of biomass from 12 tree species grown under a short rotation forestry regime were analysed. E. globulus, E. nitens and A. dealbata had the biggest trees while A. glutinosa, P. tomentosa and S. matsudana×alba 1002 had the smallest trees when the trees were harvested at the age of 3, 4 and 5 years. Higher heating value (HHV) ranged from 19.6–20.5 MJ/kg for wood, 17.4–20.6 MJ/kg for bark, and 19.5–24.1 MJ/kg for leaves, with the highest values for wood and bark being obtained from Pinus radiata. Wood basic density ranged from 250–500 kg/m3; ash content, 0.7–1.4%; volatile matter content, 91.5–95.1%; fixed carbon content, 4.2–7.3%; and extractives content, 3.3–11.9%. Wood properties were significantly different from those of bark, and also different from those of leaves. Except basic density and the proportion of bark on the stem, properties of wood did not vary with either cutting age or stocking density. Wood from coppice crops did not differ from that of single stem, first harvest crops.Differences in tree size for species planted at similar plant populations determine species yields. Variations in properties between species and between tree parts have implications for feedstock handling, transport, drying, storage, and on the design of conversion systems.
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The traditional mainstays of Hawaii's economy: sugarcane and pineapple crops, have declined such that as much as 80,000 hectares of agricultural land are now available for alternative land uses. Concurrently, imports of fossil fuels continue to accelerate and now provide over 90% of the total energy supply at a cost exceeding $1 billion annually exported from the local economy. The feasibility of short-rotation forestry on these former sugarcane and pineapple plantation lands to produce a variety of wood products, including biofuels, is being evaluated using a species-and site-specific empirical model to predict yields of Eucalyptus saligna, a system model to estimate delivered costs of wood chips to a bioconversion facility, and a geographic information system to extend the analysis to areas where no field trials exist and to present results in map form. The island of Hawaii is showcased as an application of the methodology. Modeling results are presented for using tropical hardwoods as dedicated feedstocks from biomass energy plantations to produce methanol, ethanol and electricity. A hypothetical, integrated, high-value hardwood, veneer, utility lumber and wood-chip operation is featured in contrast to the biomass energy plantation scenario. Short-rotation forestry may hold some promise for the greening of Hawaii's energy system and even greater promise for the industrial production of value-added wood products for the benefit of the state's citizens and visitors. The methodology is readily transferable to other regions of the United States and the rest of the world.
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In order to establish a relation between tree fresh biomass and tree dimensions, samples of 14 tree species indigenous to Botswana were measured, cut and weighed. The relation best suited to the indirect estimation of total tree fresh weight was the regression between tree fresh weight and stem basal area at ankle height (5–10 cm above ground level). The regression curves of the 14 tree species overlay in a narrow band. On the basis of the measured data points of all 14 tree species a single regression curve is calculated: the combi-line. The combi-line satisfactorily describes the relation between stem basal area and fresh weight for most trees. A comparison of the combi-line with some tree species from elsewhere in Africa, India and Europe shows that the combi-line also describes, to a large extent, the basal area-fresh weight relation for those trees.
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Woody biomass from poplar and aspen (Populus sp.) short rotation coppice (SRC) has good combustion properties compared to non wood solid bio fuels and fossil solid fuels. This review compiles and discusses relevant literature on fuel quality and yield for Central European conditions. The most problematic quality parameter of woody biomass from Populus SRC is its high water content at harvest time (55–60%). Storing unchipped material on the field during summer is an efficient tool to lower it. In order to control other quality parameters—mainly nitrogen (N), potassium (K) and heavy metal contents but also yield—one has to take into account the physiological background of SRC. Important features are species/clone, age of sprouts, growth pattern, site and nutrient cycling. Maximum mean annual increment (MAI) occurs later than in willows. Therefore rotations should be longer than in willow: at least 6–7 years for poplars and,—due to differences in growth pattern,—10 to 12 years for aspen. Both results in MAIs of 10– and reduced nutrient concentrations due to a lower share of branches and twigs in the harvested biomass. However, with elongated rotations costs rise because yet no automated (and thus cheap) harvest methods for large stem diameters were developed. Although sometimes ignored poplars are demanding concerning site characteristics. Basic requirements are good water (minimum rainfall during growing season) and nutrient supplies, deep soils and favourable climatic conditions (average air temperature between June and September at least 14°C). Only aspen are partly suited for poorer conditions. For Populus-SRC in general weed control during establishing phase is essential.
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Power generation using biomass could provide substantial environmental and socio-economic benefits. Production of the feedstocks to fuel biomass power plants can either add to potential environmental gains or contribute to the environmental problems which the agriculture and forestry industries already face. Likewise, the biomass energy infrastructure can help strengthen agricultural economies or speed the decline of rural communities. The purpose of this paper is to suggest a regional approach to ensure that energy crop production will proceed in an ecologically and economically sustainable way.At this juncture, we have the opportunity to build into the system some ecological and socio-economic values which have not traditionally been considered. If crop species are chosen and sited properly, incorporation of energy crops into our agricultural system could provide extensive wildlife habitat and address soil and water quality concerns, in addition to generating renewable power. We recommend that three types of agricultural land be targeted for perennial biomass energy crops: (1) highly erodible land; (2) wetlands presently converted to agricultural uses; and (3) marginal agricultural land in selected regions. Fitting appropriate species to these lands, biomass crops can be successfully grown on lands not ecologically suited for conventional farming practices, thus providing an environmental benefit in addition to producing an economic return to the land owner.
Article
Wood usage for cooking and heating is still very relevant in most developing countries especially those of sub-Saharan Africa and many parts of Asia. Therefore, sustainable means of generating it for this and other purposes are necessary bearing in mind the influence of indigenous knowledge/users' perspective on any production method regarding success and sustenance. In conformity with this view, questionnaires were administered on 240 respondents in 8 rural communities of Akinyele and Ido Local Government Areas (LGAs) of Oyo State, Nigeria, to elicit information on species that can be used as fuelwood, preferred by the respondents for incorporation into and/or retention in agroforestry plots, out of which 179 (i.e. 75% of the total number of questionnaires administered) were successfully retrieved for statistical analyses. Twelve woody species namely: Annona senegalensis, Anogeissus leiocarpus, Bridelia ferruginea, Daniellia oliveri, Detarium microcarpum, Gardenia ternifolia, Hymenocardia acida, Lophira lanceolata, Parkia biglobosa, Terminalia avicennioides, Triplochiton scleroxylon and Vitellaria paradoxa were prioritized on the basis of respondents' preference using a ranking pattern. Friedman chi-square analysis showed that there was no significant difference (p < 0.05) in the ranking pattern of the respondents from the two LGAs. The mean net calorific values (NCV) of the 12 species were found to be 17.71, 18.63, 18.04, 16.03, 17.67, 18.46, 19.00, 21.68, 19.63, 18.25, 14.65, and 19.47 MJ kg−1 respectively. The result of a two-way analysis of variance indicated a significant variation (p < 0.05) in NCV data for all the species pooled together but not for each species except for D. oliveri with a follow-up test using Fisher's Least Significant Difference. The Pearson's moment correlation analysis gave positive coefficient values (r = 0.868 and 0.874, p < 0.05) between NCV and the cumulative ranking values in Akinyele and Ido LGAs respectively. There was also a coefficient value of 0.873 (p < 0.05) between the cumulative ranking values in the two LGAs. In line with the outcome of this study, it was therefore recommended that native intelligence/indigenous knowledge and/or users' perspective should be part of the criteria for selecting potential fuelwood species for incorporation into and/or retention in agroforestry systems in this and other areas with similar characteristics.
Article
Biomass estimation procedures in short rotation forestry vary in their methodology, complexity and time demand depending on the specific aim of the estimation operation. In commercial short rotation forestry, estimates of harvestable biomass often are used to decide on harvest timing or continued management and to calculate economic gains under the actual market situation. For research purposes, weight estimates of single trees and their components are needed to describe and predict, e.g. leaf dynamics and the relative size differentiation that develops among individuals in a growing population. A biomass estimation procedure is defined as a planned chain of elements, integrated to comply with a specific aim. Elements such as defining a sampling unit, subsampling within primary units, model choice and conversions from single tree to stand area, fresh weight to dry weight and standing biomass to harvestable biomass, all may be included in a procedure. Those elements have to be modified according to the predefined aim and object of estimation. Consequently, a biomass estimation procedure is a compromise in which accuracy, speed and knowledge of the underlying biological reality together determine the final shape of the procedure and its results. This paper provides a short overview of current biomass estimation methods and gives details about the major elements in the procedures, especially on regression methods. Recent developments in biomass estimation methodology are exemplified with analyses on short rotation forests and attention is paid to the need for standardisation and automatization of the procedures.
Article
An overview of biomass for production of densified biofuels on a global scale is given. Bioenergy production as heat, electricity, and liquid fuels represents about 14% of the World's primary energy supply. About 25% of the usage is in industrialised countries and the other 75% is used in developing countries. There is an estimated 3870 (106) ha of forest worldwide. The average area of forest and wooded land per inhabitant varies between 6.6 ha in Oceania, 0.2 ha in Asia, and 1.4 ha in Europe. The world's total above-ground biomass in forests amounts to 420 (109) tonnes, of which more than 40% is located in South America. Estimates by FAO (2000) show that global production and use of woodfuel and roundwood reached about 3300 (106) m3 in 1999. About 55% is used directly as fuel, e.g. as split firewood, and about 90% of this is produced and consumed in the developing countries. The remaining 45% is used as industrial raw material, but about 40% of this is used as primary or secondary process residues, suitable only for energy production. The total sustainable worldwide biomass energy potential is about 100 EJ/a (the share of woody biomass is 41.6 EJ/a), which is about 30% of total global energy consumption today. About 40 EJ/a of available biomass is used for energy. Nearly 60% of this biomass is used only in Asia. A comparison between the available potential with current use shows that on a worldwide level about two-fifths of the existing biomass potential is used, and in most areas of the world the current biomass use is clearly below the available potential. Only in Asia does the current use exceed the available potential. Therefore, an increased biomass use is possible, e.g. for production of densified biofuels, in most countries.
Article
Woodfuels are the most heavily used energy source in sub-Saharan Africa. We analyzed the ecological impacts and modes of access of five user groups (domestic consumers, gin distillers, brick manufacturers, charcoal producers, and tea companies) drawing biomass energy from natural forests in western Uganda. While domestic consumers use the most species for fuelwood (>50), their consumption is likely sustainable because they generally harvest fast-growing species from fallows on their own land or their neighbors’. Charcoal producers prefer old-growth hardwood species and are responsible for the greatest loss of natural forests. They access forests by finding landholders who, either willingly or through coercion, allow trees on their lands to be cleared. The impact of charcoal production is exacerbated by a license system that undervalues natural forests and rewards rapid harvests across large areas. The tea industry consumes mainly eucalyptus wood (Eucalyptus spp.) from corporate plantations, but they indirectly create pressure on natural forests by hiring immigrants who subsequently settle in and clear forest remnants. If such practices continue, forest remnants will soon be exhausted, leaving Kibale National Park as the last natural forest in the region. Forest remnants are a vital source of water, medicinal plants, and energy for local citizens and to protect them from over-exploitation, policy makers should target the charcoal and tea industry for reform. Support for local land management institutions governing access to fallows and successional forests will inevitably enhance the policy interventions.
Article
Five species of eucalypts, namely Eucalyptus ovata, E. Saligna, E. globulus, E. nitens and E. regnans were planted, sampled and harvested to develop regression equations to be used for non-destructive estimations of total tree dry weight when grown under a short rotation regime. A total of 458 trees were sampled between 2 and 5 years old. Their diameters ranged between 10 and 314 mm, heights 1.6–18.1 mm and weights 0.4–199 kg. A number of equations were developed from these parameters and tested statistically. The best-fit equation for a group of Eucalyptus species incorporated the product of the square of the diameter (D2) and height (H): tree dry weight (W) = 1.22D2∗ H × 10−4. This equation predicted the above ground tree dry weight to within 20% accuracy. The equation developed for eucalypts would be suitable if directly applied to other tree crops such as Pinus radiata or Acacia dealbata under SRF management regimes.
Article
Weed management is a key element of any crop production system. Weeds are a particular problem in the production of short rotation woody and perennial herbaceous biomass crops due to the shortage of registered herbicides and integrated weed management systems. Herbicides will be an important component of weed management of biomass crops. However, producers should take a broader view of weeds and incorporate all available weed management tactics in these production systems. In both short rotation poplar and herbaceous perennial crops, weed control during the establishment period is most critical. New plantings of these species grow very slowly and do not compete well with weeds until a canopy develops. Effective weed control can double the growth of short rotation poplar crops and affect the variability of the resulting stand. In crops like switchgrass, uncontrolled weeds during establishment can result in stand failure. Cultural practices such as site preparation, using weed-free seed, fallowing, selecting the proper planting dates, companion crops and controlling weeds in previous crops must be combined with herbicides to develop integrated management systems. Weeds may also cause problems in established stands through competition with the biomass crop and by contaminating the product. Effective and economical weed management systems will be essential for the development of short rotation woody and herbaceous perennial biomass crop production systems.
Article
1) Savanna ecosystems are characterised by the codominance of two different life forms: grasses and trees. An operational understanding of how these two forms coexist is essential for understanding savanna function and for predicting its response to future environmental change. 2) The existing model, which proposes that grasses and trees coexist by a separation of rooting niches, is not supported by recent empirical investigations. Our aim was to define an alternative mechanism of grass-tree coexistence in savanna ecosystems. The model we have built concentrates on life history-disturbance interactions between grasses and trees. 3) The model demonstrates coexistence for a wide range of environmental conditions, and exhibits long periods of slow decline in adult tree numbers interspersed with relatively infrequent recruitment events. Recruitment is controlled by rainfall, which limits seedling establishment, and fire, which prevents recruitment into adult size classes. Decline in adult tree numbers is the result of continuing, but low levels of adult mortality. Both aspects of the dynamics are consistent with an established non-equilibrium mechanisms of coexistence (the storage effect). 4) A sensitivity analysis indicated that data on tree resprouting ability, stem growth rates and and the relationship between seedling establishment and wet season drought are essential for predicting both the range of conditions for which coexistence is possible and the response of savanna ecosystems to environmental change. 5) Our analysis suggests that understanding grass-tree interactions in savanna requires consideration of the lon-term effects of life history-disturbance interactions on demography, rather than fine-scale effects of resource competition on physiological performance.
Article
Biomass estimations are very important in short rotation high density stands, but usually require some destructive sampling. This paper discusses the potential use of allometric relationships based on volume index (height x diameter squared) for accurate and non-destructive estimations of stem biomass. When using this approach, one implicitly assumes a constant conversion factor from stem volume index to real stem volume as well as a constant wood infradensity (stem dry mass versus fresh volume), both assumptions being questionable. Our results on five different poplar clones grown at two different sites (Afsnee, near Gent, Belgium and Orsay, near Paris, France) and under two different cultural management regimes underscore the following points: i) stem diameter measured at 22 cm aboveground and in two perpendicular directions is a relevant parameter to compute volume index in high density poplar stands; ii) power function regression equations fit the stem volume index versus stem dry mass relationship better than simple linear regressions; iii) attention should be paid to variation in wood infradensity, which ranged from 0.35 to 0.44 kg dm(-3) in our study.
Article
The production of plant biomass on small farms and in woodland in densely populated locations in the Nigerian Sahelo-Sudan is estimated in order to test the hypothesis that conversion of land from natural vegetation to cultivation entails a loss in plant productivity. Estimates are given for reserved forest, woodland, shrubland and farmland at two sites varying in mean annual rainfall and population density. The results fail to support the hypothesis. The role of farmers in causing degradation through loss of plant productivity, and appropriate conservation strategies, may require re-evaluation.
Article
This book presents introductory economics ("principles") material using standard mathematical tools, including calculus. It is designed for a relatively sophisticated undergraduate who has not taken a basic university course in economics. It also contains the standard intermediate microeconomics material and some material that ought to be standard but is not. The book can easily serve as an intermediate microeconomics text. The focus of this book is on the conceptual tools and not on fluff. Most microeconomics texts are mostly fluff and the fluff market is exceedingly over-served by $100+ texts. In contrast, this book reflects the approach actually adopted by the majority of economists for understanding economic activity. There are lots of models and equations and no pictures of economists.
In: Le ´gumineuses (Ce ´salpinioı ¨de ´es Paris: Muse ´um National d
  • A Aubreville
  • Flore
Aubreville A. Flore du Cameroun. In: Le ´gumineuses (Ce ´salpinioı ¨de ´es), vol. 9. Paris: Muse ´um National d’Histoire Naturelle; 1970.
Vegetation of Benin Adapted farming in West Africa: issues, potentials, and perspectives
  • A Wezel
  • R Bo
  • F Graef
  • P Lawrence
Wezel A, Bo ¨cker R. Vegetation of Benin. In: Graef F, Lawrence P, von Oppen M, editors. Adapted farming in West Africa: issues, potentials, and perspectives. Stuttgart: Verlag Ulrich E. Graeur; 2000. p. 219e24.
Introduction to economic analysis. Version 2.0. Pasadena (CA): California Institute of Technology
  • Rp Mcafee
McAfee RP. Introduction to economic analysis. Version 2.0. Pasadena (CA): California Institute of Technology; 2006.
Synthèse des espèces du domaine sahélien et soudanien qui se multiplient par voie végétative
  • R Bellefontaine
  • Jm Herbès
  • Jmk Amboula
  • R Peltier
Bellefontaine R. Synthèse des espèces du domaine sahélien et soudanien qui se multiplient par voie végétative. In: d'Herbès JM, Amboula JMK, Peltier R, editors. Fonctionnement et gestion des e ´cosystèmes forestiers contractés sahéliens. Paris: John-Libbey Eurotext; 1997. p. 95e104.
Marché s ruraux de bois-é nergie au Sahel
  • R Peltier
  • A Bertrand
  • E M Lawalli
  • G Madon
  • P Montagne
Peltier R, Bertrand A, Lawalli EM, Madon G, Montagne P. Marché s ruraux de bois-é nergie au Sahel. Bois For Trop 1995; 245:75e83.
Dry forest silviculture in the Sudano-Sahelian region: Burkina Faso's experience
  • S Flandez
Flandez S. Dry forest silviculture in the Sudano-Sahelian region: Burkina Faso's experience. Unasylva 1995;46(181): 13e7.
Silvicultural study on Markhamia lutea with regard to short rotation energy plantations. Freiburg: Unique Forest Consultant GmbH
  • M Seabaeur
Seabaeur M. Silvicultural study on Markhamia lutea with regard to short rotation energy plantations. Freiburg: Unique Forest Consultant GmbH; 2008.
Management of natural forests of dry tropical zones, Conservation Guide No 32
  • Gaston R A Bellefontaine
  • Petrucci
Bellefontaine R, Gaston A, Petrucci Y. Management of natural forests of dry tropical zones, Conservation Guide No 32. Rome: FAO; 2000.
Use of woody plants by locals in mare aux hippopotames biosphere reserve in western Burkina Faso Energy value as a factor of agroforestry wood species selectivity in Akinyele and Ido local government areas of Oyo State, Nigeria
  • P Taita
Taita P. Use of woody plants by locals in mare aux hippopotames biosphere reserve in western Burkina Faso. Biodivers Conserv 2003;12:1205e17. [26] Erakhrumen AA. Energy value as a factor of agroforestry wood species selectivity in Akinyele and Ido local government areas of Oyo State, Nigeria. Biomass Bioenergy 2009;33:1428e34.
Paris: Musé um National d'Histoire Naturelle
  • A Aubreville
  • Flore Du Cameroun
Aubreville A. Flore du Cameroun. In: Lé gumineuses (Cé salpinioïdé es), vol. 9. Paris: Musé um National d'Histoire Naturelle; 1970.