Low leaf biomass yields coupled with small land sizes are some of the major constraints faced by smallholder farmers that grow protein-rich fodder trees and shrubs. Given these challenges, availability of highly productive seed sources would be important to enable farmers to produce leaf fodder in sufficient quantities. 14 accessions of Acacia angustissima were evaluated for leaf, wood and total biomass production at two subtropical sites with uni-modal rainfall in Zimbabwe, with the objective of identifying high leaf biomass yielding accessions. There were up to fourfold difference in biomass yield between the accessions. Leaf dry matter yield ranged from 1.65 to 8.81 Mg ha-1 and 3.7 to 12.4 Mg ha-1 for wood biomass at the higher altitude site (1530 m a.s.l.) but were much lower at 1272 m a.s.l. where they ranged between 0.37 and 4.88 Mg ha-1 for leaf and 0.4 and 7.2 Mg ha-1 for wood. The most productive accessions for leaf biomass were 16231 and 18579 at the higher altitude site, while 18586 and 18501 had the highest yields at the lower altitude. Although no one accession was consistently high yielding across the two sites, the least productive accessions were consistently poor at both sites. The advantage of using selected superior accessions over the unselect bulk seed was up to 85%. These findings underscore the need to promote the use of only high yielding accessions rather than unselect bulk seed. This study identified new, more productive accessions of A. angustissima that potentially widens the genetic base of the germplasm assembled in Zimbabwe.
Tag: biomass
Hunting indicators for community-led wildlife management in tropical Africa
Engaging local communities is pivotal for wildlife conservation beyond protected areas, aligning with the 30 × 30 target of the Kunming-Montreal Global Biodiversity Framework. We assessed the effectiveness of 33 offtake indicators, derived from hunter declarations, in monitoring the status and extent of degradation of hunted wildlife sourced from camera trap surveys and faunal composition analysis. The rodents:ungulates ratio in offtake and the mean body mass of total offtake emerged as practical and robust indicators of faunal degradation within hunting systems, with significant potential for broader application in similar tropical forest environments. Our findings provide a blueprint for managing and conserving natural resources in tropical regions through community-based initiatives. Involving local stakeholders ensures sustainable wildlife use and fosters ownership and responsibility. This study advances conservation efforts, bridging scientific rigor with community engagement for effective biodiversity preservation.
Carbon balance of rubber (Hevea brasiliensis) plantations: A review of uncertainties at plot, landscape and production level. Agriculture
Rapid expansion of natural rubber plantations in South-East Asia and other regions has greatly altered ecosystem based carbon (C) stocks with potential impacts on climate change mitigation and future C trading opportunities. Therefore reliable estimations of carbon sequestration and emission at the landscape level after land cover transition from forest swidden agriculture and other land use types are needed. We reviewed studies on C stocks and dynamics in rubber plantations considering the contribution of aboveground and belowground biomass soil organic matter collected latex and other minor components. C sequestration occurred after conversion of arable land to rubber plantations while C losses usually prevailed if forest was converted to rubber. These general trends strongly depended on local climate conditions and soil properties as well as on topography. Non-traditional planting of rubber under subtropical conditions with a dryer climate and at high elevations (300–1000 m above sea level) decreased the C sequestration potential of rubber. We show how rotation length rubber clone and management strategies like tapping frequency or planting density affect C stocks discuss the uncertainties in C stock estimation and highlight improved approaches. An important conclusion is that upscaling of C stocks and dynamics under different climate scenarios and rotation lengths to a regional level requires the use of time averaged C stocks. Enhanced remote sensing techniques can greatly improve C stock estimates at the regional level allowing for an accounting of the variability caused by terrain and plantation properties. A partial life cycle assessment of rubber production revealed greenhouse gas emissions as a minor contribution when compared to land use change effects on plant and soil C stocks and C accumulation in latex wood products and seed oil. The review highlights scantily explored topics and proposes directions for future studies which should decrease uncertainties in C estimates in rubber dominated landscapes.
Analysis of Tieghemella heckelii x Theobroma cacao L. Interaction in Traditional Agroforestry Systems in Western Cote d’Ivoire
Agromorphological and productivity parameters and incomes of cocoa companion trees assessment was studied to identify the ecological interaction between Tieghemella heckelii (makoré) and cocoa (Theobroma cacao) trees in Cote d’Ivoire. To this end studies have been carried out in rural areas in the locations of Duekoué and Taï. This work was conducted on the cocoa trees around the makoré trees over three distances around the tree (10, 20, and 30 m). Several parameters related to morphology, productivity, biomass, and CO2 stock were determined, for the two speculations. Results indicated that the trees of makoré used have the same characteristics (size, DBH, biomass, and CO2 stock). However, a difference in the shape of the fruit and/or the seed (weight of the fruit, length, and width of the seeds) and the number of seeds contained in the fruits was observed, thus reflecting a variability of individuals. Moreover, the density and yield of cocoa trees increased with distance. Indeed, cocoa trees located 30 m from the makoré trees recorded the highest rates of healthy pods. The rate of rotten and gnawed pods was similar for all distances considered, and cocoa trees located 20 m from the makoré trees were the most vigorous. Additionally, the biomass and the CO2 stock were high for large diameter and tall cocoa trees, especially the cocoa trees located 20 and 30 m from the makoré trees.
Analysis of the Ricinodendron heudelotii × Theobroma cacao L. Interaction in Traditional Agroforestry Systems in Côte d’Ivoire
The objective of this study was to improve cacao (Theobroma cacao) production through its association with a woody species, such as Ricinodendron heudelotii, in western Côte d’Ivoire. To do this, a design of two transects (10 m and 20 m) was installed around the species in 5 localities (Buyo, Duekoué, Guéyo, San-Pedro, and Soubré). The diameter at the breast height of the tree, the height, the number of fruits, the above biomass, and its carbon stock were measured. Results showed morphological variability of R. heudelotii according to the localities. The presence of the species within cacao trees reduces the rate of pod rot, stabilizes the rate of pods eaten away, and increases the biomass production and the carbon storage of cacao trees. The distance between the two species had no impact on the vigor and the yield of cacao trees. However, cacao density in the 10 m line was reduced compared to that of the 20 m. Therefore, the integration of R. heudelotii into cacao agroforestry systems could improve cacao production. That is why the reduction of cacao density, as well as the use of more suitable varieties of cacao, should be considered for the sustainability of this system.
How to increase cookstove adoption? Exploring cost-effective dissemination techniques in Central Mozambique
The adoption and usage of improved cookstoves have been promoted in the Global South to mitigate the adverse effects of relying on solid biomass for cooking. However, the uptake and continued use of improved cookstoves remain low. Several behavioral changing techniques have been used to increase the adoption of improved cooking stoves. Still, the monetary costs involved in the dissemination process are generally neglected, and few studies follow an experimental design to evaluate the impact of different stove dissemination approaches. Thus, we conducted an experiment to explore the cost-effectiveness of dissemination approaches and measure their effect on improved cookstoves adoption in Central Mozambique. Forty communities were randomly assigned to receive one of the following treatments: (1) individual video training, (2) on-site group training or (3) a combination of both. In total, 620 households we randomly selected from the 40 communities to participate in the study and 510 were included in the final analysis. The rates of adoption within each treatment were 53 % for individual video training, 21 % for on-site group training and 47 % for the combination of both. The monetary training costs were lower for individual video training, which stimulated the early and sustained adoption of improved cook stoves. Our findings provide strong evidence that the tool used for capacity building affects the adoption of improved cookstoves. Extension agencies should be aware of cost-effectiveness and adjust dissemination approaches to achieve the highest impact per unit of resource expenditure.
Improvements in charcoal production and the environmental implications: Potential for the invasive Prosopis juliflora in Kenya
Charcoal is a common woodfuel in sub-Saharan Africa (SSA). Unsustainable wood sourcing and inefficient carbonization result into negative environmental impacts. This action research aimed at building the capacity for sustainable charcoal production including `improving the traditional earth mound kiln (TEK) that is used by 99% of charcoal producers in Kenya. Small stems and branches of the invasive Prosopis juliflora were used and produced quality charcoal with 28 kJ/g which will save trees. Improved earth mound kiln (IEK) increased charcoal yield by 49% per mass of sun dried wood fed into the kiln and reduced emissions of carbon monoxide, carbon dioxide and hydrocarbons by 40%, 49% and 44% respectively. Net charcoal yield by a mass of dry wood in TEK and IEK was 26.4% and 28.4% respectively. Communication and capacity development on sustainable charcoal benefit people and environment. Studies on sustainable charcoal and effects on dryland socio-ecological systems will be needed.
Pruning and green manure from Alnus acuminata improve soil health, and potato and wheat productivity in Rwanda
Alnus (Alnus acuminata Kunth) has been widely promoted under climate change mitigation and adaptation programs in the East African highlands. However, information is lacking on the impact of pruning management and green manure (GM) application on soil health and the productivity of associated crops. Using a large suit of soil quality indicators, crop growth and yield measurements, this study identified appropriate combinations of alnus pruning levels and GM application for sustainable intensification of potato (Solanum tuberosum) and wheat (Triticum aestivum) production in alley cropping with Alnus. This study compared six treatments, namely, (1) sole crops of potato or wheat (control), (2) sole crop + GM, (3) 75% pruning, (4) 75% pruning + GM, (5) 90% pruning and (6) 90% pruning + GM. In all treatments potato and wheat were grown in rotation. The best treatments were the 75% pruning + GM and 90% pruning + GM, which significantly differed from the control in soil pH, soil organic carbon (SOC), total nitrogen (TN), total phosphorus (P), exchangeable calcium (Ca) contents, the N:P and C:P stoichiometric ratios and the soil structural stability index (SSI). These treatments increased soil pH by 5–6%, SOC by 74–82%, TN by 58–68%, exchangeable Ca by 76–81%, total P by 17–21%, the N:P ratio by 40%, C:P ratio by 43–51%, SSI by 71–79%, potato tuber yields by 17–21% and wheat yields by 21–32% over the control. Therefore, it is concluded that pruning and application of alnus green manure can significantly improve soil health and crop productivity on degraded soils in the study area.
Biomass and soil carbon stocks in different forest types, Northwestern Ethiopia
Attempts to mitigate global climate change have brought forestry into focus. Forests absorb carbondioxide from the atmosphere, alleviate global warming and contribute for rural livelihoods. To realize these benefits, there is a need to conserve the existing forests and establish new forests by using different restoration techniques. Information is scarce in Ethiopia on the carbon stock efficiency of the different forest types. Therefore, this study focused on comparing biomass and soil carbon stock potential of a natural forest, exclosure and Eucalyptus plantation. Primary and secondary data were collected and analysed using allometric equations. The results of this study stated that the total mean carbon stock for exclosure was 131.6 ± 45.5 t ha−1, for plantation 160.1 ± 35.8 t ha−1 and for natural forest 195.3 ± 58.3 t ha−1. The carbon stocks in each pool exhibited distinct patterns between the forest types. The above ground, below ground and soil organic carbon stock, increased in the natural forests and plantation, while the litter carbon stock showed decreasing towards the exclosure. Generally, the total natural forests store high amount of carbon and can play an important role in climate change mitigation. The carbon pool variation between different forest types was significant at (P < .05); however, there was no significance difference between forest types by aboveground and belowground biomass. From the main findings of this study, it is possible to conclude that climate change mitigation measures should consider expanding exclosure with the same priority as conserving natural forest and increasing plantation forests.
Potential energy yields of bioenergy crops in the tropics
Bioenergy can produce at least 25% of the global energy demand to combat climate change through reducing emissions in the energy sector. However, information on the bioenergy production potential of woody species and their suitability for silviculture on various soils in the humid tropics is limited. This slightly revised version of a short note published by Borchard et al. (2018) aims to identify tree species suitable for bioenergy production under these conditions. Data were compiled from 241 publications and nine freely available databases to assess environmental and silvicultural information on tropical tree species. Energy yield was derived from the estimated productivity of the reviewed species equivalent to an energy yield ranging between 2 and 444 GJ ha¯¹ yr¯¹. As such, these bioenergy yields are within the range reported for the lignocellulosic biomass of energy crops cultivated in Europe, the USA and Brazil. Our review identified some highyielding species (e.g., Dyera polyphylla (Miq.) Steenis, Metroxylon sagu (Rottb.), Pongamia pinnata (L.)) and leguminous species that could be beneficial in mixed stands (e.g., Elaeis oleifera (Kunth) and Pongamia pinnata) or are suitable species to grow on wet or re-wetted peatland (Dyera polyphylla). However, there are limitations to cultivating woody bioenergy species on wet peatland. Sustainable methods for managing and harvesting forests on wet or re-wetted peatland need to be developed.
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