1,720,977 research outputs found
Impact of common shade tree species on microclimate and cocoa growth in agroforestry systems in Ghana
No full textAbstract Climate change is a growing threat to agriculture globally, with most substantial impacts expected in tropical smallholder systems such as cocoa farms in West Africa. Cocoa agroforestry is widely believed to enhance resilience to climatic extremes due to protection and a favourable microclimate under the shade trees. Morphological traits of many locally used shade tree species and their specific contribution to microclimate for climate-resilient cocoa production remain unclear. Therefore, aboveground morphology and sub canopy microclimate of eight common shade tree species were investigated in cocoa agroforestry systems in the Ahafo region, Ghana. Additionally, the growth of cocoa trees in three different distance zones to the shade tree stem was measured. The eight different shade tree species exhibited considerable variation in their impact on microclimate and cocoa growth. M. indica and M. excelsa allowed lowest light transmission, with the highest microclimatic buffering effect, i.e., reducing vapour pressure deficit and daily fluctuations of temperature and relative humidity. Cocoa trees around M. lucida and F. capensis were the highest in growth, characterized by height and stem diameter. However, a universally superior shade tree species could not be identified implying the need for shade tree diversity allowing various microclimatic conditions within an agroforestry system to spread risk of climate extremes. Cocoa tree growth was more affected by distance to the shade tree than by shade tree species, resulting in enhanced growth with distance to the stem. These findings provide a better understanding of species-related differences on cocoa growing conditions and climate change adaptation strategies.German academic scholarship foundationDeutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Justus-Liebig-Universität Gieße
Salinity Constraints for Small-Scale Agriculture and Impact on Adaptation in North Aceh, Indonesia
No full textWe investigated the perceived effects of salinity on farming practices, income, and challenges for crop production in Blang Nibong village in North Aceh, Indonesia. We surveyed 120 smallholder farmers chosen in consultation with local leaders considering their agricultural activities and salinity susceptibility. Farmers’ perceptions of major crop production constraints (e.g., salinity) and potential adaptation strategies were assessed using open and closed questions. The study revealed that farmers in the study region primarily grew rain-fed rice using traditional monoculture. Salinity was identified as the primary crop production constraint by all respondents, resulting in plant mortality, decreased soil health and water quality, limited plant growth, and low yields. Additionally, salinity has reduced the arable area (>0.5 ha), resulting in lower total production. The implications of the salinity were further corroborated by the low farmers’ income. In fact, farming activities are not contributing positively to farmers’ income as the results revealed off-farm activities (77%) as the main source of income. Based on the farmer’s current activities to overcome salinity problems on their farms, they were clustered into adaptive and non-adaptive farmers. The non-adaptive group prefers to convert their land to pasture (81%), whereas the adaptive group prefers to improve the irrigation system (77%)
Do voluntary sustainability standards improve socioeconomic and ecological outcomes? Evidence from Ghana’s cocoa sector
No full textVoluntary sustainability standards offer potential for sustainable development by improving the livelihoods of smallholder cash crop farmers while conserving biodiversity. However, their overall implications remain poorly understood, as studies have mostly focused on assessing their effects on single sustainability dimensions. Here, we use an interdisciplinary approach to understand the simultaneous effects of sustainability standards on socioeconomic and ecological outcomes in Ghana’s cocoa sector. Our study is based on a rich dataset comprising representative household data from 814 smallholder cocoa-producing households from five major cocoa regions and ecological data from 119 cocoa plots. Results from the endogenous switching regression approach suggest that sustainability standards have positive effects on socioeconomic outcomes such as cocoa yield, net cocoa income and net returns to land. However, using generalized linear mixed effects models, we do not find any significant associations with ecological outcomes related to vegetation structure and animal diversity. Our results indicate that sustainability standards in Ghana’s cocoa sector lead to socioeconomic benefits but not to ecological benefits for the plot environment. Nevertheless, yield increases do not come at the expense of biodiversity. We conclude that sustainability standards have the potential to improve socioeconomic outcomes, without significantly creating trade-offs with ecological outcomes.Keywords: Sustainability standards; Certification; Cocoa; Ghana; Biodiversity; Trade-offsJEL codes: Q01, Q56, Q5
Agronomic and Physiological Traits Response of Three Tropical Sorghum (<i>Sorghum bicolor</i> L.) Cultivars to Drought and Salinity
No full textSorghum holds the potential for enhancing food security, yet the impact of the interplay of water stress and salinity on its growth and productivity remains unclear. To address this, we studied how drought and salinity affect physiological traits, water use, biomass, and yield in different tropical sorghum varieties, utilizing a functional phenotyping platform, Plantarray. Cultivars (Kuali, Numbu, Samurai2) were grown under moderate and high salinity, with drought exposure at booting stage. Results showed that Samurai2 had the most significant transpiration reduction under moderate and high salt (36% and 48%) versus Kuali (22% and 42%) and Numbu (19% and 16%). Numbu reduced canopy conductance (25% and 15%) the most compared to Samurai2 (22% and 33%) and Kuali (8% and 35%). In the drought*salinity treatment, transpiration reduction was substantial for Kuali (54% and 57%), Samurai2 (45% and 60%), and Numbu (29% and 26%). Kuali reduced canopy conductance (36% and 53%) more than Numbu (36% and 25%) and Samurai2 (33% and 49%). Biomass, grain yield, and a-100 grain weight declined in all cultivars under both salinity and drought*salinity, and Samurai2 was most significantly affected. WUEbiomass significantly increased under drought*salinity. Samurai2 showed reduced WUEgrain under drought*salinity, unlike Kuali and Numbu, suggesting complex interactions between water limitation and salinity in tropical sorghum
Functional groups of leaf phenology are key to build climate-resilience in cocoa agroforestry systems
No full texthttp://dx.doi.org/10.13039/501100001659 German Research Foundatio
Do voluntary sustainability standards improve socioeconomic and ecological outcomes? Evidence from Ghana's cocoa sector
No full texthttp://dx.doi.org/10.13039/501100001659 German Research Foundatio
Morphological and genetic diversity of Shea tree (Vitellaria paradoxa) in the Savannah regions of Ghana
No full textТекст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Vitellaria paradoxa C. F. Gaertn., commonly known as shea tree or Vitellaria, is ranked the most important tree species of the savannah regions in the most African countries due to its ecological and economic importance for livelihoods and national economies. However, the savannah regions are the most vulnerable areas to the global climate change. Moreover, the Vitellaria populations on farmlands are threatened by the dominance of old trees with low or lack of regeneration. In this study both morphological and genetic diversity were assessed using several phenotypic traits and 10 microsatellite markers, respectively, to assess the impact of land use and agro-ecozone types on Vitellaria in Ghana. The land use types were forests and farmlands, and the agro-ecozone types included the Transitional, Guinea, and Sudan savannah zones. The mean values of morphological traits, such as diameter at breast height (DBH) and canopy diameter (CD), were statistically different between forest (DBH = 22.20, CD = 5.37) and farmland (DBH = 39.85 CD = 7.49) populations (P < 0.00001). The Sudan savannah zone with mean petiole length of 4.96 cm showed significant difference from the other zones, likely as a result of adaptation to drier climate conditions. Genetic data analysis was based on 10 microsatellite markers and revealed high genetic diversity of Vitellaria in Ghana: mean expected heterozygosity, He was 0.667, and allelic richness, measured as number of effective alleles Ae, was 4.066. Both farmlands and forests were very diverse indicating lack of negative influence of farmer’s selection on genetic diversity. Fixation index was positive for all populations (mean FIS = 0.136) with farmlands recording relatively higher values than forests in all ecological zone types studied, probably indicating less gene flow in the farmlands. Moderate differentiation (F′ST = 0.113) was comparable to other similar tree species. Both land use and ecological zone types influenced genetic differentiation of Vitellaria at varying levels. The species was spatially structured across three ecozones and following climatic gradient. The forest reserves are used in situ conservation for Vitellaria in Ghana. High diversity observed in the most arid zones provides opportunity to find and use appropriate plant materials for breeding climate change resilient trees
Evaluating farmers' knowledge of shade trees in different cocoa agro-ecological zones in Ghana
No full textShade trees are an integral part of most cocoa growing systems across the world. This study assesses farmers' local knowledge of shade trees at two locations in Ghana with different climatic conditions and vulnerability to climate change. Akumadan is located in the northern dry part of the cocoa belt representing marginal conditions for cocoa cultivation, whereas Asankragua is located in the southern wet part, more ecologically favorable for cocoa cultivation. Inventories were conducted to assess the abundance of species, their structural characteristics and benefits to cocoa systems. Results show that cocoa farmers have detailed knowledge on the functions of shade trees in cocoa systems and prefer species that provide specific needs according to the location. However, abundance of species in a location does not necessary translate into beneficial impacts on cocoa productivity. In the drier part of the cocoa belt, income diversification through shade trees is an adaptation strategy to the increasingly marginal conditions for cocoa production, which has led to the high proportion of fruit trees among the most abundant species. In contrast, farmers in the southern part of the cocoa belt select shade trees for their high cocoa compatibility. Adaptation strategies for cocoa farmers should therefore promote species that best accommodate farmers' economic, agronomic and environmental needs
Characterization of cocoa production, income diversification and shade tree management along a climate gradient in Ghana
Full text linkReduced climatic suitability due to climate change in cocoa growing regions of Ghana is expected in the coming decades. This threatens farmers’ livelihood and the cocoa sector. Climate change adaptation requires an improved understanding of existing cocoa production systems and farmers’ coping strategies. This study characterized current cocoa production, income diversification and shade tree management along a climate gradient within the cocoa belt of Ghana. The objectives were to 1) compare existing production and income diversification between dry, mid and wet climatic regions, and 2) identify shade trees in cocoa agroforestry systems and their distribution along the climatic gradient. Our results showed that current mean cocoa yield level of 288kg ha-1yr-1 in the dry region was significantly lower than in the mid and wet regions with mean yields of 712 and 849 kg ha-1 yr-1, respectively. In the dry region, farmers diversified their income sources with non-cocoa crops and off-farm activities while farmers at the mid and wet regions mainly depended on cocoa (over 80% of annual income). Two shade systems classified as medium and low shade cocoa agroforestry systems were identified across the studied regions. The medium shade system was more abundant in the dry region and associated to adaptation to marginal climatic conditions. The low shade system showed significantly higher yield in the wet region but no difference was observed between the mid and dry regions. This study highlights the need for optimum shade level recommendation to be climatic region specific.</div
Productivity, water use and climate resilience of alternative cocoa cultivation systems
Full text linkGlobal demand for cocoa beans is projected to keep rising while future production is likely to be limited by climate variability and change. Over 70% of the global cocoa supply comes from West Africa, a region expected to be greatly affected by climate change and extreme droughts. Cocoa production in West Africa needs to be adapted to more marginal and extreme climatic conditions, mainly drought, to sustain production and avoid further deforestation of the remaining rainforest for its cultivation. In addition to the climate change effect, current yields are low due to management inefficiencies and soil limitations. Empirical data from cocoa agroforestry system studies are limited compared to those of other perennial crops such as coffee. In addition, the promotion of cocoa agroforestry as a sustainable production system is often based on anecdotes and should therefore be investigated further. There is still a huge knowledge gap on which shade tree species improve and sustain productivity, ecosystem functions (such as increase in flora and fauna diversity), and which are suitable for marginal climates with limited water supply. Studies on the effects of climatic variations on cocoa plant productivity across different regions are lacking although there is a general consensus on the requirement of developing climate change adaption options based on a sound scientific basis for the various regions.
As a contribution towards bridging this research gap and help address current and future cocoa production challenges, for this thesis several studies were performed in Ghana, the second largest and best quality cocoa producing nation: Productivity of different cocoa cultivation systems was studied at three regions along a climatic gradient (from 2014 to 2016). Climate resilience of different cocoa cultivation systems was further investigated in the marginal regions through water use experiments over periods of wet, dry and extremely dry.
Overall hypotheses of the thesis were that (i) climatic region does influence cocoa productivity, and (ii) agroforestry increases resilience of cocoa plants to marginal and extreme climatic conditions.
In chapters 2 and 3 of the thesis, characterizations of yield gaps, soil fertility status and cocoa cultivation systems were conducted through interviews and on-farm inventories of 150 cocoa farmers and their farms along a climate gradient within the cocoa belt of Ghana. The regions which are between 100 to 150km apart were denoted as dry, mid and wet, based on estimated average annual rainfall of 1200, 1400 and 1800mm from north to south of the cocoa belt respectively. These regions are representative of current and future cocoa climatic regions of West Africa. Based on yield gap and soil fertility evaluations, it was found that the study regions were significantly different. Yield levels in the wet region were significantly higher than in the dry region, mainly due to suitable climate and management intensification. Lower yield in the dry region was due to climatic limitation and farmer’s adaptation strategies in terms of income diversification and using less external inputs. Cocoa only contributed 50% to farmer’s income in the dry region while non-cocoa crops and off-farm income activities contributed 30 and 20%, respectively. For farmers in the mid and wet regions, cocoa income contributed more than 80% to their annual income, indicating higher intensification and specialization. Soil fertility also varied significantly between the regions but overall the fertility status was low. From these findings it was established that different climatic zones will require different cocoa farm management and soil fertility improvement strategies. Closing yield gaps in the dry region requires improvement in pesticide and fungicide use in addition to fertilizer application. In the mid and wet regions, the control of parasitic mistletoe, improved fertilizer use and the use of quality planting materials are recommended for yield gap closure. Shade tree use and management in cocoa agroforestry systems practiced by farmers were further characterized across all climatic regions. This was to evaluate the existing and potential use of shade trees as a measure to adapt cocoa production systems to climate change. The current cocoa agroforestry systems were characterized for the two main systems of “medium” and “low shade”. Medium and low shade systems dominated the dry and wet regions, respectively. Cocoa yield under medium shade system was significantly lower in the wet region but there was no difference in the dry and mid regions. It is therefore recommended that, shade tree selection for cocoa agroforestry should be climatic region-specific to minimize trade-offs between the productivity of cocoa farms and other ecosystem services.
In chapter 4, a detailed water use experiment was conducted in the dry region to help understand the effect of different cultivation systems on water use and drought resilience. Cocoa and shade tree water uptake (sap flow) was studied with a thermal dissipation method using Granier sensors. Soil water and microclimatic conditions were also monitored from November 2014 – March 2016. This experiment tested cocoa agroforestry as a potential adaptation strategy in sub-optimal and extreme drought conditions. Cocoa in full sun was compared with agroforestry systems: shaded by (i) a leguminous tree species, Albizia ferruginea and (ii) Antiaris toxicaria, the most common shade tree species in the dry region. The climate and drought events during the study period served us as a proxy for projected future climatic conditions in marginal cocoa cultivation areas of West Africa. The 2015/16 El Niño event resulted in the strongest drought in the region since 1982/83 when a similarly strong event occurred. Soil water was reduced under the shaded systems during drought events. Cocoa plants under Albiza and Antiaris recorded 100 and 77% mortality, respectively, during the extreme drought period. Cocoa plants under full sun survived and recovered after the drought while those under shade did not. It was then established that during extreme drought, the role of shade trees on cocoa plants became critical as competition for soil water intensified. Water limitation was found to override microclimatic benefits by the studied shade tree species. Cocoa plants under full sun showed a higher level of resilience and acclimatisation capacity to drought than shaded cocoa. These results call for further detail studies, looking above- and below-ground, to critically evaluate the promotion of shade tree use as a climate change adaptation strategy for cocoa cultivation planning especially in West Africa.
Differences in cocoa plant productivity between shaded and full sun systems across the climatic regions were studied in Chapter 5. Three treatments of high shade, medium shade and open sun plots were assessed across the three climatic regions. Three cocoa plots of each system with 20 uniformly distributed cocoa plants were monitored monthly for a whole year. The results showed higher cocoa plant yield (harvested pods) under full sun conditions than in the shaded systems in the low rainfall dry region. In the mid and wet regions, no significant differences were observed between the systems. Both cocoa plant productivity and drought resilience are therefore negatively affected by shade trees under a marginal cocoa climate. The use of shade trees as climate change adaptation strategy especially in the mid region where by 2050 marginal climatic conditions are projected, need to be carefully reconsidered. For the dry region, a potential climate change adaptation strategy would be changing from cocoa to crops that are more productive and are faced with lower climatic risk. One example of such a crop may be cashew, which is more resilient to drought than cocoa and also has a high economic value. The development of more drought tolerant cocoa planting materials could also be an option to sustain cocoa production under the projected climate change. In the mid region, where the projected climatic conditions will be similar to those of the current dry region, shade trees with proven complementary soil water use under natural conditions could be integrated with cocoa. Alternatively, a full sun system is recommended through land sparing approach to ensure biodiversity conservation in the cocoa landscape. For the wet region, where water limitations are not expected, well managed cocoa agroforestry systems could be practiced to ensure sustainable yield and biodiversity conservation. Overall, this study provided detailed results on climatic zone-specific cocoa management as well as options to help adapt plant production systems to climate change and extreme drought within the “cocoa landscape”
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