and Coˆte d’Ivoire (N’Goran 1998 ; Padi and Owusu 1998 ; Ruf and Schroth 2004 ; Asare
2005 ; Anglaaere et al. 2011 ). Treediversity in cocoa farms offers farmers a range of agronomic, economic, cultural, and ecological benefits (Rice and Greenberg 2000 ; Duguma et al. 2001 ; Di Falco and Perrings 2003 ; Somarriba and Beer 2011 ). However, the composition and structure of shade tree stands in mixed systems have been reported to also cause excessive shade, which can lead to high humidity and create favourable conditions for black pod diseases in cocoasystems (Dakwa et al. 1976 ; Opoku et al. 2002 ) and also affect the mechanisms that drive fruit losses on cocoa trees (Bos et al. 2007 ). Monocultures of cocoa tend to have higher productivity under high-input conditions (fertilizer and pesticides) than cocoa in mixed systems (Gockowski et al. 2013 ) but also have shorter economic life span compared with low input, mixed systems, which sustain production over a relatively long period of time (Obiri et al. 2007 ). Hence, discussions on treediversity, density and canopycover in cocoasystems have been polarized between envi- ronmentalists looking for the long-term sustainability and those who seek to increase cocoa bean production in the short term (Asare and Asare 2008 ).
2016 ). It must be stated here that even though it may not be biologically plausible that the yield keeps on increasing with increasing CC, however, within the observed data range with CC up to a level of approximately 30% we do not see a decrease in yield with CC. This is substantiated by recent ﬁndings of Andres et al. ( 2018 ) who found increased number of pods up to a level of 30% –50% shade, after which yields declined. Although this may seem to be at odds with the common perception that shade results in decreasing yield, we ﬁnd that there is no con ﬂict between this study and previous ﬁndings from con- trolled or semi-controlled experiments (e.g. Ahenkorah et al., 1987 ; Cunningham & Arnold, 1962 ). These studies were carried out under high-input conditions and showed higher yields in open systems than in shaded cocoasystems. Even though farmers in our study applied fertilizer and other agrochemical inputs, the quantities applied by small-scale farmers are usually below the recommended doses needed to optimize yields in full-sun grown cocoa (Appiah, Sackey, Ofori-Frimpong, & Afrifa, 1997 ). Instead, farmers tend to apply low amounts of fertilizer (Baah, Anchirinah, & Amon-Armah, 2011 ) with irregular use of fungicides and insecticides, meaning that natural maintenance of soil fertility as well as pest and disease control by non-chemical means become more important. These natural processes may be more prominent in a diverse system with emergent shade trees. Indeed, Beer, Muschler, Kass, and Somarriba ( 1998 ) suggested that shade can be bene ﬁcial under low input scenarios. Speciﬁc to Ghana, Isaac, Timmer, and Quashie-Sam ( 2007 ) docu- mented an increase in nutrient uptake by cocoa trees Figure 3. Observed yields (points) against canopycover desig-
Data were collected from 11 and 13 farms in the Ashanti and Western regions, respectively. Age of the cocoa trees ranged between 8 and 28 years, often with several ages being present on individual farms. This range is considered to be the economically favourable age of cocoa trees (Obiri et al., 2007 ). Farms in each region were selected such that they were at least 2 km apart in each community. These farms represent traditional cocoasystems in which cocoa seeds were sown on previously cleared forestlands with extremely variable CC of shade trees, spacing and age. On each farm, four circular plots of radius 10 m (341 m 2 area) were delineated, two with a tree in the middle forming a canopy above the cocoa trees and two without any shade trees in the plots. One shaded and one no-shade plot were fertilized (see later), leaving one shaded and one no-shade plot as controls. Hence, the experiment can be described as a full factorial design with two factors, shade/no-shade and fertilizer/no- fertilizer, replicated on the 24 farms (blocks). The shade trees comprised 22 different species with varying ecological classifications and guilds (Table S1).
The analysis of shade trees in cocoa agroforestry systems revealed two main clusters, which were characterized as medium and low shade systems with 30% and 10% canopycover respec- tively and consistent with the classification of mid-high and low shade systems identified across West Africa by Gockowski et al [ 41 ]. The medium shade system shade canopycover is within the Rainforest Alliance and CRIG recommendations for sustainable cocoa production [ 42 ]. Farmers with medium shade cover generally reported reduced labour costs, which can be due to weed suppression and consequent reduced weeding. The fact that cocoa farm age for medium shade systems is lower than low shade systems across all regions can be partly attrib- uted to farmers experience in changing climatic conditions [ 36 ], leading to a more positive perception on the effects of shade as adaptation strategy [ 40 ]. More medium shade system farms in the wet than the mid region can be attributed to farmers’ involvement in agroforestry interventions under Rainforest Alliance cocoa certification schemes. Such incentives encour- aged farmers to maintain shade trees [ 34 ]. The Rainforest Alliance and UTZ certification proj- ects promote shade maintenance and improvement of cocoa farm biological diversity [ 42 ]. However, the dry and mid regions represented a conventional situation of farmers’ use of shade trees as the decision of keeping shade trees were not influenced by certification. Since the climatic conditions are favourable for cocoa in the mid region, farmers did not find it nec- essary to maintain much shade compared to the dry region.
Forest products complement agricultural food systems by directly providing a diversity of healthy foods rich in micronutrients and fiber but low in sodium and refined fats and sugar, foods that are culturally valued and integral to the local food systems and food sovereignty, foods that fill seasonal or cyclical food gaps and serve as safety nets or buffers in critical times of food shortage (19). Forest within cities directly supply fruits, vegetables, seeds, oils, and nuts, which provide essential nutrients including vitamins and minerals (20). Urban forestry indirectly supplies food through urban apiculture, silvopastoral practices (e.g. Piper nigrum), taungya systems, snail and grasscutter farming (20). Urban agroforestry is a promising option that could be integrated into a broader concept of urban food forestry (21,22) to sustain food security and environmental wellbeing. The inclusion of trees in food and nutrition security is fairly recent (5). Moreover, few studies have characterized urban food tree species diversity and composition within cities in West Africa (23,24), despite evidence that children who live in areas with high forest/treecover enjoy greater dietary diversity and nutritious foods (25).
One of the reasons people find the District of Columbia so attractive and livable is its trees. Thousands of visitors come to the District each year to witness the cherry blossoms in all their splendor and to stroll along the National Mall with walkways shaded by American elm trees. District residents all have their favorite outdoor spot—whether it is walking the tree-lined boulevards of Connecticut and Minnesota Avenues, picnicking in Rock Creek or Fort Dupont Park, or enjoying a cup of coffee in one of dozens of sidewalk cafes. The one thing that all of these unique and beautiful spots have in common is their trees. It could have been different though if it were not for the vision and actions of a few important figures and the support of the residents of the District of Columbia.
et al. 2014 ; Dinnage 2013 ; Schuldt et al. 2014a ). Furthermore, variation among the herbivores themselves, in particular their way of feeding (feeding guild) or preference for many or par- ticular plant species (degree of specialization), affects the sever- ity and quality of herbivore damage ( Castagneyrol et al. 2014 ). Plant diversity can act on levels of herbivore damage by affecting the abundance and diversity of herbivores. The differ- ent hypotheses we review below make predictions on how this may affect total herbivory in a plant community or average lev- els of herbivore damage on single leaves, the variable of inter- est in the present study. Increasing plant diversity is thought to increase the difficulty for specialized herbivores to find suit- able hosts because these are more diluted (resource concentra- tion hypothesis; Root 1973 ). In contrast, generalist herbivores should not be (or be less) sensitive to resource dilution and might profit directly from more plant species available through resource complementarity (dietary mixing hypothesis; Bernays
In Africa, there was no uniformity in implementing the Washington Consensus. While some countries adopted the “shock therapy” others adopted the “gradualist” approach. In the mid 1980s, many of the African countries shifted from the “African socialism or communism” they adopted after independence to market oriented economy (see section 1.3.1). Guinea and Tanzania for instance, reformed their economies in 1986, Madagascar and Mozambique in 1987, Benin in 1990, Ethiopia and Congo in 1992 (Paulson and Gavin 1999), and Ghana in 1983. These reform programmes were all driven by the IMF and the World Bank based on the policies of the Washington Consensus- “one size fits all”, similar to what they pushed through in Latin America, Russia, CEE and Asia as noted earlier. In general, Paulson and Gavin (1999) classify most of these reforms as gradual or incremental either by design or due to inadequate implementation capacity particularly their sampled former African communist economies 6 . On the whole, the Structural Adjustment Programmes (SAPs) most Africa countries implemented were based on the policies of the Washington Consensus which compelled some of them to dismantle institutions like marketing boards particularly cocoa marketing boards in Nigeria, Cameroun and Cote d’Ivoire. What resulted among other things were poor quality production of cocoa and further decline in terms of trade while per capita growth fell from 36% (1960 -1980) to 15% (1980 -2000). By 2003, Africa’s poverty rate had increased by 75% from 200million people living on U.S. $ 1 per day in 1994 to 350 million, while per capita incomes of most Sub Sahara countries fell by 25% in 1999. In Africa, the reforms did not result in strong increase in output compared to the initial temporary growth in output in Latin America, nonetheless, there was not an economic collapse and hyper-
present stagnant situation in which the industry now finds itself. Admittedly, a significantly high rate of growth (11.4 per cent in 1957-1965) once occurred in the industry under the Board's regime (see Table 1.3), but this has not been sustained. Thus, in the long run, the Ghanaian industry is losing ground to competitors (see Chart 2). The Government of Ghana is particularly worried by the fact that the industry did not take advantage of the boom prices of the last decade to share the high foreign exchange earnings that cocoa production brought about in other cocoa-producing countries. Furthermore, it is costly, as well as embarrassing, to realise that although by the International Cocoa Agreement (ICA) of 1972 Ghana enjoys the high voting power of 300 out of a total of 1,000 votes, and accordingly carries the onus of contributing 36.7 per cent to the administrative funds of the ICA's budget, she finds herself producing only 27 per cent of the world's
and processes are still manually conducted. Leads to delays and over reliance on a large labour force.
y Over reliance on old methods of farming: The
inability of farmers to adopt modern methods of cocoa production has resulted in productivity of Ghana’s cocoa far lower than its competitors.
variables due to their stronger relationship to TCC and AGB in this study. The temporal definition of the dry season and frequency of image acquisition during this period may also merit further research. 4.2. Random Forest Regression and Variable Selection
We used the error rate calculated from the OOB data to perform variable selection with RF in order to assess its effect on the predictive performance of the resulting models. Previous research has shown this to be a statistically sound and efficient approach because the OOB data provide reliable internal estimates of error rate when compared to results derived from 10-fold cross-validation [84,105,106]. The results show that variable selection did improve predictions of both TCC and AGB. This finding is in line with previous related remote sensing research [84,86,106], and suggests that the effect of variable selection should be evaluated when RF is used for predicting treecover attributes from remote sensing data. A plausible explanation to the better performance of the reduced models is that the mechanisms of RF partly fail to block the influence of noisy predictor variables .
is the ‘Agricultural Science and Technology Indicators’ initiative, which collects data on agricultural research investments (99). The last update was done in 2011. Beginning in 2011, it also breaks down the number of researchers by crop categories: cereals, roots and tubers, pulses, oil-bearing, horticultural, other crops. Even though these are very broad categories, it allows for basic comparisons across countries if investments are proportional to what would be expected in a healthy diet. It has been argued that a research investment gap cannot be deduced directly from current R&D investment data, as countries have very different needs for innovation (100). A new indicator of research intensity based on ASTI data that takes into account various factors, including the current size of the economy of each country and the need for agricultural diversification might be an effective way of assessing the gap (100). The resulting indicator appears to be an important step forwards, but it does not consider national food system health, and gives equal weight to export diversification as to national food supplies. The indicator could be further refined to better reflect policy goals associated with agricultural R&D investments. Detailed data to measure the environmental focus, client orientation, or institutional diversity of innovation initiatives and systems are largely absent. Also, the highly aggregated existing data preclude any detailed analysis of the contribution of seed-based innovation to agricultural biodiversity and sustainable food systems. More detailed periodic inventories of seed- based innovation efforts would be needed to assess the precise contribution of these efforts to sustainable food systems. A number of country studies provide interesting models. For example, a Nepalese study of the agricultural innovation system lists plant traits and geographic areas that are being targeted (101).
Cocoa Research Institute of Ghana (CRIG) has introduced a number of innovations to increase cocoa yield per hectare. The main objective of the study was to determine the impact of intensity of adoption of these innovations on cocoa output. A sample of 600 cocoa farmers was selected through a multi-stage sampling technique for the study. An interview schedule was used to gather data and OLS was used to estimate the impact of intensity of technology adoption on output. Results of the study indicated that output of cocoa had positive relationship with household size, farm size, education, membership of association, credit access and technology adoption. It is recommended that COCOBOD should provide training to farmers, increase the number of extension officers and encourage farmers to join farmer associations. Also, financial institutions should make credit accessible to farmers.
Abstract In this paper, models are developed to explain and forecast the effect of world cocoa price on production of cocoa in Ghana by using regression model with time series errors. The focus of the investigation was to find out whether the world cocoa price can assist in forecasting the future behavior of the cocoa production in Ghana. Annual data from 1961 to 2010 were used in fitting the model while 2011 and 2012 were used as out-of-sample data. Based on the behavior of several model adequacy techniques, the regression model with ARIMA(2,2,0) errors was considered as the ‘best’ model for the production variable. The mean absolute percentage error (MAPE), as a forecast accuracy measure, was used to validate the model. Thus, the MAPE of the regression model with ARIMA (2,2,0) errors was 7.97%. However, the conventional ‘best’ ARIMA model fitted to the production variable indicated an MAPE of 16%. This shows that, the production variable has smaller MAPE, when it was modeled together with world price using regression with ARIMA errors. Hence, regression model with ARIMA (2,2,0) errors is a better statistical technique in forecasting production of cocoa in Ghana than the conventional ARIMA method.
We found that shade cover and environmental gradient such as rainfall do not confound each other. From all analyses controlling for rainfall, we found that although there is a correlation between shade and rainfall (r = 0.47), both variable do not impact biodiversity data in a similar way. Rainfall in cocoa agroforests in southern Cameroon is not the predictor of diversity of predators (ant, spiders and wasps) and plants. Instead, the shade index per plot and the shade treediversity were more suitable for predicting diversity of ants, spiders, and wasps, respectively. We also found that under same rainfall condition, shade management by farmers has a significant impact on predator and plant richness. Because shade is strongly correlated with all biodiversity data, we focused our analyses on shade impacts on biodiversity data and yields and we have downgraded rainfall effects. Plant species richness is often closely related to the diversity of other trophic levels . We also found that land use changes are driven by well-known socio- economic factors and culturally mediated innovations . These observations highlight synergies that emerge from diversified cocoa agroforests and the conditions necessary to move from an unsustainable syndrome of production to a sustainable one. To our knowledge, this is the first study examining the relationship between biodiversity, agricultural matrix and pest control in cocoa agroforests in tropical Africa.
The lack of urban vegetation such as trees and shrubs contributes to the heat island effect. Trees serve to cool surrounding air through evapotranspiration . When plants undergo photosynthesis they release water vapour, which evaporates upon release and cools the surrounding air. In general, it is thought that vegetation plays a larger role in the regulation of surface temperatures than do non-reflective surfaces . Non-impervious surfaces will absorb precipitation, and it can be evaporated slowly from the soil. Trees can reduce air conditioning use through a decrease in ambient temperature, thereby reducing ozone production and greenhouse gas emissions. Strategically planted vegetation decreases energy use in three ways. First, shading windows helps prevent direct solar radiation from entering a building. Second, the tree will reduce the amount of radiation hitting the roof and walls, reducing the amount of radiation reaching the structure. Last, shading affects the energy use by cooling the soil around the house that can act as a “heat sink” for the house .
CRIG has introduced a number of research innovations which farmers have to follow to achieve increase in output. These practices include maintenance of the farm by weeding at least twice in a year, pruning semi parasitic mistletoe plant from the cocoa trees and cutting down cocoa trees affected by swollen shoot virus disease. To improve soil fertility, the farmer has to apply fertilizer in prescribed quantities. The farmer has to spray fungicides in right quantities to control black pod disease and spray insecticides to control insects such as black ants, stem borers, mealy bugs, termites and red ants. Ripe cocoa should be harvested; fermentation should be between six and seven days and the cocoa beans should be turned twice on the third and fifth days before they are dried. The cocoa should be dried daily in the sun on raised mats and should be properly dried before they are put in sacks for sale. The activities to be performed by farmers and estimated man-days are presented in Table 1. Table 1: Cocoa Technologies and Estimated Man Days Per Hectare
Abstract: Reducing Emissions from Deforestation and Forest Degradation, sustainable forest management, enhancement of forest carbon stocks and conservation (REDD+) aims to reduce the 12-17% of global greenhouse gas emissions attributable to forest loss worldwide. As tropical countries undertake REDD+ readiness, vital questions arise around the equity of REDD+ interventions. In particular, there has been much critique of the impact of REDD+ on local forest communities, and whether these interventions serve to entrench or address existing inequalities and the structural causes of poverty. Taking Ghana’s REDD+ process as a case study, McDermott et al.’s (2013) ‘equity framework’ is used to systematically examine the contextual, procedural and distributive dimensions of equity, based on fieldwork carried out from July 2014 to March 2016. This study draws on stakeholder perspectives and document analysis to draw conclusions about the equity of Ghana’s REDD+ process. Our study shows that Ghana’s national REDD+ strategy, legal texts and documents aim to ensure that all actors, including local forest communities, are considered ‘subjects of equity’. However, according to stakeholder perspectives and general forest laws and policies, there are multiple barriers to realizing the intended goals of equity. Firstly, the complex, multiple and unclear tenurial arrangements inhibit distributive equity. Secondly, uneven stakeholder knowledge and capacity hamper effective engagement in decision- making and limit procedural equity. Thirdly, contextual factors that are remnants of colonial structures and systems, and that serve competing political and economic interests through resource exploitation impact distributive equity. The ‘equity framework’ reveals that historical contextual factors impact the achievement of equity through REDD+, even with right government policies and strategies in place.
Soil moisture values showed the overlapping trends as different samples had different values. The maximum soil moisture was recorded in Albizzia lebbeck, (L), Benth.,. On the other extreme, minimum value was recorded in Cassia fistula, Linn.,. The top soil has very little soil organic matter because high temperatures and moisture quickly decompose soil organic matter (Chart 1). The rate of soil organic matter decomposition increases when the soil is exposed to cycles of drying and wetting compared to soils that are continuously wet or dry (James, 2010). Water content in leaves, stems, tap roots and lateral root tissues significantly decreased with increasing concentration of salt in soil. There was maximum water content in lateral roots and minimum in leaves. Tissues, according to their water content can be arranged in the following decreasing order: lateral roots > tap roots > stems > leaves (Taiz, 2006). Mineral profile of the selected treecanopy soil ( table-1)
ICCRI and Kendenglembu estate. Canopy replacement technique in Kendeng- lembu was done by side cleft grafting on primary branches and top grafting on plagiotropic branches of primary branches. Number of grafted shoots per plant, i.e. 1, 2, 3, 4, 5 and 6 was used as treatments using Sca 6 and Sulawesi 1. The 12 treatments were arranged in randomized complate block design, each treatment replicated 6 times and 10 plants per treatment. Growth of shoot, canopy coverage and development of VSD incidence were the main variables. In Kaliwining, side cleft grafting was applied at 1.5 m above soil surface using Sulawesi 1 and Sca 6 clones as the scion and TSH 858 and ICS 60 clones as rootstocks. VSD intensity was observed by scoring method. Cocoa yield was the main variable. The result showed that both techniques caused similar growth rate of the shoots. The rate of canopy covering by resistant clones reduced VSD infestation following Y = -0.7848X + 69.324 (R² = 0.995) equation. Three resistant shoots per tree was effective in reduc- ing VSD inf estation. Four years after grafting were bean yield by using Sulawesi 1 was 434% over control while 360% yield for Sca 6 compared to average control of ungrafted plants of ICS 60 and TSH 858. Polyphenol content of both resistant clones was higher than that on susceptible ones, however transfer mechanism of that substance to the susceptible stocks is still unknown. It is concluded that canopy replacement using productive and resistant clones is considered to be an effective method to overcome VSD problem and to improve cocoa yield.