Agroforestry: An Appropriate and Sustainable Response to a Changing Climate in Southern Africa?

A quantitative appraisal of selected agroforestry studies in the Sub-Saharan Africa

The multiple ecosystem services and livelihood assets development challenges facing the world, including climate change, land degradation, and high poverty levels, have necessitated cross-cutting solutions. Such includes agroforestry technologies, where trees are integrated with crop and pasture lands to yield multiple ecosystem goods and services. Though an ancient approach to land management, agroforestry faces a modern and urgent demand for expansion to counter ecosystems-livelihoods imbalances in most regions across the globe. This paper sought to synthesize the dynamics and characteristics of agroforestry technologies in sub-Saharan Africa by adopting the systematic review approach. Eighty-six (86) agroforestry studies were reviewed, analysing variables such as the dominant agroforestry technologies, production systems, types of studies, and ecosystem services generated by different agroforestry technologies. It established that majority of the agroforestry studies are multiple (undefined) in nature at 36%, have moderately changed over the years, the dominant agroforestry study type is journal articles (59%), and they are mostly scientific in nature (57%). Further, income generation was the dominant provisioning service (31%), greenhouse gas emission reduction was the main regulatory service (31%), and soil fertility management was the key support service. Tradeoffs associated with agroforestry technologies, including increased deforestation rates, tree-crops competition, increased pests and diseases, and potential food insecurity due to reduced crop production were also identified. Barriers to agroforestry such as insecure land tenure systems and inadequate research development are discussed. Pathways towards increased agroforestry technologies adoption, such as creating a conducive institutional and policy environment, as well as developing business support services for agroforestry-related goods and services were identified. The study reiterates the need for increased agroforestry technologies adoption to create the ecosystems-livelihoods balances, with sufficient measures to minimize the potential tradeoffs.

Exploring the Branch Wood Supply Potential of an Agroforestry System with Strategically Designed Harvesting Interventions Based on Terrestrial LiDAR Data

Agroforestry systems hold potential for wood and tree biomass production without the need of felling trees. Branch wood harvesting provides access to considerable amounts of lignocellulosic biomass while leaving the tree standing. Aiming at alternatives for wood provision, we assessed the actual woody structure of a silvopastoral system in the African Savannah ecoregion, utilising terrestrial LiDAR technology and quantitative structure models to simulate branch removals and estimate harvesting yields. In addition, the stand structure and harvested wood were examined for the provision of four types of assortments meeting local needs, and operational metrics for each treatment were derived. The stand had large variability in woody structures. Branch harvesting interventions removed up to 18.2% of total stand volume, yielded 5.9 m3 ha−1 of branch wood, and delivered 2.54 m3 ha−1 of pole wood quality, retaining on average more than 75% of the original tree structures. Among the most intense simulations, a mean of 54.7 litres (L) of branch wood was provided per tree, or approximately 34.2 kg of fresh biomass. The choice of an ideal harvesting treatment is subject to practitioners’ interests, while the discussion on aspects of the operation, and stand and tree conditions after treatment, together with outputs, assist decision making. The partitioning of tree structures and branch removal simulations are tools to support the design of tending operations aiming for wood and tree biomass harvesting in agroforestry systems while retaining different functional roles of trees in situ.

The Future of Food: Domestication and Commercialization of Indigenous Food Crops in Africa over the Third Decade (2012–2021)

This paper follows the transition from ethnobotany to a deeper scientific understanding of the food and medicinal properties of African agroforestry tree products as inputs into the start of domestication activities. It progresses on to the integration of these indigenous trees as new crops within diversified farming systems for multiple social, economic and environmental benefits. From its advent in the 1990s, the domestication of indigenous food and non-food tree species has become a global programme with a strong African focus. This review of progress in the third decade is restricted to progress in Africa, where multi-disciplinary research on over 59 species has been reported in 759 research papers in 318 science publications by scientists from over 833 research teams in 70 countries around the world (532 in Africa). The review spans 23 research topics presenting the recent research literature for tree species of high priority across the continent, as well as that in each of the four main ecological regions: the humid zone of West and Central Africa; the Sahel and North Africa; the East African highlands and drylands; and the woody savannas of Southern Africa. The main areas of growth have been the nutritional/medicinal value of non-timber forest products; the evaluation of the state of natural resources and their importance to local people; and the characterization of useful traits. However, the testing of putative cultivars; the implementation of participatory principles; the protection of traditional knowledge and intellectual property rights; and the selection of elite trees and ideotypes remain under-researched. To the probable detriment of the upscaling and impact in tropical agriculture, there has been, at the international level, a move away from decentralized, community-based tree domestication towards a laboratory-based, centralized approach. However, the rapid uptake of research by university departments and national agricultural research centres in Africa indicates a recognition of the importance of the indigenous crops for both the livelihoods of rural communities and the revitalization and enhanced outputs from agriculture in Africa, especially in West Africa. Thus, on a continental scale, there has been an uptake of research with policy relevance for the integration of indigenous trees in agroecosystems and their importance for the attainment of the UN Sustainable Development Goals. To progress this in the fourth decade, there will need to be a dedicated Centre in Africa to test and develop cultivars of indigenous crops. Finally, this review underpins a holistic approach to mitigating climate change, as well as other big global issues such as hunger, poverty and loss of wildlife habitat by reaping the benefits, or ‘profits’, from investment in the five forms of Capital, described as ‘land maxing’. However, policy and decision makers are not yet recognizing the potential for holistic and transformational adoption of these new indigenous food crop opportunities for African agriculture. Is ‘political will’ the missing sixth capital for sustainable development?

Agroforestry Practices in Livelihood Improvement in the Eastern Cape Province of South Africa

Agroforestry plays a significant role in increasing agricultural productivity. In South Africa, there is a pressing need for promoting smallholder agriculture to promote sustainable rural livelihoods, to ensure food security, to lower inflation in food prices, and address rampant rural unemployment in the country. The agricultural economy is characterised by a monopoly structure where almost every single staple in South Africa is already produced by large manufacturers that can produce it at better quality and lower cost than the average smallholder enterprise or cooperative. Such a monopoly structure fundamentally undermines the development of local markets, where local small-scale producers sell to their local community. The novelty of this study is addressing the research gap that conventional rural livelihood analyses often neglect, i.e., the role of environmental products in general, and forest and agroforestry products. Using a log linear regression model with cross-sectional data collected from a sample of 300 households, this study explores the likely impact of agroforestry practices in promoting the livelihood of rural communities in the study areas. Results obtained from multiple linear regression analysis showed that average household income increased as a function of utilization of agroforestry practices. Agroforestry contributes to sustainable rural livelihoods in South African provinces where the predominant means of livelihoods is rural subsistence farming and agriculture. Since valuation of agroforestry products and services are technically difficult, farmers often underestimate the contribution of agroforestry to the household’s livelihood income. These findings have policy implications in promoting food security in the Eastern Cape Province of South Africa and beyond.

Agroforestry Systems and Their Contribution to Supplying Forest Products to Communities in the Chure Range, Central Nepal

Agroforestry (AF), an integration of agricultural and/or pastureland and trees, is a powerful tool for the maximization of profit from a small unit of land; however, it has been less well explored and recognized by existing policies. AF could be the best approach to conserving the fragile soils of Chure and to supplying subsistence needs to the local people. This study endeavored to understand how the adoption of various AF practices contributed to people’s livelihoods in the Bakaiya rural municipality of Makawanpur District. To achieve this, 5 focus group discussions, 10 key informant interviews and 100 household surveys were conducted. These were analyzed using various statistical analysis tools: Kruskal–Wallis test, Games–Howell post hoc comparison test and Wilcoxon test. Thematic analysis was employed to understand the status and growth process of AF in the study area. Of three different AF systems used in the area, agri-silviculture was found to be the dominant form. Local people derived forest products, especially fuelwood, fodder and leaf litter from AF, where agri-silvi-pasture was most common. The three AF systems studied here were in turn compared with community forestry (CF), which is a participatory forest management system overseen by the community. People derived almost 75% of fuelwood from CF, whereas in the case of fodder and leaf litter, contributions from CF and AF were almost equal. Despite the potentiality of AF in fulfilling the demands of local people, promotional and development activities were lacking. This study recommends a strong collaboration of local people and concerned stakeholders for the promotion and technical facilitation of AF systems.

A Scientometric Analysis of Worldwide Intercropping Research Based on Web of Science Database between 1992 and 2020

Intercropping has been practiced worldwide in both traditional and sustainable agriculture to feed the growing population. This study aims to analyze the research status and evolution of intercropping, to identify the influential authors, research centers, and articles, and to reveal the main research topics between 1992 and 2020 based on the Web of Science Core Collection database. The results show that the volume of publications in this field has increased rapidly over the past three decades. The analysis identifies the top three authors (i.e., Meine Van Noordwijk, Wenyu Yang, and Teja Tscharntke), top three contributing organizations (i.e., the World Agroforestry Center (ICRAF), the Chinese Academy of Science, and the INRA), and three most productive countries (i.e., the USA, India, and China). Co-occurrence analysis demonstrates that studies on intercropping can be divided into four clusters as centered by keywords of intercropping/maize, biodiversity/conservation, agroforestry, and carbon, respectively. Lal 2004 is the most influential study with the greatest number of citations and Agroforestry Systems is the most utilized journal. Perspectives on future studies were also given. This study helps researchers to clarify the current research status in the field of intercropping and put forward its future research.

Modelling and Comparing Shading Effects of 3D Tree Structures with Virtual Leaves

Reduced solar radiation brought about by trees on agricultural land can both positively and negatively affect crop growth. For a better understanding of this issue, we aim for an improved simulation of the shade cast by trees in agroforestry systems and a precise estimation of insolation reduction. We present a leaf creation algorithm to generate realistic leaves to be placed upon quantitative structure models (QSMs) of real trees. Further, we couple it with an enhanced approach of a 3D model capable of quantifying shading effects of a tree, at a high temporal and spatial resolution. Hence, 3D data derived from wild cherry trees (Prunus avium L.) generated by terrestrial laser scanner technology formed a basis for the tree reconstruction, and served as leaf-off mode. Two leaf-on modes were simulated: realistic leaves, fed with leaf data from wild cherry trees; and ellipsoidal leaves, having ellipsoids as leaf-replacement. For comparison, we assessed the shading effects using hemispherical photography as an alternative method. Results showed that insolation reduction was higher using realistic leaves, and that the shaded area was greater in size than with the ellipsoidal leaves or leaf-off conditions. All shading effects were similarly distributed on the ground, with the exception of those derived through hemispherical photography, which were greater in size, but with less insolation reduction than realistic leaves. The main achievements of this study are: the enhancement of the leaf-on mode for QSMs with realistic leaves, the updates of the shadow model, and the comparison of shading effects. We provide evidence that the inclusion of realistic leaves with precise 3D data might be fundamental to accurately model the shading effects of trees.