Agroforestry Systems

Although silvopastoral systems involving pigs were once widespread in Britain, the practice has largely died out. However, recent changes in pig production techniques, consumer demands and the economic climate within which farmers operate, have led to renewed interest in both traditional and novel tree-pig systems. This paper describes a financial spreadsheet model (MAST) that was developed to: provide a means of determining financial performance of integrating finishing pigs with natural woodland; identify the likely importance of different as yet largely unresearched animal-tree interactions; and, determine which interactions warrant attention in research and management. Preliminary analysis suggests that the financial performance of this agroforestry enterprise could be superior to that of a pasture-based enterprise. The most important factors in determining incremental performance are identified as sales premia for ‘forest-reared’ pork, changes to feed conversion ratios arising from the provision of a heterogeneous microclimate, and the availability of cheaper land rents.

The roots of different forest species show mixed colonization by arbuscular mycorrhizal fungi (AMF) and dark septate fungi (DSE). In temperate ecosystems, AMF colonization and community structure change according to plantation age, while colonization by DSE is apparently unaffected. However, in tropical ecosystems, little has been documented on the possible changes caused by plantation age on mycorrhizal fungal communities. We analyzed AMF and DSE colonization and described the glomerospore community structure associated with three agroforestry systems of different Cedrela odorata plantation ages (8, 13 and 17 years), in addition to a secondary forest, during the dry season in southeastern Costa Rica. We detected statistical differences in total colonization in the agroforestry systems with respect to the secondary forest (P < 0.05). Among the agroforestry systems, total colonization was higher in 8-year-old trees and DSE were only detected in agroforestry systems with higher colonization in 8-year-old trees. The abundance and richness of glomerospores were higher in the agroforestry systems than in the secondary forest, with greater richness in younger plantations. We isolated 39 morphospecies, 27 from the plantations and 17 from the secondary forest, with a greater representativeness of Acaulospora and Glomus. We also provide four new AMF reports for Costa Rica (Acaulospora laevis, A. excavata, A. spinosissima, and A. bireticulata).

Agroforestry is an ancient practice widespread throughout Africa. However, the influence of Sahelian agroforestry systems on carbon storage in soil and biomass remains poorly understood. We evaluated the carbon storage potential of three agroforestry systems (fallow, parkland and rangeland) and five tree species (Faidherbia albida, Acacia raddiana, Neocarya macrophylla, Balanites aegyptiaca and Euphorbia balsamifera) growing on three different soils (clay, sandy loam and sandy) in the Niayes zone, Senegal. We calculated tree biomass carbon stocks using allometric equations and measured soil organic carbon (SOC) stocks at four depths (0–20, 20–50, 50–80 and 80–100 cm). F. albida and A. raddiana stored the highest amount of carbon in their biomass. Total biomass carbon stocks were greater in the fallow (40 Mg C ha−1) than in parkland (36 Mg C ha−1) and rangeland (29 Mg C ha−1). More SOC was stored in the clay soil than in the sandy loam and sandy soils. On average across soil texture, SOC stocks were greater in fallow (59 Mg C ha−1) than in rangeland (30 Mg C ha−1) and parkland (15 Mg C ha−1). Overall, the total amount of carbon stored in the soil + plant compartments was the highest in fallow (103 Mg C ha−1) followed by rangeland (68 Mg C ha−1) and parkland (52 Mg C ha−1). We conclude that in the Niayes zones of Senegal, fallow establishment should be encouraged and implemented on degraded lands to increase carbon storage and restore soil fertility.

In two dry and two wet seasons forage of pigeon pea, leucaena and sesbania were fed to growing goats as supplements to natural grazing over a two year period. The supplemented goats gained live-weights faster (P < 0.05) than the control animals. Intakes of pigeon pea (63.1 to 91.4 g/head/day) and leucaena (52.6 to 93.8 g/head/day) were consistently higher (P < 0.05) than that of sesbania (49.7 to 83.4 g/head/day) and this was reflected in liveweight gains in both wet and dry season. Liveweight gains ranged from 25.5 to 43.2, 16.7 to 37.5, 14.4 to 28.3 and 6.7 to 21.6 g/head/day for goats supplemented with pigeon pea, leucaena, sesbania and the control animals respectively. Preliminary cost-benefit analysis of the results indicate that such interventions are likely to be economically attractive and the responses provide a basis for improvement of goat production in the Tabora agro-pastoral systems.

As shown in the literature, preserving ecological balance in the Spanish dehesa has traditionally depended on the exploitation of its potential for multifunctionality. Given the increasing number of ecological, climatic, economic and cultural change processes threatening its integrity, new public goods valued by society or the reinvention and revalorisation of existing public goods is, once again, required to contribute to dehesa management in this dynamic context. Historically, humans and ‘wild asparagus’ (Asparagus acutifolius L.), have cohabited within this agro-silvo-pastoral system, establishing a mutually beneficial relationship, since wild asparagus proliferates in the mosaic of forest, shrubs, crops and fields that characterize the dehesa. In addition, this species shows a positive response to collection, which has increased in the last four decades. In the past, food and nutritional values were the most important factors accounting for human interest in wild asparagus. Currently these reasons have been superseded by social and symbolic motives. Today, wild asparagus is the most relevant wild edible plant for various types of users in the dehesa, while gathering events have become a remarkable social phenomenon. In this paper, we describe how wild asparagus is exploited by different users and offer an explanation for its continuing relevance in the dehesa agro-ecosystem, and its revalued importance for rural communities in southern Extremadura (Spain).

Evaluating environmentally sustainable and culturally sensitive approaches to natural resource management issues is a necessary step towards improving livelihoods in rural South Africa. This study assessed the applicability of various agroforestry practices to natural resource management issues in the village of GaMothiba located in the northwestern region of South Africa. Agroforestry assessments were carried out using a community based approach through the application of participatory rural appraisal (PRA) methods. These methods were selected in order to assess the acceptability of agroforestry practices according to the perspective of the local people. The assessment process culminated in a variety of community designed agroforestry interventions. The acceptability of agroforestry practices is largely influenced by the degree of community cohesion, land rights, and cooperation between traditional and municipal authority figures. Understanding the opportunities and constraints of agroforestry adoption in rural sub-Saharan Africa furthers the movement towards community based natural resource management and ultimately a more sustainable approach to rural development.

A silvopastoral model that combines the production of pasture herbage with valuable native timber species has potential to simultaneously address the multiple goals of reforestation, conservation of native species and enterprise intensification. The objective of this study was to design, establish and monitor early growth of a silvopastoral experiment on a dairy farm in the north Atlantic zone of Costa Rica. Two indigenous timber species, Vochysia guatemalensis and Hyeronima alchorneoides were planted with and without the tropical pasture legume, Arachis pintoi in a split plot design, (2 × 2) factorial arrangement of treatments with four replications. After the first two years, V. guatemalensis was significantly taller (3.1 m) than H. alchorneoides (2.5 m). The mean root collar diameter for V. guatemalensis was significantly larger (6.5 cm) than H. alchorneoides (4.5 cm). Two-year establishment was acceptable for the tree component (83 to 85% survival) but poor for A. pintoi (2 to 8% of the sward). The most important pest affecting the establishment of the timber species was the leaf cutter ant, Atta cephalotes. An insect larvae, Cosmopterix sp., severely damaged 39% of the V. guatemalensis trees by repeatedly attacking their apical meristems. The two-year establishment data was insufficient to accurately predict future wood volume. A hypothetical economic analysis concluded that the silvopastoral system must average at least 1.2 m3 wood volume/paddock/year (20 m3/ha/year) throughout the first ten years of growth to assure a positive economic return from timber. The experiment is planned for a ten year period, which corresponds to the estimated rotation length for harvesting the timber species.

Following recommendations from studies on land-use issues in the tropics that were carried out by professors of the faculty of agriculture and food sciences, and of the faculty of forestry, geography and geomatics, Université Laval, Canada, a Master’s program in agroforestry was created in 1993 and implemented in 1996. This program of 45 credits leading to a Master’s degree in agroforestry offers two training types: Master of Science (M.Sc.) with thesis and M.Sc. with essay. The M.Sc. with thesis encompasses 21 course-based credits including 6 compulsory credits of internship where the student learns the biophysical, socioeconomic and cultural environments of agroforestry, and 24 research-based credits. The M.Sc. with essay consists of 33 course-based credits including the same 6 compulsory credits of internship, and 12 essay-based credits. Two professors are directly involved in this program, and 35 theses and 19 M.Sc. essays were completed during the period extending from 1996 to February 2014. Fourteen essays and 18 theses investigated biophysical aspects of agroforestry, whereas 5 essays and 17 theses focused on socioeconomic aspects, respectively. Of the 54 thesis and essays that were completed, 61.11 % focused on tropical countries, and 38.89 % on temperate countries. The program also published over 55 peer-reviewed articles, two book chapters and one textbook. The program is expanding in tropical French speaking countries through international projects on training in management of natural resources, and with the use of digital learning tools to reach out more students on-line.