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The objective was to evaluate the characteristics of the pasture and the behavior of grazing goats under continuous stocking in a silvopastoral system (SPS) of Andropogon grass (Andropogon gayanus Kunth cv. Planaltina) in comparison to its monoculture (MC). The treatments consisted of two cropping systems: monoculture of Andropogon grass and silvopastoral system—SPS of native trees mixed with Andropogon grass, evaluated in five grazing periods using goats (February, March, April, May and June). Pasture height, leaf/stem ratio and the dry mass of forage, leaf, stem and dead material were evaluated. The grazing behavior of the goats was also assessed. Significant effect of interaction was observed (p 0.05). The Andropogon grass has the potential to be used in SPS with grazing goats under continuous stocking, positively affecting the pasture and animal behavior.

In silvopastoral systems (SPS) canopy height and the existence of shaded and non-shaded environments can provide changes in plant development. The objective in this study was to evaluate the effect of shading and canopy height on morphogenic, structural and biomass production characteristics of Andropogon gayanus in an SPS. It was adopted a completely randomized design in a 2 × 3 factorial scheme, with four replications, being two luminosity intensities (shaded and non-shaded within a SPS) and three canopy heights (45, 55 and 65 cm). The studied area was used for 21 years in SPS and grazed by goats. The luminosity in the A. gayanus canopy in shaded areas was reduced by 40% in comparison to the non-shaded area in the SPS. There was effect of the interaction between heights and environments on the dry forage biomass, with higher values in non-shaded areas and in higher canopy heights. The leaf/stem ratio, as well as the leaf percentage did not differ between the environment luminosities and canopy heights, whereas the number of tillers was lower in the shaded areas, also where final leaf length was higher. The shade from Tabebuia sp. in SPS does not compromise the growth of A. gayanus. In SPS A. gayanus should be managed at a canopy height of 65 cm in order to present higher yield and maintain its sustainability.

The effect of tree species on the characteristics of the herbaceous stratum, during the first five years of a fallow, was evaluated in the North of Cameroon (average annual temperature 28.2 °C, total annual rainfall 1050 mm). Treatments included a natural grazed herbaceous fallow, a natural ungrazed herbaceous fallow and three planted tree fallows (Acacia polyacantha Willd. ssp. campylacantha (Hochst. ex A. Rich.), Senna siamea Lam. and Eucalyptus camaldulensis Dehnh.), which were protected against grazing. Because tree species influenced light interception in different ways, as well as having different root patterns, they had different effects on the herbaceous stratum in terms of species composition and biomass. The grazed herbaceous fallow maintained the greatest species richness. Protection against grazing or the introduction of tree species associated with the absence of grazing induced both a progressive evolution to a particular species composition. The ungrazed herbaceous fallow consisted mainly of Andropogon gayanus Kunth, which provided the greatest biomass (8 t dry matter ha–1 at the end of the fallow period). E. camaldulensis provided little shade and the lowest fine root mass in the top layer allowing the growth of A. gayanus and thus a greater herbaceous biomass (3.5 t DM ha–1) than that found under the other tree species. Under the heavy shade of A. polyacantha, the herbaceous stratum consisted mainly of annual Pennisetum spp. (2.2 t DM ha–1) and showed the greatest N concentration (1.3%), probably due to N2 fixation by the tree species. After the fourth year, despite the relatively open tree canopy, S. siamea, which showed the highest fine root mass, had a strong depressive effect on the herbaceous stratum.

The tree-shrub savanna ‘Foret Classee de Nazinon’ (Burkina Faso) is submitted to a management of grazing and rotational cutting of Detarium microcarpum. This species resprouts after cutting. In order to investigate whether this silvopastoral land use system is sustainable, aboveground herbaceous biomass was measured on subplots under uncut trees (‘uncut’), next to the stubs of cut trees (‘cut’) and on subplots not influenced by the (former) crowns of trees (‘open grassland’) in four lots. These lots were cut one, three, six and seven years before the study. Vegetation composition of the lots and the composition of the diet of cattle were also determined. Comparisons were made between treatments and lots. Herbaceous biomass was lower in the open grassland subplots than in uncut or cut subplots. We speculate that soil enrichment and more efficient precipitation input in (former) tree crown zones could have resulted in this pattern. Cutting and subsequent resprouting of trees did not lead to significant differences in herbaceous biomass between cut and uncut subplots. The most simple explanation for this is that the trees could extend their roots beyond the location of their neighbouring trees. Biomass and coverage of perennial grasses, mainly Andropogon ascinodis and Andropogon gayanus, did not change in lots cut one, three or six years before the study, but decreased dramatically in lots that were cut seven years before the study. When foraging, cattle spent more than 90% of their time feeding on these species. This indicates that, as a consequence of tree cutting, forage availability may be reduced to the point where local herdsmen are forced to take their cattle to another region.

Tree and windbreak species considered for the Southern Sahelian Zone (SSZ) of West Africa have to be evaluated following multiple criteria such as fast establishment, shelter efficiency, production of feed for livestock, and firewood. An on-station experiment was conducted on a sandy soil in southwest Niger between 1988 and 1993 to assess the establishment, growth, nutritive, and calorific values of seven species considered for windbreaks:Andropogon gayanus, Bauhinia rufescens, Acacia holosericea, Acacia nilotica, Acacia senegal, Faidherbia albida, andAzadirachta indica. Mortality and stem diameter were monitored twice a year. From 20 months after planting (MAP) onwards, species were annually trimmed to 2 m height and to 1 m sidewards of the main stem. Fresh and dry weight of leaves, twigs, wood, and fruits were recorded. Leaves were analyzed for crude protein (CP) and metabolizable energy (ME) content. Wood was analyzed for its gross calorific value and its ash content. At 56 MAP, all species had less than 5% morality, except forA. holosericea, which had a mortality rate of 15.9%.A. indica andA. holosericea showed the highest stem diameter among species with 12.2 and 11.8 cm, respectively, at 56 MAP.A. senegal had the highest dry matter production with 22.3 t ha−1 at 56 MAP, followed byA. indica (12.0 t ha−1),A. holosericea (11.7 t ha−1) andB. rufescens (11.2 t ha−1), butA. holosericea was most productive at earlier harvests. OnlyA. senegal (6.4 t ha−1) andA. indica (5.1 t ha−1) had a significant wood production, whereasA. holosericea (5.7 t ha−1) had the highest phyllodes production. Leaves ofA. senegal andA. indica had highest CP contents of 258 and 214 g kg−1, respectively. The leaves of all species exceptA. gayanus had a higher CP:ME ratio than natural pasture in the region. The calorific values of firewood did not differ significantly among the species.A. nilotica, the species with one of the lowest firewood production, had the highest Fuelwood Value Index of 6.6. The choice of species for planting trees and windbreaks in the SSZ must be oriented along these criteria. Further research should be directed towards cost-benefit analyses, land tenure and property rights in combination with surveys on local knowledge of rural people.