Influence of selective tree cutting, livestock and prescribed fire on herbaceous biomass in the savannah woodlands of Burkina Faso, West Africa

• Published in: Agriculture, ecosystems & environment Vol. 105; no. 1; pp. 335 - 345
• Main Authors: Sawadogo, Louis, Tiveau, Daniel, Nygård, Robert
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 2005; Elsevier Science
• Subjects: Agronomy. Soil science and plant productions; Andropogon; Biological and medical sciences; biomass; Browsing; cutting; Disturbance; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; grazing; logging; Pastoralism; prescribed burning; Protected area; Rangeland; rangelands; savannas; Selective logging; silvopastoral systems; Burkina Faso; West Africa; Africa; Rangeland; Pastoralism; Protected area; Selective logging; Browsing; Disturbance; Savannah; Range management; Forest logging; Grazing; Agroecosystem; Sustainable management; Livestock; Vegetation fire
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2004.02.004

In West Africa policies for grazing, selective tree cutting and prescribed early fire in the savannah woodlands are rarely based on long-term experimental studies. The purpose of this study was to provide scientific evidence based on field data from two case studies for an informed discussion on the effects of various management options. The main findings were by and large specific for the species, the growth form and the location. This supports the argument for devolution of management responsibility to the local level where there is such site-specific ecological knowledge. Effects of selective tree cutting (50% of basal area), livestock (1–1.4 tropical livestock unit ha −1) and prescribed early annual fire on herbaceous biomass were studied in the state forests of Laba (shallow sandy soils) and Tiogo (deep clayey soils) in the savannah woodlands in the Sudanian Zone of Burkina Faso, from 1993 to 2001. The herbaceous biomass was analysed on three levels: total herbaceous biomass, per growth form (annual and perennial grasses and forbs) and for each of the four main species in the study areas ( Andropogon pseudapricus, Loudetia togoensis, Andropogon ascinodis and Andropogon gayanus). At both sites, mean total biomass during the study period was reduced by the presence of livestock while it was not significantly affected by early prescribed fire or by selective cutting. There was interaction between the three treatments at both sites. Statistically significant treatment effects were found at each site when analysing each growth form and species individually. For instance, at the growth form level, grazing reduced the biomass of annual grasses in Tiogo, perennial grasses in Laba and forbs at both sites. Site and species-specific response to grazing was found for A. ascinodis with increased biomass in Tiogo and reduced biomass of A. gayanus in Laba. Although the effect of prescribed early fire was not statistically significant the trend was the same at both sites with increased biomass of annual grasses and decreased biomass of perennial grasses. This homogenising effect of fire was statistically significant at the species level with increased biomass of the annual grass L. togoensis and decreased biomass of the perennial grass A. gayanus at both sites. Selective cutting significantly increased mean biomass of annual grasses in Tiogo whereas there was no difference in Laba.