Associate Professor Nangui Abrogoua University Abidjan, Lagunes, Cote d'Ivoire (Ivory Coast)
Fuel load is important in wildfire management in savannas as it determines fire intensity, and therefore its impacts on vegetation. In Guinean savannas (humid savanna of West Africa), bush encroachment is increasingly occurring despite the prescribed early or mi-dry season fire. This warrants the need to experiment new time of burnings within the dry season. Recently, N’Dri et al. (2022) showed that late-dry season fire in alternance with prescribed early or mi-dry seasons could reduce bush encroachement in protected areas of the regions. However, nothing is known about the impact of these fire periods on fine fuel load (stand grass and fallen leave of grasses and trees). Our study provides the first quantitative long-term assessment of the impact of fire seasons on fuel load in the Guinean savannas. In a 8-year experimental field study in a Guinean savanna (Lamto reserve, Ivory Coast), we monitored annually fine fuel load under annual fires set in three different periods of the long dry season: early-dry season (EDS), mid-dry season (MDS) and late-dry season (LDS). We also explored how fuel load were influenced by fire-line intensity and vice-versa. Results showed that grass grows faster after fires, reaching the higher peak in November (~ 2 m) whatever fire season. Globaly fire season did not impact total fine fuel load (20.5 ± 1.1, 19 ± 1.1 and 18.4 ± 1.1 Mg ha−1 yr−1 respectively at EDS, MDS and LDS), nor grass and litter amount. Fuel load and fire-line intensity did not influence each other. However, higher fire-line intensity insured higher grass yield over the following year on EDS fire plots. These findings indicate that changing fire season to prevent bush encroachment is unlikely to modify fuel load and fire-line intensity. This result has the great implication for fire management in Guinean savannas, particularly in bush encorachment context.KEYWORDS: Fire season, Bush encroachment, Fire-line intensity, Fuel load, Guinean savanna
