Biodiversity and Structure of Woody Plants of Sahelian Rangelands of Baban Rafi, Niger

Abstract

The present study investigates the importance of harvesting regimes and natural disturbances on the diversity, the population structure and the regeneration trends of the woody plant species of Sahelian rangelands and their implication for sustainable browsing management. Woody plants data was collected in 42 plots established in the interval of 500 m, along transects distant of 500 m, in the direction South-west and North-east of the study area. In each plot, height and diameter at breast height of each individual mature tree and shrub (diameter < 4 cm), and the number of seedlings (diameter > 4 cm) were recorded. A total number of 21 plants species were recorded, with low values of the Shannon-Weaver (H') index and the evenness of Piélou (E) indicating very low diversity of rangelands. Analysis of size classes distribution of diameters and heights of the whole vegetation and the three dominants species revealed high density of juveniles, relating to stable populations. The juvenile plants represented more than 80 of the vegetation with diameters and heights respectively lower than 6 cm and 2.5 m, indicating shrubby vegetation. Combretum micranthum, Guiera senegalensis and Combretum nigricans which have the highest values of IVI, have also the greatest rates of seedling and vegetative propagation densities. Stable populations with strong capacity of regeneration under harsh area and high human pression such as logging and grazing can be related ecological success. Management practices that promote plantations or managing natural regeneration of such species can facilitate fast secondary succession towards desirable condition.

Floristic diversity and regeneration of wild edible fruit species in the Reserve of Moutourwa and its surroundings (Far-North Cameroon)

“…This may also be due to the strong anthropic pressure on this group and therefore the death of adult plants as a result of poor management or overexploitation. Thus, numerous studies carried out in the Sahelian and Sudanian zones have also confirmed this structural variability of species (Rabiou et al, 2015;Idrissa et al, 2017;Amadou et al, 2020). According to Sandjong et al (2018), adaptations to ecological conditions, competition for resources and exploitation would underlie this structural variability.…”

“…The low presence of adult individuals with a diameter greater than 15 cm was observed in species with an inverted Jshape that embodies secure regeneration. This indicates that large individuals are heavily exploited as highlighted by Idrissa et al (2017). The 'inverted J' shape type has been observed in T. indica (Fandohan et al, 2011), Dialium guineense (Assongba et al, 2013), Prosopis africana (Houètchégnon et al, 2015) and Lophira lanceolata (Lankoandé et al, 2017).…”

Expanding networks of field hedges in densely populated landscapes in the Sahel

“…The species composition of the field hedges of the study area is relatively poor by comparison with other woody populations in Niger (Mahamane et al 2009;Idrissa et al 2017) with only 16 species registered across the 12 sites over the three years of observation (Table SI 3). This poverty is reinforced by the fact that three species: G. senegalensis, C.…”