Scielo RSS <![CDATA[Bothalia - African Biodiversity & Conservation ]]> vol. 50 num. 1 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<b>Long-term changes in forest cover in a global biodiversity hotspot in southern Mozambique</b>]]> BACKGROUND: Deforestation is a complex and dynamic process of widespread concern in sub-Saharan Africa that is influenced by a range of social, economic and biophysical factors. OBJECTIVES: The aim of this study was to analyse patterns of deforestation and its potential drivers in the Licuáti Forest Reserve, a biodiversity hotspot in southern Mozambique, between 1990 and 2016. METHOD: We performed image classification on Landsat imagery at six time steps and interviewed local community members to understand the spatial pattern and rate of forest cover loss over time. We also examined changes in the incidence of fire. RESULTS: A substantial increase in the rate of deforestation since 1990 was detected in this vulnerable thicket vegetation. The probability of deforestation was significantly higher near the major roads, where houses are located. This suggests that the proximity of human settlements to the forest, and access to charcoal markets in urban areas, influenced the spatial pattern. Two key factors, charcoal production and the establishment of settlements and agricultural lands, were identified as proximate causes of deforestation. In addition, fires associated with these two causes might amplify the loss of forests in the area. CONCLUSIONS: Complex interactions between the drivers of deforestation and socioeconomic factors were suggested, as most of the charcoal produced in the region is transported to Maputo. Ongoing road improvements and infrastructural development in the region will likely accelerate the decline in forest cover in the future. This has implications for the biodiversity of the region as well as for the sustainability of local livelihoods, as they often depend on forest products for their daily uses. <![CDATA[<b>Environmental factors that influence species diversity of floodplain plant communities in different flooding phases in the Okavango Delta, Botswana</b>]]> BACKGROUND AND OBJECTIVES: Species composition and distribution in seasonal floodplain plant communities are influenced by variation in flooding. However, the influence of intra-flooding variation phases on the diversity of seasonal floodplain plant communities has not been studied in the Okavango Delta. The objective of this study was to investigate environmental factors that influence species composition and distribution of seasonal floodplain communities before and after flooding. It was hypothesised that environmental factors that influence the species composition and distribution in seasonal floodplain communities will vary with intra-flooding seasons. METHODS: Flooding depth was measured in May (before flooding) and September (flood recession/after flooding) in forty 25 m² plots. Flooding duration was recorded as the number of weeks in which the plots were inundated. The soil was sampled before and after floods and analysed for pH, extractable P K, Mg, Ca and Na. Plant identification and estimation of percentage cover were done in the 25 m² plots in which environmental variables were sampled. The relationship between environmental variables and seasonal floodplain plant community composition and distribution was sought using Non-metric Multi-dimensional Scaling. Paired Student's t test was used to compare the means of environmental variables before and after flooding RESULTS: Factors that influenced the distribution of species before flooding were Na, K, water depth and flooding duration. After flooding, the factors that influenced species composition and distribution were K, Na, Mg, pH, water depth and flooding duration CONCLUSION: These results suggest that during flooding K and Mg are deposited in the floodplains due to lateral water flow. Our results also suggest that any water abstraction from the Okavango River Basin should take into consideration the importance of flooding duration and depth in sustaining species composition and distribution of seasonal floodplain plant communities so that such developments do not disturb the ecological functioning of the Delta <![CDATA[<b>Woody vegetation change over more than 30 years in the interior duneveld of the Kalahari Gemsbok National Park</b>]]> BACKGROUND AND OBJECTIVES: Long-term studies of woody plants in South Africa are scarce. This study, initiated in the late 1970s, therefore aids understanding of vegetation dynamics in the southern Kalahari by investigating woody vegetation change at and away from a watering point. METHODS: At three sites, all woody individuals were counted by species in plots 0.5 or 1 ha in size. Seedlings were noted separately from the >0.2 m group of individuals. RESULTS: Vachellia erioloba and shrub density decreased over time whereas dwarf shrub species' numbers fluctuated markedly. Additionally, no increase in density of known bush encroaching species (e.g. Grewia flava, Rhigozum trichotomum and Senegalia mellifera) was found in this large conservation area. DISCUSSION AND CONCLUSION: The changes in density of the woody species seem to point to the importance of particular rainfall patterns or sequences of events over different years that are responsible for these changes in the southern Kalahari, and the evident lack of bush encroachment in this conservation area supports the notion that bush encroachment in arid savannas is driven primarily by land-use practices and not by elevated carbon dioxide levels that are sometimes provided as cause for encroachment.