Diversity and Structure of an Arid Woodland in Southwest Angola, with Comparison to the Wider Miombo Ecoregion

Abstract

Seasonally dry woodlands are the dominant land cover across southern Africa. They are biodiverse, structurally complex, and important for ecosystem service provision. Species composition and structure vary across the region producing a diverse array of woodland types. The woodlands of the Huíla plateau in southwest Angola represent the extreme southwestern extent of the miombo ecoregion and are markedly drier than other woodlands within this ecoregion. They remain understudied, however, compared to woodlands further east in the miombo ecoregion. We aimed to elucidate further the tree diversity found within southwestern Angolan woodlands by conducting a plot-based study in Bicuar National Park, comparing tree species composition and woodland structure with similar plots in Tanzania, Mozambique, and the Democratic Republic of Congo. We found Bicuar National Park had comparatively low tree species diversity, but contained 27 tree species not found in other plots. Plots in Bicuar had low basal area, excepting plots dominated by Baikiaea plurijuga. In a comparison of plots in intact vegetation with areas previously disturbed by shifting-cultivation agriculture, we found species diversity was marginally higher in disturbed plots. Bicuar National Park remains an important woodland refuge in Angola, with an uncommon mosaic of woodland types within a small area. While we highlight wide variation in species composition and woodland structure across the miombo ecoregion, plot-based studies with more dense sampling across the ecoregion are clearly needed to more broadly understand regional variation in vegetation diversity, composition and structure.

A taxonomic revision of Acanthaceae tribe Barlerieae in Angola and Namibia. Part 2

“…If found there, these extensive protected areas may offer some protection for this species. Recent studies of woody plant and habitat diversity and structure in Bicuar National Park have noted that this extensive site is still relatively well preserved with extensive intact dry miombo woodland assemblages, despite significant past pressures including selective logging of species and farming activity (da Silva et al 2020;Godlee et al 2020). That said, the reserve was reduced from 7,900 km 2 to 6,754 km 2 due to conversion of natural habitat to commercial and subsistence agricultural land in the west and north (Mendelsohn & Mendelsohn 2018) and there are some ongoing pressures on the park's habitats that need to be better understood and managed (da Silva et al 2020).…”

A network to understand the changing socio‐ecology of the southern African woodlands (SEOSAW): Challenges, benefits, and methods

“…To build a network capable of meeting the needs outlined above, SEOSAW collects data across the region in a decentralized but coordinated fashion. The coordination is important to facilitate cross‐site and regional comparisons, which are currently very rare (e.g., Godlee et al., 2020). The decentralization is also important to allow a diverse group of people to collaborate, given varying interests, expertise, and research funding systems.…”

“…Each plot is shown by a single line, colored according to the site. Cyan = DR Congo, protected wet miombo (Muledi et al., 2018, 2020); Pink = Tanzania dry miombo (McNicol et al., 2018); Black = Angolan dry miombo/Baikiaea (Godlee et al., 2020); Green = Mozambican dry miombo and mixed woodland (Ryan et al., 2011); Blue = South African Mimosoid savannas (Scholes et al., 2001); Red = Congolian Beteke savanna (Nieto‐Quintano et al., 2018) . Note that for clarity the figure has been clipped to 1,000 stems and 40 species.…”

“…This provides the flexibility to include the small fire-trapped stems and species which never attain large stature, while the lower POM reduces effort in heavily coppiced vegetation. SeeGodlee et al (2020) for a conversion factor between diameters measured at different heights.Smaller stems with a diameter (D) less than D t (variously called poles, saplings, etc.) can then be sampled on multiple subplots.…”

Biodiversity of Vegetation and Flora in Tropical Africa

“…Among those on the first broad topic, Abiem et al [4] present a study on forest diversity and distribution of tree species in a grassland-forest transition, a typical ecotone across the continent. The diversity and structure of miombo, one of the most important ecoregions in the continent, is studied in southwest Angola by Godlee et al [5] and compared to other miombo sub-types. In a work concerning the Cabo Verde Islands (West Africa), Neto et al [6] discuss the role of abiotic factors, particularly climate and topography, in shaping the diversity of plant communities in this semi-arid archipelago.…”