Humans and elephants as treefall drivers in African savannas

Humans have played a major role in altering savanna structure and function, and growing land-use pressure will only increase their influence on woody cover. Yet humans are often overlooked as ecological components. Both humans and the African elephant Loxodonta africana alter woody vegetation in savannas through removal of large trees and activities that may increase shrub cover. Interactive effects of both humans and elephants with fire may also alter vegetation structure and composition. Here we capitalize on a macroscale experimental opportunity – brought about by the juxtaposition of an elephant-mediated landscape, human-utilized communal harvesting lands and a nature reserve fenced off from both humans and elephants – to investigate the influence of humans and elephants on height-specific treefall dynamics. We surveyed 6812 ha using repeat, airborne high resolution Light Detection and Ranging (LiDAR) to track the fate of 453 685 tree canopies over two years. Human-mediated biennial treefall rates were 2–3.5 fold higher than the background treefall rate of 1.5% treefall ha–1, while elephant-mediated treefall rates were 5 times higher at 7.6% treefall ha–1 than the control site. Model predictors of treefall revealed that human or elephant presence was the most important variable, followed by the interaction between geology and fire frequency. Treefall patterns were spatially heterogeneous with elephant-driven treefall associated with geology and surface water, while human patterns were related to perceived ease of access to wood harvesting areas and settlement expansion. Our results show humans and elephants utilize all height classes of woody vegetation, and that large tree shortages in a heavily utilized communal land has transferred treefall occurrence to shorter vegetation. Elephant- and human-dominated landscapes are tied to interactive effects that may hinder tree seedling survival which, combined with tree loss in the landscape, may compromise woodland sustainability.Andrew Mellon Foundation; Council for Scientific and Industrial Research (CSIR) Strategic Research Panel; Dept of Science and Technology (DST); Avatar Alliance Foundation; Margaret A. Cargill Foundation; David and Lucile Packard Foundation; Gordon and Betty Moore Foundation; Grantham Foundation for the Protection of the Environment; W. M. Keck Foundation; John D. and Catherine T. MacArthur Foundation; Exxaro Chairman's Fund; Applied Centre for Climate and Earth System Science; DST/NRF Centre of Excellence in Tree Health Biotechnology; NRF Innovation Scholarship [UID: 95030].http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1600-05872018-11-30hj2017Geography, Geoinformatics and Meteorolog

Fuelwood extraction intensity drives compensatory regrowth in African savanna communal lands

Woody biomass remains the primary energy source for domestic use in the developing world, raising concerns about woodland sustainability. Yet woodland regenerative capacity and the adaptive response of harvesters to localised fuelwood shortages are often underestimated or unaccounted for in fuelwood supply–demand models. Here, we explore the rates and patterns of height‐specific woody vegetation structural dynamics in three communal lands in a semiarid savanna in South Africa. Using repeat, airborne light detection and ranging, we measured height‐specific change in woody vegetation structure, and the relative influence of geology, fire, and ease of access to fuelwood. Monitoring 634,284 trees canopies over 4 years revealed high compensatory growth, particularly in the high wood extraction communal land: 34.1% of trees increased in height >1 m. Vegetation structural patterns were associated with ease of access to the communal land but were mediated by wood extraction intensity. In these communal lands, vegetation structural dynamics show rapid woody thickening as a response to repeat harvesting. However, loss of height in vegetation structure did not follow a gradient of wood extraction intensity. We propose a conceptual framework to better understand change in vegetation structural metrics and the paradoxical phenomenon of high growth in high wood extraction scenarios. We also show coadaptive responses of humans and woody vegetation to fuelwood harvesting in human–environment systems through patterns of regrowth response relative to ease of access to fuelwood resources.LiDAR data collection was funded by the Andrew Mellon Foundation, the Council for Scientific and Industrial Research (CSIR) Strategic Research Panel and the Department of Science and Technology (DST). The CAO has been made possible by grants and donations from the Avatar Alliance Foundation, Margaret A. Cargill Foundation, David and Lucile Packard Foundation, Gordon and Betty Moore Foundation, Grantham Foundation for the Protection of the Environment, W. M. Keck Foundation, John D. and Catherine T. MacArthur Foundation, Andrew Mellon Foundation, Mary Anne Nyburg Baker and G. Leonard Baker Jr, and William R. Hearst III. B. F. N. E. is supported by the Exxaro Chairman's Fund. P. J. M. is funded by the DST/NRF Centre of Excellence in Tree Health Biotechnology and an NRF Innovation Scholarship (grant UID: 95030).http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-145X2020-01-30hj2018Geography, Geoinformatics and Meteorolog

Meeting a diversity of needs through a diversity of species: Urban residents’ favourite and disliked tree species across eleven towns in South Africa and Zimbabwe

Understanding of urban residents’ preferences and dislikes for tree species and attributes is necessary to provide them with the species they most favour. Yet there is relatively little understanding of local species preferences, the reasons underlying them and how they vary with context and scale. We interviewed 1100 urban residents in eleven towns (four in Zimbabwe, four in Limpopo Province and three in the Eastern Cape of South Africa) to determine what were their favourite and least favourite tree species and the reasons for such. Fifty-nine species were listed amongst the preferred species (the four most common being Jacaranda mimosifolia (10% or respondents), Mangifera indica (10%), Adonsonia digitata (7%) and Colophospermum mopane (7%)), and 29 as disliked (the four most common being Vachellia spp, J. mimosifolia, Euphorbia spp. and Melia azedarach), with 16 in common between the two

Cropland Abandonment in South African Smallholder Communal Lands: Land Cover Change (1950–2010) and Farmer Perceptions of Contributing Factors

Despite agricultural land abandonment threatening the food security and the livelihoods of smallholder farmers, it is pervasive globally and in developing countries. Yet land abandonment is an understudied aspect of land use change in social–ecological systems. Here we provide more information on this phenomenon by exploring cropland abandonment during 1950–2010 in four former South African ‘homelands’—part of the ‘Apartheid’ era racially-based land allocation programs—characterized by rural, smallholder farmers. Cropland abandonment 1950–2010 was widespread in all surveyed sites (KwaZulu: 0.08% year−1, Transkei: 0.13% year−1, Lebowa: 0.23% year−1, Venda: 0.28% year−1), with rates peaking between 1970 and 1990, with concomitant increases (up to 0.16% year−1) of woody vegetation cover at the expense of grassland cover. Active and past farmers attributed cropland abandonment to a lack of draught power, rainfall variability and droughts, and a more modernized youth disinclined to living a marginal agrarian lifestyle. We discuss the potential social and ecological implications of abandoned croplands at the local and regional scales, as the deagrarianization trend is unlikely to abate considering the failure of current South African national agricultural incentives

The sustainable use of wild species benefits biodiversity and human well-being in South Africa

SIGNIFICANCE : A recent report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) assessed how the sustainable use of wild species benefits people and nature, and which policies work best to prevent unsustainable exploitation. In the context of an accelerating and alarming biodiversity crisis, the assessment findings have important implications for South Africa, a megadiverse country with a population that relies extensively on the use of wild species for food, energy, medicine, and income, amongst many other purposes. This Commentary reflects on implications of the IPBES assessment for South Africa, drawing on insights from local contributing authors.http://www.sajs.co.zahj2023Geography, Geoinformatics and Meteorolog

Unsustainable trade-offs: provisioning ecosystem services in rapidly changing Likangala River catchment in southern Malawi

Provisioning ecosystem services of the Likangala River Catchment in southern Malawi are important for livelihoods of those living there. Remote sensing, participatory mapping and focus group discussions were used to explore the spatio-temporal changes and trade-ofs in land-cover change from 1984 to 2013, and how that afects provisioning ecosystem services in the area. Communities derive a number of provisioning ecosystem services from the catchment. Forty-eight species of edible wild animals (including birds), 28 species of edible wild plants and fungi, 22 species of medicinal plants, construction materials, ornamental fowers, frewood, honey, gum, reeds and thatch/weaving grasses were derived from the catchment and used by local communities

The relevance of ecosystem services to land reform policies: Insights from South Africa

Land reform is an important socio-political strategy in many countries. Despite the importance of ecosystem health in attaining land reform objectives, human-nature interactions have been largely absent from contemporary land reform discussions. In this perspectives paper, we highlight why land reform programmes could benefit from considering ecosystem services in their planning processes, to better achieve their goals of socio-economic development and equity. Drawing on examples from South Africa, we argue that an ecosystem services lens can help achieve equity in land reform programmes by providing insight into how land-use legacies and the multi-functional nature of landscapes influence who benefits from land reform across space and through time

Height-specific biomass change as a function of relative height change per grid cell.

<p>Height categories are a) 1–3 m, b) 3–5 m and c) 5–10 m for rangelands of high, intermediate and low wood extraction pressure. There were no data for the 5–10 m height class in the high wood extraction rangeland and the >10 m height class for all rangelands as there were no grid cells with an average height over 10 m. Grid cell size: 25 m x 25 m.</p