School of Earth and Environment
INSTITUTE FOR CLIMATE AND ATMOSPHERIC SCIENCE
Workshop on the Economics of Land Degradation (ELD)
Sustainable Land Management in Kgalagadi Rangelands
8th July, 2014
Ecological Findings
Prof Andy Dougill (with Lawrence Akanyang, Jeremy Perkins,
Mark Reed & Frank Eckardt ... )
A.J.Dougill@leeds.ac.uk ; @AndyDougill
Ecological Changes & Management
Participatory Rangeland Monitoring & Management:
Kgalagadi Studies
• Participatory development of rangeland degradation indicators (Reed
et al., 2008) & links to Management Guides translated to Setswana /
Afrikaans (Reed & Dougill, 2010)
• Dynamic system model from integration of local & scientific knowledge
(Dougill et al., 2010) enabling link to economic projections / sceanrios
• Limited uptake prevented progress as seen in communal rangelands
of Namibia
Soil Carbon Storage & Flux Studies
Namibia
• In-situ analysis of CO2 fluxes between soil &
atmosphere - applied for Kalahari sand (Thomas
Botswana
et al., 2011) & salt pans (Thomas et al., 2014)
South
Africa
• Findings show susceptibility of biological soil
crusts to release of CO2 with warming, drying
& disturbance (grazing)
Kalahari Sands
• Enhanced C storage predicted for Wildlife
Management Areas where grazing levels remain lower & should be
valued when considering Payment for Ecosystem Services schemes
(Dougill et al., 2012)
ELD Ecological Study Design
• ELD Study provides dual-scale ecological assessments of links
between land use, management & degradation in Kgalagadi District
• Farm-scale ecological analyses along ‘piosphere’ grazing gradients
away from borehole waterpoints on communal grazing lands, private
cattle ranches & private game ranches in March 2014
• Landscape-scale analysis of remotely sensed data of vegetation
cover (NDVI as measure of green biomass 2000 – 2013) & animal
numbers (from 2012 national aerial animal census)
Ecological Findings 1
• Below average rainfall in 2014 led to a high % of bare ground (7090%) & forb cover (5-20%) across all land uses, with temporal variability
also shown clearly by NDVI anomalies by year
Ecological Findings 2
• Widespread bush encroachement found across the semi-arid study
sites with Acacia mellifera, Grewia flava & Dichrostachys cinerea cover
& density increased at expense of perennial grass layer on which cattle
production is based
• Bush encroachment extensive across communal grazing areas &
private cattle ranches displaying that privatisation is not directly leading
to more sustainable land management
Ecological Findings 3
• For arid sites in the SW, Rhigozum trichotomum forms impenetrable
thickets close to boreholes, but otherwise bush encroachment absent
• Dune instability occurs to a distance of c. 1.2km from boreholes
following the removal of Stipagrostis amabilis grass cover
• Ecological change pressures observed around Molopo river where the
exotic Prosopis glandulosa observed & blamed locally for declining soil
moisture & groundwater levels & expensive to remove
Ecological Findings 4
• Regional patterns of key wildlife species (eland, wildebeest) shows
that the expansion of cattleposts & fenced ranches has led to large
areas of southern Kgalagadi with low biodiversity even where cattle
production not practiced
•
Conclusions
• Dual-scale ecological analyses add new insights into rangeland
degradation problems of arid and semi-arid Kgalagadi rangelands
• Bush encroachment (semi-arid) & dune mobilisation (arid) are most
notable forms of land degradation linked to shifts in land use towards
more widespread intensive cattle grazing & have impacts on reduced
biodiversity & soil C storage
• Land tenure changes (to private ownership) have not prevented
rangeland degradation across Kalahari
• Sustainable land management practices & rehabilitation options
available by integration of local & scientific knowledges locally if
facilitated together with landscape-scale land use planning
regionally to ensure heterogeneity in, & connectivity of, land uses
Full report @ http://www.see.leeds.ac.uk/research/sri/eld