Anthropogenically disturbed
Mopaneveld: Is the ecosystem
getting even?
Nanette van Staden¹, F. Siebert¹, S.J. Siebert¹ & A.M. Swemmer²
¹Unit of Environmental Sciences and Management, North-West University, Private Bag
X6001, Potchefstroom 2520, South Africa
²SAEON Office, Ndlovu Node, Kruger National Park, Phalaborwa 1390, South Africa
Introduction
• More than three quarters of terrestrial biomes transformed to anthropogenic
biomes (anthromes) through a variety of land-use practices (Wilson et al., 2004).
• Pressure on the environment is increasing (Davis et al., 2013)
− escalating human population
− habitat fragmentation
− harvesting of natural resources
− mining activities
• Necessary to study diversity in a changing environment to determine how
vegetation is affected by land-uses.
Introduction
• Land-use
− affects species richness & evenness across various communities (Chapin
et al. 2000; Hillebrand et al., 2008 Crowder et al., 2010).
− affects community assembly & species diversity (Mayfield et al., 2010).
• Ecosystems can be more susceptible to degradation  reduce provision of
ecosystem services in the future (Yachi & Loreau, 1999; Mori et al., 2013).
Introduction
• Diversity-stability hypothesis
− Diversity provides insurance & minimizes deterioration of ecosystems
(Chapin et al., 2000; McCann, 2000).
− More diverse ecosystems = more stable (Allan et al., 2011).
− High species diversity promotes ecosystem resilience & resistance
(Chapin et al., 2000).
• Intermediate disturbance hypothesis
− Diversity and/or species richness highest at moderate levels of
disturbance (Conell, 1978; Grime 1979, Begon et al., 2006; Biswas & Mallik, 2010).
• Phalaborwa-Timbavati Mopaneveld 5% already altered (Mucina & Rutherford,
2006), provided a setting to test these hypotheses.
Introduction
• Few studies have investigated the effect of anthropogenic disturbances in
Mopaneveld (Shackleton 1993; Shackleton et al, 1994; Shackleton, 2000; Rutherford et al., 2012, Davis
et al., 2013; Rutherford & Powrie, 2013).
• How resilient is the Mopaneveld herbaceous layer to land-use change &
disturbance?
• Aim
− Quantify & evaluate the extent to which anthropogenic disturbances
affect herbaceous species composition & diversity in a semi-arid
savanna.
Study area
Study area
• 3 land-uses: mining,
communal farming &
protected areas
• Communal lands
(rangelands & old
fields)
• Strip mines (post & pre
2000 strip mines)
Pompeye: strip mining
Lulekani: communal area
& natural Mopaneveld
Palabora Mining Company
(PMC): mine dumps
• Mine dumps (rock
dumps & tailings dam)
• Koppies
• Mopaneveld
Cleveland Nature Reserve:
koppies & natural Mopaneveld
Figure 1. Location of study area, Phalaborwa, Limpopo
Province.
Study area
Study area
Study area
Study area
Methodology
• Fixed quadrat method.
• Herbaceous layer (grass & forbs).
• 40 quadrats (1 m²) sampled per land-use.
• All grass & forb species identified & counted.
• Data was analyzed using PRIMER, PAST & STATISTICA.
• Rare species were omitted for multivariate analyses (NMDS).
• Data was fourth root transformed.
Results & Discussion
a) Composition
ANOSIM  R-value=0.5398, p<0.05
Key grass species
Urochloa mosambicensis, Aristida adscensionis &
Enneapogon cenchroides.
Key forb species
Ocimum americanum &Tephrosia
purpurea.
Figure 2. Multi-dimensional Scaling (NMDS) scatter plots of species
assemblages of strip mines benchmarked against natural Mopaneveld
Results & Discussion
a) Composition
Figure 3. Multi-dimensional Scaling (NMDS) scatter plots of species
assemblages of strip mines benchmarked against natural Mopaneveld
Results & Discussion
a) Composition
Figure 4. Multi-dimensional Scaling (NMDS) scatter plots of species
assemblages of communal areas benchmarked against natural Mopaneveld
Results & Discussion
a) Composition
Figure 5. Multi-dimensional Scaling (NMDS) scatter plots of species
assemblages of mine dump vegetation benchmarked against natural
Mopaneveld and koppies.
Results & Discussion
b) Species richness
Species richness:
F(4,204) = 23.2544512, p = 0.0000
•Communal land-use 
marginal disturbance =
highest mean species
richness per plot.
2.1
2.0
Species richness
1.9
•Consistent with findings of
Shackleton et al. (1994) &
Rutherford et al. (2012).
1.8
1.7
1.6
1.5
Koppies
Natural
Strip mines
Treatment
Communal
Mine dumps
Mean
Mean±SE
Mean±1.96*SE
Figure 6. Mean index values of species richness across
different land-uses.
•Koppies  lowest species
richness = uniquely adapted
species, harsh conditions as
koppies (Porembski et al., 1996).
Results & Discussion
b) Species richness
Species richness:
F(4,204) = 23.2544512, p = 0.0000
2.1
2.0
•Mine dumps low species
richness ascribed to total
land transformation.
Species richness
1.9
1.8
•Strip mines intermediate
level of species richness.
1.7
1.6
1.5
Koppies
Natural
Strip mines
Treatment
Communal
Mine dumps
Mean
Mean±SE
Mean±1.96*SE
Figure 7. Mean index values of species richness across
different land-uses.
Results & Discussion
c) Total individuals (function of density)
Total individuals:
F(4,204) = 32.9519, p = 0.0000
3.8
3.6
•Communal areas highest
mean density per plot.
3.4
Total individuals
3.2
3.0
•Communal species =
pioneer species, creeping,
stoloniferous or fast
colonizing species.
2.8
2.6
2.4
2.2
2.0
Koppies
Natural
Strip mines
Treatment
Communal
Mine dumps
Mean
Mean±SE
Mean±1.96*SE
Figure 8. Mean index values of total individuals across
different land-uses.
Results & Discussion
c) Total individuals (function of density)
Total individuals:
F(4,204) = 32.9519, p = 0.0000
3.8
3.6
•Koppies lowest mean
density per plot.
3.4
Total individuals
3.2
3.0
•Strip mines intermediate
level of density, dominated
by fast colonising pioneer
species
2.8
2.6
2.4
2.2
2.0
Koppies
Natural
Strip mines
Treatment
Communal
Mine dumps
Mean
Mean±SE
Mean±1.96*SE
Figure 9. Mean index values of total individuals across
different land-uses.
Results & Discussion
d) Evenness
•Koppies highest mean
evenness per plot.
Pielou: F(4,204) = 7.9349, p = 0.00001
0.86
0.84
0.82
•Strip mines most uneven
plant communities,
dominated by Urochloa
mosambicensis, Aristida
adscensionis & Ocimum
americanum.
0.80
0.78
0.76
Pielou
0.74
0.72
0.70
0.68
0.66
0.64
0.62
0.60
0.58
0.56
Koppies
Natural
Strip mines
Treatment
Communal
Mine dumps
Mean
Mean±SE
Mean±1.96*SE
Figure 10. Mean index values of evenness across
different land-uses
•Evenness responds rapidly
& sensitive to anthropogenic
disturbances (Chapin et al., 2000;
Wittebolle et al., 2009; Crowder et al.,
2010).
Results & Discussion
e) Diversity (Shannon-Wiener)
Shannon: F(4,204) = 2.6911, p = 0.0322
2.1
2.0
•Natural Mopaneveld
highest mean diversity per
plot.
Shannon
1.9
1.8
1.7
•Strip mines displayed
lowest mean diversity per
plot.
1.6
1.5
1.4
Koppies
Natural
Strip mines
Treatment
Communal
Mine dumps
Mean
Mean±SE
Mean±1.96*SE
Figure 11. Mean index values of Shannon-Wiener
diversity across different land-uses.
Results & Discussion
e) Diversity (Simpson)
•Koppies & Mopaneveld
displayed high mean
Simpson diversity per plot.
Simpson: F(4,204) = 1.6859, p = 0.1546
0.82
0.80
0.78
0.76
• Strip mines average
species richness & density
but low evenness & thus low
mean Simpson diversity.
Simpson
0.74
0.72
0.70
0.68
0.66
0.64
0.62
0.60
0.58
Koppies
Natural
Strip mines
Treatment
Communal
Mine dumps
Mean
Mean±SE
Mean±1.96*SE
Figure 12. Mean index values of Simpson diversity
across different land-uses.
• Indication of heterogeneity,
land-uses responsible for
homogenization of plant
communities.
Results & Discussion
Table 1. Performance scores for land-uses. Indices of diversity and abundance are scored
as 1, very low; 2, low; 3, low to average; 4, average; 5, average to high; 6, high; and 7, very
high according to an interval scale.
Koppies
Mopaneveld
Strip mines
Communal
area
Mine dumps
Species
1
5
5
7
2
No. Because if the system was getting even, strip mines,
richness
communal areas & mine dumps would have displayed high
Indication
ecosystem health
Highest
species
richness
and
density
Low richness,
density
&of
evenness,
evenness.
Is the average
system
getting
even???
Density
1diversity
2
6
7
4
AND
high
Shannon
higher
diversity
than
High
richness
& strip mines
density, lowest
Evenness
7
6
1
2
4
evenness, lowest
Rehabilitation
of mine dumps
diversity.
Shannon
2 rehabilitated,
6 EVENNESS
2
MANAGEMENT
FOR
Strip mines
not
emphasize significance of
rehabilitation of Mopaneveld
Simpson
6
6
2
6
2
4
4
Summary
• Land-uses are characterized by different herbaceous species
assemblages  alteration of abiotic and biotic conditions.
• Marginal disturbances (e.g. communal land-use) enhance species
richness and density  intermediate disturbance hypothesis.
• Evenness=not enhanced by marginal disturbances strip mines and
communal land-use displayed LOW evenness.
Summary
• Complete land transformation (e.g. mine dumps) responsible for
species loss.
• Loss of species diversity  unstable ecosystem = diversity-stability
hypothesis  implications for provision of ecosystem services.
• However dominant species may compensate for certain ecosystem
functions due to their response traits.
The way forward
• Functional diversity = more sensitive to changes in the environment & a
useful tool to measure ecosystem resilience (Zhang et al., 2012).
• Species in the tail of the distribution (Walker, 1999; Kotschy, 2013)
− Response traits?
− Redundancy = functions of dominant species?
− Contribution to resilience?
• Combining species diversity & response diversity = promote understanding
of resilience of anthropogenically altered Mopaneveld
− linking ecosystem functioning and plant diversity.
References
Allan, E., Weisser, W., Weigelt, A., Roscher, C., Fischer, M. & Hillebrand, H. 2011. More diverse plant communities have higher functioning over time due to
turnover in complementary dominant species. Proceedings of the National Academy of Sciences, 108 (41):17034-17039.
Begon, M., Townsend, C.R. & Harper, J.L. 2006. Ecology: from individuals to ecosystems (Fourth ed.). Oxford: Blackwell.
Biswas, S.R. & Mallik, A.U. 2010. Disturbance effects on species diversity and functional diversity in riparian and upland plant communities. Ecology, 91 (1):2835.
Chapin, F.S., Zavaleta, E.S., Eviner, V.T., Naylor, R.L., Vitousek, P.M., Reynolds, H.L., Hooper, D.U., Lavorel, S., Sala, O.E. & Hobbie, S.E. 2000.
Consequences of changing biodiversity. Nature, 405 (6783):234-242.
Connell, J.H. 1978. Diversity in tropical rain forests and coral reefs. Science, 199 (4335):1302-1310.
Crowder, D.W., Northfield, T.D., Strand, M.R. & Snyder, W.E. 2010. Organic agriculture promotes evenness and natural pest control. Nature, 466 (7302):109112.
Davis, A.L., Swemmer, A.M., Scholtz, C.H., Deschodt, C.M. & Tshikae, B. 2013. Roles of environmental variables and land usage as drivers of dung beetle
assemblage structure in mopane woodland. Austral Ecology, 39 (3):313-327.
Grime, J.P. 1973. Competitive exclusion in herbaceous vegetation. Nature, 242 (5396):344-347.
Hillebrand, H., Bennett, D.M. & Cadotte, M.W. 2008. Consequences of dominance: a review of evenness effects on local and regional ecosystem processes.
Ecology, 89 (6):1510-1520.
Kotschy, K.A. 2013. Biodiversity, redundancy and resilience of riparian vegetation under different land management regimes. Johannesburg: University of the
Witwatersrand. (Dissertation - PhD) 229 p.
Mayfield, M.M., Boni, M.F., Daily, G.C. & Ackerly, D. 2005. Species and functional diversity of native and human-dominated plant communities. Ecology, 86
(9):2365-2372.
Mori, A.S., Furukawa, T. & Sasaki, T. 2013. Response diversity determines the resilience of ecosystems to environmental change. Biological Reviews, 88
(2):349-364.
Mucina, L. & Rutherford, M.C. 2006. The vegetation of South Africa, Lesotho and Swaziland. Pretoria: South African National Biodiversity Institute.
Porembski, S., Szarzynski, J., Mund, J.-P. & Barthlott, W. 1996. Biodiversity and Vegetation of Small-Sized Inselbergs in a West African Rain Forest (Tai, Ivory
Coast). Journal of Biogeography, 23 (1):47-55.
Rutherford, M. & Powrie, L. 2013. Impacts of heavy grazing on plant species richness: A comparison across rangeland biomes of South Africa. South African
Journal of Botany, 87:146-156.
Rutherford, M., Powrie, L. & Thompson, D. 2012. Impacts of high utilisation pressure on biodiversity components in Colophospermum mopane savanna. African
Journal of Range & Forage Science, 29 (1):1-11.
Shackleton, C., Griffin, N., Banks, D., Mavrandonis, J. & Shackleton, S. 1994. Community structure and species composition along a disturbance gradient in a
communally managed South African savanna. Vegetatio, 115 (2):157-167.
Shackleton, C.M. 1993. Are the communal grazing lands in need of saving? Development Southern Africa, 10 (1):65-78.
Shackleton, C.M. 2000. Comparison of plant diversity in protected and communal lands in the Bushbuckridge lowveld savanna, South Africa. Biological
Conservation, 94 (3):273-285.
Walker, B., Kinzig, A. & Langridge, J. 1999. Original articles: plant attribute diversity, resilience, and ecosystem function: the nature and significance of dominant
and minor species. Ecosystems, 2 (2):95-113.
Wilson, S.D., Bakker, J.D., Christian, J.M., Li, X., Ambrose, L.G. & Waddington, J. 2004. Semiarid old-field restoration: is neighbor control needed? Ecological
Applications, 14 (2):476-484.
Wittebolle, L., Marzorati, M., Clement, L., Balloi, A., Daffonchio, D., Heylen, K., De Vos, P., Verstraete, W. & Boon, N. 2009. Initial community evenness favours
functionality under selective stress. Nature, 458 (7238):623-626.
Yachi, S. & Loreau, M. 1999. Biodiversity and ecosystem productivity in a fluctuating environment: the insurance hypothesis. Proceedings of the National
Academy of Sciences, 96 (4):1463-1468.
Zhang, J.T., Fan, L. & Li, M. 2012. Functional diversity in plant communities: Theory and analysis methods. African Journal of Biotechnology, 11 (5):1014-1022.
Acknowledgements
• South African Observation Network (SAEON)
• Palabora Mining Company (PMC)
• Fieldworkers