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The 2007
Arid Zone Ecology Forum meeting focussed
specifically on drought in southern Africa's arid
areas. Many of the speakers who attended, and the
two associated Farmers' workshops, were funded by
the Critical Ecosystem Partnership Fund (CEPF),
through their Succulent Karoo Ecosystem
Partnership (SKEP) fund. A suite of papers emerged
from that meeting, and have been published in
Volume 105 of the South African Journal of
Science. They are posted here with kind
permission from The Editor, SAJS.
Abstract:
This article offers information on
the mismatch between socio-economic
realities and government policy in
solving drought problems in South
Africa. The South African
Department of Agriculture is
boosting full-time reliance on
commercial livestock production
against a background of climatic,
economic and political uncertainty.
In addition, despite the
water-stressed status of South
Africa, half of the proposed
projects for the Accelerated and
Shared Growth Initiative for South
Africa are unlikely to be
sustainable and water-intensive.
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Abstract: Arid
environments remind one of the punctuated
equilibrium theory of evolution: they experience
long periods of stasis and low productivity,
interrupted with episodic rainfall which spurs
reproduction and movement. Birds, as highly
dispersive organisms, are among the most dramatic
indicators of these fluctuations. Here we review
birds' two main strategies, residency and nomadism,
and the trade-offs faced by individuals in
uncertain times. In general, wet years stimulate
higher densities of nests (i.e. smaller
territories), larger clutch sizes, unseasonal
breeding, and at some times of year, higher
breeding success. Rainfall above a certain
threshold triggers breeding in resident species
and an influx of nomadic species which breed and
then move on. The environmental cues which trigger
nomadism are sometimes poorly understood, but
include distant thunderstorms for aquatic species,
and perhaps for insectivores. Environmental cues
that draw nomadic granivores to areas that have
had recent rain are not known. [ABSTRACT FROM
AUTHOR]
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Abstract: Droughts
can have serious ecological and economic
consequences and will pose an increasing challenge
to rangeland users as the global climate is
changing. Finding ways to reduce ecological and
economic impacts of drought should thus be a major
research thrust. Resilience, defined as the amount
of perturbation a social or ecological system can
absorb without shifting to a qualitatively
different state, has emerged as a prominent
concept in ecosystem ecology and more recently as
a conceptual framework for understanding and
managing complex social-ecological systems. This
paper discusses the application and relevance of
resilience to understanding and managing ecosystem
change, and enhancing the capacity of land users
to adapt to droughts. Drought can trigger
vegetation change and factors such as grazing
management can influence the likelihood of such
transitions. Drought can cause differential
mortality of perennial plants and this could
provide an opportunity for rangeland restoration
by opening up establishment sites for desirable
species. The capacity of land users to cope with
drought is influenced by the resilience of their
agro-ecosystems, the diversity of livelihood
options, access to resources and institutional
support. By these criteria, current agricultural
development approaches in South Africa,
particularly in communal rangelands and areas of
land reform, are unlikely to enhance land users'
resilience to drought and other perturbations.
[ABSTRACT FROM AUTHOR]
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Abstract: Human
adaptation and response to drought is primarily
through evasion or endurance. A review of
historical agricultural practices in southern
Africa demonstrates evidence of drought evasion
response strategies in well-established
transhumance routes, where herders move livestock
on a seasonal basis in order to exploit resources
subject to different climatic regimes. European
settlers to the arid regions of South Africa
quickly recognised the necessity of these evasion
options to survive drought, and adopted the
transhumance practices of indigenous farmers.
Areas of geographically diverse resource bases
became hotly contested by settlers and indigenous
farmers. The success of evasion systems are shown
to hinge on good social and institutional support
structures. When movement is not an option,
drought endurance is pursued by attempting to
limit the damage to the natural resource base.
This is through a number of means such as forage
conservation, varying livestock types and numbers,
water and soil conservation and taking up
alternative livelihood options. State responses to
drought over the last century reflect the general
South African pattern of racially divided and
unjust policies relating to resource access.
Historically the state provided considerable
support to white commercial farmers. This support
was frequently contradictory in its aims and
generally was inadequate to enable farmers to cope
with drought. Since the advent of democracy in
1994, the state has intervened less, with some
support extended to previously disadvantaged and
poor communal farmers. Climate change predictions
suggest an increase in drought, suggesting that
the adoption of mitigating strategies should be a
matter of urgency. To do this South Africa needs
to build social and institutional capacity, strive
for better economic and environmental
sustainability, embed drought-coping mechanisms
into land restitution policy to ensure the success
of this programme, and acknowledge the...
[ABSTRACT FROM AUTHOR]
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Abstract:
The Klein Karoo is situated in the
Western Cape, South Africa, and is characterised
by low rainfall (100–450 mm yr–1). The Klein Karoo
is situated in the primary catchment of the
Gouritz River. The mean annual runoff (MAR) for
the three major tributaries of the Gouritz River
arising in or feeding the Klein Karoo (Touws,
Gamka, Olifants) is 540 Mm3 yr–1. Groundwater
recharge in the three Klein Karoo catchments is
±257 Mm3 yr–1, but only a portion of this reaches
the rivers. The very variable flows result in low
1:50 year yield of 161 Mm3 (30% of MAR). The
current demand for water in these catchments is
182 Mm3 yr–1, which exceeds the yield, and demand
is projected to increase between 23% and 150% by
2025. Changes in the approach to water management
are required, including improving the efficiency
of irrigation and land restoration to improve
water infiltration and reduce soil erosion. We
believe that it is time to change to a water
management approach that is designed to anticipate
and manage the inherent variability in water
resources in the Klein Karoo, thereby placing the
region on a path to sustainable development.
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Abstract: For the
winter-rainfall region of South Africa, the
frequency of drought is predicted to increase over
the next 100 years, with dire consequences for the
vegetation of this biodiversity hotspot. We
analysed historical 20th century rainfall records
for six rainfall stations within the succulent
karoo biome to determine if the signal of
increasing drought frequency is already apparent,
and whether mean annual rainfall is decreasing. We
found no evidence for a decrease either in mean
annual rainfall or in the incidence of drought, as
measured by the Standardised Precipitation Index (SPI)
over the 20th century. Evidence points to a drying
trend from 1900-1950 while no significant trend in
rainfall and drought was found at most stations
from 1951-2000. In a second analysis we
synthesised the information concerning the
response of adult succulent karoo biome plants and
seedlings to extended drought conditions. General
findings are that responses to drought differ
between species, and that longevity is an
important life history trait related to drought
survival. Growth form is a poor predictor of
drought response across the biome. There was a
range of responses to drought among adult plants
of various growth forms, and among non-succulent
seedlings. Leaf-succulent seedlings, however,
exhibited phenomenal drought resistance, the
majority surviving drought long after all the
experimentally comparative non-succulent seedlings
had died. Our synthesis showed that previous
studies on the impact of drought on succulent
karoo biome plants differ greatly in terms of
their location, sampling design, measured values
and plant responses. A suite of coordinated
long-term field observations, experiments and
models are therefore needed to assess the response
of succulent karoo biome species to key drought
events as they occur over time and to integrate
this information into conservation planning.
[ABSTRACT FROM AUTHOR]
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Abstract: South
Africa in general has been approximately 2% hotter
and at least 6% drier over the ten years between
1997 and 2006 compared to the 1970s. The use of
water has also increased greatly over this same
period. By 2000, 98.6% of that year's surface
water yield and 41% of the annual utilisable
potential of groundwater was allocated to use.
Irrigation agriculture, comprising 60% of total
consumption, is by far the largest single consumer
of water. Given these climatic and water use
changes as a backdrop, we employed a panel data
econometric model to estimate how sensitive the
nation's agriculture may be to changes in
rainfall. Net agricultural income in the
provinces, contributing 10% or more to total
production of both field crops and horticulture,
is likely to be negatively affected by a decline
in rainfall, especially rain-fed agriculture. For
the country as a whole, each 1% decline in
rainfall is likely to lead to a 1.1% decline in
the production of maize (a summer grain) and a
0.5% decline in winter wheat. These results are
discussed with respect to both established and
emerging farmers, and the type of agriculture that
should be favoured or phased out in different
parts of the country, in view of current and
projected trends in climate, increasing water use,
and declining water availability. [ABSTRACT FROM
AUTHOR]
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