A newsletter produced by Albaeco,
Sweden
Dr. Fredrik Moberg, Editor
EDITORIAL:
<< Biodiversity
FEATURE:
Rainwater for food security
IN BRIEF:
Food Security &
Global Climate Change
BIODIVERSITY WILL MATTER EVEN MORE IN THE FUTURE
I read in the newly released “Red List” from IUCN - The World Conservation Union about threatened species of plants and animals in the world. IUCN updates its Red List each year, with the help of 8,000 experts around the world.
This year’s list concludes that island plants and animals are the world's most threatened species. This is mainly due to invasive species that eat the natives and destroy their habitat. On Hawaii, 85 plant species that are found nowhere else are in danger of extinction. This is also the case for 35 species of snail on the Galapagos Islands. So what? Who cares? Does it matter at all if a few species disappear? Or as former US-president Ronald Reagan put it in the 60s when opposing expansion of the Redwood National Park in California: "A tree is a tree. How many more do you need to look at?”
Today scientists estimate that species extinctions are occurring 100 to 1000 times faster than without human influence. It is obvious to many that the earth's poorest people use dozens or even hundreds of species of wild and semi-domesticated plants and animals for food, medicine, fodder, energy, clean water, cash incomes, and insurance. But also people in urban and industrial contexts depend on healthy ecosystems. Natural ecosystems and their biodiversity support our health, our environment and our economies. They supply food, much of our raw materials, including genetic materials for agriculture, medicine, and industry, they help maintain the chemical balance of the atmosphere, protect watersheds, control pests, absorb pollutants, renew soils, and nutrients.
So biodiversity matters. It is not just a large number of peculiar insect
species on a remote tree in the rainforest or a bunch of seemingly insignificant
invertebrates in a coral reef. It concerns us all. Everyday.
Biological diversity also plays a significant role in the long-term capacity
of ecosystems to cope with disturbances and environmental change, that is,
it provides the capacity of ecosystems to sustain the production of essential
goods and services on which human development depends.
In this sense, many scientists argue that biodiversity will matter even more in face of forthcoming global environmental change and increased uncertainty. Biodiversity is much more than a red list of threatened species. It is the future.
- Dr. Fredrik Moberg, Editor
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SDU FEATURE
RAINWATER HARVESTING:
LOW TECH HELP IN DRY REGIONS FOR FUTURE FOOD
PRODUCTION
In the coming 50 years food production will have to quadruple in dry regions in Sub-Saharan Africa and South Asia in order to feed the growing population. Harvesting of rainwater is a low-tech alternative solution to increase food production in dry areas with high rainfall variability.
- One of the most widespread misconceptions of semiarid savannahs is that there is no water, says Dr. Johan Rockström from Unesco-IHE, in The Netherlands.
- During rains there is plenty of water. The problem is that the water that falls on the land rapidly runs off the soil and that the gullies dry up so quickly.
Johan Rocktröm has focused much of his research on the possibilities of what he calls ”closing the yield gap” between the actual yields achieved by farmers and the potential yields that could be met with a better management of the limited soil and water resources. Taking advantage of the vast amount of water that falls on land during heavy rainfall events is one of the most promising areas for increased food production in the dry tropics, according to Rockström and his colleagues within the new Sida-financed research programme "Smallholder system innovations in integrated watershed management: Strategies of water for food and environmental security in drought prone tropical and subtropical agro-ecosystems (SSI)" (see box 1 and 2 below). However, some other scientists argue that it is much more important to focus on better management of nutrient levels in the soil.
Water or nutrients the limiting factor?
The population growth in Sub-Saharan Africa and South Asia has forced people
to start cultivating more marginal land with low soil fertility. One area
of intense scientific debate is whether crop yields in the dry tropics primarily
are limited by scarcity of nutrients or of water. Experiments have illustrated
that both fertilisation and supplementary irrigation can increase yields.
Patrick Fox, at the Department of Systems Ecology, Stockholm University, has studied the role of fertilisation and supplementary irrigation for increased yields of Sorghum. His research was carried out in northern Burkina Faso, in the dry Sahel region of West Africa. Here the soils have low fertility and the main staple crops are Sorghum and Millet. Fox’s three year long experiment illustrated that crop yields could be increased by an average of 50% through supplementary irrigation alone. However, when only fertilisers (and no irrigation) were applied the crop yields increased by roughly 90%.
At a first glance the interpretation of these results seems to be that nutrient scarcity is the main limiting factor in this region. However, Fox has strongly emphasised the tight interaction between both water and nutrients. His experiments showed that when fertilisation and supplementary irrigation was combined the yields increased with as much as 300%.
Rainwater harvesting in Tanzania: a low-tech alternative to increase food production in dry regions with variable rainfall.
Photo: Elin Enfors
Securing water supply generates interest in investing in the land
Farmers in the semi-arid regions have to deal with great uncertainty due to
a variable rainfall. Some regions have an annual rainfall of 600 mm, which
can vary between 200 mm in a bad year and 1000 mm in a good year.
The rainfall variability within a year can also be high. There is always a risk of crop failure if the region is hit by a drought spell in a sensitive phase of the crop development, even if the total rainfall throughout that specific year is higher than average.
Patrick Fox illustrated that one of the most crucial points is having water available when dry spells occur. The heavy, but short rainfall events in the region generates substantial amounts of rapidly disappearing runoff that flows through the landscape. To collect a small amount of this runoff water in a storage pond is one way of securing water availability for drier parts of the season. These small-scale ponds (with a capacity to store roughly 150-300m3) can be constructed with limited availability of external inputs and at low costs. Since pumps are expensive, the pond should preferably be situated upstream of the fields in order to take advantage of gravity when it is time for irrigation.
One hypothesis that often has been brought forward is that if it is possible to secure water supply for the crops the farmer would be more interested in investing in his land. Today the risks of investing in nutrients are often perceived by the farmers to be too high due to the risk of crop failures from droughts.
There are several alternative methods of ”harvesting” rainwater in order to improve water availability in the soils for crop production. Sentido bounding, ridges and terracing are example of small-scale, local solutions. Intentional diversion of gully flows during rainfall into the fields by the construction of simple canals is another method. These methods can be used to increase soil moisture after rainfall, but does not store water for usage later in the season.
The wide variety of innovative water use systems illustrate the ability of farmers to come up with agricultural innovations that help them make the most of the short periods of rainfall. Several water-harvesting structures have been around for a long time. They have, however, so far not been analysed from a broader spatial and temporal perspective in order to understand potential impacts on systems at different scales.
Increased need for a system perspective
If rainwater harvesting proves to be as effective as Rockström, Fox and
several other water experts believe there is a possibility of more investments
in these small-scale systems. The potential consequences of up-scaling rainwater
harvesting have however not been addressed previously. There has, for example,
not been any scientific study so far of the potential downstream effects on
ecosystem services due to a larger water use in water harvesting systems upstream.
The new large international research programme "SSI", mentioned above, will take the challenge of studying the potential of rainwater harvesting for improved livelihoods among poor rural farmers in the dry tropics (see box 1 and 2). One of the main research focuses is on the effects of up-scaling rainwater harvesting on the generation of ecosystem services in the surrounding landscape.
It is possible that the effects of rainwater harvesting on surrounding ecosystems primarily will be positive, and that this provides a tool of reversing some of the trends in land degradation. If more of the rainwater infiltrates the soil during high rainfall events, erosion can potentially be decreased. More infiltration can also lead to higher base flow of water through the soils to downstream rivers. As described above, there is also the possibility that with decreased risks of crop failures, farmers might be more willing to invest in their land. Hopefully rainwater harvesting is one way of increasing intensification of agriculture without compromising the capacity of surrounding ecosystems to produce goods and services. If this proves to be the case there is a huge potential for livelihood improvement for poor farmers, through small-scale and low-tech agricultural development in dry tropical regions.
- Line Gordon
More at:
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BOX 1 - SSI: The SSI is an integrated multi-disciplinary programme that will combine high quality science with outreach efforts for development. The programme focuses on two river basins; the Pangani River in Tanzania and the Thukela River in South Africa. It involves researchers and PhD-students from 6 countries (Holland, Kenya, Sweden, South Africa, Tanzania and Zimbabwe). Participating institutions: |
|
BOX 2 - SSI objectives: To advance the knowledge for improved “eco-hydrological” landscape management at the watershed and basin scale. Particular focus will be on system interactions between water for food requirements in upgraded smallholder rain-fed farming systems and water to sustain ecological functions and other societal needs. To analyse the hydrological, environmental and socio-economic consequences of up-scaling water system innovations in small-holder, predominantly rain-fed agriculture at watershed scale, To develop methodologies and decision support tools for improved rainwater management and equitable sharing of water between upstream and downstream users and uses in nature and society. |
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FOOD SECURITY & GLOBAL CLIMATE
CHANGE:
THE NEED FOR ADAPTIVE STRATEGIES IN VULNERABLE
AREAS
The potentially serious impacts of climate change provide additional incentive to manage present climatic risks. Disaster mitigation and early warning are essential, but will only be effective if adaptive capacity is enhanced. This means greater emphasis on resource management, environmental planning and governance.
Climate change and food security: reasons for concern in relation to different predictions of global warming. Click to enlarge...
Climate change poses risks to agricultural systems and vulnerable populations
in addition to the climate stresses currently experienced. Most developing
countries depend heavily on agriculture, hence the anticipated effects of
global warming on agriculture is a particular threat to both the welfare and
future development potential in these countries. Figure 1 suggests five areas
of concern about agricultural systems over the next 100 years. At the global
level, an enduring concern is the threat to global food supply. The adaptability
of commercial agriculture suggests that this is not a serious risk for the
next few decades at least—although warming beyond 4°C might start
to endanger productivity of key agricultural systems. However, small agrarian
economies and those based on a narrow range of crops, i.e. parts of Central
America, are at much greater risk.
At present and in the near term, the most serious concerns are production
variability, food security of vulnerable populations, and increases in extreme
events (Figure 1). While vulnerability is often closely correlated with poverty,
other factors including farming practices, diversification of income, access
to social services and networks, age, and gender are also significant determinants.
Too much or too little water
A genuine worry is that an increase of less than 2°C in the average global
temperature in the next 100 years may exacerbate the frequency and magnitude
of droughts in parts of Asia, Africa, the Middle East, the Mediterranean,
and Australia. Droughts will most likely entail reduced crop productivity
as well as food, economic, and health insecurity, particularly among currently
vulnerable populations. In other areas, climate change may increase flooding
and severe storms. The impact on small-island economies could be devastating,
as these events can devastate agriculture, as well as livelihoods, assets,
shelter, and public infrastructure. The potentially enormous toll of climatic
disasters on public funds could jeopardise economic growth in some countries.
What adaptive options are feasible and worth pursuing?
Mainstreaming climate change. Improving the integration of climate concerns
in resource management, planning, poverty reduction, and governance policy
is a key strategy for increasing adaptive capability. Over the next decade
or so this effort to increase overall capacity may be more valuable than specific
responses to future climate change.
Strengthening disaster mitigation and early warning. Assuring timely and appropriate
responses is a priority. Better indicators and profiles at local levels are
required to create more accurate picture of affected people and their needs.
For instance, implementing disaster mitigation through improving urban land-use
planning could reduce flooding. Security of adequate freshwater supply can
be improved by drought early warning and planning efforts.
Other options will become increasingly important as climate change and climatic
risks become greater in the future. For example, insurance will be needed
to support local livelihoods as well as ensure replacement of key infrastructure.
Public health systems need to address the potential spread of diseases, such
as malaria.
- Mattias Nordström, Linda Stephen,
Kirstin Dow & Thomas E. Downing
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