Photo credit: Google
Photo credit: International Business Times
The Sahara desert was lush and green 10,000 years ago. Within a few thousand years it became barren. Humans are now thought to have pushed it over the edge – Wonker / Flickr
Cattle grazing on pastures that were on an ecological knife edge could have pushed the Sahara onto the path of desertification.
The Sahara used to be a fertile landscape with lush vegetation thousands of years ago, but something killed that landscape, leaving only desert behind. Neolithic humans may have played a role in pushing it over the edge of an ecological tipping point, an archaeological study finds.
The Sahara used to be a lush, green environment as little as 6,000 years ago, when humans grazed cattle on green pastures. Theories for what turned the Sahara into a desert in a period of just a few thousand years include shifting circulation in the tropical atmosphereand changes in the Earth’s tilt.
Archaeological evidence now suggests that Neolithic humans who grazed cattle on the Saharan pastures played a role as well. These pastoral communities pushed the delicate ecosystem past a tipping point that led to widespread desertification, according to a paper published in the journal Frontiers in Earth Science.
Study author David Wright of Seoul National University, South Korea, mapped the spread of scrub vegetation, which is a precursor to full desertification, and evidence of Neolithic cattle grazing. As more and more vegetation was removed from the land, the albedo – or amount of light reflected from the ground – increased, changing the atmospheric conditions over the Sahara. This in turn made monsoon rains less frequent.
About 8,000 years ago, cattle-grazing communities originated near the River Nile and began gradually to spread to the west of the continent. Rather than the spread of the communities happening in response to desertification and loss of vegetation, the humans could have been actively driving the desertification, Wright suggests.
Read the full story: International Business Times
17-year experiment finds present climate near optimal for plant growth
Results from one of the longest-running and most extensive experiments to examine how climate change will affect agricultural productivity show that California grasslands will become less productive if the temperature or precipitation increases substantially above average conditions from the past 40 years.
Read the full article: Science Daily
Photo credit: Google
Figure 3.1: Portulacaria afra Jacq. (spekboom) tree. Notice the skirt of rooted branches
by Prof. Dr. Willem VAN COTTHEM
Ghent University (Belgium)
One of the most interesting African plant species used to combat desertification, limiting soil erosion, producing a dense vegetation cover and a remarkable number of small, edible leaves (fodder, but also vitamin-rich food for humans), is the Spekboom or Elephant’s Bush (Portulacaria afra).
This plant species is swiftly covering dry, eroding soils and should be recommended to all global projects for alleviation of drought, combat of land degradation and halting of wind erosion.
My good friend Johan VAN DE VEN of Bamboo Sur was so kind to offer me some rooted cuttings. These are growing very well in pots and PET-bottles in my garden in Belgium.
In order to study different ways of multiplication of this Spekboom (with succulent branches and leaves), I started taking off small lateral shoots (cuttings) and planted them in some potting soil in a cake box. I also planted some of the succulent leaves (see my photos below).
Within the plastic cake box humidity is kept high (condensation of droplets on the cover). Therefore, I opened the cover from time to time to let some fresh air (oxygen) in.
Quite soon both the cuttings and the separate leaves started rooting. The cuttings swiftly developed some new leaves. A month later I transplanted them into small plastic bottles, twice perforated 2-3 cm above the bottom (for drainage, keeping a small quantity of water at the bottom for moistening the bottle’s content and the rootball).
Once fully rooted within the plastic bottle, I cut off the bottom of the bottle to set the lower part of the rootball free. Then I planted the young Spekboom in a plant pit without taking off the plastic bottle, sitting as a plastic cylinder around the rootball. That plastic cylinder continued to keep the rootball moistened (almost no evaporation) and it offered possibilities to water the sapling from time to time, whenever needed. Irrigation water runs through the plastic cylinder towards the bottom of the rootball, growing freely in the soil (irrigation water directed towards the roots growing into the soil at the bottom of the plant pit). Thus a high survival rate was guaranteed.
It is clear that multiplication of the Spekboom with rooting cuttings and leaves is very easy. It is another interesting aspect of this remarkable plant. I can only recommend a broader use of the Spekboom for reforestation, fodder production and even production of bonsais for enhancement of the annual income (export to developed countries).
Here are some photos of this experiment.
—————-Considering that people working at the Great Green Wall in Africa (or any other interested group on other continents) are looking for practical solutions to cover as soon as possible huge areas of a desertified region, one is tempted to believe that setting up nurseries to produce a sufficient number of plants should not be a problem (as these plants only need a minimum of water).
I keep dreaming of successes booked with this nice edible plant species in the combat of desertification. The day will come that the Elephant bush will be growing in all the drought-affected regions of the world. Animals will eat from it, but also malnourished children and hungry adults will find it an interesting supplement to their food.
Experiments show grazing pressures compound drought stress, delay recovery
A new study by scientists at Duke University and Beijing Normal University may hold the answer why.
The researchers found that these tipping points can happen much sooner than current models predict because of the added pressures placed on drought-weakened plants by grazing animals and fungal pathogens.
“Our work provides the first real-world experimental evidence that these natural enemies of plants can play a dramatic role in lowering ecosystems’ tipping point by killing drought-weakened vegetation and preventing plants from recovering,” said Brian R. Silliman, Rachel Carson Associate Professor of Marine Conservation Biology at Duke’s Nicholas School of the Environment.
Ecologists have long known that drought can stimulate this type of attack on plants, he said, but they mostly discounted it as a secondary stress and not a main cause of ecosystem collapse.
“What we found is the opposite,” Silliman said. “Grazers have a strong compounding effect. This means these ecosystems are far more vulnerable to drought than the current models predict. With grazers present, they can handle much less drought stress.”
Read the full story: Science Daily
Photo credit: FAO
Farmers in the Horn of Africa need urgent support to recover from consecutive lost harvests and to keep their breeding livestock healthy and productive at a time that pastures are the driest in years.
Countries in the Horn of Africa are likely to see a rise in hunger and further decline of local livelihoods in the coming months, as farming families struggle with the knock-on effects of multiple droughts that hit the region this year, FAO warned today. Growing numbers of refugees in East Africa, meanwhile, are expected to place even more burden on already strained food and nutrition security.
Currently, close to 12 million people across Ethiopia, Kenya and Somalia are in need of food assistance, as families in the region face limited access to food and income, together with rising debt, low cereal and seed stocks, and low milk and meat production. Terms of trade are particularly bad for livestock farmers, as food prices are increasing at the same time that market prices for livestock are low.
Farmers in the region need urgent support to recover from consecutive lost harvests and to keep their breeding livestock healthy and productive at a time that pastures are the driest in years. Production outputs in the three countries are grim.
“We’re dealing with a cyclical phenomenon in the Horn of Africa,” said Dominique Burgeon, Director of FAO’s Emergency and Rehabilitation Division. “But we also know from experience that timely support to farming families can significantly boost their ability to withstand the impacts of these droughts and soften the blow to their livelihoods,” he stressed.
For this reason, FAO has already begun disbursing emergency funds for rapid interventions in Kenya and Somalia.
Read the full article: FAO
Silas Mdoe has a weapon against poverty and drought. It’s so unassuming that most farmers completely overlook it: livestock grass.
As this recent study shows, keeping livestock can help farmers like Silas earn more money and put more food on the table, especially during unpredictable weather. In Tanzania, drought has decimated many farmers’ harvests, including Silas’ maize, which he relies on for an income.
In his village of Mbuzii in Lushoto, in the east of the country, one-fifth of farmers generate around 40 percent of their income from milk. “Cows give manure for crops and provide milk all year, which we can sell to buy sugar or pay school fees. Banks will lend money if you have a cow,” explained Mdoe.
But investing in higher quality varieties of grass for livestock like Napier or Brachiaria hybrids like Mulato II, which improve livestock health and the amount of milk produced by up to two liters per cow a day, is not that simple for many farmers.
That’s because it’s not a priority for most farmers in Tanzania or across East Africa to grow feed for animals when crops for their families naturally come first. This is compounded by the fact that with population growth, grazing land disappears and farm plots become smaller. Forages – quality grasses grown specifically to feed animals – are therefore in short supply.
Read the full story: CIAT