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Imaggeo on Mondays: Dragon Blood Tree

Imaggeo on Mondays: Dragon Blood Tree

On a small and isolated island in the Indian Ocean you’ll find an endemic population of Dragon Blood Trees (Dracaena cinnabari). Burly, with an interesting umbrella-shaped fractal canopy, these unique trees are a sight to behold.

To see them for yourself, you’ll have to travel to the little known Socotra archipelago. Off the coast of Somalia, but belonging to Yemen, the group of islands boast an impressive assortment of endemic plant life, making them know as the ‘Galapagos of the Middle East’.

Crucial to the uniqueness of the flora and fauna of the archipelago is Socotra’s geographical position and how it came to be there. The African plate extends out from the Horn of Africa, east of the Guardafui graben, in what is known as the Socotra Platform. Here you’ll find four islands, of which Socotra is the largest, as well as two scars of former islands which have been eroded away by wave action.

At in excess of 240 kilometres east of the Horn of Africa and 380 kilometres south of the Arabian Peninsula there is no getting away from the remoteness of the archipelago. Testament to this is the presence of seven endemic bird species on the island.

So how did the strange looking Dragon Blood Tress and other flora and fauna come to populate Socotra and its neighbours?

It is thought that until 43 million years ago, the Socotra archipelago remained largely submerged. Although there were some brief emergence events during the Jurassic/Cretaceous and Cretaceous/Tertiary, given the area was re-submerged after this time, they are considered of little importance.

Subsequently, Socotra Island continued to grow due to uplift. Despite changing sea depths, there are indications that land species could migrate over from mainland African and Arabia via land bridges and stepping stones. With ‘cousin’ species present in Somalia and Arabia, it’s likely the Dragon Blood Trees originated there in the distant past.

From 16,000 years ago onwards, the isolation of the archipelago grew due to a combination of further flooding of low-lying areas, the formation of large basins (namely the Guardafui and Brothers basin) and increasing distance from the mainland. Since then, the species on Socotra and its neighbouring islands have had time to evolve and adapt to their surroundings, become different, albeit sometimes closely related, to their continental counterparts.

It was only around the third century BC that Socotra started to emerge from its isolation after attracting the attention of the young Alexander the Great during one of his war campaigns. The island then became known in the Hellenic World and all the Mediterranean for being one of the main sources of incense, myrrh and dragon’s blood powder resin.

As Socotra commercial importance gradually faded away in the centuries to follow, Dragon’s Blood resin remained one of the main exports of the island. The resin was considered a precious ingredient of dyes, lacquers and varnishes, and the legend has it that Antonio Stradivari – the famous seventeenth century luthier from Cremona – used Socotra’s red resin to varnish his violins.

yemen

The landscape of the Socotra archipelago. Credit: Annalisa Molini via Flickr.

One thing is for sure, as Annalisa Molini’s (Assistant Professor at the Institute Center for Water and Environment, in Abu Dhabi), photographs attest to: Socotra island and it’s Dragon Blood Trees are stunning.

However, the remoteness of the Socotra archipelago and the current armed conflict in Yemen threaten to put at risk the island’s important and unique natural heritage; one that no doubt, should be protected and preserved.

References

M. Culek: Geological and morphological evolution of the Socotra Archipelago (Yemen) from the biogeographical view, Journal of Landscape Ecology, 6, 3, 84–108, DOI: 10.2478/jlecol-2014-0005, 2014

Brown, B.A. Mies, Vegetation Ecology of Socotra, Springer Netherlands, Dordrecht, 2012. doi:10.1007/978-94-007-4141-6.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Geosciences Column: The calamity of eruptions, or an eruption of benefits?

Geosciences Column: The calamity of eruptions, or an eruption of benefits?

So here is a question: why would anyone want to live in the vicinity of an active volcano? The risks are well known, with hazards arising from lava flows, lahars, ash falls, debris avalanches, and pyroclastic density currents, with many often having deadly consequences. But despite the danger, more than half a billion people live in the direct vicinity of volcanoes. Could it be that communities proactively choose to settle in areas surrounding volcanoes; and if so, why? That is the very question research published earlier this year in the EGU open access Journal, Natural Hazards and Earth System Science (NHESS), seeks to address.

The team of scientists, led by Syamsul Bachri, a researcher at the University of Innsbruck, approach the question from a novel angle. Often, when studying hazards and risk management strategies associated with volcanoes, the focus is on the volcano itself, with researchers commonly taking a very scientific approach to the problem. Instead of focusing on how people are able to adapt to living near the constant threat of an erupting volcano, the new study takes a more holistic view: perhaps a volcano presents opportunities as well as hazards, and society and nature are complexly interlinked?

Previous studies of a similar nature found that people often live in hazardous regions due to a lack of hazard knowledge, a lack of alternatives and/or because they are forced to due to a marginalised social status. However, the new study considered a new option: ‘upside risks’, or opportunities, may offset some of the downsides of living in hazardous areas and should be taken into account in disaster risk reduction and management strategies.

In order to fully understand the complex interaction between humans and volcanoes the researchers used an approach which bridges social and natural sciences. They conducted a series of interviews and focus groups with communities living around Mt. Bromo in Java, Indonesia.

(Left) Bromo Volcano and its landforms: (1) Gunung Bromo and its crater; (2) a Strombolian cone, Gunung Batok; (3) complex of rest volcanic cone (G. Kursi); (4) complex of rest volcanic cone (G.Widodaren) and SegaraWedi; (5) Sand of Sea ; (6) Tengger caldera formation (upper and middle slope); (7) foot slope of Tengger caldera (Sukapura Barranco); (8) Sapi Kerep outlet valley (interpretation from SRTM Image and field survey.) (Right) Human–volcano system at Bromo Volcano. (1) Mt. Batok, (2) Bromo Volcano, (3) Mt. Kursi, (a) Ngadas Village, (b) Ranupane Village, (c) Ngadirejo Village, (d) Sumber Village, (e) Ngadisari Village, (f) Wonokitri Village, (g) Tosari Village, (h) Wringinanom Village. From Bachri et al., 2015.

(Left) Bromo Volcano and its landforms: (1) Gunung Bromo and its crater; (2) a Strombolian cone, Gunung Batok; (3) complex of rest volcanic cone (G. Kursi); (4) complex of rest volcanic cone (G.Widodaren) and SegaraWedi; (5) Sand of Sea ; (6) Tengger caldera formation (upper and middle slope); (7) foot slope of Tengger caldera (Sukapura Barranco); (8) Sapi Kerep outlet valley (interpretation from SRTM
Image and field survey.) (Right) Human–volcano system at Bromo Volcano. (1) Mt. Batok, (2) Bromo Volcano, (3) Mt. Kursi, (a) Ngadas Village, (b) Ranupane Village, (c) Ngadirejo Village, (d) Sumber Village, (e) Ngadisari Village, (f) Wonokitri Village, (g) Tosari Village, (h) Wringinanom Village. From Bachri et al., 2015. (Click to enlarge).

 

The volcano has erupted 56 times since 1804 and continues to be active today. The most recent eruption took place in 2010, and was sustained over a period of nine months. The estimated total economic loss was valued at USD ~15.5, affecting agriculture and the tourism industry, as well as causing significant loss of property. Disruption caused to the electricity supply, transport and water availability is more difficult to quantify. In total, 70,000 people, across 33 villages were affected by the eruption.

The communities living around the volcano are known as the Tenggerese, a Javanese ethnic minority, counting a population of about 600,000. The Tenggerese consider Mt. Bromo a deity and symbol of their culture. At lower altitudes, on the flanks of the volcano, they cultivate the fertile volcanic soils and raise livestock, while at higher altitudes they live as nomadic herds.

Despite the significant disruption caused to the Tenggerese by the 2010 eruption, the interviews conducted by the researchers revealed that the local communities benefited from the main resulting hazards: tephra fall, lahars and landslides. They found that the communities felt the effects of the eruption were negative whilst the eruption was ongoing and for a short period after. However, once the short-term disruption ended, the overall perception was one where the hazards presented opportunity.

Year and duration (days) of Mt. Bromo eruption in a 200-year period (for 1804–2010, CVGHM 2010; and for 2011–2012, Field survey, 2012).

Year and duration (days) of Mt. Bromo eruption in a 200-year period (for 1804–2010, CVGHM 2010; and for 2011–2012, Field
survey, 2012). From Bachri et al., 2015. (Click to enlarge).

Areas covered by volcanic ash and fine rock material could not be planted for two years following the eruption, but areas covered only by fine volcanic ash became more fertile. The Tenggerese farmers referred to this as Berkah Bromo (Bromo’s opportunity), and stated that Mt.Bromo provided benefits for the continuity of their livelihood.

The eruption also caused a number of lahars – volcanic mud flows known locally as lahar hujan – which destroyed some 20 houses. Despite the short-term negative effects of the lahars, agricultural productivity in the affected region was increased and is already being exploited by the local farmers. Bapak Kirno* (the head of Wrininganom village) stated during the interviews:

“Areas which are affected by lahar hujan from Bromo will be more fertile after some period if they are not dominated by sand materials.”

Landslides caused significant disruptions, in particular causing road accessibility problems, but at the same time, transferred fertile materials to new areas, contributing positively to soil quality.

(Top) Tenggerese priests during Dutch East Indies era which lasted from 1800 to 1949. (Bottom left) Tenggerese woman with two children. (Bottom right) Tenggerese priest holding a dedication ceremony of a new build house. (images provided to Wikimedia Commons by the Tropenmuseum, author unknown).

(Top) Tenggerese priests during Dutch East Indies era which lasted from 1800 to 1949. (Bottom left) Tenggerese woman with two children. (Bottom right) Tenggerese priest holding a dedication ceremony of a new build house. (images provided to Wikimedia Commons by the Tropenmuseum, author unknown). Click to englarge.

The research also found that volcanoes are a powerful force in shaping cultural identity. The essence of who the Tenggerese are is intrinsically linked to Mt. Bromo and they have a deep spiritual connection with the volcano. The Tenggerese believe that the attitude they have towards the mountain will play a role in how Mt. Bromo behaves towards them. Bapak Wahyu*, a participant of a focus group discussion, considers that the unusually sever 2010 eruption was a result of the abandonment of old customs. The younger generations used the benefits from plentiful agricultural yields, not to save in the traditional fashion, but to purchase unnecessary consumer gadgets. He argues this left villager’s ill prepared, with insufficient resources to survive the sustained eruption.

The interviews and focus groups allowed Bachri and his team to identify five ways in which the Tenggerese have culturally adapted to living in the shadow of Mt. Bromo and which have also enhanced their life. They have, not only a heightened resilience to hazards, but a greater capacity to recover from them, too. The limited and unique extent of the territory they inhabit gives the Tenggerese a strong local attachment and a deep knowledge of the hazard posed by the volcano. At the same time, their proximity to the volcano instils a sense of social and moral order and allows them to frame and voice dissent in a larger cosmological setting. Finally, volcanic eruptions are often the catalysts for change and this is largely viewed positively by the local inhabitants.

 “I am never scared of Bromo’s eruption because I always believe that this is temporary. Bromo’s eruption always benefit us. We believe that Bromo always gives us what we need to live here,” says Bapak Rudi*, Ngadirejo village official.

*All names used in the study were changed to protect the identity of the informants.

By Laura Roberts Artal, EGU Communications Officer

References

Bachri, S., Stötter, J., Monreal, M., and Sartohadi, J.: The calamity of eruptions, or an eruption of benefits? Mt. Bromo human–volcano system a case study of an open-risk perception, Nat. Hazards Earth Syst. Sci., 15, 277-290, doi:10.5194/nhess-15-277-2015, 2015.

Tilling, R.I.: Volcano hazard, in: Volcanoes and the Environment, edited by: Mart, J. and Ernst, G., Cambridge University Press, United States of America, 55-90, 2005.

Imaggeo on Mondays: Mountains, rivers and agriculture

This week’s Imaggeo on Mondays image blends a range of geoscience disciplines. The post, by Irene Marzolff, a researcher at Johann Wolfgang Goethe-Universitaet, explores how the mountains, rivers and soils of the High Atlas in Morocco are intrinsically linked to the agriculture of the region.

High Atlas landscape. Credit: Irene Marzolff (distributed via imaggeo.egu.eu)

High Atlas landscape. Credit: Irene Marzolff (distributed via imaggeo.egu.eu)

The image was taken in the southern slopes of the Western High Atlas, north of the city of Taroudannt. The snow of these mountains, which in April is still prevailing on the highest ranges in the background of the photo, is a significant water resource for the region. The high interannual variability of precipitation and its changing patterns associated to climate change present a serious challenge for natural environment and for the sustainable use of water as a resource in agriculture and tourism, the two major economic sectors in the area.

A characteristic open cover of Argan trees (Argania spinosa) can be seen on the lower mountain slopes in the middle distance of the photo: an endemic species with small, oil-rich fruits resembling olives that yield high-quality oil used in medicine, food and cosmetics. The species is a relic of the Tertiary (66 to 2.8 million years ago) but has been under threat from human exploitation for centuries, by excessive grazing, fire-wood cutting, charcoal making and changes to the groundwater table. The area is part of the UNESCO-MAB Biosphere Reserve “Arganeraie” committed to the preservation and sustainable use of the trees.

The river bed in the foreground is formed by fluvial processes typical for this high-mountain region, with highly variable seasonal discharges controlled both by rainfall and snowmelt. It will in the near future drain into the Sidi Abdellah Reservoir that is currently being constructed near Tamaloukt. This reservoir will add to the 10 already existing water storage lakes in the region of Souss Massa Drâa, which is in urgent need of additional water resources: The Souss Valley to the South of the High Atlas is one of Morocco’s most intensely farmed agricultural regions, with agro-industrial production of bananas, vegetables and citrus fruit. Much of this, including 90% of Morocco’s tomato production, is exported to the European market.

By Irene Marzolff, researcher at the Institut fuer Physische Geographie, Johann Wolfgang Goethe-Universitaet, Frankfurt.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Geosciences Column: When water is scarce, understanding how we can save it is important

Geosciences Column: When water is scarce, understanding how we can save it is important

Supplies of water on Earth are running dry. The rate at which an ever growing population consumes this precious resource is not matched by our Planet’s ability to replenish it. Water scarcity is proving a problem globally, with regions such as California and Brazil facing some of the most severe water shortages on record. Used for drinking, agriculture and industrial processes, water forms an fundamental part of our day to day life, so finding ways in which to preserve this vital resource is important.

The global population now exceeds 7.3 billion people. One of the greatest challenges of the 21st century will be to feed this ever growing population – by 2050 crop production will have to double to meet demand. At the same time, agricultural irrigation currently accounts for approximately 80-90% of global freshwater consumption, while agricultural areas requiring irrigation in the past 50 years having roughly doubled. With both space and freshwater in short supply, innovative solutions and fresh approaches will be need if the increase in crop demand is to be met.

The fields in the image are farmed on seemingly vertical hillsides, terrace their fields nearly to the top of every available mountain, and plough by hand or with a draft animal. Terraces, by Cheng Su, distributed via Imaggeo.

The fields in the image are farmed on seemingly vertical hillsides. Terraced fields are  present nearly to the top of every available mountain, and ploughed by hand or with a draft animal. Terraces, by Cheng Su, distributed via imaggeo.

It might come as a bit of a surprise that current irrigations systems operate at efficiency of 50% or below. Water is wasted as it is transported to the crops as well as whilst it is applied to the plants and is affected, not only by the irrigation system itself, but also meteorological and environmental factors. A recent paper published in the open access, EGU Journal, Hydrology and Earth System Sciences, has found that improving current irrigation practices can contribute to sustainable food security.

To better understand where efficiencies might be made in irrigation systems, the scientists used a new approach: They took into account ‘manageable’ factors such as water lost through evaporation, run-off, deep percolation and that taken on by weeds. At the same time, assessing mechanical performance of the systems and the vegetation dynamics, climate, soils and land use properties of a particular region. These factors were fed into a global irrigation model implemented on the three main irrigation types: surface, sprinkler and drip.

The researchers created maps of the global distribution of irrigation systems at a country level, based on the results from their model. The maps showed that areas where surface irrigation – were water is distributed over the surface of a field – is common, irrigation system efficiency was low, sometimes registering values of less than 30%! This is particularly applicable to Central, south and Southeast Asia due to the widespread cultivation of rice. In contrast, areas where there is a high usage of sprinkler systems – similar to natural rainfall – and drip systems (were water is allowed to drip slowly to the root of the plant), such as North America, Brazil, South Africa, Ivory Coast and Europe, efficiency was above the global average.

Global patterns of beneficial irrigation efficiency (Eb, ratio of transpired and diverted water) for each irrigation system – (a) surface, (b) sprinkler, and (c) drip, calculated as area-weighted mean over CFTs (excl. “others” and pastures). This figure is based on theoretical scenarios, in which each system is respectively assumed to be applied on the entire irrigated area.

Global patterns of beneficial irrigation efficiency for each irrigation system (a) surface, (b) sprinkler, and (c) drip. This figure is based on theoretical scenarios, in which each system is respectively assumed to be applied on the entire irrigated area. From Jägermeyr et al., 2015. Click to enlarge.

To investigate how the three irrigation system types compared to one another, irrespective of their geographical distribution, the researchers produced another map. They found that surface irrigation is the least efficient of the three methods, with values at less than 29%. Sprinkler and drip systems perform significantly better, with values of 51 and 70%, respectively. Interestingly, regardless of the system used, irrigation efficiency in Pakistan, northeast India and Bangladesh is always at below global average values. Crop type can also play an important role: rice, pules and rapeseed are linked to poor system efficiencies, whilst, maize sugarcane and root crops (such as potatoes) are above average.

Jägermeyr, the study’s lead author, and his team calculated that 2469km³ of water is withdrawn yearly for irrigation purposes – that is close to 5 times the volume of water held in the Canadian/American Lake Erie. Of that, 608 km³ is non-beneficially consumed. In other words, lost through evaporation, interception (by foliage leaves) and during delivery to the plants and represents an area where substantial water savings could be made.

Replacing surface irrigation with a sprinkler or drip system proves one of the best solutions to the problem, with a potential 76% reduction in non-beneficial consumption of water. This would mean that up to 68% less water would be needed for the purposes of irrigating crops.

Therefore, irrigation system improvements could make an important contribution to sustainably increase food production. The water saved would allow for irrigated areas to be expanded and yields increased on farms where production is currently limited by an insufficient water supply.

The upgrade of irrigations systems seems a very attractive solution to the problem, but the researchers warn that its suitability must be assessed on a river basin level. Factors such as crop management, soil type and local climate may affect the suitability of this approach in some geographical areas. The study finds that regions such as the Sahel, Korea and Madagascar, as well as temperate regions in Europe, North America, Brazil and parts of China would benefit the most from irrigation system improvements.

 

By Laura Roberts Artal, EGU Communications Officer.

 

References

Jägermeyr, J., Gerten, D., Heinke, J., Schaphoff, S., Kummu, M., and Lucht, W.: Water savings potentials of irrigation systems: global simulation of processes and linkages, Hydrol. Earth Syst. Sci., 19, 3073-3091, doi:10.5194/hess-19-3073-2015, 2015.

Gleick, P.H., Christian-Smith, j., Cooley, H.: Water-use efficiency and productivity: rethinking the basin approach, Water International, 36, 7, doi: 10.1080/02508060.2011.631873, 2011.

Tilman, D., Blazer, C., Hill, J., Befort, B.L.: Global food demand and the sustainable intensification of agriculture, PNAS 108, (50), 20260-20264, doi:10.1073/pnas.1116437108, 2011.

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